Inf J Radiarron Oncology Bml PhTs VoI Printed in the U.S.A. All rights reserved.
0360.3016/92 $5.00 + .oO CoDyright 6 1992 Pergamon Press Ltd.
22. pp. 925-928
0 Clinical Original Contribution RADIOTHERAPY
FOR PLEOMORPHIC
ADENOMA
J. BARTON, FRCR,* N. J. SLEVIN, FRCR*
OF THE PAROTID
GLAND
AND E. N. GLEAVE, FRCSt
Christie Hospital, Manchester M20 9BX, U.K. A study was madeof 187 patientswith parotidpleomorphicadenomatreatedby radiotherapy.This followedsurgery but with incomplete removal or tumor spillage. In the early years of the study radiotherapy was given by radium needle implant done usually at the time of surgery, but from the late 1960s beam-directed external radiotherapy with a head shell was used most commonly. A 3-field technique or wedge pair was the standard technique. The median age was 46 with nearly half the patients (87/187) aged between 40 and 60, and the ratio of women to men was 1.4:1 (110:77). Median follow-up for all patients was 14 years. One hundred fifteen patients had radiotherapy immediately after their first operation with a recurrence rate of 0.9% (l/115). Of the 115 there were 2 cases of radionecrosis (1 major, 1 minor), 1 case of permanent facial nerve palsy, 1 Frey Syndrome (post-gustatory sweating), and 1 salivary fistula. Seventy-two patients had radiotherapy delayed until one or more recurrences had been surgically treated. Nine (12.5%) of these developed yet further recurrence after radiotherapy. There were 2 cases of radionecrosis (1 major), 4 cases of facial nerve palsy (3 of which were complete), 16 cases (22.2%) of Frey Syndrome, and 1 case of malignant change in a parotid tumor. In addition one squamous cell carcinoma developed at the site of a needle implant 25 years later. Recurrences after radiotherapy continued beyond 20 years of followup. Patients having unsatisfactory surgery due to spill at operation or residual tumor left behind should have radiotherapy immediately and not delayed until local recurrence occurs because of the increased morbidity and the higher incidence of yet further recurrence. Parotid pleomorphic adenoma, Radiotherapy, Surgery, Recurrence, Morbidity.
INTRODUCTION
report 4 cases of malignant recurrence 14-20 years after treatment (2 adenocarcinomas, 1 sarcoma and 1 carcinoma arising in a pleomorphic adenoma). Armistead et al. (1) report 1 case of malignancy in 76 patients treated by enucleation and radiotherapy. This occurred at the time of the third local recurrence. Watkin and Hobsley (12) in an extensive review of the literature, conclude that the role of irradiation in the induction of parotid malignancies is not conclusively proven, but suggest that available evidence is enough to warrant caution in using radiotherapy to treat this benign condition. The aim of this study was to evaluate the role of radiotherapy in the treatment of pleomorphic adenoma of the parotid gland with particular reference to prevention and control of local recurrence and incidence of long term side effects.
Pleomorphic adenoma of the parotid gland is a benign tumor occurring from childhood to old age with a malignant potential. It is more common in women. There is no doubt that simple enucleation alone is an inadequate operation with a high local recurrence rate of up to 84% (6, 10). However, there is disagreement on both the optimal extent of surgery and the usefulness of radiotherapy following operation. Those who advocate definitive surgery by local extra capsular dissection, partial parotidectomy, or superficial parotidectomy (5,6,7, 11) quote local recurrence rates of between 0 and 2% with morbidity of permanent facial nerve damage in O-1.3%, Frey’s Syndrome in l l-20%, together with isolated cases of salivary fjstula. The proponents of simple enucleation and postdperhtive radiotherapy (1, 8) argue against such surgery and cite local recurrence rates of 1.3-2.7%. The long-term potential side effects from radical radiotherapy include skin changes with induration and telangiectasia, audio vestibular damage, dry mouth, and the risk of late malignancy. Dawson and Orr (2) in a review of 3 11 patients in Edinburgh treated by local excision and radiotherapy,
A retrospective study was made of 187 cases of pleomorphic adenoma of the parotid gland treated by radiotherapy at the Christie Hospital, Manchester, during the period 195 l- 1984. It was the policy of the surgeons at the
* Department of Radiotherapy. +Department of Surgery. Reprint requests to: Dr. J. Barton, Department of Radio-
therapy, Weston Park Hospital, Whitham Road, Sheffield SlO 2SJ, England. Accepted for publication 29 August 1991.
METHODS
925
AND MATERIALS
926
I. J. Radiation Oncology 0 Biology 0 Physics
Christie Hospital to remove an intact tumor and to preserve the integrity of the facial nerve. The procedures used in adhering to these two principles included local extra capsular dissection (local dissection in an extra capsular plane taking adherent plaques of parotid tissue with the tumor), partial parotidectomy (removal of part of the “superficial lobe” of the parotid including the tumour and necessitating identification of the facial nerve and dissection of some of its branches), superficial parotidectomy (removal of all parotid tissue lying superficial to the plane of the facial nerve including the tumor and necessitating identification of the facial nerve and dissection of all its branches), and conservative parotidectomy (superficial parotidectomy with removal of islands of parotid tissue from between branches of the facial nerve). If an intact tumor was removed, postoperative radiotherapy was not routinely given. The choice of operation was determined at the time of surgical exploration of the tumor, and the indications for local extra capsular dissection included a superficial tumor, mobility within the parenchyma of the parotid gland, thus excluding invasive growth due to malignancy, and a tumor big enough to manipulate digitally during dissection. Very occasionally, a tumor encompassed a branch of the facial nerve necessitating resection of part of it rather than spill of tumor. Anastomosis of the cut ends was often possible without loss of function. The patients in this study given radiotherapy fall into two distinct groups. One hundred fifteen patients (61%) were given radiotherapy immediately after their first operation. Surgery was either performed at a peripheral hospital (in 74 cases), in which case full operative details were not given in the patient records, but was most likely to have been local excision alone; or after definitive surgery at the Christie Hospital (4 1 cases). Referral for radiotherapy in the latter case was made because the surgeon was unhappy with clearance or because of capsular tear or spillage during the operation. Seventy-two patients (39%) were referred for radiotherapy after one or more excisions for tumor recurrence. Forty-four of these had further surgery at the Christie Hospital, but because the recurrence was often found to be multinodular, the surgeon was not satisfied with clearance of the disease. The remaining 28 patients were surgically managed at peripheral hospitals and were referred for radiotherapy because clearance was felt to be incomplete. In all cases pathology of the tumor was available and verified as pleomorphic adenoma.
Volume 22, Number 5, 1992 Table I. Age distribution O-9.9 Patient numbers
1. Needle implant (3): a single plane or V plane with the posterior needles deep to the ascending ramus of the mandible. The intended dose was 60 Gy at 0.5 cm in 7 days. The last implant in this series was done in 1976. Radium or caesium needles were used.
0
10
50-59.9
60-69.9
41
24
Patient numbers
20-29.9
30-39.9
40-49.9
37
46
18 70-79.9
80 and over
11
0
2. External beam radiotherapy using megavoltage linear accelerators (4): occasionally by a wedged pair of fields but most often using a 3 field technique with a dominant plain lateral field and wedged anterior and posterior oblique fields. An inclined plane was used to avoid the eyes, and the tumor dose was 50 Gy in 15- 16 fractions in 20 days. Patient characteristics
There was an excess of female patients in the ratio 1.4: 1 ( 110:77) and a slight preponderance of right-sided tumors (98 right:89 left). Table 1 shows the age distribution of all 187 patients; note that nearly half the patients are aged between 40 and 60 years with a median age of 46 years. These figures are in keeping with those of a much larger series of new pleomorphic adenoma. Seventy-two patients had surgery for recurrence before receiving radiotherapy, and although nearly 60% were referred after their first recurrence, a minority had three or more operations before being referred, as shown in Table 2. The majority of recurrences had occurred by 10 years after surgery (Table 3), but prolonged follow-up is needed and should be indefinite. Follow-up
Because of the tendency for tumors to recur after many years, long term follow-up was pursued either by clinic attendance or by written enquiry to the patient or general practitioner. For the patients who died, an attempt was made to determine whether the patient died with or without recurrent disease. Only two patients are known to have died with definite evidence of disease. Median followup was 14 years.
Table 2. Surgically treated recurrences before radiotherapy: 72 cases
Radiotherapy
All patients received radiotherapy, which was given by one of two techniques.
10-19.9
(years) all patients
Number of recurrences before radiotherapy 1 2 3 4 >4
Number
of patients 41 20 6 3 2
(57) (28) (8.3) (4.2) (2.5)
(%)
Radiotherapy for parotid pleomorphic adenoma 0 J. BARTON et
Table 5. Radiotherapy
Table 3. Time to first recurrence after surgery (years): 72 cases
Patients numbers
o-4.9
s-9.9
10-14.9
15-19.9
> 20
24
29
10
6
3
927
a/.
for recurrence: 72 cases
Recurrent after radiotherapy
Complications These are listed in Tables 4 and 5 which show the incidence of radionecrosis, permanent facial nerve palsy, Frey, salivary fistula, and malignant change. Most case notes did not routinely document the cosmetic result in the skin following radiotherapy. RESULTS The rate of recurrence, rate of complications, and length of follow-up for the 115 patients treated with radiotherapy immediately after primary surgery are shown in Table 4. Only one of these patients recurred after radiotherapy. He had local excision of his tumor at a peripheral hospital in 1960 during which there was tumor spillage. This was followed up by a V plane implant (5600R in 128 hrs). In 1982 he had incomplete excision of multinodular recurrence, but no further radiotherapy could be given as residual disease was present within the previously treated area. He appeared disease-free in 1987. Similar details are given in Table 5 for the 72 patients who had recurrences treated by surgery before being referred for radiotherapy. One patient aged 79 developed a squamous cell carcinoma over the mandible at the site of a needle implant 35 years previously and died after attempted radical head and neck surgery. The other patient who developed a malignancy had incomplete excision of recurrent tumor in 1982 (the first operation being in 1980). This was followed by external beam radiotherapy 50 Gy in 20 days in 1982. In 1987 a left radical parotidectomy for recurrence was performed and the histology was highly suspicious of malignant change within the parotid. Of the 9 out of 72 patients who recurred after radioTable 4. Postoperative radiotherapy for new pleomorphic adenoma:
115 cases
Recurrence after radiotherapy Complications Radionecrosis (1 major, 1 minor) Permanent facial nerve palsy Frey
No.
%
l/l 15
0.9
2 1 1
1.7 0.9 0.9
Length of follow up (Alive when last seen) O-4.9 years 5-9.9 years 10-14.9 years >15 years
5 25 17 68
Intercurrent
27
deaths
Complications Radionecrosis (I major, 1 minor) Frey Facial nerve palsy Malignancy within irradiated area
Malignant change within parotid Salivary fistula
No.
(%)
9172
(12.5)
2 16 4 1
(2.8) (22.2) (5.6)
(Squamous cell carcinoma mandible) I 2
Length of follow up (years) o-4.9 5-9.9 o-14.9 >I5
14 13 9 36
Intercurrent
15
death
5 had had one recurrence excised before radiotherapy, 2 had two recurrences, 1 had three recurrences and 1 had four recurrences. Recurrences occurred between 2 and 15 years after radiotherapy. Twenty-three out of these 72 patients were treated by an implant and 2 recurred (8.7% recurrence rate); the remaining 49 had external beam radiotherapy and 7 recurred (14.3% recurrence rate). therapy,
DISCUSSION For the 41 patients with new pleomorphic adenoma considered to have incomplete clearance following definitive surgery, radiotherapy given immediately after operation completely prevented further recurrence. Only 1 of 74 patients having local excision and immediate postoperative radiotherapy recurred, a recurrence rate of 1.4%. This figure is as good as that from large surgical series of patients managed by definitive surgery alone. Maynard (7) reports 130 cases treated by wide local excision of the tumor after identification of the facial nerve with only 1 recurrence (0.8%), but 75% of his patients had less than 10 years follow-up. In an update of the surgical series of 369 cases reported by Gleave et al. (5) there is now a total of 550 patients with a 1.6% recurrence rate (Gleave, oral communication, November 1990). All patients had indefinite follow-up. For the patient with new pleomorphic adenoma who has an inadequate first operation, radiotherapy does seem to be an effective adjunct in achieving local control. The Manchester figures for recurrence are broadly similar to those from Ravasz et al. (9) but in his series, the median follow-up was only 11 years and the maximum follow-up 18 years. Thirty-one out of the 120 Manchester patients (25.8%) registered before 1970 had documented follow-up of more than 20 years. Note that
I. J. Radiation Oncology 0 Biology 0 Physics
928
the surgical figures are quoted from large series by experienced operators. For the surgeon who does parotid surgery on an occasional basis, recurrence rates are likely to be much higher. To completely answer the question concerning the usefulness of radiotherapy following local excision alone or in salvage of the failed definitive clearance, prospective randomized trials first comparing local excision and radiotherapy against definitive surgery and second failed definitive surgery plus radiotherapy against failed definitive surgery alone, would need to be done. As pointed out by Stevens and Hobsley (1 l), very long followup would be needed and the very large numbers of patients necessary for a statistically valid trial would make this impractical. With this latter point in mind, consideration of the morbidity from each approach to treatment for new pleomorphic adenoma reveals some worthwhile information. The incidence of serious complications from definitive surgery by experienced operators is low, with l/l 30 (0.8%) (7) and 6/369 (1.6%) (5) cases of permanent facial nerve paralysis. Immediate postoperative radiotherapy in 115 cases produced 2 cases of radionecrosis, 1 of which was combined with a salivary fistula. One of these patients needed excision of the necrotic area and skin grafting 18 years after radiotherapy. The exact extent of the skin changes following radiotherapy is not easy to quantify from the case notes but occasionally marked induration, telangiectasia, and atrophic change are mentioned. These undoubtedly relate to the radiotherapy technique which uses wax bolus bringing the maximum dose onto the skin. Also difficult to evaluate is damage to the ear. Within 5 years of radiotherapy not only crusting and discomfort in the external auditory canal is reported, but also impairment of hearing. Pleomorphic adenoma of the parotid is a benign tumor with a malignant potential. As the majority of patients will be middle aged females (Table 1) who may expect to live more than 30 years after treatment and who would
Volume 22, Number
5, 1992
suffer most from the potential adverse effects of radiation, referral for definitive surgery by the expert should be undertaken. Surgical morbidity is acceptable and the only risk of malignancy would be from malignant change within any residual tumor. Because the morbidity from surgery for recurrent disease is greatly increased (see below), postoperative radiotherapy should be reserved for the patient who has had inadequate initial clearance. Considering the 72 patients with surgically treated recurrence before radiotherapy, it is apparent that re-operation is more difficult and radiotherapy is less effective in obtaining local control. From review of the operation notes of recurrent patients, it is clear that a major reason for failing to eradicate disease is that there are multifocal deposits of recurrent tumor whose removal would entail major surgery. The 5.6% incidence of permanent facial nerve palsy must be a direct reflection of the hazard of surgery for the recurrent patient. Even when the surgeon is satisfied with his clearance there is still a high recurrence rate. Gleave et al. (5) operated on 61 recurrent patients previously treated surgically elsewhere and reported an 18% recurrence rate. Although radiotherapy can reduce incidence of further recurrence, the benefit is not absolute. Because of the small numbers of patients involved it is not possible to draw any conclusions about the effectiveness of radiotherapy after increasing numbers of recurrences excised. The problems resulting from surgery and radiation for recurrent pleomorphic adenoma can be avoided to a large extent by good initial surgery. If spill occurs at first operation or, for some reason, residual tumor is left, then the addition of adjuvant radiation should be considered. For patients with multi-nodular recurrence treated by surgery alone, the addition of radiation must also be considered. The risk of complications after radiation such as skin stigmata, necrosis, and induced malignancy must be weighed against the risk of damage to the facial nerve from successive operations.
REFERENCES Armistead, P. R.; Smiddy, F. G.; Frank, H. G. Simple enucleation and radiotherapy in the treatment of the pleomorphic salivary adenoma of the parotid gland. B. J. Surg. 66: 716-717; 1979. 2. Dawson, A. K.; Orr, J. A. Long term results of local ex1.
cision and radiotherapy parotid. Int. J. Radiat. 1985.
in pleomorphic adenoma of the Oncol. Biol. Phys. 11: 45 l-455;
3. Duthie, M. B.; Gupta, N. K.; Pointon, R. C. S. Head and neck. In: Easson, E. C., Pointon, R. C. S., eds. The radiotherapy of malignant disease. England: Springer-Verlag; 1985: 211. 4. Duthie, M. B.; Gupta, N. K.; Pointon, R. C. S. Head and neck. In: Easson, E. C.; Pointon, R. C. S., eds. The radiotherapy of malignant disease. England: Springer-Verlag; 1985: 212. 5. Cleave, E. N.; Whittaker, J. S.; Nicholson, A. Salivary tumours-experience 257; 1979.
over 30 years. Clin Otolaryngol.
4: 247-
6. Maimaris, C. V.; Ball, M. J. Treatment of parotid tumours by conservative parotidectomy. B. J. Surg. 73: 897; 1986. 7. Maynard, J. D. Management of pleomorphic adenoma of the parotid. B. J. Surg 75: 305-308; 1988. 8. McEvedy, B. V.; Ross, W. M. The treatment of mixed parotid turnours by enucleation and radiotherapy. B. J. Surg. 63: 341-342; 1976. 9. Ravasz, L. A.; Terhaard, C. H. J.; Hordijk, G. J. Radiotherapy in epithelial tumours of the parotid gland: case presentation and literature review. Int. J. Radiat. Oncol. Biol. Phys. 19: 55-59; 1990. 10. Smiddy, F. G. Treatment of mixed parotid tumours. BMJ 322-325; 1956. 11. Stevens, K. L.; Hobsley, M. The treatment of pleomorphic adenomas by formal parotidectomy. B. J. Surg. 69: 1-3; 1982. 12. Watkin, G. T.; Hobsley, M. Should radiotherapy be used routinely in the management of benign parotid tumours? B. J. Surg. 73: 601-603; 1986.
0360.3016/92 $5.00 + .oO CoDyright 6 1992 Pergamon Press Ltd.
22. pp. 925-928
0 Clinical Original Contribution RADIOTHERAPY
FOR PLEOMORPHIC
ADENOMA
J. BARTON, FRCR,* N. J. SLEVIN, FRCR*
OF THE PAROTID
GLAND
AND E. N. GLEAVE, FRCSt
Christie Hospital, Manchester M20 9BX, U.K. A study was madeof 187 patientswith parotidpleomorphicadenomatreatedby radiotherapy.This followedsurgery but with incomplete removal or tumor spillage. In the early years of the study radiotherapy was given by radium needle implant done usually at the time of surgery, but from the late 1960s beam-directed external radiotherapy with a head shell was used most commonly. A 3-field technique or wedge pair was the standard technique. The median age was 46 with nearly half the patients (87/187) aged between 40 and 60, and the ratio of women to men was 1.4:1 (110:77). Median follow-up for all patients was 14 years. One hundred fifteen patients had radiotherapy immediately after their first operation with a recurrence rate of 0.9% (l/115). Of the 115 there were 2 cases of radionecrosis (1 major, 1 minor), 1 case of permanent facial nerve palsy, 1 Frey Syndrome (post-gustatory sweating), and 1 salivary fistula. Seventy-two patients had radiotherapy delayed until one or more recurrences had been surgically treated. Nine (12.5%) of these developed yet further recurrence after radiotherapy. There were 2 cases of radionecrosis (1 major), 4 cases of facial nerve palsy (3 of which were complete), 16 cases (22.2%) of Frey Syndrome, and 1 case of malignant change in a parotid tumor. In addition one squamous cell carcinoma developed at the site of a needle implant 25 years later. Recurrences after radiotherapy continued beyond 20 years of followup. Patients having unsatisfactory surgery due to spill at operation or residual tumor left behind should have radiotherapy immediately and not delayed until local recurrence occurs because of the increased morbidity and the higher incidence of yet further recurrence. Parotid pleomorphic adenoma, Radiotherapy, Surgery, Recurrence, Morbidity.
INTRODUCTION
report 4 cases of malignant recurrence 14-20 years after treatment (2 adenocarcinomas, 1 sarcoma and 1 carcinoma arising in a pleomorphic adenoma). Armistead et al. (1) report 1 case of malignancy in 76 patients treated by enucleation and radiotherapy. This occurred at the time of the third local recurrence. Watkin and Hobsley (12) in an extensive review of the literature, conclude that the role of irradiation in the induction of parotid malignancies is not conclusively proven, but suggest that available evidence is enough to warrant caution in using radiotherapy to treat this benign condition. The aim of this study was to evaluate the role of radiotherapy in the treatment of pleomorphic adenoma of the parotid gland with particular reference to prevention and control of local recurrence and incidence of long term side effects.
Pleomorphic adenoma of the parotid gland is a benign tumor occurring from childhood to old age with a malignant potential. It is more common in women. There is no doubt that simple enucleation alone is an inadequate operation with a high local recurrence rate of up to 84% (6, 10). However, there is disagreement on both the optimal extent of surgery and the usefulness of radiotherapy following operation. Those who advocate definitive surgery by local extra capsular dissection, partial parotidectomy, or superficial parotidectomy (5,6,7, 11) quote local recurrence rates of between 0 and 2% with morbidity of permanent facial nerve damage in O-1.3%, Frey’s Syndrome in l l-20%, together with isolated cases of salivary fjstula. The proponents of simple enucleation and postdperhtive radiotherapy (1, 8) argue against such surgery and cite local recurrence rates of 1.3-2.7%. The long-term potential side effects from radical radiotherapy include skin changes with induration and telangiectasia, audio vestibular damage, dry mouth, and the risk of late malignancy. Dawson and Orr (2) in a review of 3 11 patients in Edinburgh treated by local excision and radiotherapy,
A retrospective study was made of 187 cases of pleomorphic adenoma of the parotid gland treated by radiotherapy at the Christie Hospital, Manchester, during the period 195 l- 1984. It was the policy of the surgeons at the
* Department of Radiotherapy. +Department of Surgery. Reprint requests to: Dr. J. Barton, Department of Radio-
therapy, Weston Park Hospital, Whitham Road, Sheffield SlO 2SJ, England. Accepted for publication 29 August 1991.
METHODS
925
AND MATERIALS
926
I. J. Radiation Oncology 0 Biology 0 Physics
Christie Hospital to remove an intact tumor and to preserve the integrity of the facial nerve. The procedures used in adhering to these two principles included local extra capsular dissection (local dissection in an extra capsular plane taking adherent plaques of parotid tissue with the tumor), partial parotidectomy (removal of part of the “superficial lobe” of the parotid including the tumour and necessitating identification of the facial nerve and dissection of some of its branches), superficial parotidectomy (removal of all parotid tissue lying superficial to the plane of the facial nerve including the tumor and necessitating identification of the facial nerve and dissection of all its branches), and conservative parotidectomy (superficial parotidectomy with removal of islands of parotid tissue from between branches of the facial nerve). If an intact tumor was removed, postoperative radiotherapy was not routinely given. The choice of operation was determined at the time of surgical exploration of the tumor, and the indications for local extra capsular dissection included a superficial tumor, mobility within the parenchyma of the parotid gland, thus excluding invasive growth due to malignancy, and a tumor big enough to manipulate digitally during dissection. Very occasionally, a tumor encompassed a branch of the facial nerve necessitating resection of part of it rather than spill of tumor. Anastomosis of the cut ends was often possible without loss of function. The patients in this study given radiotherapy fall into two distinct groups. One hundred fifteen patients (61%) were given radiotherapy immediately after their first operation. Surgery was either performed at a peripheral hospital (in 74 cases), in which case full operative details were not given in the patient records, but was most likely to have been local excision alone; or after definitive surgery at the Christie Hospital (4 1 cases). Referral for radiotherapy in the latter case was made because the surgeon was unhappy with clearance or because of capsular tear or spillage during the operation. Seventy-two patients (39%) were referred for radiotherapy after one or more excisions for tumor recurrence. Forty-four of these had further surgery at the Christie Hospital, but because the recurrence was often found to be multinodular, the surgeon was not satisfied with clearance of the disease. The remaining 28 patients were surgically managed at peripheral hospitals and were referred for radiotherapy because clearance was felt to be incomplete. In all cases pathology of the tumor was available and verified as pleomorphic adenoma.
Volume 22, Number 5, 1992 Table I. Age distribution O-9.9 Patient numbers
1. Needle implant (3): a single plane or V plane with the posterior needles deep to the ascending ramus of the mandible. The intended dose was 60 Gy at 0.5 cm in 7 days. The last implant in this series was done in 1976. Radium or caesium needles were used.
0
10
50-59.9
60-69.9
41
24
Patient numbers
20-29.9
30-39.9
40-49.9
37
46
18 70-79.9
80 and over
11
0
2. External beam radiotherapy using megavoltage linear accelerators (4): occasionally by a wedged pair of fields but most often using a 3 field technique with a dominant plain lateral field and wedged anterior and posterior oblique fields. An inclined plane was used to avoid the eyes, and the tumor dose was 50 Gy in 15- 16 fractions in 20 days. Patient characteristics
There was an excess of female patients in the ratio 1.4: 1 ( 110:77) and a slight preponderance of right-sided tumors (98 right:89 left). Table 1 shows the age distribution of all 187 patients; note that nearly half the patients are aged between 40 and 60 years with a median age of 46 years. These figures are in keeping with those of a much larger series of new pleomorphic adenoma. Seventy-two patients had surgery for recurrence before receiving radiotherapy, and although nearly 60% were referred after their first recurrence, a minority had three or more operations before being referred, as shown in Table 2. The majority of recurrences had occurred by 10 years after surgery (Table 3), but prolonged follow-up is needed and should be indefinite. Follow-up
Because of the tendency for tumors to recur after many years, long term follow-up was pursued either by clinic attendance or by written enquiry to the patient or general practitioner. For the patients who died, an attempt was made to determine whether the patient died with or without recurrent disease. Only two patients are known to have died with definite evidence of disease. Median followup was 14 years.
Table 2. Surgically treated recurrences before radiotherapy: 72 cases
Radiotherapy
All patients received radiotherapy, which was given by one of two techniques.
10-19.9
(years) all patients
Number of recurrences before radiotherapy 1 2 3 4 >4
Number
of patients 41 20 6 3 2
(57) (28) (8.3) (4.2) (2.5)
(%)
Radiotherapy for parotid pleomorphic adenoma 0 J. BARTON et
Table 5. Radiotherapy
Table 3. Time to first recurrence after surgery (years): 72 cases
Patients numbers
o-4.9
s-9.9
10-14.9
15-19.9
> 20
24
29
10
6
3
927
a/.
for recurrence: 72 cases
Recurrent after radiotherapy
Complications These are listed in Tables 4 and 5 which show the incidence of radionecrosis, permanent facial nerve palsy, Frey, salivary fistula, and malignant change. Most case notes did not routinely document the cosmetic result in the skin following radiotherapy. RESULTS The rate of recurrence, rate of complications, and length of follow-up for the 115 patients treated with radiotherapy immediately after primary surgery are shown in Table 4. Only one of these patients recurred after radiotherapy. He had local excision of his tumor at a peripheral hospital in 1960 during which there was tumor spillage. This was followed up by a V plane implant (5600R in 128 hrs). In 1982 he had incomplete excision of multinodular recurrence, but no further radiotherapy could be given as residual disease was present within the previously treated area. He appeared disease-free in 1987. Similar details are given in Table 5 for the 72 patients who had recurrences treated by surgery before being referred for radiotherapy. One patient aged 79 developed a squamous cell carcinoma over the mandible at the site of a needle implant 35 years previously and died after attempted radical head and neck surgery. The other patient who developed a malignancy had incomplete excision of recurrent tumor in 1982 (the first operation being in 1980). This was followed by external beam radiotherapy 50 Gy in 20 days in 1982. In 1987 a left radical parotidectomy for recurrence was performed and the histology was highly suspicious of malignant change within the parotid. Of the 9 out of 72 patients who recurred after radioTable 4. Postoperative radiotherapy for new pleomorphic adenoma:
115 cases
Recurrence after radiotherapy Complications Radionecrosis (1 major, 1 minor) Permanent facial nerve palsy Frey
No.
%
l/l 15
0.9
2 1 1
1.7 0.9 0.9
Length of follow up (Alive when last seen) O-4.9 years 5-9.9 years 10-14.9 years >15 years
5 25 17 68
Intercurrent
27
deaths
Complications Radionecrosis (I major, 1 minor) Frey Facial nerve palsy Malignancy within irradiated area
Malignant change within parotid Salivary fistula
No.
(%)
9172
(12.5)
2 16 4 1
(2.8) (22.2) (5.6)
(Squamous cell carcinoma mandible) I 2
Length of follow up (years) o-4.9 5-9.9 o-14.9 >I5
14 13 9 36
Intercurrent
15
death
5 had had one recurrence excised before radiotherapy, 2 had two recurrences, 1 had three recurrences and 1 had four recurrences. Recurrences occurred between 2 and 15 years after radiotherapy. Twenty-three out of these 72 patients were treated by an implant and 2 recurred (8.7% recurrence rate); the remaining 49 had external beam radiotherapy and 7 recurred (14.3% recurrence rate). therapy,
DISCUSSION For the 41 patients with new pleomorphic adenoma considered to have incomplete clearance following definitive surgery, radiotherapy given immediately after operation completely prevented further recurrence. Only 1 of 74 patients having local excision and immediate postoperative radiotherapy recurred, a recurrence rate of 1.4%. This figure is as good as that from large surgical series of patients managed by definitive surgery alone. Maynard (7) reports 130 cases treated by wide local excision of the tumor after identification of the facial nerve with only 1 recurrence (0.8%), but 75% of his patients had less than 10 years follow-up. In an update of the surgical series of 369 cases reported by Gleave et al. (5) there is now a total of 550 patients with a 1.6% recurrence rate (Gleave, oral communication, November 1990). All patients had indefinite follow-up. For the patient with new pleomorphic adenoma who has an inadequate first operation, radiotherapy does seem to be an effective adjunct in achieving local control. The Manchester figures for recurrence are broadly similar to those from Ravasz et al. (9) but in his series, the median follow-up was only 11 years and the maximum follow-up 18 years. Thirty-one out of the 120 Manchester patients (25.8%) registered before 1970 had documented follow-up of more than 20 years. Note that
I. J. Radiation Oncology 0 Biology 0 Physics
928
the surgical figures are quoted from large series by experienced operators. For the surgeon who does parotid surgery on an occasional basis, recurrence rates are likely to be much higher. To completely answer the question concerning the usefulness of radiotherapy following local excision alone or in salvage of the failed definitive clearance, prospective randomized trials first comparing local excision and radiotherapy against definitive surgery and second failed definitive surgery plus radiotherapy against failed definitive surgery alone, would need to be done. As pointed out by Stevens and Hobsley (1 l), very long followup would be needed and the very large numbers of patients necessary for a statistically valid trial would make this impractical. With this latter point in mind, consideration of the morbidity from each approach to treatment for new pleomorphic adenoma reveals some worthwhile information. The incidence of serious complications from definitive surgery by experienced operators is low, with l/l 30 (0.8%) (7) and 6/369 (1.6%) (5) cases of permanent facial nerve paralysis. Immediate postoperative radiotherapy in 115 cases produced 2 cases of radionecrosis, 1 of which was combined with a salivary fistula. One of these patients needed excision of the necrotic area and skin grafting 18 years after radiotherapy. The exact extent of the skin changes following radiotherapy is not easy to quantify from the case notes but occasionally marked induration, telangiectasia, and atrophic change are mentioned. These undoubtedly relate to the radiotherapy technique which uses wax bolus bringing the maximum dose onto the skin. Also difficult to evaluate is damage to the ear. Within 5 years of radiotherapy not only crusting and discomfort in the external auditory canal is reported, but also impairment of hearing. Pleomorphic adenoma of the parotid is a benign tumor with a malignant potential. As the majority of patients will be middle aged females (Table 1) who may expect to live more than 30 years after treatment and who would
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suffer most from the potential adverse effects of radiation, referral for definitive surgery by the expert should be undertaken. Surgical morbidity is acceptable and the only risk of malignancy would be from malignant change within any residual tumor. Because the morbidity from surgery for recurrent disease is greatly increased (see below), postoperative radiotherapy should be reserved for the patient who has had inadequate initial clearance. Considering the 72 patients with surgically treated recurrence before radiotherapy, it is apparent that re-operation is more difficult and radiotherapy is less effective in obtaining local control. From review of the operation notes of recurrent patients, it is clear that a major reason for failing to eradicate disease is that there are multifocal deposits of recurrent tumor whose removal would entail major surgery. The 5.6% incidence of permanent facial nerve palsy must be a direct reflection of the hazard of surgery for the recurrent patient. Even when the surgeon is satisfied with his clearance there is still a high recurrence rate. Gleave et al. (5) operated on 61 recurrent patients previously treated surgically elsewhere and reported an 18% recurrence rate. Although radiotherapy can reduce incidence of further recurrence, the benefit is not absolute. Because of the small numbers of patients involved it is not possible to draw any conclusions about the effectiveness of radiotherapy after increasing numbers of recurrences excised. The problems resulting from surgery and radiation for recurrent pleomorphic adenoma can be avoided to a large extent by good initial surgery. If spill occurs at first operation or, for some reason, residual tumor is left, then the addition of adjuvant radiation should be considered. For patients with multi-nodular recurrence treated by surgery alone, the addition of radiation must also be considered. The risk of complications after radiation such as skin stigmata, necrosis, and induced malignancy must be weighed against the risk of damage to the facial nerve from successive operations.
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3. Duthie, M. B.; Gupta, N. K.; Pointon, R. C. S. Head and neck. In: Easson, E. C., Pointon, R. C. S., eds. The radiotherapy of malignant disease. England: Springer-Verlag; 1985: 211. 4. Duthie, M. B.; Gupta, N. K.; Pointon, R. C. S. Head and neck. In: Easson, E. C.; Pointon, R. C. S., eds. The radiotherapy of malignant disease. England: Springer-Verlag; 1985: 212. 5. Cleave, E. N.; Whittaker, J. S.; Nicholson, A. Salivary tumours-experience 257; 1979.
over 30 years. Clin Otolaryngol.
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6. Maimaris, C. V.; Ball, M. J. Treatment of parotid tumours by conservative parotidectomy. B. J. Surg. 73: 897; 1986. 7. Maynard, J. D. Management of pleomorphic adenoma of the parotid. B. J. Surg 75: 305-308; 1988. 8. McEvedy, B. V.; Ross, W. M. The treatment of mixed parotid turnours by enucleation and radiotherapy. B. J. Surg. 63: 341-342; 1976. 9. Ravasz, L. A.; Terhaard, C. H. J.; Hordijk, G. J. Radiotherapy in epithelial tumours of the parotid gland: case presentation and literature review. Int. J. Radiat. Oncol. Biol. Phys. 19: 55-59; 1990. 10. Smiddy, F. G. Treatment of mixed parotid tumours. BMJ 322-325; 1956. 11. Stevens, K. L.; Hobsley, M. The treatment of pleomorphic adenomas by formal parotidectomy. B. J. Surg. 69: 1-3; 1982. 12. Watkin, G. T.; Hobsley, M. Should radiotherapy be used routinely in the management of benign parotid tumours? B. J. Surg. 73: 601-603; 1986.
