Inl. J. Rndiation
Oncology
Biol. Phys.. I!W
Vol. 4, pp. 103107.
Pergamon Press.
0 Single Agent Chemotherapy
Printed in the U.S.A.
and Radiation
METHOTREXATE MARGARET Consultantin Radiotherapy
AND RADIATION?
F. SPITTLE, M.Sc.,
MB.BS.,
FRCR
and Oncology, The Meyerstein Institute of Radiotherapy, Hospital, London WIN 8AA, England
INTRODUCTION Methotrexate is an anatlogue of aminopterin which was first used in the treatment of acute leukaemia in 1947. However, because of its better therapeutic
The Middlesex
mitosis in that although there was no change in prophase, metaphases were increased and anaphases and telophases decreased. Thus metaphase arrest is a appearance of observable histopathologically chromosome distribution within the cell nucleus which reflects the Methotrexate effect on the oomponent DNA.
index, the closely related amethopterin superseded aminopterin and was marketed as Methotrexate. Methotrexate is a folic .acid antagonist and its essential action is disruption of DNA synthesis. The con-
INTERACTION WITH RADIATIONEXPERIMENTAL
version of deoxyuridine to thymidine requires tetrahydrofolic acid which is, during this process, oxidized to dihydrofolic acid. The kinetics of this system are dependent on the reconversion of dihydrofolic acid to the tetrahydro form by the enzyme folic acid reductase. It is at this site that Methotrexate exerts its action by electrostatic binding of the enzyme for which it has an affinity 100,000 times that of the substrate. Thus tlhe synthesis of thymidine and formation of DNA is prevented. Berenbaum’s diagram illustrates the action (Fig. l).’ Fortunately the addition of exogenous formyl tetrahydrofolic acid, folic acid or folinic acid (Leucovorin) bypasses this block and allows the continued production of thymidine-an effect which has been utilized to therapeutic advantage. In this way ‘Methotrexate probably affects both normal and malignant cells as DNA synthesis is attempted and kills cells in the S phase of the cell cycle thus causing a block at the GI-S transition. This results in synchronization of the cell population and the arrest of cells at a relatively radiosensitive stage (Fig. 2). Jacobson7 in his study of Methotrexate on the bone marrow also demonstrated an effect on
Methotrexate is a phase specific cytotoxic drug. What evidence is there that it interacts with radiation? With radiotherapy it must act either by: (1) Shrinking the tumour mass rapidly so that a course of fractionated radiotherapy finds more tumour cells in well vascularized areas. These are more sensitive to radiation effects than hypoxic cells in near necrotic sites. (2) By potentiating the effect of radiation upon the anoxic or hypoxic cells in a tumour more than the effect upon the well-oxygenated cells of normal tissues. (3) By protective effects upon normal tissues, assuming that the more poorly vascularized areas of tumour will not be protected equally. There is some evidence that Methotrexate has the first two actions in vitro. The use of Methotrexate as an adjuvant to irradiation was developed empirically but has been rationalized by in vitro studies which show Methotaught by Sir Stanford was the importance of continued reappraisal and integration of diverse modalities. This approach underlies the spirit of this Symposium.
tit is a great personal pleasure to be asked to speak at the Sir Stanford Cade Memorial Symposium since my early radiotherapy and oncology teaching and experience were gained at the Westminster Hospital where I count it an honour to have been the houseman towards the end of Sir Stanford’s career. One of the characteristics of this great man was that he maintained an uncompromising attitude towards viewing the cancer problem as a whole. In the early days of oncology, with rapid development of machinery, drugs and diagnostic methods a vital lesson
Acknowledgements-I would like to thank Dr. Ivan Robertson for his help and encouragement, Mrs. A. Beck and Mrs. H. Freyhan for help with references and Miss G. Fergusson for secretarial assistance. The Photographic Department of the Middlesex Hospital kindly supplied illustrations. 103
Radiation
Oncology
0
Biology
0 Physics
dUMP
--EiGq FAR
1/ F”2
dTMP
ib)
(a) dUMP
(c)
dTMP
Fig. 1. (a) The tetrahydrofolic-dihydrofolic acid cycle. (b) Disruption of the cycle by combination of folic-acid antagonists with folic-acid reductase. (c) Substitution of exogenous formyltetrahydrofolic acid for endogenous tetrahydrofohc acid. FAR, folic acid reductase; FH.,, tetrahydrofolic acid; FH,, dihydrofolic acid; C, one-carbon fragments; dUMP, deoxyuridylic acid; dTMP, thymidylic acid; FAA, folid-acid antagonist; f.FH+ formyltetrahydrofolic acid.
January-February
trexate to arrest cells at the Gi-S phase of the cell cycle which is in many systems a relatively radiosensitive phase. Berry has shown with Hela cells grown in culture, that administration of Methotrexate
I
and No. 2
when the cells are in the exponential phase of growth makes them more sensitive to the lethal action of radiation and concludes that in this situation Methotrexate is a true radiosensitizer.’ The concentration of Methotrexate needed to achieve this enhanced cell kill produces no killing effect when the Hela cells are plated out after incubation in this medium alone. However, cells in the stationary phase had already reached this enhanced sensitivity which persists irrespective of the addition of Methotrexate to the culture medium.4 The level of Methotrexate used left less than 10% of exponentially growing Hela cells intact but killed few of the same cells which had accumulated in an unfed stationary phase. The probable explanation is that these cells are not all actively synthesizing DNA and their relative radiosensitivity irrespective of the drug is due to their arrest at the Gr-S transition. In vitro therefore Methotrexate seems to act as a sensitizer of log phase cells while the radiosensitivity of stationary phase cells is not affected by the addition of the same concentration of Methotrexate. The increased radiosensitivity can be shown to be due to induced proliferative synchrony as when the cell cultures were irradiated 24 hr after the Methotrexate was withdrawn the response to irradiation was no different to cells which had not been exposed to this agent. There was also a reduced level of hypoxic protection in those cells irradiated immediately after exposure to Methotrexate (Fig. 3). Unfortunately the extrapolation from in vitro to the in viuo situation is not easy since Berry3 also repeated this work using the ascitic leukaemia P 388. The same methotrexate concentration in the ascitic fluid which had killed 90% of Hela cells killed only 40% of the P 388 cells. When irradiated at this time the well oxygenated tumour cells were no more radiosensitive than those which had not been exposed to Methotrexate and it may be that a large proportion of the population is not synthesizing DNA.’ Although this work therefore acts as a useful and consistent model possibly for the anoxic situation its clinical implications may not be great.
INTERACTION
Fig. 2. S, phase of DNA synthesis, which is blocked by the binding of methotrexate with dihydrofolic reductase; g,, premitotic phase; M, mitosis; g,, postmitotic phase.
1978, Vol. 4, No.
WITH
RADIATION-CLINICAL
Methotrexate has been used with irradiation with some success notably in head and neck tumours. Unfortunately the oral mucositis which is often the limiting side effect of Methotrexate administration may preclude attaining the full dose of irradiation. This results in the second line modality prejudicing the first and often makes comparison of series difficult. Recently published work by Lustig et al. in June 1976,” suggests that Methotrexate coupled with ir-
Methotrexate
(a)
No methotrexote
and radiation
(b)
105
0 M. F. SPITTLE
Methotrexate
0.3 pg/ml
lc)
24h after removing drug
1.0
10-1
1
Hypoxic
Aerated
Aerated
10-q 0 Dose, rod
Dose, rad
,
,
1000
2000
Dose, rod
Fig. 3. Survival of reproductive capacity of HeLa cells in vitro: (a) After irradiation under normal culture conditions when growing exponentially; (b) When irradiated immediately after 24 hr exposure to Methotrexate, 0.3 pg/ml in the growth medium; (c) When exposed to Methotrexate, 0.3 pg/ml in the growth medium, but only irradiated 24 hr after the removal of the drug from the medium.
radiation may give enhanced results in advanced tumours of the head and neck. In a study of patients with any stage primary ciarcinoma with Nj nodes, or Tj and T4 primaries with any nodal stage, 48 nonrandomized patients treated between 1961 and 1965 received oral Methotrexate 2.5 mg three times a day for 5 days prior to starting radiotherapy and continued this dosage during the radiotherapy until signs of Methotrexate toxicity developed. The Methotrexate was then stopped an’d the irradiation continued. Later they examined a further group of 75 patients treated between 1968 and 1972 who were randomized either to receive radiothlerapy alone or intravenous Methotrexate followed by irradiation. 25 mg of Methotrexate was given intravenously every three days for a total of five doses. The irradiation then began within 13-26 days after the initial dosage. Thirteen patients-2 in the oral Methotrexate group, 7 in the intravenous group .and 4 in the irradiation only group received planned preoperative radiotherapy. The groups were compared on parameters of histology, grade and site of .tumour. The 3 year survival of the oral Methotrexate group was 33%, the intravenous group was 20% and the radiotherapy alone group 10%. The median survival was 20 months for the oral Methotrexate group, 17 months for the intravenous group and 13 months for the radiotherapy alone group. The difference in survival between the oral Methotrexate and the radiation alone groups was statistically significant at p = 0.04. Within the randomized groups, i.e. the intravenous versus radiation therapy alone the difference in survival did not reach statistical significance. Scoring response as a reasonable decrease in diameter of the primary within 21 days of the initial Methotrexate, there was a significant
difference between the number of responders to oral Methotrexate and intravenous Methotrexate-43 of 48 (90%) oral responding but only 20 of 36 (56%) intravenous Methotrexate responding. There were also more marked responses in the oral group. No correlation of total drug dose to survival was noted. However, the mean dose of radiation achieved was higher in the oral groups, 1836 rets vs 1773 rets for the intravenous Methotrexate and 1775 rets for the radiation alone group. This may in part account for the improved response. Scatter plots of individual survival versus dose however did not show any correlation. The toxicity problems were significantly greater in the oral group arising in 43 of 48 (90%) and only 10 of 36 (28%) in the intravenous group. The degree of toxicity was not related to survival. It is interesting that the occurrence of metastases was significantly increased in those patients not exhibited to the drug. Severe fibrosis, soft tissue damage and radionecrosis were seen more frequently in the oral Methotrexate group and (Fig. 4) in both Methotrexate groups there was an 8% incidence of death directly attributable to treatment. However, the fact that the oral Methotrexate group showed more toxicity from the drug and received a higher mean dose of irradiation suggests that they were treated more vigorously which may account for the improved survival. Southard, Kramer and Manfield” when initially reporting the oral Methotrexate group noted the high incidence of toxicity, yet felt that the results were far superior to those obtained by radiotherapy in the past. Thirty one per cent of their series survived from 1.5 to 5.5 years with a local clearance rate of 44% in a group of patients many of whom were chronic alcoholics and derelicts and all of whom had massively advanced tumours. The administration of Metho-
Radiation Oncology 0
106
Oral methoxtrexate and radiation
i.v. methotrexate and radiation
Fig. 4. Complications
at the primary
0 Physics
Radiation alone 3(8%)
5(14%) 0 7(1%) 8(22%) 2(6%) 0
12(25%) 2(4%) 9(1%) 12(25%) 3(6%) 3(6%)
Soft tissue Radionecrosis Edema, mild Edema, severe Fibrosis, mild Fibrosis, severe
Biology
:(lS%) 4( 10%) 3(8%) 0
January-February
1978, Vol.
I
4. No.
and No.
2
Friedman and Daly6 described a series of I50 patients treated with oral Methotrexate 7.5 mg daily for 1-2 weeks prior to irradiation and continuing while irradiation was given. Before starting the
radiotherapy 67% of all primary tumours were found to have decreased more than 25% in volume. This shrinkage was such that it was believed that only a sublethal dose of irradiation would be required to produce a permanent lethal effect on the tumour. Thus one group of patients received Methotrexate
site in treatment
groups.
IO
I, t\.
0.4 \, trexate however sometimes did require suspension of the radiotherapy or reduction of the drug dosage for short periods. The feeling that there was an enhancement of the effect of irradiation by Methotrexate echoed the suggestion of Condit et aL5 in their early work of 1964. However the final report of the Methotrexate Head and Neck Study of the Radiation Therapy Oncology Group was published in 1975. 631 patients were randomized as already described between radiotherapy alone and intravenous Methotrexate plus irradiation. Taking into account the influence of general condition, sex, extent of disease and consumption of alcohol on survival the curves were not found to show a dramatic effect due to the addition of Methotrexate. However, in both the hypopharynx (Fig. 5) and oral cavity there was a marginal improvement in the combined therapy group. The oropharynx and supraglottic larynx groups showed little improvement due to Methotrexate (Fig. 6). It seems from this study that the intravenous Methotrexate regime while giving less toxicity than the earlier oral regime was also less effective.
:~
1: \________ 0.2 r
1
6
12
16
24
Time,
30
36
42
46
months
Fig. 6. Survivals for the supraglottic larynx adjusted for TN, general condition, sex, and drinking habits. (T,N,, General Condition 1, male, drinker). ---, Methotrexate and radiation therapy (36 cases, 20 deaths); -, radiation therapy alone (36 cases, 22 deaths).
7ow-
I
??
I
0
-i-_I_lA IO
20
30
40
Time, days
I 6
12
Time,
16
24
30
36
42
46
Months
Fig. 5. Survivals for the hypopharynx adjusted for TN, genera1 condition, sex, and drinking habits. (T,N*, Genera1 Condition 1, male, drinker). ---, Methotrexate and radiaradiation tion therapy (24 cases, 18 deaths); -, therapy alone (33 cases, 26 deaths).
Fig. 7. Sublethal X-ray doses given to 17 lesions. Solid dots are doses which arrested the tumour for more than 1 year. Circles are doses following which the tumour recurred. These are compared with lethal dose ranges published by Patterson (P), Strandqvist (S) and Friedman and Davis (shaded area). 10 of the 17 lesions which received Methotrexate plus sublethal doses of X-rays were arrested and the patients were free of recurrence more than one year later. These data constitute the chief evidence that Methotrexate can enhance irradiation effects. 0, Tumor arrested; 0, Recurrence.
Methotrexate
and radiation
0 M. F. SPITTLE
107
In sites other than the head and neck there is little suggestion of interaction between Methotrexate and irradiation. The early improvement in disease free survival attributed to high-dose Methotrexate in the treatment of osteosarcoma is one of the exciting new facets of the chemotherapy of solid tumours but is unrelated to radiotherapy. In combination therapy of many types Methotrexate has an important part to play the more so because its actions and toxicity can in large part be reversed by the administration of folinic acid. The place of Methotrexate in the treatment of leukaemias is traditional. It is a well established pillar among the multiplicity of drugs used. Methotrexate therefore is a first line cytotoxic drug useful alone and in combination with other cytotoxics and with a wide spectrum of usefulness in malignant disease. Although not consistently demonstrated in controlled trials there is a suggestion that its use in addition to irradiation in head and neck tumours may be of added benefit to the patient. * REFERENCES
plus a sublethal dose of irradiation. Of 17 such patients 10 showed complete tumour destruction (Fig. 7). It was felt that few or no tumour arrests would be seen without Methotrexa.te. However, these patients were a non-randomized group and evidence in so few cases becomes anecdotal. The authors concluded that combined therapy with Methotrexate and irradiation for advanced head and neck tumours improves the cure rate. However, even in this small field conflicting evidence can be found. Knowlton et aI.* randomized 96 patients with advanced squamous carcinoma of the head and neck between treatment with intravenous Methotrexate followed by radical irradiation or and found no significant radiotherapy alone differences in local disease control or actuarial survival rate at 3 and 5 years. Although randomized trials show little advantage of adding Methotrexate to irradiation the consistent opinion of other investigators is that improvement in results is seen.
M.C.: Discussion in ‘Methotrexate in the ed. by Worral, P.M., Espener, H.J. Bristol, John Wright, p. 83, 1966. 2. Berry, R.J.: Some Observations on the combined effects of X-rays and Methotrexate on human tumour cells in vitro with poasible relevance to their most useful combination in ra.diotherapy. Am. J. Roentgenol. 102: 509, 1968. 3. Berry, R.J., Asquith, J.C.: Cell cycle-dependent and hypoxic radiosensitizers. In Advances in Chemical Radiosensitization. Vienna, International Atomic Energy Agency, 1974, pp. 25-36. 4. Berry, R.J., Huckle, J.M.: Radiation and Methotrexate effects on stationary phase cells (Letter). Br. J. Radiol.
Am. J. Roentgenol., Med. 99: 289-301, 1967.
1. Berenbaum,
and irradiation.
treatment of Cancer’,
45: 710, 1972. 5. Condit, P.T. et al.: Met.hotrexate
treatment 1524-1533, 6. Friedman,
of patients
7. Jacobson,
9.
10.
and radiation in the with cancer. Cancer Res. 24:
1974.
M., Daly, J.F:.: The treatment of squamous cell carcinoma of the head and neck with Methotrexate
W.: The mode of action of folic acid anand the function of folinic acid. In Methotrexate in the Treatment of Cancer, ed. by Worrall, P.M., Espener, H.J. Bristol, John Wright, 1%6, pp. 77-83. Knowlton, A.H. et al.: Methotrexate and radiation therapy in the treatment of advanced head and neck tumours. Radiology 116: 709-712, 1975. Kramer, S.: Methotrexate and radiation therapy in the treatment of advanced squamous cell carcinoma of the oral cavity, oropharynx, supraglottic larynx and hypopharynx. Can. J. Otolaryngol. 4: 213-218, 1975. Lustig, R.A. et al.: Adjuvant Methotrexate in the radiotherapeutic management of advanced tumours of the head and neck. Cancer 37: 2703-2708, 1976. Southard, M.E., Kramer, S., Mansfield, C.M.: Advances in the management of tumours of the head and neck. Surg. Clin. North Am. 47: 1139-1143, 1967. tagonists
8.
11.
Radium Ther. Nucl.
Oncology
Biol. Phys.. I!W
Vol. 4, pp. 103107.
Pergamon Press.
0 Single Agent Chemotherapy
Printed in the U.S.A.
and Radiation
METHOTREXATE MARGARET Consultantin Radiotherapy
AND RADIATION?
F. SPITTLE, M.Sc.,
MB.BS.,
FRCR
and Oncology, The Meyerstein Institute of Radiotherapy, Hospital, London WIN 8AA, England
INTRODUCTION Methotrexate is an anatlogue of aminopterin which was first used in the treatment of acute leukaemia in 1947. However, because of its better therapeutic
The Middlesex
mitosis in that although there was no change in prophase, metaphases were increased and anaphases and telophases decreased. Thus metaphase arrest is a appearance of observable histopathologically chromosome distribution within the cell nucleus which reflects the Methotrexate effect on the oomponent DNA.
index, the closely related amethopterin superseded aminopterin and was marketed as Methotrexate. Methotrexate is a folic .acid antagonist and its essential action is disruption of DNA synthesis. The con-
INTERACTION WITH RADIATIONEXPERIMENTAL
version of deoxyuridine to thymidine requires tetrahydrofolic acid which is, during this process, oxidized to dihydrofolic acid. The kinetics of this system are dependent on the reconversion of dihydrofolic acid to the tetrahydro form by the enzyme folic acid reductase. It is at this site that Methotrexate exerts its action by electrostatic binding of the enzyme for which it has an affinity 100,000 times that of the substrate. Thus tlhe synthesis of thymidine and formation of DNA is prevented. Berenbaum’s diagram illustrates the action (Fig. l).’ Fortunately the addition of exogenous formyl tetrahydrofolic acid, folic acid or folinic acid (Leucovorin) bypasses this block and allows the continued production of thymidine-an effect which has been utilized to therapeutic advantage. In this way ‘Methotrexate probably affects both normal and malignant cells as DNA synthesis is attempted and kills cells in the S phase of the cell cycle thus causing a block at the GI-S transition. This results in synchronization of the cell population and the arrest of cells at a relatively radiosensitive stage (Fig. 2). Jacobson7 in his study of Methotrexate on the bone marrow also demonstrated an effect on
Methotrexate is a phase specific cytotoxic drug. What evidence is there that it interacts with radiation? With radiotherapy it must act either by: (1) Shrinking the tumour mass rapidly so that a course of fractionated radiotherapy finds more tumour cells in well vascularized areas. These are more sensitive to radiation effects than hypoxic cells in near necrotic sites. (2) By potentiating the effect of radiation upon the anoxic or hypoxic cells in a tumour more than the effect upon the well-oxygenated cells of normal tissues. (3) By protective effects upon normal tissues, assuming that the more poorly vascularized areas of tumour will not be protected equally. There is some evidence that Methotrexate has the first two actions in vitro. The use of Methotrexate as an adjuvant to irradiation was developed empirically but has been rationalized by in vitro studies which show Methotaught by Sir Stanford was the importance of continued reappraisal and integration of diverse modalities. This approach underlies the spirit of this Symposium.
tit is a great personal pleasure to be asked to speak at the Sir Stanford Cade Memorial Symposium since my early radiotherapy and oncology teaching and experience were gained at the Westminster Hospital where I count it an honour to have been the houseman towards the end of Sir Stanford’s career. One of the characteristics of this great man was that he maintained an uncompromising attitude towards viewing the cancer problem as a whole. In the early days of oncology, with rapid development of machinery, drugs and diagnostic methods a vital lesson
Acknowledgements-I would like to thank Dr. Ivan Robertson for his help and encouragement, Mrs. A. Beck and Mrs. H. Freyhan for help with references and Miss G. Fergusson for secretarial assistance. The Photographic Department of the Middlesex Hospital kindly supplied illustrations. 103
Radiation
Oncology
0
Biology
0 Physics
dUMP
--EiGq FAR
1/ F”2
dTMP
ib)
(a) dUMP
(c)
dTMP
Fig. 1. (a) The tetrahydrofolic-dihydrofolic acid cycle. (b) Disruption of the cycle by combination of folic-acid antagonists with folic-acid reductase. (c) Substitution of exogenous formyltetrahydrofolic acid for endogenous tetrahydrofohc acid. FAR, folic acid reductase; FH.,, tetrahydrofolic acid; FH,, dihydrofolic acid; C, one-carbon fragments; dUMP, deoxyuridylic acid; dTMP, thymidylic acid; FAA, folid-acid antagonist; f.FH+ formyltetrahydrofolic acid.
January-February
trexate to arrest cells at the Gi-S phase of the cell cycle which is in many systems a relatively radiosensitive phase. Berry has shown with Hela cells grown in culture, that administration of Methotrexate
I
and No. 2
when the cells are in the exponential phase of growth makes them more sensitive to the lethal action of radiation and concludes that in this situation Methotrexate is a true radiosensitizer.’ The concentration of Methotrexate needed to achieve this enhanced cell kill produces no killing effect when the Hela cells are plated out after incubation in this medium alone. However, cells in the stationary phase had already reached this enhanced sensitivity which persists irrespective of the addition of Methotrexate to the culture medium.4 The level of Methotrexate used left less than 10% of exponentially growing Hela cells intact but killed few of the same cells which had accumulated in an unfed stationary phase. The probable explanation is that these cells are not all actively synthesizing DNA and their relative radiosensitivity irrespective of the drug is due to their arrest at the Gr-S transition. In vitro therefore Methotrexate seems to act as a sensitizer of log phase cells while the radiosensitivity of stationary phase cells is not affected by the addition of the same concentration of Methotrexate. The increased radiosensitivity can be shown to be due to induced proliferative synchrony as when the cell cultures were irradiated 24 hr after the Methotrexate was withdrawn the response to irradiation was no different to cells which had not been exposed to this agent. There was also a reduced level of hypoxic protection in those cells irradiated immediately after exposure to Methotrexate (Fig. 3). Unfortunately the extrapolation from in vitro to the in viuo situation is not easy since Berry3 also repeated this work using the ascitic leukaemia P 388. The same methotrexate concentration in the ascitic fluid which had killed 90% of Hela cells killed only 40% of the P 388 cells. When irradiated at this time the well oxygenated tumour cells were no more radiosensitive than those which had not been exposed to Methotrexate and it may be that a large proportion of the population is not synthesizing DNA.’ Although this work therefore acts as a useful and consistent model possibly for the anoxic situation its clinical implications may not be great.
INTERACTION
Fig. 2. S, phase of DNA synthesis, which is blocked by the binding of methotrexate with dihydrofolic reductase; g,, premitotic phase; M, mitosis; g,, postmitotic phase.
1978, Vol. 4, No.
WITH
RADIATION-CLINICAL
Methotrexate has been used with irradiation with some success notably in head and neck tumours. Unfortunately the oral mucositis which is often the limiting side effect of Methotrexate administration may preclude attaining the full dose of irradiation. This results in the second line modality prejudicing the first and often makes comparison of series difficult. Recently published work by Lustig et al. in June 1976,” suggests that Methotrexate coupled with ir-
Methotrexate
(a)
No methotrexote
and radiation
(b)
105
0 M. F. SPITTLE
Methotrexate
0.3 pg/ml
lc)
24h after removing drug
1.0
10-1
1
Hypoxic
Aerated
Aerated
10-q 0 Dose, rod
Dose, rad
,
,
1000
2000
Dose, rod
Fig. 3. Survival of reproductive capacity of HeLa cells in vitro: (a) After irradiation under normal culture conditions when growing exponentially; (b) When irradiated immediately after 24 hr exposure to Methotrexate, 0.3 pg/ml in the growth medium; (c) When exposed to Methotrexate, 0.3 pg/ml in the growth medium, but only irradiated 24 hr after the removal of the drug from the medium.
radiation may give enhanced results in advanced tumours of the head and neck. In a study of patients with any stage primary ciarcinoma with Nj nodes, or Tj and T4 primaries with any nodal stage, 48 nonrandomized patients treated between 1961 and 1965 received oral Methotrexate 2.5 mg three times a day for 5 days prior to starting radiotherapy and continued this dosage during the radiotherapy until signs of Methotrexate toxicity developed. The Methotrexate was then stopped an’d the irradiation continued. Later they examined a further group of 75 patients treated between 1968 and 1972 who were randomized either to receive radiothlerapy alone or intravenous Methotrexate followed by irradiation. 25 mg of Methotrexate was given intravenously every three days for a total of five doses. The irradiation then began within 13-26 days after the initial dosage. Thirteen patients-2 in the oral Methotrexate group, 7 in the intravenous group .and 4 in the irradiation only group received planned preoperative radiotherapy. The groups were compared on parameters of histology, grade and site of .tumour. The 3 year survival of the oral Methotrexate group was 33%, the intravenous group was 20% and the radiotherapy alone group 10%. The median survival was 20 months for the oral Methotrexate group, 17 months for the intravenous group and 13 months for the radiotherapy alone group. The difference in survival between the oral Methotrexate and the radiation alone groups was statistically significant at p = 0.04. Within the randomized groups, i.e. the intravenous versus radiation therapy alone the difference in survival did not reach statistical significance. Scoring response as a reasonable decrease in diameter of the primary within 21 days of the initial Methotrexate, there was a significant
difference between the number of responders to oral Methotrexate and intravenous Methotrexate-43 of 48 (90%) oral responding but only 20 of 36 (56%) intravenous Methotrexate responding. There were also more marked responses in the oral group. No correlation of total drug dose to survival was noted. However, the mean dose of radiation achieved was higher in the oral groups, 1836 rets vs 1773 rets for the intravenous Methotrexate and 1775 rets for the radiation alone group. This may in part account for the improved response. Scatter plots of individual survival versus dose however did not show any correlation. The toxicity problems were significantly greater in the oral group arising in 43 of 48 (90%) and only 10 of 36 (28%) in the intravenous group. The degree of toxicity was not related to survival. It is interesting that the occurrence of metastases was significantly increased in those patients not exhibited to the drug. Severe fibrosis, soft tissue damage and radionecrosis were seen more frequently in the oral Methotrexate group and (Fig. 4) in both Methotrexate groups there was an 8% incidence of death directly attributable to treatment. However, the fact that the oral Methotrexate group showed more toxicity from the drug and received a higher mean dose of irradiation suggests that they were treated more vigorously which may account for the improved survival. Southard, Kramer and Manfield” when initially reporting the oral Methotrexate group noted the high incidence of toxicity, yet felt that the results were far superior to those obtained by radiotherapy in the past. Thirty one per cent of their series survived from 1.5 to 5.5 years with a local clearance rate of 44% in a group of patients many of whom were chronic alcoholics and derelicts and all of whom had massively advanced tumours. The administration of Metho-
Radiation Oncology 0
106
Oral methoxtrexate and radiation
i.v. methotrexate and radiation
Fig. 4. Complications
at the primary
0 Physics
Radiation alone 3(8%)
5(14%) 0 7(1%) 8(22%) 2(6%) 0
12(25%) 2(4%) 9(1%) 12(25%) 3(6%) 3(6%)
Soft tissue Radionecrosis Edema, mild Edema, severe Fibrosis, mild Fibrosis, severe
Biology
:(lS%) 4( 10%) 3(8%) 0
January-February
1978, Vol.
I
4. No.
and No.
2
Friedman and Daly6 described a series of I50 patients treated with oral Methotrexate 7.5 mg daily for 1-2 weeks prior to irradiation and continuing while irradiation was given. Before starting the
radiotherapy 67% of all primary tumours were found to have decreased more than 25% in volume. This shrinkage was such that it was believed that only a sublethal dose of irradiation would be required to produce a permanent lethal effect on the tumour. Thus one group of patients received Methotrexate
site in treatment
groups.
IO
I, t\.
0.4 \, trexate however sometimes did require suspension of the radiotherapy or reduction of the drug dosage for short periods. The feeling that there was an enhancement of the effect of irradiation by Methotrexate echoed the suggestion of Condit et aL5 in their early work of 1964. However the final report of the Methotrexate Head and Neck Study of the Radiation Therapy Oncology Group was published in 1975. 631 patients were randomized as already described between radiotherapy alone and intravenous Methotrexate plus irradiation. Taking into account the influence of general condition, sex, extent of disease and consumption of alcohol on survival the curves were not found to show a dramatic effect due to the addition of Methotrexate. However, in both the hypopharynx (Fig. 5) and oral cavity there was a marginal improvement in the combined therapy group. The oropharynx and supraglottic larynx groups showed little improvement due to Methotrexate (Fig. 6). It seems from this study that the intravenous Methotrexate regime while giving less toxicity than the earlier oral regime was also less effective.
:~
1: \________ 0.2 r
1
6
12
16
24
Time,
30
36
42
46
months
Fig. 6. Survivals for the supraglottic larynx adjusted for TN, general condition, sex, and drinking habits. (T,N,, General Condition 1, male, drinker). ---, Methotrexate and radiation therapy (36 cases, 20 deaths); -, radiation therapy alone (36 cases, 22 deaths).
7ow-
I
??
I
0
-i-_I_lA IO
20
30
40
Time, days
I 6
12
Time,
16
24
30
36
42
46
Months
Fig. 5. Survivals for the hypopharynx adjusted for TN, genera1 condition, sex, and drinking habits. (T,N*, Genera1 Condition 1, male, drinker). ---, Methotrexate and radiaradiation tion therapy (24 cases, 18 deaths); -, therapy alone (33 cases, 26 deaths).
Fig. 7. Sublethal X-ray doses given to 17 lesions. Solid dots are doses which arrested the tumour for more than 1 year. Circles are doses following which the tumour recurred. These are compared with lethal dose ranges published by Patterson (P), Strandqvist (S) and Friedman and Davis (shaded area). 10 of the 17 lesions which received Methotrexate plus sublethal doses of X-rays were arrested and the patients were free of recurrence more than one year later. These data constitute the chief evidence that Methotrexate can enhance irradiation effects. 0, Tumor arrested; 0, Recurrence.
Methotrexate
and radiation
0 M. F. SPITTLE
107
In sites other than the head and neck there is little suggestion of interaction between Methotrexate and irradiation. The early improvement in disease free survival attributed to high-dose Methotrexate in the treatment of osteosarcoma is one of the exciting new facets of the chemotherapy of solid tumours but is unrelated to radiotherapy. In combination therapy of many types Methotrexate has an important part to play the more so because its actions and toxicity can in large part be reversed by the administration of folinic acid. The place of Methotrexate in the treatment of leukaemias is traditional. It is a well established pillar among the multiplicity of drugs used. Methotrexate therefore is a first line cytotoxic drug useful alone and in combination with other cytotoxics and with a wide spectrum of usefulness in malignant disease. Although not consistently demonstrated in controlled trials there is a suggestion that its use in addition to irradiation in head and neck tumours may be of added benefit to the patient. * REFERENCES
plus a sublethal dose of irradiation. Of 17 such patients 10 showed complete tumour destruction (Fig. 7). It was felt that few or no tumour arrests would be seen without Methotrexa.te. However, these patients were a non-randomized group and evidence in so few cases becomes anecdotal. The authors concluded that combined therapy with Methotrexate and irradiation for advanced head and neck tumours improves the cure rate. However, even in this small field conflicting evidence can be found. Knowlton et aI.* randomized 96 patients with advanced squamous carcinoma of the head and neck between treatment with intravenous Methotrexate followed by radical irradiation or and found no significant radiotherapy alone differences in local disease control or actuarial survival rate at 3 and 5 years. Although randomized trials show little advantage of adding Methotrexate to irradiation the consistent opinion of other investigators is that improvement in results is seen.
M.C.: Discussion in ‘Methotrexate in the ed. by Worral, P.M., Espener, H.J. Bristol, John Wright, p. 83, 1966. 2. Berry, R.J.: Some Observations on the combined effects of X-rays and Methotrexate on human tumour cells in vitro with poasible relevance to their most useful combination in ra.diotherapy. Am. J. Roentgenol. 102: 509, 1968. 3. Berry, R.J., Asquith, J.C.: Cell cycle-dependent and hypoxic radiosensitizers. In Advances in Chemical Radiosensitization. Vienna, International Atomic Energy Agency, 1974, pp. 25-36. 4. Berry, R.J., Huckle, J.M.: Radiation and Methotrexate effects on stationary phase cells (Letter). Br. J. Radiol.
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W.: The mode of action of folic acid anand the function of folinic acid. In Methotrexate in the Treatment of Cancer, ed. by Worrall, P.M., Espener, H.J. Bristol, John Wright, 1%6, pp. 77-83. Knowlton, A.H. et al.: Methotrexate and radiation therapy in the treatment of advanced head and neck tumours. Radiology 116: 709-712, 1975. Kramer, S.: Methotrexate and radiation therapy in the treatment of advanced squamous cell carcinoma of the oral cavity, oropharynx, supraglottic larynx and hypopharynx. Can. J. Otolaryngol. 4: 213-218, 1975. Lustig, R.A. et al.: Adjuvant Methotrexate in the radiotherapeutic management of advanced tumours of the head and neck. Cancer 37: 2703-2708, 1976. Southard, M.E., Kramer, S., Mansfield, C.M.: Advances in the management of tumours of the head and neck. Surg. Clin. North Am. 47: 1139-1143, 1967. tagonists
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