Screening for Breast Cancer DIMITRIOS PANOUSSOPOULOS, M.D., JOSEPH CHANG, M.D., LOREN J. HUMPHREY, M.D., PH.D.
Mammography is of real assistance to the surgeon in evaluating breast problems not associted with a breast mass. Use of mammography in the detection of early breast cancer in breast demonstration projects has brought forth the time honored value judgement of benefit vs risk. This report introduces an additional aspect in the consideration of benefit vs risk, the interval cancer. From the demonstration project at KUMC, 326 biopsies were performed and 65 proved to be cancer. However, 24 additional women developed cancer before their next recommended screening date. This reduces the accuracy of mammography and physical examination by trained nurses in screening for breast cancer to 73%o. M
AMMOGRAPHY HAS CONTRIBUTED greatly in de-
tecting breast cancer during the last two decades and is considered the most efficient diagnostic tool for this purpose.' As high as 90-99% accuracy has been claimed by various investigators; furthermore Wolfe2 advocates the use of mammography in assessing the risk of breast cancer. Recent controversy surged over the benefit vs the risk of mammography for asymptomatic women under the age of 50. Repeated mammography in young Presented at the Annual Meeting of the American Surgical Association. Boca Raton, Florida, March 23-25, 1977. Supported in part by National Cancer Institute Contract #NO1CN-55303. Reprint requests: Loren J. Humphrey, M.D., University of Missouri Medical School at Kansas City, Kansas City, Missouri 64100.
From the Departments of Surgery and Radiology, Kansas University Medical Center and the Department of Surgery, Truman Medical Center and the University of Missouri Medical School, Kansas City, Missouri
women, and multiple fluoroscopies, have been con-
sidered potentially carcinogenic.24 Overlooked in this controversy is the "interval cancer", the cancer which developed during the interval between visits to the detection center. Hence this report attempts to bring into focus the accuracy of mammography and the physical examination performed by trained nurses in detection of early breast cancer.
Patients and Methods
Ten thousand asymptomatic women volunteers, of varying age, between 38 and 78 years, have been screened in the Breast Detection Center at K.U.M.C. The screening program involved three modalities: 1) Physical examination, performed by nurse-clinicians especially trained for this purpose, 2) Mammography, 3) Thermography. In this study an "interval cancer" is defined as the cancer that developed or was recognized after a negative screening visit of the patient and prior to the recommended subsequent examination.
356
VOl. 186.o NO. 3
BREAST CANCER SCREENING
357
TABLE 1. Data From Women Screened in Demonstration Project of 326 Biopsies Performed
Recommendation Based on:
Number Per cent
Positive Biopsies
Mammography Only
MAM/PHY + P. Ex. Only
P. Exam
Only
MAM/PHY and P. Ex. Combined-Total
65 19.9
44 67.6
19 29.2
2 3.0
63 97
Total number of women screened Number of biopsies recommended Number of biopsies performed
10,000 536 326
5.36% 3.26% of Total 60%o of Recom.
Non-interval cancer is defined as the lesion which detected by one of the three modalities mentioned above or any combination of these modalities. The breast size has been classified into small, medium and large by measuring the lateral and craniocaudal diameters of the breast in cm (from the mammographic views). Therefore, if the two diameters (craniocaudal x lateral) were between 5-8 cm, the size was designated as small, 8-10 cm equals medium, and more than 10 cm equals large. The family history, age, past medical history, body weight and breast size have been considered in comparing the interval and noninterval patients in this study. was
Results From the total patient population of 10,000 women, 536 patients have been recommended for breast biopsy. However, only 326 biopsies were performed. Of these, 65 patients proved to have a positive biopsy and the patients were submitted to mastectomy (these represent the non-interval patients as depicted in Table 1). Forty-five biopsies out of 65 patients were recommended purely on mammographic findings only and 19 other cases on a combination of mammographic and physical examination. Therefore, in terms of percentages, 63 out of 65 cancers were diagnosed by mammography with an accuracy rate of 97%. Physical examination performed by trained nurses produced 21 out of the 65 cases with cancer accounting for a 32% accuracy. The number of interval cancers totals 24. Therefore with a total of 89 positive biopsies, 26.9o (24) were cancers. Simple mathematics shows that this reduces the mammographic accuracy for detection of early breast cancer to 73%. The two groups, interval and non-interval cancer cases, are compared with respect to the family history (Table 2). As can be seen the family history is not significantly different between the groups but inter-
estingly as high as 50%o and 63% positive family history in each group respectively is found. As is to be seen in Table 3, the mean age of women who belong in the group of interval cancers is slightly younger than those in the group of non-interval cases. The body weight and the breast size made little difference. As seen in the data (Table 4) eight out of 24 (33.3%) interval cancers were 50 years of age or younger, whereas in the noninterval cases the percentage was 26.9o (17 of 65 cases). Women taking estrogens represent 33.3% of the interval cases and only 16.9o of the non-interval ones (Table 5). History of a previous biopsy or mastectomy in the interval group appeared frequently, accounting for 16.6 and 12.5% respectively. Discussion
This study has been conducted to illustrate an overlooked problem in screening for breast cancer. The data do not reflect on the importance of mammography for high risk and symptomatic patients. However, these data on the interval cancer must be scrutinized in considering the risk vs the benefit of mammographic screening.2'3 Thus in this screening project almost one-third of the patients with breast cancer (interval cancer) were not detected. On the other hand, these 24 cases do not detract from the benefit realized by the 73% who were diagnosed by mammography; these patients have a survival rate as high as 95%.4 TABLE 2. Correlation of Interval and Non-interval Breast Cancer with Family History
Interval Pts.
NonInterval Pts.
Family History
#
%
#
%
#
%
Any cancer Breast cancer
7 5
29.1 20.8
26 15
40 23
33 20
37 22.4
Total
Ann. Surg. a September 1977
PANOUSSOPOULOS, CHANG AND HUMPHREY
358
TABLE 3. Characteristics of Interval and Non-interval Cases Body Wt. in Lb.
Age in Years
Non-interval pts. Interval pts. Total *
Breast Size
No. of Pts.
Range
Mean
Range
Mean
S
M
L
65 24 89
38-78 39-74 38-78
58.04 55.29 57.30
105-300 118-215 105-300
149.52 159.41 152.19
19* 6 25*
30 9 39
20 9 29
See text for definition.
While the screening process missed almost one-third of the positive cases, of the total number of 10,000 women seen in the center, less than one per cent (0.3%) were missed. Hence the diagnostic value of the screening program is quite remarkable. At the same time the doctor and the patient must be cognizant of the fact that the screening program is not an absolute guarantee for detecting early breast cancers. Self examination must be practised by the patient and any suspicious findings or any symptoms should prompt a visit to the doctor. Finally it is interesting to note that in comparing the interval and non-interval cancers, women on estrogen therapy have a greater incidence rate of breast cancer. Therefore, this group of cases should receive special scrutiny in the screening process. These data seem to indicate that the results of screening could
be improved if serious consideration were given to the above by the staff performing the physical examination. Furthermore, the accuracy of physical examination and mammography would have been enhanced if the 8 of 24 interval cases (Table 4 with asterisks) reported as benign mass and/or thickening, had been sent for biopsy and if the five with nodularity, on mammograms, had been sent for verification by a physician. Summary
In general, mammography is of great value for the surgeon and high risk patient. In this screening program, almost one-third of cancers were missed, but as such, these interval cancers do not detract from the benefit accured to those patients whose cancers were detected by screening methods.
TABLE 4. Pertinent Data in Interval Cancer Patients Pt. #
Age
Mammo/P.E.
Phys. Exam
1 2 3
66 42 50 52 46 58 46 54 62 48 49 39 70 57 68 74 48 62 52 52 62 58 59 53
Suspicious mass Normal Well defined mass Normal Benign small mass Multiple small masses Punctate calcification Ill defined mass III defined mass Normal Multiple small masses Normal Ring calcification Benign mass Benign mass Benign calcification Normal Normal Small mass Bilateral masses Arch. distortion Arch. distortion Suspicious mass Benign mass
Nodularity Nodularity Benign mass Nodularity Benign mass Thickening, mass Nodularity Multiple masses Normal Multiple masses Multiple masses Mass and thickening Normal Normal Normal Normal Benign mass Normal Normal Benign masses Normal Normal Normal Normal
4
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
* Should be verified by physician. t Should be sent for biopsy.
F.H.
+ + +
+ +
+ +
+
+ +
Interval (Months)
Lymph Nodes
10 3 8 4 I 5 6 9 10 8 10 I 2 8 1 5 6 1 1 1 1 1 1 11
* * t * t
+
3/1St * t t * t
Yes Yes t
10/17t 4/22 1/18
.
BREAST CANCER SCREENING
Vol. 186 No. 3
TABLE 5. Screening for Breast Cancer Interval Pts.
NonInterval Pts.
Total
Past Medical History
#
%
#
%
#
%
Previous breast biopsy Previous mastectomy Previous uterine ca. Previous skin ca. Diabetes Medication: Thyroxine Estrogens Cortisone Anticoag. Antihist.
4 3 1 0 1
16.6 12.5 4.1 0 4.1
3 1 0 1 6
4.6 1.5 0 1.5 9.2
7 4 1 1 7
7.8 4.4 1.1 1.1 7.8
1 8 0 1 2
4.1 33.3 0 4.1 8.3
7 11 2 0 3
10.7 16.9 3 0 4.6
8 19 2 1 5
8.9 21.3 2.2 1.1 5.6
DISCUSSION
DR. JOHN STRICKLIN SPRATT, JR. (Louisville, KY): Dr. Humphrey has pinpointed an important issue. The interval cancer rate and the biological behavior of interval cancer holds the key to the evaluation of screening mammograms. Beginning with GershonCohen, and extending through a series of studies at the Ellis Fischel and from Europe, the gross rates of growth of primary and metastatic breast cancers are now known, but these data may all be truncated, since the time between observations may be too great to permit quantitation of the growth rates of the fastestgrowing breast cancers, as might account for the interval cancers. From extant growth data we have estimated that some breast cancers are so acute that they can go from the inception of the cancer to the death of the host in as brief a period of time as 120 days. Othet breast cancers are so chronic that the patient might live 23 years with no treatment at all. These chronic cancers, obviously, would be picked up by the annual mammography, while the acute cancers would be interval cancers. We have estimated, based on threshold size for diagnosis and metastases, that all breast cancers with doubling times of less than 17 days would be interval cancers. All patients that have cancers with doubling times of nine days or less will die within less than a year of inception. Based on present truncated data, we estimate that at least five per cent of all breast cancers fall in this acute category. If the theory of Gompertzian growth during the first 20 doublings of a clone of cancer cells is correct, then the interval rate might be higher than this. Further, many arguments regarding the biological effect of radiation on the induction of breast cancer can be answered by the accurate and diligent monitoring of cohort-specific interval cancer rates. A rate rising faster than could be accounted for by the aging of the cohort might, for example, mandate an early cessation of mammography. A falling rate would support the continuance of screening mammography. DR. WILLIAM WARNER SHINGLETON (Durham, North Carolina): I second what Dr. Spratt has said. I think the problem of the interval breast cancer in mass screening is a very important problem. I would like to present the data from our own screening clinic at Duke University. We're now in the fourth year of this screening project. Therefore, there have been 10,000 women who have been screened on three occasions.
359
However, the patient and the doctor must be aware that interval cancers occur frequently, thereby avoiding significant delay. Certain characteristics should draw attention to a special group of screenees such as those taking estrogens as well as those with a part history of a breast biopsy or mastectomy. References 1. Egan, R.: Mammography. The New Physician. 295, August 1963. 2. Mammography finds new use-assessing risk of breast cancer. JAMA 234(8):797, 1975. 3. Simon, N.: Breast Cancer Induced by Radiation. JAMA, 237(8): 789 1977. 4. Wanebo, H. J., Huvos, A. G., and Urban, J. A.: Treatment of Minimal Breast Cancer. Cancer, 33(2):349, 1974.
Our data is somewhat different than that presented by Dr. Humphrey. We have detected 70 cancers, and we have in this group found nine so-called interval cancers. Now, looking at the problem of the detection by nurse examination, we find that in these nine interval cancers six of them were not detected by the nurse who examined the patient, nor was the patient examined by a physician. In three other patients both the nurse and the physician examined the patient, and the cancer was not detected. The over-all accuracy, then, for mammography plus physical examination in our group is about 95%. However, since the nine interval cancers were missed on mammography, the accuracy of the mammography alone is approximately 82%. Now, I think most of the controversial points that have arisen about the detection of breast cancer by mass screening have been based on the Health Insurance Plan of New York study, with which you all are familiar. This study is about ten years old, and the techniques, including the amount of radiation used for the mammogram, was quite different than that being used in the demonstration projects today. I do believe that the data will soon be available to answer many of these perplexing problems. Dr. Oliver Beahrs, who is a member of this organization, is now chairing a committee to look at all the data from the twenty-seven screening clinics around the country. This will be data, then, on 270,000 women, approximately, who have undergone multiple screenings. I think this data might be available in six to nine months. DR. J. D. LEWIS (Milwaukee, Wisconsin): As has been pointed out, Dr. Humphrey and his group have highlighted some significant problems associated with screening, problems that generally have been recognized before screening started. We in Milwaukee have had the opportunity to follow our patients 4+ years at this time. (Slide) As with the other screening projects, we have screened approximately 10,000 patients. We have recommended 801 biopsies, of which 486 have been performed, which is consistent with the experience in Kansas. We have found 85 cancers in this group, 27 of which have been minimal; in other words, in situ cancers, or cancers with microinvasion less than five millimeters in size. During this period of time we have had (slide) a total of 118 interval procedures performed. This represents procedures that were not recommended at the last time that screening was done; 12 have
Mammography is of real assistance to the surgeon in evaluating breast problems not associted with a breast mass. Use of mammography in the detection of early breast cancer in breast demonstration projects has brought forth the time honored value judgement of benefit vs risk. This report introduces an additional aspect in the consideration of benefit vs risk, the interval cancer. From the demonstration project at KUMC, 326 biopsies were performed and 65 proved to be cancer. However, 24 additional women developed cancer before their next recommended screening date. This reduces the accuracy of mammography and physical examination by trained nurses in screening for breast cancer to 73%o. M
AMMOGRAPHY HAS CONTRIBUTED greatly in de-
tecting breast cancer during the last two decades and is considered the most efficient diagnostic tool for this purpose.' As high as 90-99% accuracy has been claimed by various investigators; furthermore Wolfe2 advocates the use of mammography in assessing the risk of breast cancer. Recent controversy surged over the benefit vs the risk of mammography for asymptomatic women under the age of 50. Repeated mammography in young Presented at the Annual Meeting of the American Surgical Association. Boca Raton, Florida, March 23-25, 1977. Supported in part by National Cancer Institute Contract #NO1CN-55303. Reprint requests: Loren J. Humphrey, M.D., University of Missouri Medical School at Kansas City, Kansas City, Missouri 64100.
From the Departments of Surgery and Radiology, Kansas University Medical Center and the Department of Surgery, Truman Medical Center and the University of Missouri Medical School, Kansas City, Missouri
women, and multiple fluoroscopies, have been con-
sidered potentially carcinogenic.24 Overlooked in this controversy is the "interval cancer", the cancer which developed during the interval between visits to the detection center. Hence this report attempts to bring into focus the accuracy of mammography and the physical examination performed by trained nurses in detection of early breast cancer.
Patients and Methods
Ten thousand asymptomatic women volunteers, of varying age, between 38 and 78 years, have been screened in the Breast Detection Center at K.U.M.C. The screening program involved three modalities: 1) Physical examination, performed by nurse-clinicians especially trained for this purpose, 2) Mammography, 3) Thermography. In this study an "interval cancer" is defined as the cancer that developed or was recognized after a negative screening visit of the patient and prior to the recommended subsequent examination.
356
VOl. 186.o NO. 3
BREAST CANCER SCREENING
357
TABLE 1. Data From Women Screened in Demonstration Project of 326 Biopsies Performed
Recommendation Based on:
Number Per cent
Positive Biopsies
Mammography Only
MAM/PHY + P. Ex. Only
P. Exam
Only
MAM/PHY and P. Ex. Combined-Total
65 19.9
44 67.6
19 29.2
2 3.0
63 97
Total number of women screened Number of biopsies recommended Number of biopsies performed
10,000 536 326
5.36% 3.26% of Total 60%o of Recom.
Non-interval cancer is defined as the lesion which detected by one of the three modalities mentioned above or any combination of these modalities. The breast size has been classified into small, medium and large by measuring the lateral and craniocaudal diameters of the breast in cm (from the mammographic views). Therefore, if the two diameters (craniocaudal x lateral) were between 5-8 cm, the size was designated as small, 8-10 cm equals medium, and more than 10 cm equals large. The family history, age, past medical history, body weight and breast size have been considered in comparing the interval and noninterval patients in this study. was
Results From the total patient population of 10,000 women, 536 patients have been recommended for breast biopsy. However, only 326 biopsies were performed. Of these, 65 patients proved to have a positive biopsy and the patients were submitted to mastectomy (these represent the non-interval patients as depicted in Table 1). Forty-five biopsies out of 65 patients were recommended purely on mammographic findings only and 19 other cases on a combination of mammographic and physical examination. Therefore, in terms of percentages, 63 out of 65 cancers were diagnosed by mammography with an accuracy rate of 97%. Physical examination performed by trained nurses produced 21 out of the 65 cases with cancer accounting for a 32% accuracy. The number of interval cancers totals 24. Therefore with a total of 89 positive biopsies, 26.9o (24) were cancers. Simple mathematics shows that this reduces the mammographic accuracy for detection of early breast cancer to 73%. The two groups, interval and non-interval cancer cases, are compared with respect to the family history (Table 2). As can be seen the family history is not significantly different between the groups but inter-
estingly as high as 50%o and 63% positive family history in each group respectively is found. As is to be seen in Table 3, the mean age of women who belong in the group of interval cancers is slightly younger than those in the group of non-interval cases. The body weight and the breast size made little difference. As seen in the data (Table 4) eight out of 24 (33.3%) interval cancers were 50 years of age or younger, whereas in the noninterval cases the percentage was 26.9o (17 of 65 cases). Women taking estrogens represent 33.3% of the interval cases and only 16.9o of the non-interval ones (Table 5). History of a previous biopsy or mastectomy in the interval group appeared frequently, accounting for 16.6 and 12.5% respectively. Discussion
This study has been conducted to illustrate an overlooked problem in screening for breast cancer. The data do not reflect on the importance of mammography for high risk and symptomatic patients. However, these data on the interval cancer must be scrutinized in considering the risk vs the benefit of mammographic screening.2'3 Thus in this screening project almost one-third of the patients with breast cancer (interval cancer) were not detected. On the other hand, these 24 cases do not detract from the benefit realized by the 73% who were diagnosed by mammography; these patients have a survival rate as high as 95%.4 TABLE 2. Correlation of Interval and Non-interval Breast Cancer with Family History
Interval Pts.
NonInterval Pts.
Family History
#
%
#
%
#
%
Any cancer Breast cancer
7 5
29.1 20.8
26 15
40 23
33 20
37 22.4
Total
Ann. Surg. a September 1977
PANOUSSOPOULOS, CHANG AND HUMPHREY
358
TABLE 3. Characteristics of Interval and Non-interval Cases Body Wt. in Lb.
Age in Years
Non-interval pts. Interval pts. Total *
Breast Size
No. of Pts.
Range
Mean
Range
Mean
S
M
L
65 24 89
38-78 39-74 38-78
58.04 55.29 57.30
105-300 118-215 105-300
149.52 159.41 152.19
19* 6 25*
30 9 39
20 9 29
See text for definition.
While the screening process missed almost one-third of the positive cases, of the total number of 10,000 women seen in the center, less than one per cent (0.3%) were missed. Hence the diagnostic value of the screening program is quite remarkable. At the same time the doctor and the patient must be cognizant of the fact that the screening program is not an absolute guarantee for detecting early breast cancers. Self examination must be practised by the patient and any suspicious findings or any symptoms should prompt a visit to the doctor. Finally it is interesting to note that in comparing the interval and non-interval cancers, women on estrogen therapy have a greater incidence rate of breast cancer. Therefore, this group of cases should receive special scrutiny in the screening process. These data seem to indicate that the results of screening could
be improved if serious consideration were given to the above by the staff performing the physical examination. Furthermore, the accuracy of physical examination and mammography would have been enhanced if the 8 of 24 interval cases (Table 4 with asterisks) reported as benign mass and/or thickening, had been sent for biopsy and if the five with nodularity, on mammograms, had been sent for verification by a physician. Summary
In general, mammography is of great value for the surgeon and high risk patient. In this screening program, almost one-third of cancers were missed, but as such, these interval cancers do not detract from the benefit accured to those patients whose cancers were detected by screening methods.
TABLE 4. Pertinent Data in Interval Cancer Patients Pt. #
Age
Mammo/P.E.
Phys. Exam
1 2 3
66 42 50 52 46 58 46 54 62 48 49 39 70 57 68 74 48 62 52 52 62 58 59 53
Suspicious mass Normal Well defined mass Normal Benign small mass Multiple small masses Punctate calcification Ill defined mass III defined mass Normal Multiple small masses Normal Ring calcification Benign mass Benign mass Benign calcification Normal Normal Small mass Bilateral masses Arch. distortion Arch. distortion Suspicious mass Benign mass
Nodularity Nodularity Benign mass Nodularity Benign mass Thickening, mass Nodularity Multiple masses Normal Multiple masses Multiple masses Mass and thickening Normal Normal Normal Normal Benign mass Normal Normal Benign masses Normal Normal Normal Normal
4
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
* Should be verified by physician. t Should be sent for biopsy.
F.H.
+ + +
+ +
+ +
+
+ +
Interval (Months)
Lymph Nodes
10 3 8 4 I 5 6 9 10 8 10 I 2 8 1 5 6 1 1 1 1 1 1 11
* * t * t
+
3/1St * t t * t
Yes Yes t
10/17t 4/22 1/18
.
BREAST CANCER SCREENING
Vol. 186 No. 3
TABLE 5. Screening for Breast Cancer Interval Pts.
NonInterval Pts.
Total
Past Medical History
#
%
#
%
#
%
Previous breast biopsy Previous mastectomy Previous uterine ca. Previous skin ca. Diabetes Medication: Thyroxine Estrogens Cortisone Anticoag. Antihist.
4 3 1 0 1
16.6 12.5 4.1 0 4.1
3 1 0 1 6
4.6 1.5 0 1.5 9.2
7 4 1 1 7
7.8 4.4 1.1 1.1 7.8
1 8 0 1 2
4.1 33.3 0 4.1 8.3
7 11 2 0 3
10.7 16.9 3 0 4.6
8 19 2 1 5
8.9 21.3 2.2 1.1 5.6
DISCUSSION
DR. JOHN STRICKLIN SPRATT, JR. (Louisville, KY): Dr. Humphrey has pinpointed an important issue. The interval cancer rate and the biological behavior of interval cancer holds the key to the evaluation of screening mammograms. Beginning with GershonCohen, and extending through a series of studies at the Ellis Fischel and from Europe, the gross rates of growth of primary and metastatic breast cancers are now known, but these data may all be truncated, since the time between observations may be too great to permit quantitation of the growth rates of the fastestgrowing breast cancers, as might account for the interval cancers. From extant growth data we have estimated that some breast cancers are so acute that they can go from the inception of the cancer to the death of the host in as brief a period of time as 120 days. Othet breast cancers are so chronic that the patient might live 23 years with no treatment at all. These chronic cancers, obviously, would be picked up by the annual mammography, while the acute cancers would be interval cancers. We have estimated, based on threshold size for diagnosis and metastases, that all breast cancers with doubling times of less than 17 days would be interval cancers. All patients that have cancers with doubling times of nine days or less will die within less than a year of inception. Based on present truncated data, we estimate that at least five per cent of all breast cancers fall in this acute category. If the theory of Gompertzian growth during the first 20 doublings of a clone of cancer cells is correct, then the interval rate might be higher than this. Further, many arguments regarding the biological effect of radiation on the induction of breast cancer can be answered by the accurate and diligent monitoring of cohort-specific interval cancer rates. A rate rising faster than could be accounted for by the aging of the cohort might, for example, mandate an early cessation of mammography. A falling rate would support the continuance of screening mammography. DR. WILLIAM WARNER SHINGLETON (Durham, North Carolina): I second what Dr. Spratt has said. I think the problem of the interval breast cancer in mass screening is a very important problem. I would like to present the data from our own screening clinic at Duke University. We're now in the fourth year of this screening project. Therefore, there have been 10,000 women who have been screened on three occasions.
359
However, the patient and the doctor must be aware that interval cancers occur frequently, thereby avoiding significant delay. Certain characteristics should draw attention to a special group of screenees such as those taking estrogens as well as those with a part history of a breast biopsy or mastectomy. References 1. Egan, R.: Mammography. The New Physician. 295, August 1963. 2. Mammography finds new use-assessing risk of breast cancer. JAMA 234(8):797, 1975. 3. Simon, N.: Breast Cancer Induced by Radiation. JAMA, 237(8): 789 1977. 4. Wanebo, H. J., Huvos, A. G., and Urban, J. A.: Treatment of Minimal Breast Cancer. Cancer, 33(2):349, 1974.
Our data is somewhat different than that presented by Dr. Humphrey. We have detected 70 cancers, and we have in this group found nine so-called interval cancers. Now, looking at the problem of the detection by nurse examination, we find that in these nine interval cancers six of them were not detected by the nurse who examined the patient, nor was the patient examined by a physician. In three other patients both the nurse and the physician examined the patient, and the cancer was not detected. The over-all accuracy, then, for mammography plus physical examination in our group is about 95%. However, since the nine interval cancers were missed on mammography, the accuracy of the mammography alone is approximately 82%. Now, I think most of the controversial points that have arisen about the detection of breast cancer by mass screening have been based on the Health Insurance Plan of New York study, with which you all are familiar. This study is about ten years old, and the techniques, including the amount of radiation used for the mammogram, was quite different than that being used in the demonstration projects today. I do believe that the data will soon be available to answer many of these perplexing problems. Dr. Oliver Beahrs, who is a member of this organization, is now chairing a committee to look at all the data from the twenty-seven screening clinics around the country. This will be data, then, on 270,000 women, approximately, who have undergone multiple screenings. I think this data might be available in six to nine months. DR. J. D. LEWIS (Milwaukee, Wisconsin): As has been pointed out, Dr. Humphrey and his group have highlighted some significant problems associated with screening, problems that generally have been recognized before screening started. We in Milwaukee have had the opportunity to follow our patients 4+ years at this time. (Slide) As with the other screening projects, we have screened approximately 10,000 patients. We have recommended 801 biopsies, of which 486 have been performed, which is consistent with the experience in Kansas. We have found 85 cancers in this group, 27 of which have been minimal; in other words, in situ cancers, or cancers with microinvasion less than five millimeters in size. During this period of time we have had (slide) a total of 118 interval procedures performed. This represents procedures that were not recommended at the last time that screening was done; 12 have
