Philip Strax

Mammography and clinical examination in mass screening for cancer of the breast

Periodic screening for cancer of the breast using mammography as well as clinical examination is being conducted by the Health Insurance Plan in a large random sample of women aged 40 to 64 years. A similar group of women has been assigned as controls. The long term objective is to determine whether the screening program results in lowering of mortality from mammary cancer. From the first screening examination among 20,211 women, the following observations can be made: 1. Screening has resulted in substantial detection of cancer; mammary cancer is detectable through screening an average of 21 months sooner than usual. 2. A higher proportion of cancers has been detected in the screened group (65%) in an early stage (as shown by the absence of axillary node involvement) than in the control group (41%). 3. Both mammography and clinical examination contribute to the early detection of cancer in mass screening. 4. Mammography and clinical examination are complimentary in detection. 5. Under different conditions of age, breast type and lesion characteristics, the two procedures have different rates of accuracy. 6. Mammography does comparatively well when the woman is older than 50, when the breasts are mostly fatty in type and when the lesion is in the lower half of the breast; clinical examinations do comparatively well when the woman is younger than 50, when the breasts are small and when the breasts are of the glandular type.

Results of mass screening for breast cancer in 50,000 examinations.

Detection of earlier breast cancer, especially in its preclinical stage, offers the only method available today for reducing mortality from this disease. The Health Insurance Plan study, conducted since 1963 under contract with the National Institutes of Health, has achieved a one‐third reduction in death rate in a study group compared to a matched control which has persisted in 7 years of follow‐up. The Guttman Institute, founded in 1968 to develop practical methods for large scale screening, is operating a tandem approach using interview, clinical examination, improved mammography, and thermography for greatest yield. Emphasis is placed on motivation to accept the examination, teaching and encouragement of breast self‐examination, and emphasis on periodic reexaminations. At the present time, almost 300 women receive this complete examination per day at the Institutes fixed facility. Periodic examination leads to marked increase in number of cancers detected free of axillary nodal involvement. The tandem approach emphasizes substantial percentage of cancers detected on only one modality, two‐thirds of which are without nodal involvement. Breast self‐examination is necessary to detect “interval” cancers in more localized stage.

Strategy (motivation) for detection of early breast cancer

For successful strategy to increase motivation for mass screening for detection of early breast cancer, three elements are needed: 1) women at risk must be taught the necessity of the examination; 2) they must be made aware of the existence of the facility, which must be made easily accessible; and 3) they must be reassured that the examination is simple, effective, and safe.

New techniques in mass screening for breast cancer

The substantial short‐term reduction in mortality achieved in the mass screening for breast cancer program of the Health Insurance Plan of Greater New York was the impetus for development of more practical methods for mass screening. We describe here some of the newer concepts in this regard. A complete examination should include interview, clinical examination, mammography, and thermography. Paramedical personnel can be trained for prescreening in all phases of the procedure.

Value of Mammography

Clinical examination with inspection and palpation for detection of breast cancer has been found increasingly inadequate in recent years. It is becoming evident that breast cancer is present for a substantial period of time in a non-palpable stage. It is also apparent that detection and treatment of the disease in this occult stage leads to increased survival and improved cure rate. Mammography is the only practical means available today to detect and localize the lesion before it can be felt. Mammography is of great value under the following conditions: a. In the presence of a questionable mass on palpation, mammography can help clarify the issue. b. When a palpable lesion is present which appears benign but requires surgery, another lesion which is not palpable may be present in the same breast and be detectable only on mammography. The latter lesion may be a cancer. c. The breast opposite to the one with a palpable lesion may harbor a non-palpable cancer. d. The greatest value of mammography may lie in screening for breast cancer. In all studies to date, up to 45% of cancers are negative to palpation and detected on mammography alone. These are in a particularly early stage with a high degree of curability. The radiation dose used has been reduced by use of film-screen combinations to under 5% of 1 rad to the mid breast, at the same time that quality has been greatly improved. Such minute doses are considered negligible in light of the great potential benefit. Mammography is widely accepted as a valuable modality in the detection and diagnosis of breast cancer. It is becoming increasingly apparent that breast cancer may exist for a substantial period of time before it becomes clinically obvious by palpation. During this time, it may be detectable by mammography. Such detection may be possible when the immunocompetence of the host is intact and when removal of the growth results in a high rate of curability.