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Background: Women with proliferative benign breast lesions are at increased risk of breast cancer, and some studies have provided evidence that microscopic calcifications in such lesions enhance the risk., Purpose: This study was performed to determine whether calcifications on mammograms are predictive of subsequent breast cancer., Methods: Data for this study were collected on women enrolled at four of the clinics that participated in the Breast Cancer Detection and Demonstration Project (BCDDP). The presence, morphology, and distribution of calcifications visualized on baseline mammograms for 686 women who developed breast cancer over a 7- to 10-year period of follow-up were compared with those for 1357 controls who remained cancer free. We also compared presence and types of calcifications in breasts in which cancer subsequently developed with those in the contralateral breast., Results: Calcifications were evident at baseline in at least one breast in 381 (55.5%) of 686 cases and in 606 (44.7%) of 1357 controls. The estimated relative risk (RR) of breast cancer was 1.68 in women with calcifications, compared with those having none. There was a statistically significant trend of increasing risk with number of breasts with calcifications; RR increased from 1.28 to 2.14 in women with calcifications in one and both breasts, respectively. In women with unilateral calcifications, RR was greater for the breast in which the calcification occurred (1.48) than for the opposite breast (1.08). The elevated risk persisted for more than 6 years from identification of the calcification, suggesting that these lesions were not indicative of existing carcinomas detected later. Risk was greatest in women with clustered calcifications of any morphology or linearly distributed punctate calcifications (RR = 3.64), and the cancer in women with such calcifications was 4.65 times more likely to occur in the involved breast than in the contralateral breast. Multiple and scattered punctate calcifications, and those of any number or distribution that were ring-shaped or linear, were also associated with subsequent risk of breast cancer (RR = 2.09 and 1.76, respectively) but were not strongly predictive of the side on which the breast cancer occurred. Risk was not altered in women with single punctate or large conglomerate calcifications, although the cancers that subsequently occurred in women with the latter lesions were over three times more likely to develop in the breast with the calcification than in the opposite breast., Conclusions: These findings are consistent with previously reported relationships between breast cancer and specific histologic types of noninvasive breast lesions. Some types of mammographic calcifications appear to be independent risk factors for breast cancer., Implications: If these results are confirmed by other investigators, mammographic calcifications could serve as an additional indicator of women at high risk for breast cancer who may benefit from intensified follow-up.

Mammographic parenchymal patterns have been proposed as a method of determining women at high risk of developing breast cancer. Wolfe's original report of relative risks as high as 37:1 for "dysplastic" breasts (DY) as compared with adipose breasts (N1), with intermediate values of P1 and P2, were not uniformly confirmed by others. (Relative risks are used here as the equivalent of odds ratios.) A case-control study of 706 breast cancers, each with two matching controls, drawn from 40,000 participants in four Breast Cancer Detection Demonstration Project clinics, was conducted to assess the role of the Wolfe classification of breast parenchymal patterns as a breast-cancer risk factor together with a set of well-established risk factors for breast cancer. Relative risks of 3.1 for DY to N1, 3.5 for P2 to N1, and 2.0 for P1 to N1 were determined. These are comparable to or greater than other known risk factors found in the same population. The Wolfe classification of parenchymal patterns strengthens the basis for clinical judgment, but should not be used exclusively to determine intervention in an individual patient's care.

The Wolfe Classification System of evaluating risk of developing breast cancer from analysis of mammographic parenchymal patterns (MPP) has received worldwide attention. In addition to confirming its validity, it is necessary to establish the ability of radiologists to apply the classification of mammograms consistently and reproducibly. This paper reports the results of 12 radiologists associated with the former Breast Cancer Detection Demonstration Projects (BCDDP) in Ann Arbor, Honolulu, Seattle, and Tucson. The participating radiologists had all had some experience with classifying mammograms, then were exposed to more intensive instruction, and finally worked with atlases developed at each institution. The results reported here show the comparisons of the radiologists' readings with Dr. Wolfe in a series of three separate exercises and also three tests of intraobserver consistency. Two of the participating institutions used xeromammograms and two, film mammograms. The study was designed and supervised by an independent data coordinating center with masking of mammograms, without benefit of information of previous readings and no information available except age. The results indicate that this group of radiologists could classify mammograms in the method of Wolfe at an acceptable level compared to other similar exercises.

Non-visualization of the retromammary space and ribs has been a source of concern to mammographers. In six years, 186 cancers were detected in our experience of 10 034 self-referred asymptomatic women at the University of Michigan Breast Cancer Detection Demonstration Project. These cancers were used to analyze the need to visualize the retromammary space and ribs, or both sites, if adequate technical factors were used. All the cancers were analyzed for position on the film, number of films required for visualization, relationship of the tumor to the posterior edge of the film, number of occult tumors, tumor size, histologic type, sensitivity of detection method and the number of interval cancers. Of the 186 cancers, 168 (90%) were detected on mammograms. All of the cancers were visualized on the mediolateral view; three were not visualized on the craniocaudal view. Six per cent of the cancers were within 1 cm of the posterior edge of the film; the remaining 94% were located more anteriorly in the breast. The imaged tumors were smaller and had a significantly higher percentage of non-invasive cancers than found in a symptomatic clinical population. Therefore, mammography, using proper technique, will consistently permit visualization of cancer in the breast, regardless of tumor size, histologic type, or location in the breast.