Some limitations on studies about the relation between gross cystic disease and risk of subsequent breast cancer.

Studies about the relationship between gross cysts and risk of subsequent carcinoma of the breast should be interpreted with caution. When the study material is limited to microscopic review of benign biopsy specimens, there is considerable chance of misclassification of cases both of those with and of those without gross cysts. Moreover, statistical analyses based on internal comparisons of such data tend to separate the influence of gross cysts from that of any associated proliferative disease process. Thus, while they may provide information about whether or not gross cysts identified under a microscope influence the risk of breast cancer, independently of other, associated pathology, they do not address the question of whether or not gross cysts serve as a marker for an increased risk of breast cancer. On the other hand, statistical analyses based on external comparisons do not allow estimates of relative risks associated with gross cysts that are clearly unaffected by other factors related to breast cancer risk. Follow-up data on over 2500 patients who consulted Dr. C. D. Haagensen for gross cystic disease of the breast provide evidence of an increased risk of breast cancer, when compared with an external standard. A microscopic biopsy review of Dr. Haagensen's benign breast cases, with and without GCD, is currently under way to classify the cases in a way that is comparable to the Dupont and Page criteria. It is hoped that a statistical analysis that incorporates these microscopic findings with the clinical information and the gross pathology will shed further light on the role of gross cysts in relation to breast cancer.