Microscopic Benign and Invasive Malignant Neoplasms and a Cancer-Prone Phenotype in Prophylactic Oophorectomies

Abstract

The occurrence of approximately 5% of common epithelial malignant tumors of the ovary can be traced to inheritance of risk. One prohylactic strategy to decrease the probability of development of disease in individuals within families where this mendelian-dominant pattern of occurrence is apparent is to remove the ovaries of individuals at risk for ovarian cancer. The procedure, when done for this purpose, is recommended soon after completion of childbearing. Our goal was to compare the histologic features of the ovaries of women at increased risk for ovarian cancer to those at no known increased risk for the disease. Ovaries removed for prophylaxis from 20 women considered to be at increased risk for developing ovarian cancer were examined histologically. During the course of this work, it seemed apparent that these ovaries contained numerous atypical features compared with the expected appearance of normal ovaries. Hence, we expanded the study to include a control group whose ovaries were removed for reasons unrelated to cancer. The study, therefore, was not blinded. The increased risk in the cancer-prone individuals was determined by family history, specifically the presence of at least one first-degree relative and one second-degree relative with ovarian and/or breast cancer and positive linkage or mutational analysis of BRCA1 in some. The difference in mean ages of patients in the control and high-risk groups was not statistically significant. The difference among both groups with respect to the number of atypical features as well as the intensity of those features was ascertained by computing probabilities using Fisher's exact test (two-sided) for rows × columns contingency tables. Two unanticipated microscopic or near-microscopic malignant neoplasms and other benign and borderline tumors were discovered in the ovaries of the high-risk individuals. Of substantial interest was the finding that among the ovaries of high-risk women, 85% presented two or more and 75% presented three or more of the following histologic features: surface epithelial pseudostratification; surface papillomatosis; deep cortical invaginations of the surface epithelium, frequently with multiple papillary projections within small cystic spaces (microscopic papillary cystadenomas); epithelial inclusion cysts, frequently with epithelial hyperplasia and papillary formations; cortical stromal hyperplasia and hyperthecosis; increased follicular activity; corpus luteum hyperplasia; or hilar cell hyperplasia. Two or more or three or more such changes were observed in a lesser percentage (30% or 10%, respectively) of ovaries obtained from the control individuals, with a statistically significant difference ( P =.001 or P =.00007, respectively), particularly considering that a detailed determination of a family history of cancer in the control group was not possible. The frequency of these changes in the high-risk ovaries compared with control ovaries suggests a characteristic histologic preneoplastic phenotype defined by an increased frequency and intensity of the above-described histologic features in the high-risk ovaries. Limited access to numerous small (stage I) ovarian cancers or cancer-prone ovaries by any one pathologist may explain the failure to identify the phenotype in the past. We suggest that the ovaries removed from ovarian cancer-prone individuals as a preventative measure should be thoroughly examined histologically to identify or rule out microscopic or near-microscopic invasive neoplasms. [J Natl Cancer Inst 1996;88:1810–20]