T he accurate classification of the primary site and histology of reportable malignancies by cancer registrars requires careful review of the medical records, especially pathology and surgery reports. The pathologic distinction between cancer of the ovary and cancer of extraovarian tissue can be difficult. Extraovarian primary peritoneal carcinoma (EOPPC) is a cancer that arises in the peritoneum and mimics epithelial ovarian cancer in terms of symptoms, microscopic appearance, pattern of spread, treatment, and prognosis. [1][2][3] Primary serous carcinoma of the endometrium, fallopian tubes, broad ligament, or other specified female genital organs also may be misdiagnosed as primary epithelial ovarian cancer. 4 Little is known about the epidemiologies of EOPPC and other extraovarian cancers, such as mucoepidermoid carcinoma, cystadenocarcinoma, serous cystadenocarcinoma, and serous cystadenoma of borderline malignancy, that typically arise in ovarian tissue. Published reports are limited to descriptions of small case series. [1][2][3][5][6][7] The purpose of this report is to describe the incidence and distribution of selected extraovarian primary cancers by age, race and ethnicity, histology, grade, and stage. Three subsets of potentially misclassified extraovarian cancers that are known to influence the incidence of ovarian cancer were identified: 1) extraovarian cancers of the peritoneum; 2) extraovarian cancers of the endometrium; and 3) extraovarian cancers diagnosed in nonperitoneal and nonendometrial tissue of the corpus uteri, uterus, or other female genital tract organs. The extraovarian cancer subsets were drawn from women diagnosed with cancer between 1992 and 1997 in selected areas of the United States.
EOPPC: extraovarian primary peritoneal carcinoma; ESC: endometrial serous cystadenocarcinoma; EONPPC: extraovarian nonperitoneal primary carcinoma. a Includes only cancers with selected histology types (8430, 8440, 8441, and 8442).