Metastases to the genital tract may occur as a result of recognizable widely disseminated disease from another site or as an isolated lesion. In the latter case, it may be difficult to distinguish between a primary tumor of the gynecologic tract or metastases to the gynecologic tract from a nongynecologic site. Because treatment planning and appropriateness of surgery may be dictated by the primary site of the tumor, it is important to make the distinction between primary and metastatic disease. This chapter focuses on common sites of metastases to the gynecologic tract, characteristic clinical presentations, and radiologic and pathologic considerations that may be clinically helpful in treatment planning.
Metastatic disease to the gynecologic organs most commonly arises from colorectal, breast, gastric, and appendiceal primary malignancies.
Within the reproductive tract, the ovaries and vagina are the organs most commonly affected by metastatic disease.
Malignant masses or lesions in the gynecologic organs should be considered as potential sites of metastases if an established primary malignancy is of advanced stage or demonstrates poor prognostic factors.
Metastatic disease to the genital tract from nongenital tract malignancies is relatively uncommon but is influenced by geographic differences in cancer incidence. For instance, in Asian countries where gastric cancer is more common, metastatic disease to the genital tract is more prevalent. In Japan, 18% to 29% of tumors found in the reproductive organs may be nongynecologic in origin; in Thailand, where cholangiocarcinoma is quite prevalent, 7% of all metastases to the genital tract may arise from the gallbladder or extrahepatic biliary tract.1 A single-institution review from the United States of 445,000 accessioned cases identified 325 metastatic tumors to the genital tract over a 32-year time period; 149 (45.8%) were from extragenital sites including the colon and rectum, breast, stomach, and appendix. Additional primary sites included the bladder, ileum, and cutaneous melanoma. The remaining sites of metastases originated from other areas within the genital tract such as the endometrium.2
The ovaries and vagina are, by far, the structures most commonly involved with nongenital tract metastases. Although percentages may vary by geographic area, the most common primary sites of disease metastatic to the ovaries typically arise from the gastrointestinal (GI) tract (large intestine and stomach, pancreas, biliary tract, and appendix) and breast. These sites comprise 50% to 90% of the metastatic cancers to the ovaries (Table 17-1). Although the histology of a metastatic breast cancer may look uniquely like breast cancer, metastases from other sites, such as the pancreas and appendix, are mucinous and can be difficult to distinguish from a primary mucinous tumor of the ovary. Endometrioid-appearing histologies in the ovary can arise from metastatic colon cancer, and clear cell histology can be confused with signet ring cells from a gastric cancer or a metastatic clear cell renal carcinoma. In the case of breast cancer, metastases ...