5. The correct answer is C. The tumors are serous papillary cystadenocarcinomas of the ovaries. These tumors express CA-125 and are apparently derived from the surface epithelium of the ovaries.
Alpha-fetoprotein (choice A) is not produced by this type of ovarian tumor but can be produced by testicular tumors and, less commonly, by ovarian tumors with a yolk sac tumor component.
Bombesin (choice B) is a marker for neuroblastoma, small cell carcinoma, gastric carcinoma, and pancreatic carcinoma.
PSA (choice D) is a marker for prostatic carcinoma.
S-100 (choice E) is a marker for melanoma, neural tumors, and astrocytomas.