After a prophylactic oophorectomy, a small percentage of women may develop a primary peritoneal carcinoma, similar in appearance to ovarian cancer. The prognostic information presented below deals only with epithelial carcinomas. Stromal and germ cell tumors are relatively uncommon and comprise less than 10% of cases. (Refer to the PDQ summaries on Ovarian Germ Cell Tumor Treatment and Ovarian Low Malignant Potential Tumor Treatment for more information.)
Ovarian cancer usually spreads via local shedding into the peritoneal cavity followed by implantation on the peritoneum and via local invasion of bowel and bladder. The incidence of positive nodes at primary surgery has been reported to be as much as 24% in patients with stage I disease, 50% in patients with stage II disease, 74% in patients with stage III disease, and 73% in patients with stage IV disease. In this study, the pelvic nodes were involved as often as the para-aortic nodes. Tumor cells may also block diaphragmatic lymphatics. The resulting impairment of lymphatic drainage of the peritoneum is thought to play a role in development of ascites in ovarian cancer. Also, transdiaphragmatic spread to the pleura is common.
Prognosis in ovarian cancer is influenced by several factors, but multivariate analyses suggest that the most important favorable factors include:[17,18,19,20,21]
- Younger age.
- Good performance status.
- Cell type other than mucinous and clear cell.
- Lower stage.
- Well-differentiated tumor.
- Smaller disease volume prior to any surgical debulking.
- Absence of ascites.
- Smaller residual tumor following primary cytoreductive surgery.
For patients with stage I disease, the most important prognostic factor is grade, followed by dense adherence and large-volume ascites. DNA flow cytometric analysis of stage I and stage IIA patients may identify a group of high-risk patients. Patients with clear cell histology appear to have a worse prognosis. Patients with a significant component of transitional cell carcinoma appear to have a better prognosis.
Although the ovarian cancer-associated antigen, CA 125, has no prognostic significance when measured at the time of diagnosis, it has a high correlation with survival when measured 1 month after the third course of chemotherapy for patients with stage III or stage IV disease. For patients whose elevated CA 125 normalizes with chemotherapy, more than one subsequent elevated CA 125 measurement is highly predictive of active disease, but this does not mandate immediate therapy.[27,28]
Case-control studies suggest that BRCA1 and BRCA2 mutation carriers have improved responses to chemotherapy when compared with patients with sporadic epithelial ovarian cancer. This may be the result of a deficient homologous DNA repair mechanism in these tumors, which leads to increased sensitivity to chemotherapy agents.[29,30]
Most patients with ovarian cancer have widespread disease at presentation. This may be partly explained by relatively early spread (and implantation) of high-grade papillary serous cancers to the rest of the peritoneal cavity. Conversely, symptoms such as abdominal pain and swelling, gastrointestinal symptoms, and pelvic pain often go unrecognized, leading to delays in diagnosis. Screening procedures such as gynecologic assessment, vaginal ultrasound, and CA 125 assay have had low predictive value in detecting ovarian cancer in women without special risk factors.[32,33] Efforts have been made to enhance physician and patient awareness of the occurrence of these nonspecific symptoms.[34,35,36,37,38] (Refer to the PDQ summaries on Pain and Gastrointestinal Complications for more information.) As a result of these confounding factors, yearly mortality in ovarian cancer is approximately 65% of the incidence rate. Long-term follow-up of suboptimally debulked stage III and stage IV patients showed a 5-year survival rate of less than 10% with platinum-based combination therapy prior to the current generation of trials including taxanes. By contrast, optimally debulked stage III patients treated with a combination of intravenous taxane and intraperitoneal platinum plus taxane achieved a median survival of 66 months in a Gynecologic Oncology Group trial. Numerous clinical trials are in progress to refine existing therapy and test the value of different approaches to postoperative drug and radiation therapy. Patients with any stage of ovarian cancer are appropriate candidates for clinical trials.[40,41] Information about ongoing clinical trials is available from the NCI Web site.