This is the first time in more than 15 years, since cisplatin was developed and incorporated into the initial therapy of ovarian cancer, that these patients have shown a notable improvement in survival. Results from McGuire's study were presented in May at the American Society of Clinical Oncology (ASCO) meeting in Los Angeles. The trials were held in conjunction with the Gynecologic Oncology Group of the National Cancer Institute.
Standard therapy for advanced (stage III and IV) ovarian cancer has typically been cisplatin and cyclophosphamide, although survival has been poor. Of the women receiving the new therapy of cisplatin and paclitaxel, 73 percent responded favorably, meaning that their tumors shrank, compared to only 60 percent in the standard therapy group. The interval between the favorable response and a recurrence of new tumor cell growth was on average five months longer with the new treatment.
"Gaining some extra time while still feeling relatively good means a lot to patients," said McGuire. "This is a disease that gives few warning signs and is not easy to detect early. The knowledge we have gained in this trial makes improving cure rates a far more realistic goal."
Physicians are now evaluating paclitaxel for use as a primary treatment in earlier stages of ovarian cancer. "We think it may have an even greater effect for the early patients," said McGuire.
Preliminary data from the study were reported in 1993. However, the duration of follow-up was too short to allow assessment of overall survival. This announcement represents the mature data on survival, with about 42 percent of the patients treated still being followed.
While side effects such as fever and white blood cell loss were more common in the paclitaxel/cisplatin group, they were longer lasting in the standard therapy group. Persistently low white counts caused delays in scheduled treatments more often with the cisplatin/cyclophosphamide patients. More patients in the paclitaxel group finished all six courses of therapy.
Although ovarian cancer has a high mortality rate (60 percent), significant progress has been made in treatment. Paclitaxel was initially approved by the Food and Drug Administration in 1992 for treating women with ovarian cancer on the basis of the results of trials of 24-hour infusions of paclitaxel alone. Studies have shown that a three-hour infusion of paclitaxel is as effective as the longer infusion, but as a salvage regimen only. McGuire cautioned that "the use of shorter infusion schedules in primary therapy may reduce response and survival."
Early, curable ovarian cancer produces no symptoms. The most common sign is enlargement of the abdomen caused by the accumulation of fluid. In women over 40, vague digestive disturbances (stomach discomfort, gas, distention) that persist and cannot be explained by any other cause may indicate a need for a thorough exam.
The American Cancer Society estimates that 14,500 women will die of ovarian cancer in 1995, and 26,600 new cases will be diagnosed. Ovarian cancer accounts for four percent of all cancers among women and ranks second in incidence among gynecologic cancers. It causes more deaths than any other female reproductive system cancer.
-- Kate Egan