Chemotherapy standard for ovarian cancer
By V. UPENDER RAO
Published April 25, 2005
Ovarian cancer is the most lethal of all gynecological cancers. This year, there will be an estimated 22,000 new cases and 16,000 deaths from it.
Early diagnosis followed by surgery and chemotherapy offers the best chance for cure. Unfortunately, most ovarian cancers in early stages cause either no symptoms or mild nonspecific symptoms that are attributed to other common ailments. As a result, more than 70 percent of patients are diagnosed with an advanced stage, where the possibility of cure is significantly decreased.
Unlike Pap smears for cervical cancer, mammography for breast cancer and colonoscopy for colorectal cancer, there is no reliable marker for early detection of ovarian cancer. Blood marker Ca 125 and vaginal ultrasound have been studied for early detection of high-risk patients, without much success. Blood tests to assess the molecular footprints of early ovarian cancer are possible but not perfected for routine use at this time.
For recurrent ovarian cancer, chemotherapy is the standard treatment. A number of active agents are available whose efficacy largely depends on the initial response to treatment and the amount of time the patient remained disease free prior to recurrence.
Those patients whose disease recurs after at least six to 12 months of remission can be expected to respond to platinum-based chemotherapy, and those with shorter remission times can respond to other agents such as Doxil, Gemzar, Topotecan and the Taxanes.
Weekly treatments are equally effective and generally less toxic and better tolerated. Weekly administration also overcomes drug resistance by recruiting the process of anti-angiogenesis in addition to its usual cytotoxic effect.
A monoclonal antibody, Ova Rex, is being evaluated. Results of a large double blind study from multiple centers in the United States and Canada are pending. Monoclonal antibodies have recently become available for malignant lymphoma, breast, lung and colon cancers.
These monoclonals are safe, effective and are widely used in oncology practices today.
Using the available agents in combination and in sequence, many years of useful and functional life can be expected for patients with recurrent ovarian cancer. Some patients, however, have particularly aggressive disease that acquires multiple drug resistance early in the course of the disease. It is hoped that such tumors could be analyzed by molecular techniques for the purpose of identification and development of targeted therapies.
--Dr. V. Upender Rao, FACP, practices at the Cancer and Blood Disease Center in Lecanto.