September 16, 2009
Ovarian Cancer Screening: The Elusive Goal
“I don’t understand why there isn’t a test to pick this up earlier! I just saw my gynecologist 6 months ago.â€ I often hear questions like this from distraught women who have just been given a new diagnosis of advanced stage ovarian cancer. I understand their profound frustration. One day they are feeling relatively well and the next they find themselves battling the most aggressive gynecologic cancer.
If ever there was a cancer in need of an effective screen, its ovarian cancer. Consider these facts; approximately 20,000 new cases of ovarian cancer are diagnosed each year in the United States and approximately 16,000 deaths are attributed to the disease. The 5- year survival rate for patients diagnosed with cancer confined to the ovary is over 90% but drops to 25-30% for women whose disease has spread to the upper abdomen or distant sites. The problem with ovarian cancer is that the vast majority of newly diagnosed patients are found with disease that has already spread. An effective screening test would shift diagnosis towards the early stages and would thus result in a significant improvement in measurements of survival. This is what the Pap smear did for cervical cancer and mammography did for breast cancer. So why is there no effective screen for ovarian cancer?
Unfortunately our knowledge of the mechanisms and timing of how ovarian cancer spreads is limited. It is possible that in some patients with advanced ovarian cancer, the disease started in the ovary and other sites simultaneously. Screening would be of limited benefit in such a patient because she never had an “early stage.â€ It has also proven difficult to find screening tests with sufficient sensitivity to detect small volumes of ovarian cancer while limiting false-positives.
Studies are in progress to identify a single test or combination of tests that can be offered to women, as part of routine examinations, that will improve the survival rate in ovarian cancer. Most of these studies have involved a combination of serial pelvic sonograms and blood tests that can detect early ovarian cancer. The most extensively studied blood test is CA-125.Â CA-125 is a protein found at elevated levels in the blood of 75% women with ovarian cancer. Unfortunately, those levels can also be elevated in cases of a number of common benign disorders such as uterine fibroids and pelvic endometriosis, thereby increasing the possibility of false-positives.Â A large randomized trial sponsored by the National Cancer Institute to examine the efficacy of screening for ovarian cancer with pelvic sonogram and CA-125 blood tests is underway. Over 38,000 women were screened with the combination and only 20 invasive ovarian cancers were detected. Many of these cancers were found to be at an advanced stage, reducing the likelihood of a survival benefit.Â Only 1% of women with an abnormal sonogram, 3.5 % of women with an abnormal CA 125 level and 23% of women with both tests abnormal were ultimately diagnosed with ovarian cancer.
While survival data comparing screened and unscreened women is still pending, the recommendation against routine ovarian cancer screening in women at average risk remains unchanged for now. The search goes on for alternative approaches, such as novel tumor markers to be used in conjunction with CA-125.
Until the development of an effective screen for ovarian cancer, it is important that patients and their physicians are sensitive to the ways that ovarian cancer expresses itself symptomatically.Â It is not the silent disease we once believed it to be. Recent studies have shown that many women diagnosed with advanced stage ovarian cancer had symptoms of the disease in the months preceding their diagnosis. These symptoms, often vague and nonspecific, include abdominal bloating, crampy abdominal pain, an inability to eat as much as usual, as well as changes in bowel and bladder habits such as constipation or urinary frequency. Often patients have a constellation of these symptoms but the possibility of ovarian cancer is not considered and diagnostic tests such as pelvic sonograms are delayed. The majority of women with these symptoms do not have ovarian cancer, but for the small minority that do early detection may be the difference between life and death. So listen to your body closely because while ovarian cancer will speak to you, often it whispers.
Dr. Kevin Holcomb, MD, is presently an associate professor of clinical obstetrics and gynecology at the Weill Medical College of Cornell University as well as a member of the division of gynecologic oncology at New York Presbyterian Hospital. Named one of America’s Leading Doctors by Black Enterprise in 2009, he has a strong clinical interest in the role of laparoscopic and robotic surgery in gynecologic oncology and has contributed to the literature regarding the treatment of locally advanced cervical cancer and pre-invasive cervical lesions in HIV-positive women.