Women who have had ovarian cancer typically undergo routine blood testing every three months that measures levels of a protein called CA125. The test is used to detect the recurrence of the disease before symptoms appear, so that patients can decide if they wish to begin chemotherapy earlier. However, a new study conducted in 10 countries, including Britain, has found that earlier detection in women who have already had the disease does not help them live longer.
The researchers compared 265 women who had begun chemotherapy after finding that their CA125 levels had risen against 264 women who had waited until symptoms appeared to begin chemo. On average the women in the first group had undergone chemotherapy five months earlier. The researchers found that overall median survival rates for both groups were approximately the same: about 41 months from the start of their remission. And for those women who underwent chemotherapy earlier, their quality of life seemed to worsen. The findings go against the common wisdom that it’s always better to detect and treat cancer earlier.
“For the first time, women can be reassured that there’s no benefit to early detection of relapse from routine CA125 testing,” says Dr. Gordon J. S. Rustin, director of medical oncology at Mount Vernon Hospital in Middlesex, England, and the lead author of the study. Dr. Rustin says that the reason for the counterintuitive results was not that CA125 was a poor predictor of cancer’s return. Rather, he says, “Some cancers are sensitive to chemotherapy, so it does not matter if they are treated early. Other tumors are resistant to chemotherapy and do not respond to treatment no matter when it was given.”
The study only refers to women whose ovarian cancer is in remission – not women who have been initially diagnosed. Early detection is critical for women who have never had the disease, which can be treated by surgery. For relapsed ovarian cancer patients, surgery is not typically an option.
Dr. Beth Karlan, director of gynecologic oncology at Cedars Sinai Medical Center in Los Angeles, says the results of the new trial would “make us all rethink the approach to treating patients with recurrent ovarian cancer.” Dr. Karlan was not involved in the study, but provided commentary on it. Unlike Dr. Rustin, who suggests that women could safely forgo such testing, Dr. Karlan says that CA125 testing should be done less frequently. But she did not say it should be eliminated and that patients would not accept that anyway. “Many women often say they live from one CA125 to the next,” she says.
Study findings were presented at the recent annual meeting of the American Society of Clinical Oncology, held in Orlando, Florida. The research is another in a series suggesting that early detection doesn’t always lead to better outcomes. This past March, a prostate cancer study found that earlier detection of the disease using the PSA blood test led to unnecessary treatments, but didn’t help men live any longer.
News Release: Doubts on Ovarian Cancer Relapse Test www.nytimes.com May 31, 2009
