Tervooren had her ovaries removed because there is no proven method to detect cancer in that organ early. Ovarian cancer, like other cancers, is screaming for some kind of advance in early detection. And the search is on for "biomarkers"—DNA, RNA, or proteins in the blood and other bodily fluids that indicate the presence or progress of disease in the body. In fact, says Lee Hartwell, president and director of Fred Hutchinson, the hope is that these markers will not only point out cancer early but also help characterize it, reveal whether it's responding to therapy, and indicate whether a recurrence is likely.
Researchers at Fred Hutchinson are now investigating whether the body's immune response to the earliest presence of lung cancer can be detected in the blood, much the way an HIV test searches for antibodies to the virus. Other researchers have identified a potential protein biomarker for ovarian cancer called HE4, now in use to determine how far a tumor has advanced and being studied for screening.
The challenge is not so much finding markers as it is knowing what they mean. Don Listwin, founder and chair of the Canary Foundation, a nonprofit devoted to early-detection research, points out that markers aren't very useful unless they indicate only cancer and can distinguish the lethal types from ones that aren't likely to progress.
Prostate-specific antigen, or PSA, for example, can indicate the presence of prostate cancer. But it also leads to false alarms and detects slow-growing cancers that most likely would never have caused harm. Just this month, the Food and Drug Administration chastised the manufacturer of OvaSure for marketing—without approval—the new blood test that measures the level of six proteins associated with ovarian cancer. It's not definitive, and gynecologists worry that it will lead women to have unnecessary surgery to remove their ovaries. Canary has launched a clinical study to identify biomarkers that predict the more aggressive forms of prostate cancer and is also investigating early detection of lung, pancreatic, and ovarian cancers.
While researchers are optimistic, it's important to note that biomarkers have to be shown not just to find cancer early but to reduce mortality from the disease, says Beth Karlan, director of the Women's Cancer Research Institute at Cedars-Sinai Medical Center in Los Angeles and a member of the team that identified HE4. As history teaches, when it comes to cancer, there's good reason to temper optimism with caution. Fulfilling all this promise will take time, which won't please those who are tired of waiting. But "in 10 or 20 years," predicts M.D. Anderson's DuBois, "there will be a whole different way of detecting and treating cancer."