Early ovarian cancer test sought
Does a test that promises to detect ovarian cancer sooner really do so? Could other tests nearing the market prolong survival by getting patients the right care faster?
A race is on for blood tests to better detect this intractable killer, but the Food and Drug Administration is probing whether to crack down on the first one to sell.
It’s a time of both hope and confusion.
First, the question is whether testing giant LabCorp jumped the gun in selling OvaSure as an ovarian cancer screening test before researchers proved that it caught the tumor in an early, treatable stage without falsely alarming too many healthy women. A legal quirk let sales begin without formal FDA approval.
In fact, U.S. and British scientists are just beginning studies specially designed to prove whether signs of ovarian cancer can be measured reliably in a blood test months or even a year before a tumor becomes life-threatening.
“You really need evidence that screening actually saves lives, or at least prolongs survival,” cautions Dr. Robert Bast Jr., an ovarian biomarker expert at M.D. Anderson Cancer Center in Houston.
Although the FDA won’t discuss its ongoing probe of OvaSure, it is watching the field closely.
“It’s not a question of if, it’s a question of when the right test will come along with the right credentialing to help improve healthcare in this important area,” says Dr. Steven Gutman, FDA’s diagnostic testing chief.
At the same time, competing companies are seeking FDA approval for a different approach: blood tests to help identify which women with an ovarian lump or cyst are most likely to have cancer, so they can have their crucial first surgery -- the one that diagnoses malignancy -- done by a specialist.
Thousands of women get cysts but only a fraction of those turn into cancer. Studies show that even advanced patients can live many months longer if that first, diagnostic operation is done by a gynecologic oncologist, who knows where cancer hides and how to remove pelvic lymph nodes, instead of the general surgeon most see women today.
“That’s a big, big step forward for women because it allows them to get the proper care,” says Dr. Richard Moore of Brown University, who led a study of Fujirebio Diagnostics Inc.’s so-called triage test that correctly predicted cancerous cysts more than 90% of the time.
“It really is an unmet need,” Bast said.
Nearly 22,000 U.S. women will be diagnosed with ovarian cancer this year. Most see a doctor after experiencing symptoms -- bloating, a swollen abdomen, pelvic pain, frequent urination -- that appear after the cancer has spread, when long-term survival plummets. More than 15,000 patients die each year.
Women at high risk because of gene mutations are advised to have their ovaries removed for protection. For the general population, the goal is a blood test to detect early cancer signs such as molecules that tumor cells shed, or perhaps unusual hormone changes, without sending too many women to unnecessary surgery. In the pipeline:
* Two tumor markers, CA125 and one just approved by the FDA called HE4, used to track whether chemotherapy is working or cancer is returning. A one-time CA125 test can’t screen seemingly healthy women because levels rise with benign cysts, endometriosis, even normal menstruation. But Fujirebio’s triage test uses HE4 and CA125 to assess who most likely has a benign cyst and whose may be cancer.
* LabCorp in June began marketing to high-risk women a screening test developed by Yale University, under a law that allows a single laboratory to offer testing without FDA review. Yale researchers used OvaSure on blood samples stored from cancer patients and healthy women, and found it correctly identified cancer 95% of the time with few false alarms. But specialists say that doesn’t prove OvaSure can detect when cancer is forming -- just that it spotted tumors in a few patients already diagnosed with early-stage disease.
“We believe you are offering a high-risk test that has not received adequate clinical validation and may harm the public health,” the FDA warned LabCorp last month.
The FDA several years ago forced a similarly marketed ovarian test off the market. LabCorp spokesman Eric Lindblom wouldn’t disclose results of a recent FDA meeting, but said Yale was working to validate OvaSure and “we’re continuing to offer the test at this time.”
* Tracking seemingly healthy women well before they’re diagnosed is the only way to prove a test finds cancer early, says Dr. Michael Birrer of the National Cancer Institute -- work that is just beginning.
Dr. Nicole Urban of Seattle’s Fred Hutchinson Cancer Center is heading a multi-hospital test of blood stored a full year before 120 women were diagnosed with ovarian cancer to see which biomarkers are most promising.
“The thing we did not know is how early these markers give a signal,” said Urban, whose hunt is joined by Yale, M.D. Anderson and other leading ovarian cancer centers.
Also, British researchers have enrolled 200,000 women in a study to see if annual CA125 testing will spot simmering tumors. The idea: High jumps in CA125 levels might give a better signal than a one-time test.
