Misdiagnosis w/Ova & GI Cancers

Misdiagnosis a problem with ovarian, GI cancers OB/GYN UPDATE

By Jenny Manzer

MONTREAL

Almost 10% of women who undergo surgery for ovarian cancer actually have gastrointestinal (GI) cancer, according to new research out of Quebec City.

Misdiagnosis could lead to patients receiving a useless course of chemotherapy and an inaccurate estimate of their life expectancy, warns lead researcher Dr. Marie Plante, a gynecologic oncologist and associate professor at Laval University in Quebec City.

"It's a little bit embarrassing," she said, noting patients with advanced GI cancer have a much shorter life expectancy than those with ovarian cancer. Knowing they only have a few months to live, patients may make different decisions about treatment, she said.

Using database software, researchers retrospectively reviewed all presumed advanced ovarian cancer managed with upfront surgery where final pathology revealed a non-ovarian primary.

Study subjects ranged in age from 36 to 78, and were operated on at Pavillon L'Hôtel-Dieu de Québec between January 1997 and July 1999. Their diagnosis was based on signs, symptoms and thorough preoperative investigation. In general, patients received a CT scan or a sonogram of their abdomen and pelvis and a GI investigation directed according to symptoms, said Dr. Plante.

Researchers discovered that out of 193 women, 10% of those operated on for advanced ovarian cancer actually had a non-ovarian primary. Of the cancers that weren't ovarian, 95% originated from the GI tract.

Dr. Plante said she undertook the study to determine the value of "neoadjuvant" or upfront surgery in managing advanced ovarian cancer. At the moment, there is debate over whether it may be preferable to shrink the mass with chemotherapy before undertaking surgery, she said.

Currently, the standard treatment for advanced ovarian cancer is to operate first to remove as much cancer as possible, with the idea that the remaining cancer will be more treatable, said Dr. Plante during an interview.

Maximal surgery is extremely aggressive—often involving removal of the colon and spleen—and the risk of complications is high, she said. "That's why there is a lot of interest in seeing whether we can change the timing of treatment to try and diminish the bulk of the tumour with chemotherapy first, then do surgery," she said. "That's the controversy."

Their findings indicate upfront surgery should remain the gold standard to achieve an accurate diagnosis, despite the risks involved, said Dr. Plante, who presented the study at the meeting here.

"My main concern is that when you do the chemotherapy first, you may be treating as an ovarian cancer (patient) someone that doesn't have an ovarian cancer. Because the signs, the symptoms, the X-ray findings, even a small biopsy can give you the impression it's an ovarian cancer, but it's not."

As well as the risk of subjecting patients to the wrong chemotherapy, misdiagnosis may lead to the patient's family history being skewed, which can interfere with attempts for screening or genetic testing, she said.

Some physicians are already working "off-protocol" and giving patients chemotherapy before surgery, she noted. Dr. Plante called it an "attractive and interesting approach," but said she has reservations. "We just have to be sure we have a real ovarian cancer and not colon cancer," she stressed.

Several centres in Canada and Europe are at work on a new randomized study that will attempt to determine which order of treatment is best for presumed ovarian cancer, said Dr. Plante. One group of patients will have surgery first, followed by six cycles of chemotherapy. The other will receive three cycles of chemotherapy, then surgery, followed by three more cycles of chemotherapy. "This study should answer the questions about what's the best way to go about it," she said

The Medical Post VOLUME 36, NO. 26, July 18, 2000

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