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Who can safely skip chemo for breast cancer?

Tens of thousands of women undergo chemo for breast cancer every year when they don’t really need it, but doctors don’t have an easy way to tell who can gamble on skipping the harsh drugs.
/ Source: The Associated Press

Claudia Lowry had a scary decision: Could she safely skip chemotherapy after surgeons removed her breast cancer?

Tens of thousands of women undergo chemo for breast cancer every year when they don’t really need it, but doctors don’t have an easy way to tell who can gamble on skipping the harsh drugs.

A simple gene test now promises to help women like Lowry make that nerve-wracking choice — and a major government study is enrolling more than 10,000 patients around the country to see just how well it does the job.

“Most of the patients are advised to have chemotherapy. Most of the patients are going to do very well without it,” says Dr. Sheila Taube of the National Cancer Institute. “So how can we spare the patients that don’t need it?”

Breast cancer is only the opening salvo. Researchers are furiously developing who-to-treat gene tests for colorectal cancer — particularly for early Stage 2 disease that doctors fear is being under-treated — and other malignancies, too.

Gene-tailored therapy
But if the new breast cancer study pans out, it will mark a big step toward genetically tailored therapy that specialists expect will rapidly replace today’s simplistic guidelines for treating early-stage cancer.

More than 100,000 U.S. women a year are diagnosed with early breast cancer that has a remarkably good prognosis: The tumors are small, haven’t spread, and are hormone-sensitive. The vast majority would survive with surgery, radiation and hormone treatment. Yet guidelines today recommend chemotherapy as well for most of those women to catch the few who need more aggressive help.

In other words, 100 women get chemo, and the risk of harsh, sometimes life-threatening, side effects, to prevent two or three of them from relapsing.

The Oncotype DX test is supposed to help winnow out some of that overtreatment. It checks a woman’s surgically removed tumor for 21 different genes whose interactions can predict the likelihood of a relapse. Those odds are calculated on a scale from zero to 100.

Having a high “recurrence score” — greater than 30 — makes chemotherapy a good bet: Adding chemo for those patients improves their chances of being cancer-free 10 years later from 61 percent to 88 percent, concluded a manufacturer-funded study that tested tumors stored from hundreds of patients.

But giving chemo to a low-risk patient — a recurrence score of less than 18 — made no difference, researchers reported in the Journal of Clinical Oncology.

The problem: Women with scores in the middle, between 18 and 30, were in a grey zone; it’s unclear if they benefited from chemo or not.

The new study, funded by the National Cancer Institute, aims to settle how the $3,000 gene test affects treatment decisions.

The main purpose: to determine how to treat the half of patients estimated to fall into that grey zone, with intermediate risk of a relapse. Researchers will randomly assign those women to either get chemotherapy or skip it, and see who fares best. (To double-check the earlier findings, the study also will track low-risk women who skip chemo and high-risk women who get it. )

Results can’t come soon enough, as women like Lowry already struggle to decipher an intermediate score.

A veteran oncology nurse, Lowry knew she didn’t want to undergo the chemo side effects she’d watched patients suffer. But the Kokomo, Ind., woman also had fought back uterine cancer a year earlier. Was she cancer-prone and thus chemo would help?

Oncotype DX didn’t give a clear answer; Lowry’s score was 24, solidly in the grey zone. Still, her doctor used the rating in pouring over previous research to estimate that chemo would only slightly lower her odds of breast cancer returning, validating her decision to skip it.

“It gives us a number, it’s not just a doctor thinking,” Lowry said of the test. “I think it will help a lot of women make up their minds.”