WASHINGTON — Breast cancer survivors may face increased risk of heart disease, and doctors are debating if it’s time to largely abandon a chemotherapy mainstay that is one reason for the problem.
Drugs called anthracyclines are a breast chemo staple despite a well-known risk: They weaken some women’s hearts. What’s new is research suggesting the drugs work no better than safer alternatives for most women.
Chemo is only one cardiac culprit. Other factors play a role, too: Chest radiation, the weight gain that plagues many survivors, physical inactivity during treatment and stress.
“In the process of curing their breast cancer, we’ve exposed them to some pretty nasty things. And it’s not just one nasty thing, it’s a sequence of nasty things,” explains Dr. Pamela Douglas, a Duke University cardiologist.
But much of the debate centers on who should use anthracyclines, including the best-known Adriamycin, that can damage heart muscle, sapping its pumping strength.
Dr. Dennis Slamon of UCLA’s Jonsson Cancer Center cites nine studies, here and abroad, that conclude that only the 20 percent of patients whose tumors have an overactive gene called Her2 are specifically sensitive to anthracyclines.
Then Slamon’s closer inspection found that not all Her2 patients are alike — and only those who have a second overactive gene, called TopoII, derive special benefit from anthracyclines. That’s about 8 percent of breast cancer patients.
The powerful Her2-targeting drug Herceptin — key for women with Her2-positive tumors — also comes with a heart-damage warning. But adding it to anthracyclines increases the heart risk fivefold, with no extra benefit, Slamon found.
Outright heart failure during chemo is rare, about 2 percent of patients. But Douglas cites research that anywhere from 10 percent to half of anthracycline users experience more subtle heart weakening, making them vulnerable to aging’s rigors, like high blood pressure and cholesterol.
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