WASHINGTON – Breastÿcancer 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.

It’s a controversy born of success: treatment advances are enabling more women than ever before to beat breastÿcancer, and some 2.4 million survivors are alive today. Now a move is under way to determine just how many women are vulnerable to heart disease because of their cancer battle, and how to help them.

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 breastÿcancer, 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 who is planning research into how to protect these women’s hearts.

“This is really coming at you from all sides,” says Douglas, who outlined the “multiple hits” in this month’s Journal of the American College of Cardiology.

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 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 breastÿcancer 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.

Outright heart failure during chemo is rare.. But Douglas cites research that anywhere from 10 percent to half of anthracycline users experience more subtle heart weakening, making them more vulnerable to aging’s usual rigors, like high blood pressure and cholesterol.

And in this month’s Journal of Clinical Oncology, researchers tracked breastÿcancer survivors ages 66 to 70 who had undergone chemo 10 years earlier. Those who had received an anthracycline were 26 percent more likely to have developed heart failure in the following decade than those on different chemo.