Telephone-based weight loss program shows promise for obese breast cancer patients

Breast cancer arrives with its own arithmetic of risk. For women carrying extra weight at diagnosis, the numbers shift in the wrong direction: higher chances the cancer returns, higher chances a second cancer develops, higher chances the disease proves fatal. Yet losing weight after diagnosis has always felt like asking someone to climb a mountain while recovering from surgery. A large clinical trial now suggests there may be a practical path forward—one that works by telephone.

Researchers at Dana-Farber Cancer Institute enrolled nearly 3,200 women across more than 600 cancer treatment centers in the United States and Canada in what they called the Breast Cancer Weight Loss trial. All had been diagnosed with stage 2 or 3 HER2-negative breast cancer. All had completed their chemotherapy and radiation. The researchers then split them into two groups: one received phone-based coaching in eating less and moving more, plus standard health education; the other received the health education alone. Twelve months later, they measured what had changed.

The difference was substantial. Women who received the telephone coaching lost an average of 4.8 percent of their starting weight. Women in the control group, by contrast, gained weight—an average increase of 0.9 percent. On its surface, that gap might seem modest. But in the context of cancer survivorship, where even small reductions in body weight can shift the odds, the finding carried weight of its own. "We found the weight-loss program was highly successful in helping patients lower their weight," said Jennifer Ligibel, the principal investigator, who presented the results at the American Society of Clinical Oncology Annual Meeting in June 2023.

What made the results particularly striking was their consistency. The benefits held across age groups, across racial and ethnic lines, across different education levels and income brackets, across different types of breast cancer within the trial's parameters. This was not a program that worked for some women and failed for others. It worked. The uniformity suggested something important: that a simple intervention—coaching by phone, focused on basic behavioral change—could reach and help a diverse population of cancer survivors.

There were subtle variations worth noting. Younger women lost somewhat less weight than older women in the intervention group, though younger women in the control group also gained more weight, evening out the relative difference. Black women in the program lost less weight on average than other participants, yet Black women in the control group gained more weight than their counterparts, meaning the intervention still closed the gap. These patterns hinted at complexity beneath the headline numbers—different bodies, different circumstances, different starting points—but they did not undermine the core finding.

The trial was only the beginning. Ligibel and her team plan to continue following these nearly 3,200 women to answer the question that matters most: Does losing weight after a breast cancer diagnosis actually improve survival? Does it reduce the risk that cancer returns? Does it lower the chance of developing a second cancer? Those answers will take years to emerge. But if the weight loss translates into better outcomes—if the pounds shed become years gained—then this telephone-based program could become routine care, offered to every woman diagnosed with breast cancer as naturally as chemotherapy itself. For now, the trial has shown that the path exists. The next phase will determine where it leads.