Weight-Loss Medication Helps Some Breast Cancer Survivors Reach 5% Goal

Breast cancer survivors who did not lose at least 5% of their body weight after two months of a behavioral weight-loss program were more likely to reach that goal after the weight-loss medication Contrave (naltrexone/bupropion) was added, according to findings from the phase 2 A-NEW study.

The study evaluated a personalized approach to weight management among women with a history of stage 0 to 3 breast cancer who were overweight or had obesity. All participants first received nutrition counseling, physical activity guidance, remote coaching and self-monitoring. Researchers assessed participants after two months to determine whether additional treatment could help those who had not reached the 5% weight-loss goal.

Weight management after breast cancer may require different approaches for different survivors, according to Dr. Jenni Sheng, a breast medical oncologist at Johns Hopkins and study leader.

“Diet and exercise changes, that is the foundation of the treatment of excess weight ... but on top of that, there are certain people that may benefit from other strategies,” Sheng said.

How much weight did breast cancer survivors lose in the A-NEW study?

Among the 53 participants evaluated after two months, 15 (28.3%) had lost at least 5% of their body weight and continued the behavioral program alone. The remaining 38 participants (71.7%) had not reached the 5% goal and received Contrave in addition to the behavioral intervention.

By six months, 16 of the 38 participants (42%) who received the medication had achieved at least 5% weight loss. Participants who received the adaptive combination approach lost an average of 5.1% of their body weight.

Participants who responded to the behavioral intervention during the first two months lost an average of 10.8% of their body weight by six months.

“I hope people realize that behavioral interventions can be really effective,” Sheng said. “For some people, yes, that can yield the right result for you. But don't lose hope because there are some other unique strategies that can be a little bit more personalized.”

Why did the A-NEW study use Contrave for breast cancer survivors?

The A-NEW study was designed in 2019, before weight-loss medications became as widely discussed as they are today. Researchers worked with obesity medicine specialists and patient advocates to select a medication based on its benefits, side effects and method of administration.

The researchers selected the oral medication Contrave for the study because patient advocates who had experienced injections during breast cancer treatment preferred an alternative method.

What other health changes occurred with weight loss in the A-NEW study?

Participants who achieved at least 5% weight loss reported improvements in physical functioning and pain. Researchers also observed improvements in hemoglobin A1c, a measure of average blood sugar, and triglycerides, a type of fat in the blood, among participants who received the adaptive treatment approach.

Sleep and mental health may also play a role in weight management, Sheng noted. Depression and anxiety may affect appetite and other factors related to weight and should be considered alongside nutrition and physical activity.

Who should breast cancer survivors talk to about weight-loss medication?

A breast medical oncologist may start a conversation about weight management, but the cancer care team may not be responsible for prescribing weight-loss medications, according to Sheng.

A primary care physician may discuss weight-loss medications with a survivor or recommend an obesity medicine specialist. Cancer care teams can also connect survivors with nutrition counseling, structured exercise programs, clinical trials and other available resources.

The timing of weight-loss medication also matters for survivors receiving breast cancer treatment.

“If a patient is starting new treatments for their breast cancer, and it could be chemotherapy, it could be endocrine therapy, I usually tell patients that's not the ideal time to introduce a weight loss medication,” Sheng said.

Patients considering medication should be at a stable point in their breast cancer care and have a prescribing physician who can monitor them closely, Sheng explained. Diet and exercise changes can still be incorporated during cancer treatment.

What side effects occurred with Contrave in the A-NEW study?

Contrave was generally well tolerated in the A-NEW study. Gastrointestinal side effects, including constipation and nausea, were the most commonly reported side effects. One participant stopped treatment because of medication-related side effects.

Patients who start a weight-loss medication should be followed closely by the clinician prescribing it, particularly during the first weeks and months when side effects may occur, Sheng explained. The oncology team should also remain informed about new medications a survivor is taking.

The A-NEW study was small and was not designed as a randomized comparison. Sheng also cautioned against drawing firm conclusions from differences observed among Black, younger and premenopausal participants because of the small number of participants. She noted that biological, environmental and socioeconomic factors could contribute to differences in early weight loss, but more research is needed to understand the reasons.

Larger randomized studies are needed to confirm the findings and determine whether similar approaches with other weight-loss medications could improve outcomes for breast cancer survivors.

Reference

1. Sheng JY, et al. “Weight Loss Responses to Pharmacotherapy in Breast Cancer Survivors: Results from the Adaptive Nutrition and Exercise Weight Loss (A-NEW) Study.” Clinical Cancer Research. Published Aug. 4, 2026.

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