Weight loss medications challenges for breast cancer survivors

Weight loss medications may not work as well for breast cancer survivors.


Breast cancer is a devastating disease affecting numerous women worldwide. While advancements in treatment have significantly improved survival rates, there are concerns regarding the potential impact of specific breast cancer treatments on weight loss medications.

The interaction between these treatments and weight loss medications may limit the latter’s effectiveness, posing challenges for patients seeking to manage their weight during and after breast cancer treatment. This article delves into the intricate relationship between breast cancer treatments and weight loss medications, highlighting the potential implications and offering insights into how healthcare professionals can address this issue to optimize patient outcomes.

Breast cancer medications known as aromatase inhibitors have been found to potentially diminish the effectiveness of weight loss drugs, as revealed by a recent study presented at ENDO 2023, the annual meeting of the Endocrine Society in Chicago, Illinois. The study highlights that weight loss medications may have reduced efficacy in breast cancer survivors undergoing treatment with aromatase inhibitors compared to women without a history of breast cancer who are not taking these inhibitors.

Aromatase inhibitors are commonly used to treat specific types of breast cancer and prevent its recurrence by blocking the activity of the enzyme aromatase, thereby reducing estrogen production in the body. This mechanism is crucial as it inhibits the growth of cancer cells that rely on estrogen for their proliferation.

Lead researcher Dr. Sima Fansa from the Mayo Clinic in Rochester, Minnesota, emphasized that weight gain is a prevalent concern among breast cancer survivors. Previous studies have indicated that aromatase inhibitors could potentially contribute to weight gain. It is important to note that weight gain and obesity increase the risk of breast cancer recurrence and breast cancer-related mortality and raise the likelihood of developing heart disease and experiencing heart-related mortality.

Fansa said, “This is the first study assessing response to weight loss medications in a subgroup of breast cancer survivors taking aromatase inhibitors. Our results highlight the need to develop better approaches to manage weight gain in patients with a history of breast cancer taking aromatase inhibitors. Preventing weight gain in this group or treating obesity effectively will improve breast cancer outcomes, prevent further health complications, and improve quality of life for these people.”

In a study involving 99 participants, comprising 63 women with a history of breast cancer using both aromatase inhibitors and weight loss medications (such as liraglutide, semaglutide, or phentermine), along with 36 women without breast cancer who were solely taking weight loss medications, it was observed that the breast cancer group experienced less weight loss at 3, 6, and 12 months compared to the non-breast cancer group. The weight loss percentages were notably lower in the breast cancer group, with values of 3.7% versus 5.6% at three months, 3.9% versus 9.5% at six months, and 5.2% versus 10.5% at 12 months.

Dr. Sima Fansa, the lead researcher, explained that this difference could be partially attributed to the anti-estrogen effect of aromatase inhibitors, which can result in reductions in muscle mass, increases in fat mass, and changes in energy expenditure. These factors influence the body’s response to weight loss interventions, including the effectiveness of weight loss medications.

Researchers presented their findings at the Endocrine Society‘s annual meeting in Chicago.

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