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Experts say daily physical activity can help women maintain a healthy weight after breast cancer treatment. robert reader/Getty Images
  • Researchers are reporting that almost one in five breast cancer survivors experience weight gain of more than 10% of their body weight.
  • The researchers note that excess weight increases risk of cancer recurrence and also raises the risk of cardiovascular disease.
  • Experts say there are numerous factors that can contribute to weight gain in breast cancer survivors and women in this group shouldn’t feel shame for weight gain.

Nearly 20% of breast cancer survivors may experience weight gain of more than 10% after their treatment.

That’s according to new research presented this weekend at the Endocrine Society’s ENDO 2024 annual meeting.

In their study, which hasn’t been published yet in a peer-reviewed journal, researchers reported there are many factors that can contribute to the weight gain after breast cancer treatment.

“Weight gain after breast cancer diagnosis and treatment is a common concern among survivors and poses a risk factor for breast cancer recurrence,” Dr, Maria Daniela Hurtado Andrade, the lead author of the research and an endocrinologist at the Mayo Clinic in Jacksonville, Florida, said in a press statement.

“In addition to increasing the risk of breast cancer recurrence, weight gain increases the risk of cardiovascular disease. In breast cancer survivors, cardiovascular disease is the leading cause of death after breast cancer itself,” she added.

The researchers examined a registry of 4,744 survivors of breast cancer. Over a period of six years from breast cancer diagnosis, the weight of the survivors increased an average of 2 pounds. About 18% of the survivors gained more than 10% of their body weight by six years.

Researchers reported that the factors that contributed to the weight gain of 10% of body weight included having an initial lower weight, having hormone-positive breast cancer, having cancer that was more advanced at the time of diagnosis, being a younger age, having mutations to the BRCA2 gene, undergoing chemotherapy and endocrine therapy, and undergoing breast surgery that was more aggressive.

The researchers say being able to identify these factors could improve outcomes for those who survivor breast cancer.

“The variables we found to be associated with excess weight gain could be used as predictors of weight gain in this population,” Hurtado Andrade said.

“Identifying these patients early in the survivorship course will allow us to institute measures to prevent excess weight gain, thereby improving breast cancer and cardiovascular disease outcomes,” she noted. “Our overarching goal is to promote a healthy longevity in breast cancer survivors.”

After skin cancer, breast cancer is the most common cancer in women in the United States. One in three new cancers in females each year are breast cancer.

Across the life span, the average risk for a woman developing breast cancer in the United States at some stage in her life is roughly 13%.

The five-year survival rate for localized breast cancer is 99%, for regional breast cancer it’s 86%, and for distant breast cancer it is 31%. The five-year survival of all stages combined is 91%.

There are more than 4 million breast cancer survivors in the United States.

Research suggests that 25% to 30% of people with breast cancer will develop recurrence.

Weight gain is a known risk factor for recurrence.

“From a cancer perspective, obesity is associated with increased risk of cancer, breast cancer and cancer recurrence,” Dr. Louis Vandermolen, a breast oncologist with Keck Medicine of USC in California who was not involved in the study, told Medical News Today.

“Some studies have suggested actually that maintaining a normal body weight provides as much benefit in reducing the risk of recurrence of breast cancer as some of the pharmacologic interventions that we might apply,” Vandermolen noted.

“Adipose tissue, fat tissue, does metabolize estrogens and it can lead to higher levels of estrogen, which can stimulate breast cancers that are estrogen driven,” he added.

Dr Bhavana Pathak is a hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in California. She says fat tissue can also have an impact on inflammation levels in the body.

“Adipose tissue or fat cells are inflammatory and we know that chronic inflammation is a risk factor for the development of cancers in general and the carcinogenesis process. It sort of impairs natural surveillance of cancer cells… It just overall creates an inflammatory state, a state that’s more hormonal reactive, and that ultimately, unfortunately, can lead to increased incidence of breast cancer,” Pathak, who wasn’t involved in the study, told Medical News Today.

The American Cancer Society advises breast cancer survivors to try to reach and maintain a healthy weight, be physically active, and eat a healthy diet to reduce the risk of breast cancer recurrence.

They note that losing weight can improve physical functioning and quality of life for breast cancer survivors. Losing weight also reduces risk of getting other forms of cancer as well as some forms of chronic disease.

Vandermolen says while it is important that breast cancer survivors try to reach and maintain a healthy weight, they shouldn’t feel shame or guilt about weight gain.

“There is stress, and I think some people eat when they’re under stress. But I also think there’s another factor… when you’ve gone through something and you faced a life threatening illness and going through something that was in many ways unpleasant, such as chemotherapy, maybe you look at life a little bit differently and maybe your perspectives are different. I’ve had women tell me, ‘Oh, you know, before I had cancer, I wouldn’t have dessert, but now I do,’” he said.

“A lot of women might feel shame, might feel guilt because they’ve gained weight. And it’s not something to be shameful of. It’s not something to feel guilty about. It’s a part of the illness. It’s no different from other side effects, toxicities or consequences of the diagnosis of cancer,” Vandermolen said.