Boosting breast cancer survival

For a deceptively basic question, the answer held profound implications: could women with early-stage but high-risk breast cancer — which is deemed more likely to spread — improve their odds of avoiding a recurrence and living longer just by taking daily aspirin?

Harvard researchers decided to find out. As part of a 534-location clinical trial that tracked participants for up to six years, they studied more than 3,000 women (average age 53) who were treated with standard therapies for their cancer. Half were randomly assigned to also take 300 milligrams of aspirin once a day, while the others took a placebo.

But the researchers' hopes were dashed — prompting an early end to the trial — when it became clear there was no difference in survival or recurrence rates between the two groups. The analysis, published May 28, 2024, in JAMA, came after some observational studies—which can't produce results as robust as clinical trials — had suggested that women with breast cancer who took aspirin seemed much less likely to die from the disease.

"This is one of those scientific questions a lot of people wanted answered," says study co-author Dr. Wendy Chen, a breast oncologist at Harvard-affiliated Dana-Farber Cancer Institute. "The good news about a negative study is it shows that it doesn't make sense to continue barking up this tree."

Silver linings were scarce, however. "I was disappointed, yes, because I would have loved to find a simple, inexpensive way to improve breast cancer survival rates," says study co-author Dr. Michelle Holmes, a professor of medicine at Harvard Medical School. "It would have been wonderful if it worked, because aspirin is inexpensive and available all over the world, in many places where people can't afford expensive cancer treatment."

Hunger for information

Scientists sometimes hesitate to publish research with negative findings, but this study's publication should help guide women to more effective therapies and perhaps overall better health. While the clinical trial may have shown aspirin couldn't help women with breast cancer avert recurrence or improve survival, several other evidence-backed measures might accomplish those goals, Harvard experts say.

Many women are hungry for such guidance. An estimated 310,000 women were diagnosed with invasive breast cancer in 2024 and more than 42,000 died of it, according to the American Cancer Society (ACS). Though more than nine in 10 patients with breast cancer are diagnosed at an early stage, about one-quarter will eventually die of metastatic cancer (that is, cancer that has spread elsewhere in the body).

The risk that breast cancer will come back is based on many factors, including the type and stage of the initial malignancy. About two-thirds of breast cancer cases are diagnosed at a localized stage, before the cancer has spread outside the breast, according to the National Breast Cancer Foundation. Nearly all women diagnosed while their breast cancer is still localized will be alive five years later.

It's natural for women with breast cancer to want to investigate anything they can do — in addition to treatment — to lower the odds of the malignancy returning. "Obviously, everyone wants to improve their survival and decrease their chance of recurrence, but it's important to understand what's evidence-based and what isn't," Dr. Chen says.

What helps—or doesn't

Dr. Chen and Dr. Holmes highlight lifestyle factors linked with better or worse breast cancer survival odds:

Exercise. Considered the strongest tool in the breast cancer survival kit, physical activity can lower the odds of dying from the disease by about 40%. Exercise is believed to reduce the body's levels of insulin and estrogen, two hormones that can fuel cancer cell growth. It can also promote weight loss, which can lower the odds of cancer recurrence and death (see more below).

Women who exercised at least 2.5 hours each week either before or after being diagnosed with breast cancer deemed at high risk of spreading were significantly less likely to die or have their cancer come back over the next 15 years, according to a 2021 study of 1,340 women in the Journal of the National Cancer Institute.

Exercise might also boost the immune system's ability to halt any cancer progression. "But in all of medicine, exercise is kind of the silver bullet. It seems to make every illness better," says Dr. Holmes.

Weight control. Evidence suggests being overweight or obese during or after breast cancer treatment increases both the risk the cancer will return and the risk of dying from the disease. Part of the reason is that fat tissue "holds" estrogen — which can fuel breast cancer — more effectively than lean tissue. Obesity can also ramp up damaging inflammation.

"We do know being at a healthy weight leads to better cancer and overall survival compared to people who are heavier," Dr. Chen says. "Body composition — not just what you weigh on a scale — is also important. Focus on building muscle mass, not just on losing weight."

Diet. While no specific foods have been identified that help lower the odds of breast cancer recurrence, studies indicate that survivors who eat more vegetables, fruits, whole grains, poultry, and fish tend to live longer than those with diets heavy in refined sugar, fat, and red and processed meats, according to the ACS.

"The benefits of a healthy diet are not confined to just breast cancer," Dr. Holmes says. "The evidence for eating a healthy diet and preventing many other diseases is very strong."

Soy products such as tofu and soy milk once fell under scrutiny because they contain compounds called isoflavones, which can mimic estrogen in the body. But soy products haven't been found to increase breast cancer recurrence rates and may lower them, the ACS says. "The concern that soy products might stimulate tumors and cause recurrence has been pretty thoroughly debunked," Dr. Holmes says.

Alcohol. Much scientific evidence backs the notion that drinking alcohol — even as little as a few drinks per week — raises our risk of developing breast cancer. But the link between drinking and breast cancer recurrence isn't as clear. The ACS recommends that women who have had breast cancer ideally avoid alcohol or at least limit their consumption to no more than one drink per day. "My take is that you certainly shouldn't start drinking if you don't already drink, and you should balance your risk based on your overall health," Dr. Holmes says.

Supplements. Wouldn't it be ideal if popping a supplement could help lower the chances that breast cancer will progress or prove fatal? But there's no evidence that's the case, according to the ACS. "Most supplement use doesn't seem to be harmful, but it's not clear if it's helpful," Dr. Holmes says. "It's better to get your micronutrients like vitamins and minerals from a healthy diet rather than a pill."

Smoking. There's nothing healthy about smoking, the top preventable cause of death in the United States. It's also clear that women with breast cancer who've smoked face higher odds of dying from their malignancy. And women who quit smoking after being diagnosed with breast cancer enjoy higher odds of survival over all. "To decrease your risk of cancer death, nothing is better than not smoking," Dr. Chen says.

Treatment trumps all

It's not always clear how various lifestyle measures help women with breast cancer avoid recurrence or death from the cancer itself. But these approaches almost certainly improve their ability to keep other potentially deadly conditions at bay or manage them more effectively, Harvard experts say.

For example, while physical activity and weight control appear likely to help people with breast cancer avoid dying from it, "of course they also help lengthen life and help people avoid high blood pressure, heart disease, and diabetes," Dr. Holmes explains.

The lifestyle changes that promote better outcomes with breast cancer are "kind of a one-size-fits-all," she says. "You may be helping your breast cancer, and you're definitely helping your overall health."

Ultimately, however, a woman's treatment plan contributes most to her ability to fight breast cancer, Dr. Chen says. Someone undergoing treatment can arm herself with knowledge by asking her doctor why various approaches have been selected for her. Typically, therapies are tailored to each woman based on specific characteristics of her cancer, including the stage, tumor size, cell type, whether it has spread, and her overall health.

"When I look at patients who do best, it's usually those who follow through with their treatment plan," Dr. Chen says. "Adherence to treatment is clearly shown to improve outcomes. If you only do half your treatment versus 100% of it, you're not going to do as well."

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