MSK Research Reveals Connection Between Diet and Cancer

If you or a loved one is facing cancer, you may wish you could regain some sense of control when so much feels beyond your power.

You may wonder what you can or should eat. Comfort food? Healthy food? How much does it matter?

The effort at Memorial Sloan Kettering Cancer Center (MSK) to answer these deeply personal questions stretches from the laboratory to the exam room to kitchens and dinner tables. Along the way, we are researching diet with the same rigor used to investigate new therapies, with innovative clinical trials that are uncovering new insights into our dietary habits and health.

The Connection Between Fat Cells and Cancer

One key to understanding the complicated relationship between what we eat and cancer is the humble fat cell.

While many people who develop cancer are at a healthy weight, there is growing awareness of the association between obesity and a higher risk of cancer.

“There are at least 13 types of cancer, including breast, prostate, endometrial (uterine), colorectal, and others that we know are linked to obesity,” says Neil Iyengar, MD, a breast cancer oncologist at MSK and a nationally recognized expert on the relationship of obesity, metabolic health, and cancer.

“Separate from obesity,” Dr. Iyengar adds, “having higher levels of body fat is associated with an increased risk of several forms of cancer.”

It turns out that fat cells are not as sluggish as people may think. “Fat is dynamic — it doesn’t just sit there,” explains Dr. Iyengar. “It can become dysfunctional, resulting in inflammation, which increases the risk of developing cancer. Many of the cancers linked to obesity are in organs that are embedded in pads of fat.”

Fat cells can also influence the entire body. “People with dysfunctional fat tissue often have altered levels of hormones, such as insulin and estrogen,” says Dr. Iyengar. “These changes can damage DNA and lead to several kinds of cancers, including some blood cancers, such as multiple myeloma.”

What Should People Eat After a Cancer Diagnosis?

Urvi Shah, MD, is an MSK specialist caring for patients with multiple myeloma, which is a cancer of white blood cells called the plasma cells. She explains that many people who develop the disease first have what is called a precursor condition, meaning a precancerous stage that may or may not progress to full-blown cancer.

These precursor conditions are without symptoms and known as MGUS (monoclonal gammopathy of undetermined significance) and smoldering multiple myeloma (SMM).

“People who are overweight or obese have twice the risk of these precursor conditions progressing to full-blown myeloma,” Dr. Shah says. “This presents an opportunity to see if a clinical trial that gives people with MGUS a new pattern of eating could help them lose weight and slow or stop the possible progression of the disease.”

Dr. Shah feels deep empathy for her patients who have been diagnosed with MGUS. “Standard practice is just observation. You tell someone: You have a precancerous state, but there’s nothing you can do. Just watch and wait to see if you get cancer. Of course, patients don’t like that and may develop anxiety.”

Dr. Shah also empathizes with patients who wonder what they should be eating. She herself was diagnosed with a blood cancer called Hodgkin lymphoma during her first year as a hematology-oncology fellow.

“We don’t really get taught in medical school what we should or should not eat after a cancer diagnosis,” Dr. Shah says. “But as a patient, I realized it was a natural question. Patients really want to feel empowered to do something for their own health.”

Spurred by her own cancer journey, Dr. Shah decided to research nutrition and cancer. Previous studies suggested that an eating pattern focused on high-fiber unprocessed plant foods would be most beneficial. “These studies evaluate data generated from large populations,” she explains. “But there had been no interventional study where we ask people to change their dietary habits and evaluate outcomes. MGUS provided an opportunity to study this and help patients.”

She designed a clinical trial called Nutrivention, which began as a pilot with 20 patients and has since expanded to multiple trials.

Dr. Shah’s novel clinical trial also had special features.

“First, we contracted with a food company to deliver food directly to people’s homes for three months — food that is high in fiber and focuses on beans, whole grains, vegetables, fruits, and minimally processed plant-based food. Second, we told people to eat as much as they want of these high-fiber foods. We didn’t ask them to count or restrict calories. We provided coaching for six months and monitored them for a year.”

Helping a First Responder

William Walters joined Dr. Shah’s clinical trial in early 2022, after being diagnosed with MGUS during a medical exam as he was retiring from the New York Fire Department because of a chronic injury.

“I kind of went crazy,” he recalls, “I was only 39, and my wife and I had three young children. Suddenly I find out I have a condition that usually affects people in their 70s and can progress to cancer. I researched clinical trials for MGUS and Dr. Shah’s was the only one I could find.”

William describes himself as eating like a typical fireman. “It was red meat seven days a week, and the only vegetable I ever ate was a potato.” But he says, “Dr. Shah completely made sense when she told me that they were studying a high-fiber plant-based diet to see if it would help to quiet down the cells that had the potential to turn into full-blown myeloma.”

With food delivery on the trial lasting three months, William said he found his groove around the two-month mark. “I started to really like eating this way, based only on plants. Now there are tofu dishes I love, even though I didn’t like it at the beginning. In fact, my wife made a vegan lasagna, and it was amazing — the best thing I’ve eaten since I started this diet.”

This new pattern of eating improved his health dramatically. “I dropped a lot of weight and many of my blood numbers got better.”

And the benefits went even further. “I had been on antidepressants after I retired, but the diet made me feel good enough to stop. My grandfather and father both had serious heart problems early in life. But my cardiovascular markers improved dramatically.”

Dr. Shah reported similar improvements for other participants on the trial when she announced results in December 2024 at the annual meeting of ASH (American Society of Hematology), the country’s largest conference for blood cancers.

Over the course of a year, the trial found that participants lost weight, enjoyed better quality of life, improved metabolic markers such as cholesterol and insulin, and saw an improvement in biomarkers that measure the health of the immune system and microbiome. Two participants saw their progressing disease stabilize, as measured by MGUS biomarkers.

“This is the first study of its kind to show that a high-fiber plant-based intervention improves biomarkers and for some patients may delay progression from MGUS or SMM to multiple myeloma,” says Dr. Shah.

Breast Cancer Patients and a Surprising Side Effect

MSK researchers are also breaking ground with studies focused on the diet of breast cancer patients.

It may come as a surprise to learn that “most people experience weight gain following breast cancer diagnosis,” says breast medical oncologist Sherry Shen, MD. “This can cause anxiety about body image,” she says, and there can also be health consequences of serious weight gain, including increased risk of cancer recurrence as well as cardiovascular disease.

Dr. Shen explains that chemotherapy and hormone therapy can put patients into menopause, altering their metabolism, and “we need to give steroids and lots of fluids, which can induce weight gain.”

But patients should never forgo lifesaving treatments because they are worried about gaining weight, says Dr. Iyengar. “Interventions such as weight-loss programs can work with therapies but cannot replace them — people need to be clear about that.”

Drs. Shen and Iyengar and their MSK colleagues are trying a variety of approaches to help people maintain healthy body weight during breast cancer treatment and afterward, when hormonal therapies can last for a decade.

One approach, led by Dr. Shen, uses the mobile app Noom. The app was provided to 31 patients with early-stage breast cancer. “They could use it to talk with support groups and coaches, log the food they eat, and access information about health and diet.”

After six months with the program, “people lost an average of 5.6% of their body weight, which is quite high and can improve breast cancer outcomes,” says Dr. Shen.

A separate trial used an approach more like Dr. Shah’s, delivering plant-based meals directly to patients alongside personal exercise training. This more intensive intervention saw an average weight loss of 14% of body weight.

Dr. Shen and Dr. Iyengar also conducted an analysis of 75 breast cancer patients who took the weight-loss drugs often grouped together as GLP-1 agonists that include Ozempic and Wegovy.

“These patients were taking the drugs because of diabetes, not for weight loss,” explains Dr. Shen. “But they averaged around 5% weight loss over the period we analyzed, which is very encouraging for overall health and breast cancer outcomes, although much larger, controlled studies need to be done.”

Recipe for Success

For William Walters, MSK’s expertise on the relationship between diet and cancer has proven life changing.

“I’m going to continue eating this way forever,” he says. “I’ve had full confidence in Dr. Shah from the first time I sat down with her. And what she’s shown me has put me, my wife, and our children at ease. For anyone facing what I did, there is just no reason not to give it a try, to help you and your family.”