More than 3,000 women in the Netherlands pass away because of breast cancer each year. Most women with this disease are diagnosed with hormone-dependent cancer and receive hormone therapy to block tumor growth. This treatment can suppress the disease for years, but resistance often occurs and the tumor can regrow despite therapy, requiring more intensive treatments.
Recent research by Irene Caffa and Alessio Nencioni at the University of Genoa and San Martino Hospital suggests that patients who follow a specific low-calorie diet may respond better to hormone therapy, which might delay the necessity to switch to more intensive treatments, such as chemotherapy.
The idea of modified diets to improve cancer treatment is appealing, but due to the low amount of calories ingested per day (sometimes as little as 300 to 600), it is incredibly hard for people to follow such a diet, especially when they are ill. Not to mention the associated risks of malnutrition. Patients who follow this kind of diet as part of clinical studies do so only under close medical guidance.
The Italian study immediately caught the attention of Nuno Padrão, PhD candidate at the Netherlands Cancer Institute. He was determined to find out how this diet aids sensitivity to hormone therapy, as there was no conclusive underlying biological explanation. Nuno: “My grandmother was diagnosed with breast cancer a few years earlier, and I realized how hard it would have been for her to follow such an extreme diet. It would be great if we could help patients like her in a more feasible way.”
He convinced his group leader Wilbert Zwart, contacted the Italian team, and initiated a joint investigation. Through a clever combination of experiments in cells, mice and patient samples, the researchers discovered that cortisol plays a key role. This hormone is produced when the body is under physical or psychological stress, including times of very low calorie intake.
“We witnessed cortisol levels rise sharply in the blood of patients and mice when they consumed very few calories,” Zwart recalls. “This hormone can enter tumor cells and slow their growth. When we modified cancer cells to no longer respond to cortisol, the positive effect of the diet on the response to hormone therapy disappeared. That’s when I knew we were onto something big.”