By Sarah Webb
Obesity may be linked to breast cancer recurrence
By Sarah Webb
Carrying around extra body weight can lead to a variety of health consequences including increased risk of cardiovascular disease and many types of cancer. In particular, growing evidence has linked obesity to higher rates of breast cancer diagnosis, relapse and mortality—problems that are exacerbated in communities with more limited access to treatment. A new study, presented at an American Association for Cancer Research conference on the science of cancer health disparities in November 2007, is now further supporting this connection.
Dolly Quispe, a hematology-oncology fellow, and her colleagues at the Feist-Weiller Cancer Center in Shreveport, La., examined the medical records of 349 women diagnosed with breast cancer at the center between 1990 and 2004. Louisiana has one of the highest poverty rates of all U.S. states, and more than a quarter of its residents are obese. Fifty-two percent of the women in the study were obese, with a body mass index (BMI) of 30 or greater, while 29 percent were overweight, with a BMI between 25 and 29.9. The researchers found that among overweight and obese women, a higher BMI at breast cancer diagnosis corresponds to an increased risk of relapse.
Although the study sample was small, it looked at a unique patient population, says Christopher Li, an epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle who was not part of the research team. The study included African-American patients (45 percent), overweight or obese patients (81 percent), and patients receiving free care or Medicaid (47 percent). The researchers “confirm that obesity is related to recurrence regardless of various factors such as socioeconomic status, race, age of diagnosis and stage of disease,” says Li.
Biological factors could explain why obesity is related to relapse, Li says. “In postmenopausal women, fat tissue is the primary producer of estrogen,” he says. Increased estrogen from fat could interact with lingering breast cancer cells and promote recurrence after treatment. Because of these biological differences, obese women might need higher doses or longer treatment courses with available therapies compared with women who have a BMI in the normal range. Obese women may also respond better to different therapies, Li speculates. “Just given what we know about the biology of breast cancer in relation to obesity, there must be certain things that we could do better to treat those women,” he says.
According to physician Cheryl Perkins, a senior clinical adviser for Susan G. Komen for the Cure, in Dallas, the ultimate challenge is to understand “the biology of breast cancer and the socioeconomic factors, and how they all interplay to ultimately cause breast cancer in different people.”
Although a correlation between low socioeconomic status and cancer recurrence was not statistically significant in the new study, poverty and obesity have been linked in past studies. Moreover, lower-income patients are frequently diagnosed at later stages of the disease, says Quispe, and poverty often limits access to adequate medical care after diagnosis.
Quispe and her colleagues are now considering new studies to test interventions aimed at promoting better outcomes for low-income breast cancer patients. So far, there’s no conclusive data to show if diet modifications or exercise might help prevent breast cancer recurrence for these women. But socioeconomic factors may limit patient participation in any follow-up trial, Quispe notes. “It’s going to be extremely difficult,” she says. “These [patients] really are very poor, sometimes traveling 200 or 300 miles for treatment.”
Such barriers make it hard to develop treatment solutions for medically underserved populations and to get those treatments to them. Perkins notes, “It won’t do us any good if we have answers to cancer [but] can’t get them to the people who need them.”