Obesity Linked to Increased Recurrence Rates in Breast Cancer

Obesity was associated with an increased recurrence risk for patients with postmenopausal HR-positive early-stage breast cancer that was treated with aromatase inhibitors, according to a study published in JAMA Network.

“Recurrence is the reappearance of cancer after a period of remission. It happens when, despite cancer treatment, some of the cancer cells survive and begin to grow once more,” explained Sixten Harborg, PhD student, Department of Oncology, Aarhus University Hospital, in a recent interview with CURE®.“Recurrence can occur in several ways: as a local recurrence (in the same location as the original cancer), a regional recurrence (in the lymph nodes or nearby tissue of the original cancer site) or as a distant recurrence (when the cancer cells have spread to distant organs or tissues far from the original cancer site, also known as metastasis).”

Information from various health care databases in Denmark were analyzed. Researchers looked at postmenopausal women diagnosed with stage 1 to 3 HR-positive breast cancer throughout the time of 1998 and 2016. To meet the requirement for the study, each patient had to be undergoing endocrine therapy and have information based on their recorded body mass index (BMI) levels.

More than 13,000 patients were studied with early-stage HR-positive breast cancer, their median age of diagnosis being 64. Throughout the six-year period that these patients were being followed by their progression, there were over 1,500 recurrences. When these patients were being followed after diagnosis, 2.2% of patients were underweight, 44.4% had a healthy weight, 32.5% of patients were overweight, 14.4% were obese and 6.5% of patients were severely obese. Patients who had healthy weights or were overweight were older compared to those who were obese and severely obese during their time of diagnosis.

Patients who were underweight had a recurrence rate of breast cancer similar to those with a healthy weight, with a hazard ratio (the probability that if the event in question has not already occurred, it will occur in the next time interval) of 1.12, and patients who were overweight had a higher risk compared to those with a healthy weight, although the difference wasn’t significant, with a hazard ratio of 1.10.

When it came to obesity and severe obesity, patients in these groups had a higher risk of recurrence with breast cancer. The hazard ratio for patients with obesity was 1.18, while those who were severely obese had a hazard ratio of 1.32, which showed results that based on the various BMI levels, recurrence increased when the specified BMI levels did.

“In this study, patients with overweight, obesity and severe obesity had a higher prevalence of comorbidities when compared to patients with healthy weight. Furthermore, they were more likely to present with tumors of a higher histological grade, larger tumor sizes, and lymph node involvement at the time of diagnosis compared to patients with healthy weight,” explained Harborg. “These characteristics are all associated with poorer survival and potential side effects of cancer treatment. It is worth noting that this study did not investigate long-term side effects. In a previous study, we delineated the complications and toxicities associated with obesity in cancer patients.”

Obesity was observed to increase the risk of recurrence rates for patients with breast cancer, but there are no guild lines recommending weight-loss for patients with obesity and cancer, explained Harborg.

“Nevertheless, as concluded by the ASCO Guidelines for Exercise, Diet and Weight Management During Cancer Treatment, there is a significant gap in the evidence base regarding this. Therefore, several ongoing clinical studies are assessing the addition of physical activity and diet plans as a weight-loss intervention in the adjuvant treatment of breast cancer for patients with overweight and obesity. I am eagerly anticipating the results of these studies. The ASCO Guidelines for Exercise, Diet and Weight Management During Cancer Treatment do however recommend that patients undergoing cancer treatment start or continue aerobic and resistance exercise to mitigate side effects of the treatment,” noted Harborg.

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