Obesity linked to breast cancer recurrence in women treated with aromatase inhibitors

Key takeaways:

• Obesity and severe obesity were linked to increased breast cancer recurrence risk among postmenopausal women.
• Overweight was linked to greater breast cancer recurrence, but it was not statistically significant.

Obesity was linked to an increased breast cancer recurrence risk among postmenopausal women with hormone receptor-positive early-stage breast cancer who were treated with aromatase inhibitors, researchers reported in JAMA Network Open.

“More evidence is needed about the efficacy of aromatase inhibitor-mediated estrogen suppression in patients with breast cancer and obesity,” Sixten Harborg, BSc, from the department of oncology at Aarhus University Hospital and the department of clinical epidemiology at Aarhus University, Denmark, and colleagues wrote.

“High BMI has been identified as a risk factor for developing postmenopausal breast cancer, and at the same time, obesity can influence hormone receptor status, with a higher likelihood of hormone receptor-positive tumors in people with obesity,” they wrote. “As a consequence of the ongoing obesity epidemic, more people with obesity will be treated with aromatase inhibitors.”

Harborg and colleagues conducted a cohort study utilizing data from 13,230 postmenopausal women (median age, 64.4 years) from the Danish Breast Cancer Group. All women were diagnosed with stage I to III hormone receptor-positive breast cancer from 1998 to 2016. Researchers classified participants with underweight (n = 296), healthy weight (n = 5,873), overweight (n = 4,294), obesity (n = 1,909) and severe obesity (n = 858).

All participants were followed from 6 months after breast cancer surgery until the first event of recurrence, contralateral breast cancer, new primary malignant neoplasm, death, emigration or the end of clinical follow-up at 10 years.

Overall, researchers observed 1,587 breast cancer recurrences. Obesity (adjusted HR = 1.18; 95% CI, 1.01-1.37) and severe obesity (aHR = 1.32; 95% CI, 1.08-1.62) were associated with an increased risk for breast cancer recurrence compared with women with healthy weight in multivariable analyses. Women with overweight had a greater risk for breast cancer recurrence, but these findings were not statistically significant (aHR = 1.1; 95% CI, 0.97-1.24).

In addition, women with underweight had similar breast cancer recurrence risk as women with healthy weight (aHR = 1.12; 95% CI, 0.77-1.64).

“To secure equal treatment regardless of body composition, further research ought to examine whether estrogen suppression is sufficient in patients with breast cancer and obesity treated with aromatase inhibitors,” the researchers wrote.