However, among women with HOMA-IRs in the third and fourth quartile, risk was elevated whether they were normal weight or overweight. These results were corroborated using fasting insulin to define metabolic health.

“These findings are consistent with recent reports that overweight individuals with normal insulin sensitivity are not at increased risk of cardiovascular disease, and collectively provide further evidence of the existence of a healthy obese phenotype,” the article noted.

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“Metabolic health, as determined by insulin, may be as important for determining breast cancer risk as obesity, but more research is needed in this area,” Dr. Gunter said. “Postmenopausal women should aim to maintain a healthy weight though physical activity and a healthy diet.”

When asked whether clinicians should now regularly determine baseline levels of HOMA-IR or fasting insulin in determining breast cancer risk, he said, “our findings require further validation before such recommendations are made. If other studies find that insulin is predictive of breast cancer risk, then it may be considered as a risk factor in evaluating a woman’s breast cancer risk.”

Study limitations included the availability of only a single insulin and glucose measurement for each participant and that the sample size did not allow them to stratify participants by breast cancer subtypes.

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“Given potential crosstalk between estrogen and insulin signaling, it is possible that the association of metabolic health with breast cancer varies by breast tumor estrogen receptor subtype,” he noted, with future studies needing sufficient sample sizes to address this hypothesis.

Studies have shown that women who make changes in their lifestyles after a diagnosis of breast cancer—including weight loss, increased physical activity, and dietary changes—experience both physical and psychologic benefits.


  1. Gunter MJ, Xie X, Xue X, et al. Breast cancer risk in metabolically healthy but overweight postmenopausal women. Cancer Res. 2015;75(2):270-274.
  2. Ligibel JA, Strickler HD. Obesity and its impact on breast cancer: tumor incidence, recurrence, survival, and possible interventions. Am Soc Clin Oncol Educ Book. 2013;33:52-59.