People with breast cancer, diabetes at higher risk for chemotherapy-associated complications

Data from an observational hypothesis-generating study indicated that people with breast cancer and diabetes are at increased risk for chemotherapy-related toxicities, have a higher rate for all-cause mortality and are less likely to receive adjuvant chemotherapy compared with people without diabetes not receiving chemotherapy.

Researchers from the University of Texas M.D. Anderson Cancer Center pooled data from the SEER-Medicare database on 70,781 men and women aged 66 years and older. Patients were diagnosed with stages I through III breast cancer; 14,414 also had diabetes.

The effects of diabetes on chemotherapy use, toxicity and outcome were determined by multivariate analysis. Researchers used the Kaplan-Meier method to estimate the risks for all-cause mortality and breast cancer-specific mortality.

Results of the multivariate analysis indicated that people with diabetes who received chemotherapy had lower odds of receiving anthracyclines (OR=0.78; 95% CI, 0.71-0.87) and taxanes (OR=0.86; 95% CI, 0.75-0.99).

Diabetes was associated with increased odds for being hospitalized for any cause (OR=1.32; 95% CI, 1.19-1.46), for any chemotherapy toxicity (OR=1.38; 95% CI, 1.23-1.56), for infection or fever (OR=1.43; 95% CI, 1.2-1.7), for anemia (OR=1.24; 95% CI, 1.05-1.47) and neutropenia (OR=1.22; 95% CI, 1.03-1.45).

An association was also found between diabetes and all-cause mortality (HR=1.35; 95% CI, 1.31-1.39). A higher rate for breast cancer-specific mortality was found for people with diabetes who received chemotherapy vs. people without diabetes who received chemotherapy (OR=1.20; 95% CI, 1.07-1.35).

“Despite these findings, patients with diabetes should continue to be offered standard chemotherapy regimens because this study cannot definitely answer which chemotherapy offers the best risk-benefit ratio for patients with diabetes. Future studies are necessary to define the optimal management of breast cancer in patients who have diabetes,” the researchers wrote. – by Jennifer Southall

Srokowski T. J Clin Oncol. 2009; doi:10.1200/JCO.2008.17.5935.

As people age, they are at higher risk for a number of illnesses including many cancers and diabetes. This study reminds us that comorbid conditions like diabetes can affect what type of therapy patients receive for cancer. It suggests that such alterations might be linked to changes in outcome.

–Nancy Davidson, MD

HemOnc Today Editorial Board member