Hormone therapy raises diabetes risk in breast cancer survivors

Hormone therapy for breast cancer more than doubles a woman’s risk for developing type 2 diabetes, results of a case-cohort study suggest.

Hormone therapy with tamoxifen was associated with a more than twofold increase in risk of diabetes, and aromatase inhibitors were associated with a more than fourfold increase, reported Hatem Hamood, MD, of Leumit Health Services in Karmiel, Israel, and colleagues.

Among 2,246 women with breast cancer and no diabetes at baseline, followed for a mean of 5.9 years (longest follow-up 13 years), the crude cumulative lifetime incidence rate of diabetes was 20.9%, the investigators wrote. The report was published in the Journal of Clinical Oncology.

“[Hormone therapy] is a significant risk factor of diabetes among breast cancer survivors. The underlying mechanism is unclear, and additional research is warranted. Although cessation of treatment is not recommended and progression of breast cancer often is inevitable, devised strategies aimed at lifestyle modifications in patients at high risk of diabetes could at least preserve the natural history of breast cancer,” they wrote.

Diabetes has previously been identified as a possible risk factor for breast cancer, but the potential for breast cancer therapy as a precipitating factor for diabetes is uncertain, the authors said.

“Given the detrimental impact of diabetes on breast cancer survival, additional exploration of the role of breast cancer treatment in the development of diabetes is important not only because it would add valuable information on the etiology of diabetes but also because it would help to identify high-risk patients in need of accentuated clinical care,” they wrote.

To explore the possible association between hormone therapy and diabetes risk, the investigators performed a retrospective case-cohort study of 2,246 women who had been diagnosed with primary nonmetastatic breast cancer treated with hormone therapy from 2002 through 2012.

They examined data on a randomly selected cohort of 448 breast cancer survivors and all patients in the parent (no diabetes at baseline) cohort who developed diabetes during the study period (324 patients).

They found that the prevalence of diabetes among their source population of 2,644 breast cancer survivors (including those with baseline diabetes) increased “drastically” from 6% in 2002 to 28% in 2015. The prevalence exceeded Israeli national norms from 2010 through 2013, with standardized prevalence ratios of 1.61 to 1.81 (P less than .001).

As noted, in the population without baseline diabetes, the crude cumulative incidence rate of diabetes in the presence of death as a competing risk factor was 20.9%.

In multivariate analyses controlling for demographic and socioeconomic factors, and for chemotherapy type, hypertension, outpatient visits, use of corticosteroids, thiazide diuretics, beta-blockers, statins, and year of breast cancer diagnosis, factors significantly associated with diabetes risk were use of hormone therapy (adjusted hazard ratio [HR] 2.40, P = .008), tamoxifen (aHR 2.25, P = .013), aromatase inhibitors (aHR 4.27, P = .013), therapy duration more than 1 year (aHR 2.36, P = .009), and 1 year or less (aHR 6.48, P = .004).

The investigators noted that although other reports have found no association between aromatase inhibitors and diabetes risk, those studies had small samples or offered no explanation of the lack of association.

In contrast, a 2016 joint ACS/ASCO breast cancer survivorship-care guideline notes that aromatase inhibitors may raise the risk of diabetes, the investigators noted.

The study was supported by grants from the Israeli Council for Higher Education. The investigators reported no conflicts of interest.

SOURCE: Hamood H et al. J Clin Oncol. 2018 Apr 24. doi: 10.1200/JCO.2017.76.3524.

Hormone therapy for breast cancer more than doubles a woman’s risk for developing type 2 diabetes, results of a case-cohort study suggest.

Hormone therapy with tamoxifen was associated with a more than twofold increase in risk of diabetes, and aromatase inhibitors were associated with a more than fourfold increase, reported Hatem Hamood, MD, of Leumit Health Services in Karmiel, Israel, and colleagues.

Among 2,246 women with breast cancer and no diabetes at baseline, followed for a mean of 5.9 years (longest follow-up 13 years), the crude cumulative lifetime incidence rate of diabetes was 20.9%, the investigators wrote. The report was published in the Journal of Clinical Oncology.

“[Hormone therapy] is a significant risk factor of diabetes among breast cancer survivors. The underlying mechanism is unclear, and additional research is warranted. Although cessation of treatment is not recommended and progression of breast cancer often is inevitable, devised strategies aimed at lifestyle modifications in patients at high risk of diabetes could at least preserve the natural history of breast cancer,” they wrote.

Diabetes has previously been identified as a possible risk factor for breast cancer, but the potential for breast cancer therapy as a precipitating factor for diabetes is uncertain, the authors said.

“Given the detrimental impact of diabetes on breast cancer survival, additional exploration of the role of breast cancer treatment in the development of diabetes is important not only because it would add valuable information on the etiology of diabetes but also because it would help to identify high-risk patients in need of accentuated clinical care,” they wrote.

To explore the possible association between hormone therapy and diabetes risk, the investigators performed a retrospective case-cohort study of 2,246 women who had been diagnosed with primary nonmetastatic breast cancer treated with hormone therapy from 2002 through 2012.

They examined data on a randomly selected cohort of 448 breast cancer survivors and all patients in the parent (no diabetes at baseline) cohort who developed diabetes during the study period (324 patients).

They found that the prevalence of diabetes among their source population of 2,644 breast cancer survivors (including those with baseline diabetes) increased “drastically” from 6% in 2002 to 28% in 2015. The prevalence exceeded Israeli national norms from 2010 through 2013, with standardized prevalence ratios of 1.61 to 1.81 (P less than .001).

As noted, in the population without baseline diabetes, the crude cumulative incidence rate of diabetes in the presence of death as a competing risk factor was 20.9%.

In multivariate analyses controlling for demographic and socioeconomic factors, and for chemotherapy type, hypertension, outpatient visits, use of corticosteroids, thiazide diuretics, beta-blockers, statins, and year of breast cancer diagnosis, factors significantly associated with diabetes risk were use of hormone therapy (adjusted hazard ratio [HR] 2.40, P = .008), tamoxifen (aHR 2.25, P = .013), aromatase inhibitors (aHR 4.27, P = .013), therapy duration more than 1 year (aHR 2.36, P = .009), and 1 year or less (aHR 6.48, P = .004).

The investigators noted that although other reports have found no association between aromatase inhibitors and diabetes risk, those studies had small samples or offered no explanation of the lack of association.

In contrast, a 2016 joint ACS/ASCO breast cancer survivorship-care guideline notes that aromatase inhibitors may raise the risk of diabetes, the investigators noted.

The study was supported by grants from the Israeli Council for Higher Education. The investigators reported no conflicts of interest.

SOURCE: Hamood H et al. J Clin Oncol. 2018 Apr 24. doi: 10.1200/JCO.2017.76.3524.

Hormone therapy for breast cancer more than doubles a woman’s risk for developing type 2 diabetes, results of a case-cohort study suggest.

Hormone therapy with tamoxifen was associated with a more than twofold increase in risk of diabetes, and aromatase inhibitors were associated with a more than fourfold increase, reported Hatem Hamood, MD, of Leumit Health Services in Karmiel, Israel, and colleagues.

Among 2,246 women with breast cancer and no diabetes at baseline, followed for a mean of 5.9 years (longest follow-up 13 years), the crude cumulative lifetime incidence rate of diabetes was 20.9%, the investigators wrote. The report was published in the Journal of Clinical Oncology.

“[Hormone therapy] is a significant risk factor of diabetes among breast cancer survivors. The underlying mechanism is unclear, and additional research is warranted. Although cessation of treatment is not recommended and progression of breast cancer often is inevitable, devised strategies aimed at lifestyle modifications in patients at high risk of diabetes could at least preserve the natural history of breast cancer,” they wrote.

Diabetes has previously been identified as a possible risk factor for breast cancer, but the potential for breast cancer therapy as a precipitating factor for diabetes is uncertain, the authors said.

“Given the detrimental impact of diabetes on breast cancer survival, additional exploration of the role of breast cancer treatment in the development of diabetes is important not only because it would add valuable information on the etiology of diabetes but also because it would help to identify high-risk patients in need of accentuated clinical care,” they wrote.

To explore the possible association between hormone therapy and diabetes risk, the investigators performed a retrospective case-cohort study of 2,246 women who had been diagnosed with primary nonmetastatic breast cancer treated with hormone therapy from 2002 through 2012.

They examined data on a randomly selected cohort of 448 breast cancer survivors and all patients in the parent (no diabetes at baseline) cohort who developed diabetes during the study period (324 patients).

They found that the prevalence of diabetes among their source population of 2,644 breast cancer survivors (including those with baseline diabetes) increased “drastically” from 6% in 2002 to 28% in 2015. The prevalence exceeded Israeli national norms from 2010 through 2013, with standardized prevalence ratios of 1.61 to 1.81 (P less than .001).

As noted, in the population without baseline diabetes, the crude cumulative incidence rate of diabetes in the presence of death as a competing risk factor was 20.9%.

In multivariate analyses controlling for demographic and socioeconomic factors, and for chemotherapy type, hypertension, outpatient visits, use of corticosteroids, thiazide diuretics, beta-blockers, statins, and year of breast cancer diagnosis, factors significantly associated with diabetes risk were use of hormone therapy (adjusted hazard ratio [HR] 2.40, P = .008), tamoxifen (aHR 2.25, P = .013), aromatase inhibitors (aHR 4.27, P = .013), therapy duration more than 1 year (aHR 2.36, P = .009), and 1 year or less (aHR 6.48, P = .004).

The investigators noted that although other reports have found no association between aromatase inhibitors and diabetes risk, those studies had small samples or offered no explanation of the lack of association.

In contrast, a 2016 joint ACS/ASCO breast cancer survivorship-care guideline notes that aromatase inhibitors may raise the risk of diabetes, the investigators noted.

The study was supported by grants from the Israeli Council for Higher Education. The investigators reported no conflicts of interest.

SOURCE: Hamood H et al. J Clin Oncol. 2018 Apr 24. doi: 10.1200/JCO.2017.76.3524.