Breast cancer and diabetes.

Abstract

e12507 Background: Diabetes and Breast Cancer are common conditions in women and there have been various links proposed between the two conditions. Methods: To clarify the potential association between diabetes, related factors, treatments and breast cancer risk, a series of meta-analyses were carried out following PRISMA guidelines. Results: For breast cancer at all ages, the risks obtained from prospective studies were: diabetes (SRR=1.27, 95% CI (1.16, 1.39); physical activity (SRR=0.88 (0.85, 0.92)); glycaemic load (SRR=1.05, (1.00, 1.10)); glycaemic index (SRR=1.05, (1.00, 1.09)); fasting glucose (SRR=1.14, (0.94, 1.37)); serum insulin (SRR=1.11, (0.75, 1.85)); c-peptide (SRR=1.00, (0.69, 1.46)) and adiponectin (SRR=1.16, (0.93, 1.46. An increase of 5 units in BMI was associated with post-menopausal breast cancer (SRR=1.12, 95% CI (1.08, 1.16)) but not at pre-menopausal ages (SRR=0.83, 95% CI (0.72, 0.95)). Serum insulin and c-peptide were associated with breast cancer at post-menopausal ages but not at pre-menopausal. For IGF-1, Hodge’s Standardised Mean Difference (HSMD) was calculated and there was no significant association with breast cancer (HSMD=0.026, 95% CI (-0.031, 0.084). The SRR for breast cancer among users of insulin glargine was 1.08 (0.98, 1.20) and was 0.92 (0.32, 2.65) when restricted to randomized trials. Among new users, the SRR for breast cancer was 1.09 (0.98, 1.21) and there was no trend of increasing breast cancer risk with increasing duration of use of glargine (β=0.04)(p=0.52). Risk of breast cancer in a prospective cohort declined with increasing follow-up, from 1.99 (1.31, 2.03) with two years of follow-up, to 1.60 (1.10, 2.32) with 3 years, 1.50 (1.10, 2.10) with four years and 1.18 (0.84, 1.66) with five years of follow-up. There is no reduction in risk of breast cancer associated with metformin use (SRR=0.96, 95% CI (0.85, 1.08)) even for the longest duration of use (SRR=0.94, 95% CI (0.81, 1.09)). Conclusions: An association between these two common diseases could have important implications for public health with common risk factors driving further increases in both diseases yet holding the tantalizing possibility for prevention of both. Overweight/Obesity and Physcal activity appear to be common links with the two diseases.