Association between prediabetes and breast cancer: a comprehensive meta-analysis.

Background: Breast cancer accounts for up to 30% of cancer cases in women in the US. Diabetes mellitus has been recognized as a risk factor for breast cancer. Some studies have suggested that prediabetes may also be associated with breast cancer whereas other studies have shown no or an inverse association; thus, we conducted a meta-analysis to assess the risk of breast cancer in prediabetes.

Methods: We searched PubMed/Medline, EMBASE, Google Scholar, and Scopus to identify studies that reported breast cancer risks in patients having prediabetes compared to normoglycemic patients. Binary random-effects model was used to calculate a pooled odds ratio (OR) with 95% confidence intervals. I² statistics were used to assess heterogeneity. Leave-one-out sensitivity analysis and subgroup analyses were performed.

Results: We analyzed 7 studies with 24,586 prediabetic and 224,314 normoglycemic individuals (783 and 5739 breast cancer cases, respectively). Unadjusted odds ratio (OR) for breast cancer was 1.45 (95% CI = 1.14, 1.83); adjusted OR was 1.19 (95% CI = 1.07, 1.34) in prediabetes. Subgroup analysis revealed a higher breast cancer risk in individuals aged less than 60 years (OR = 1.86, 95% CI = 1.39, 2.49) than in those aged 60 years or more (OR = 1.07, 95% CI = 0.97, 1.18). Subgroup analysis by median follow-up length indicated a higher risk of breast cancer for follow-ups of less than or equal to 2 years (OR = 2.34, 95% CI = 1.85, 2.95) than in those of over 10 years (OR = 1.1, 95% CI = 0.99, 1.23) and 6 to 10 years (OR = 1.03, 95% CI = 0.88, 1.21).

Conclusions: In conclusion, individuals with prediabetes have higher risk of developing breast cancer than those with normoglycemia, especially younger prediabetes patients. These individuals may benefit from early identification, monitoring, and interventions to reverse prediabetes.