Background: The aim of the present paper is to provide some further data on the relationship between β-blocker treatment and the incidence of cancer, using two different approaches (epidemiological study and meta-analysis of clinical trials).
Methods: In a consecutive series of 1340 diabetic patients starting insulin therapy, 112 cases of cancer during a mean follow-up of 75.9 months were identified as first hospital admission or death. For each case, the controls were chosen randomly from those members of the cohort matched for age, sex and BMI. The main predefined analysis was the comparison of cases and controls for length of exposure to β-blockers and proportion of patients exposed using a conditional logistic regression which takes into account the matching structure. For the meta-analytic sub-study, an extensive search of Medline and the Cochrane Library (any date up to December 31st, 2011) was performed for all trials in which a β-blocker was used. Mantel-Haenszel Odds Ratios (MH-OR) with 95% confidence intervals for incident malignancies were calculated using a random effect model.
Results: After adjusting for mean daily dose of glargine and metformin, and ischemic heart disease, exposure to β-blockers was associated with a reduced overall risk of cancer (HR 0.33 [0.13; 0.83], p = 0.019; HR for each month of exposure 0.87 [0.77; 0.98], p = 0.025). In the meta-analysis sub-study, performed on nine trials, β-blockers were associated with a non-significant trend toward lower risk of cancer (MH-OR 0.93 [0.86; 1.01], p = 0.070).
Study limitation: Limitations of the observational study are the small sample size that limits the statistical power of analyses, that it was performed on diabetic patients only, and that diagnoses of malignancies were derived from administrative data.
Conclusions: In conclusion, this research seem to confirm a possible beneficial effect of β-blockers against the risk of cancer development.