Is there a shift from cardiovascular to cancer death in lipid-lowering trials? A systematic review and meta-analysis.

BACKGROUND: Lipid-lowering therapy (LLT) reduces cardiovascular (CV) events, but data are conflicting on all-cause mortality, especially among older adults. Though LLT does not induce cancer, some randomized clinical trials (RCTs) found a pattern of increased cancer death under LLT. Our objective was to assess a possible shift from CV to cancer death in LLT trials (i.e. an increase in cancer and decrease in CV death) and to investigate potential subgroups at risk.

METHODS: We performed a systematic review and meta-analysis. We retrieved RCTs from MEDLINE, Embase, and Cochrane Central until 08/2023. We extracted the number of CV and cancer deaths in the treatment vs. in the control arm, calculated the relative risk (RR) by dividing the risk of death in the treatment over the risk of death in the control group and then pooled them using random-effect meta-analysis. We performed subgroup analyses on primary and secondary prevention, and according to different age cut-offs.

RESULTS: We included 27 trials with 188'259 participants (23 statin; 4 ezetimibe trials). The trials reported 4056 cancer deaths, 2061 under LLT and 1995 in control groups. Overall, there was no increased risk of cancer mortality (RR 1.03, 95% confidence interval 0.97-1.10), with no difference between primary and secondary prevention. In the subgroup analyses for RCTs with ≥15% of participants aged ≥75 years, the RR of cancer death was 1.11 (1.00-1.23), while the RR for CV death was 0.96 (0.91-1.01). For RCTs with a mean age ≥ 70 years, the RR for cancer death was 1.21 (0.99-1.47).

CONCLUSION: LLT does not lead to a shift from CV to cancer death. However, there might be a possible shift with a pattern of increased cancer deaths in trials with more older adults, particularly ≥75 years. Individual participant data from LLT trials should be made public to allow further investigations.

PROSPERO REGISTRATION: CRD42021271658.