Statins have been implicated in the regulation of cell proliferation, apoptosis and tumor progression in cancer patients and statin use at the time of cancer diagnosis has been reported to be associated with reduced cancer risk and improved survival, irrespective of concomitant anti-cancer therapy. A systematic literature search of relevant databases through May 2015 was conducted to identify studies assessing the prognostic impact of statin use on prognostic outcomes in cancer patients. Literature search identified 95 cohort studies that met the inclusion criteria. A meta-analysis of 55 articles showed that statin use was significantly associated with decreased risk of all-cause mortality (HR 0.70, 95% Cl 0.66 to 0.74) compared with nonusers. The observed pooled estimates were retained for cancer-specific mortality (HR 0.60, 95% Cl 0.47 to 0.77), progression-free survival (HR 0.67, 95% Cl 0.56 to 0.81), recurrence-free survial (HR 0.74, 95% Cl 0.65 to 0.83) and disease-free survival (HR 0.53, 95% Cl 0.40 to 0.72). These associations almost remained consistent across those outcomes when stratified by publication type, tumour location, study design, sample size, initiation of statins, disease stage, research country, follow-up duration or research hospital involved. Subgroup analyses according to initiation of statins showed postdiagnosis statin users (HR 0.65, 95% Cl 0.54 to 0.79) gained significantly more recurrence-free survival benefit than prediagnosis statin users (HR 0.86, 95% Cl 0.77 to 0.96) (p for interaction = 0.018). Statin therapy has potential survival benefit for patients with malignancy. Further large-scale prospective studies emphasising survival outcomes of individual cancer type are strongly encouraged.

Objective:Since metabolic syndrome is a significant risk factor for cardio-cerebrovascular diseases, and the relationship between metabolic syndrome (including its components) and the prognosis of stroke are controversial, this study was conducted to evaluate whether metabolic syndrome is associated with a high recurrence and mortality of stroke.Methods:This study was registered in the PROSPERO database (CRD42020177118). We searched for relevant observational cohort studies published from inception to April 23, 2020 using PubMed, Embase, and the Cochrane Library. Effect estimates with 95% CIs were pooled using the random-effects model. The primary and secondary outcomes were stroke recurrence and all-cause mortality, respectively. Leave-one-out sensitivity analyses and nonparametric trim and fill method were used to identify the stability of the results.Results:Thirteen cohort studies comprising 59,919 participants aged >60 years were included for analysis. Overall, metabolic syndrome was significantly associated with stroke recurrence (RR 1.46, 95% CI 1.07-1.97, P = 0.02). Among the metabolic syndrome components, low levels of high density lipoprotein cholesterol (HDL-C) (RR 1.32, 95% CI 1.11-1.57, P = 0.002) and number of metabolic syndrome components(≥ 2) (RR 1.68, 95% CI 1.44-1.94, P <0.001) significantly predicted stroke recurrence, whereas elevated triglyceride, elevated waist circumference, hyperglycemia, or hypertension failed to account for risk factors for stroke recurrence. Moreover, metabolic syndrome, not its components, was significantly associated with all-cause mortality (RR 1.27, 95% CI 1.18-1.36, P < 0.001). The stability of these results was further confirmed by the leave-one-out sensitivity analyses and nonparametric trim and fill method.Conclusions:The present study indicates that metabolic syndrome and some of its components (low HDL-C and number of metabolic syndrome components) seem to be risk factors for stroke recurrence. Though metabolic syndrome is also associated with all-cause mortality, the role of its components to predict all-cause mortality deserves further study.