“Statin sceptics” often cite increased risk of cancer in statin users. The American Society of Clinical Oncology (ASCO) 2015 Annual Meeting (abstracts 1506 and 5018, presented May 30, 2015) suggests the opposite, with statin use associated with a significant reduction in cancer mortality. This was concluded from two separate studies, one in women and the other in men.
Specifically, statin use was associated with a 22% reduction in deaths from various cancer types in women and a 55% reduction in deaths from bone/connective tissue cancers. The study in men looked at statin use together with the anti-diabetes medication metformin and found a 40% reduction in prostate cancer mortality, with the effect more pronounced in men with obesity/metabolic syndrome.
Statin Use Analysis of WHI Study Data
The results in women came from the data examined from the Women’s Health Initiative (WHI), the 15-year research program involving postmenopausal women aged 50 to 79 years who were enrolled between 1993 and 1998 at 40 centers in the United States.
The observation was between patients’ never having used statins, current statin use, and past statin use, as well as the incidence and number of deaths from cancer among 146,326 women. The median follow-up period was a substantial 14.6 years.
Among the participants, there were 23,067 cases of incident cancer for which complete follow-up data were available. There were 7411 all-cause deaths, including 5837 deaths from cancer, 613 cardiovascular deaths, and 961 deaths from other causes. In all, 3152 cancer deaths were included in the analysis, of which 708 were among current statin users and 2443 among patients who had never used statins. Importantly, multivariate analysis demonstrated that statin use was not associated with cancer incidence, and there was no association between past statin use and cancer mortality.
However, compared with never having used statins, current statin use was associated with a significant reduction in cancer mortality, with an adjusted hazard ratio (aHR) of 0.78 vs. never use (P < .0001). The association was unaffected by statin potency, lipophilicity/ hydrophobicity, type, or duration.
Statin use was associated with significant reductions in deaths from multiple cancers including breast (aHR = 0.60), ovarian (aHR = 0.58), colorectal (aHR = 0.57), digestive (aHR = 0.68), and bone/connective tissue cancers (aHR = 0.45), but not from lung cancer (aHR = 1.17).
Clearly as this was a prospective post hoc analysis of the WHI data no definitive causality could be established but the data are certainly reassuring for statin users given the widespread use and growing use of statins under the new US, NICE and ESC guidelines and the high burden of cancer,
Reduction in Prostate Cancer Death
The other study quoted at the ASCO 2015 meeting showed a reduction in prostate cancer mortality in both statin and metformin users. The researchers used Surveillance, Epidemiology and End Results–Medicare linked data to follow 22,110 patients diagnosed with high-risk prostate cancer, defined as a prostate-specific antigen (PSA) score of ≥20, a Gleason score of 8-10, or stage III or IV cancer.
There were 1365 deaths from prostate cancer between 2007 and the end of 2009. The majority of metformin users were also prescribed statins. Patients who took both statins and metformin (n = 1315) were more likely than other patients to have a comorbidity score of ≥2 and to have obesity/metabolic syndrome. Patients who took metformin alone (n = 455) experienced no reduction in overall mortality.
Patients who took both statins and metformin had a substantial reduction in both overall mortality (HR, 0.66). A similar pattern was seen in patients who took statins alone (n = 4353; HR, 0.75).
The impact of combined statin and metformin therapy on overall mortality was more pronounced in patients with documented obesity/metabolic syndrome, although the differences did not reach statistical significance.
Several UK newspapers have added voice with a press release issued by Cancer Research UK suggesting that the balance of evidence indicate statins have an anticancer effect.