NEW ORLEANSIn a retrospective, observational study of nearly 4,000 patients in northern Israel, statin use for at least 5 years reduced the risk of colorectal cancer by 46%, after adjustment for known protective factors, including use of aspirin(Drug information on aspirin) and nonsteroidal anti-inflammatory drugs (NSAIDs). The effects seen do not appear to be the result of a reduction in cholesterol levels. While the investigators, from the Molecular Epidemiology of Colorectal Cancer (MECC ) Study Group, cautioned that it is premature to change either the standard of care for colorectal cancer or the indications for statins, they said statins merit further investigation in this area.
Jenny N. Poynter, MPH, of the University of Michigan, presented the study results at the 40th Annual Meeting of the Society of Clinical Oncology (abstract 1), on behalf of the MECC Study Group. MECC is led by Stephen B. Gruber, MD, PhD, MPH, director of clinical cancer genetics, University of Michigan Comprehensive Cancer Center, and Gadi Rennert, MD, director of the National Cancer Control Center for Clalit Health Services, Israel’s largest HMO.
The MECC study, initiated in 1999 with a $4.8 million grant from the National Cancer Institute and additional funding from the Irving Weinstein and Ravitz Foundations, explores how genes, diet, exercise, and other factors interact to produce colon cancer.
Given that the descendants of Ashkenazi Jews have unusually high rates of colon cancer (with a novel cancer susceptibility allele, APC I1307K, identified in 6% and appearing to double colorectal cancer risk), the researchers believed an Israeli-based population study including this ethnic group, as well as Arab patients and Jews of non-Ashkenazi ethnicity, might provide interesting information about possible nongenetic factors influencing development of this disease.
Statins were assessed in this population, Ms. Poynter said, "because they inhibit HMG CoA reductase, which is overexpressed in colorectal cancer cell lines, and induce apoptosis in colorectal cancer cell lines at physiologically relevant concentrations. They have also been shown to reduce tumor formation in animal models of colorectal cancer."
Eligible patients were those diagnosed with colon or rectal cancer between 1998 and 2004 (n = 1,814 cases). Controls (n = 1,959) were matched to cases based on age, sex, and Jewish vs non-Jewish ethnicity. The researchers also performed matched analyses on 1,570 perfectly matched case-control pairs.
Medication use, including statins, was assessed in a structured in-person interview. Classified as "statin users" were those reporting use of any statin for at least 5 years; nonusers had no reported statin use. Regular statin use (prescriptions filled more than three times per year) was validated from prescription records from the Clalit Health System database for the majority of patients who reported using these drugs. All pathology was independently confirmed by a single pathologist at the University of Michigan.