Smoking and Colorectal Cancer in Lynch Syndrome: Results from the Colon Cancer Family Registry and The University of Texas MD Anderson Cancer Center

Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
Clinical Cancer Research (Impact Factor: 8.19). 02/2010; 16(4):1331-9. DOI: 10.1158/1078-0432.CCR-09-1877
Source: PubMed

ABSTRACT Lynch syndrome family members with inherited germline mutations in DNA mismatch repair (MMR) genes have a high risk of colorectal cancer (CRC), and cases typically have tumors that exhibit a high level of microsatellite instability (MSI). There is some evidence that smoking is a risk factor for CRCs with high MSI; however, the association of smoking with CRC among those with Lynch syndrome is unknown.
A multicentered retrospective cohort of 752 carriers of pathogenic MMR gene mutations was analyzed, using a weighted Cox regression analysis, adjusting for sex, ascertainment source, the specific mutated gene, year of birth, and familial clustering.
Compared with never smokers, current smokers had a significantly increased CRC risk [adjusted hazard ratio (HR), 1.62; 95% confidence interval (95% CI), 1.01-2.57] and former smokers who had quit smoking for 2 or more years were at decreased risk (HR, 0.53; 95% CI, 0.35-0.82). CRC risk did not vary according to age at starting. However, light smoking (<10 cigarettes per day) and shorter duration of smoking (<10 years) were associated with decreased CRC risk (HR, 0.51; 95% CI, 0.29-0.91 and HR, 0.52; 95% CI, 0.30-0.89, respectively). For former smokers, CRC risk decreased with years since quitting (P trend <0.01).
People with Lynch syndrome may be at increased risk of CRC if they smoke regularly. Although our data suggest that former smokers, short-term smokers, and light smokers are at decreased CRC risk, these findings need further confirmation, preferably using prospective designs.

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    ABSTRACT: Lynch syndrome (LS) is one of the inherited colorectal cancer (CRC) syndromes and is due to germline mutations in one of the mismatch repair (MMR) genes. Within LS affected-families the expression of the syndrome varies, which suggests that other factors, such as lifestyle factors, have an influence on the LS phenotype. This review gives an overview of studies that assessed the role of lifestyle factors in the development of CRC in LS. Several published studies investigated smoking habits or body fatness (BMI) in relation to colorectal tumours. Those studies fairly consistently suggest that smoking and a high BMI markedly increase the risk of CRC in persons with LS. Other lifestyle factors, such as physical activity, alcohol or diet have not or only scarcely been studied. Lifestyle factors may indeed affect CRC risk in LS. However, more prospective studies with only confirmed MMR gene mutation carriers should be done to further elucidate the role of all lifestyle factors in CRC and in other types of cancer in persons with LS. Information on the role of lifestyle factors in the development of LS-associated cancers may help in establishing lifestyle and dietary recommendations with the ultimate goal of decreasing cancer risk in persons with LS.
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