The CpG island methylator phenotype is not associated with a personal or family history of cancer

Abstract

Colorectal cancers with widespread CpG island methylation display a number of distinct clinicopathological features, and it has been suggested that the condition has an inheritable genetic component. To address this possibility, histories of cancer were obtained from 562 individuals undergoing curative surgery for unselected colorectal cancer at one institution. Microsatellite status and methylation at p16, MINT1, 2, 12, and 31 loci were determined on fresh tumor tissue using standard methods. Fifty-five of 562 probands in this study provided a personal history of at least one other colorectal cancer, 10 reported at least one extracolonic cancer of hereditary nonpolyposis colorectal cancer type, and 84 individuals had another type of cancer. Age was strongly associated with the risk of multiple cancers, but there was no evidence that microsatellite instability or the CpG island methylator phenotype were independent risk factors for their development, either in the colorectum or elsewhere. Of the 547 individuals with knowledge of their family history, 80 (14.6%) reported a family history of colorectal cancer in a first-degree relative, and 60% of individuals reported a history of any cancer in a first-degree relative. Neither tumor CpG island methylator phenotype status nor microsatellite instability was predictive of a positive history of cancer in first- or second-degree relatives. The probability of a positive family or personal history of cancer did not increase with increasing number of methylated loci. Epigenetic silencing of multiple genes seen in some tumors is at best rarely the result of an inherited defect in the methylation apparatus. There is no justification for altering the personal or family cancer screening recommendations on the basis of tumor CpG island methylator phenotype status.