A single founder allele of the CHEK2 gene has been associated with predisposition to breast and prostate cancer in North America and Europe. The CHEK2 protein participates in the DNA damage response in many cell types and is therefore a good candidate for a multisite cancer susceptibility gene. Three founder alleles are present in Poland. Two of these result in a truncated CHEK2 protein, and the other is a missense substitution of an isoleucine for a threonine. We ascertained the prevalence of each of these alleles in 4,008 cancer cases and 4,000 controls, all from Poland. The majority of the common cancer sites were represented. Positive associations with protein-truncating alleles were seen for cancers of the thyroid (odds ratio [OR] 4.9; P=.0006), breast (OR 2.2; P=.02), and prostate (OR 2.2; P=.04). The missense variant I157T was associated with an increased risk of breast cancer (OR 1.4; P=.02), colon cancer (OR 2.0; P=.001), kidney cancer (OR 2.1; P=.0006), prostate cancer (OR 1.7; P=.002), and thyroid cancer (OR 1.9; P=.04). The range of cancers associated with mutations of the CHEK2 gene may be much greater than previously thought.

Stomach cancer ranks second to lung cancer in the global cancer burden. It is estimated that 25% of families meeting the criteria for hereditary diffuse gastric carcinoma (HDCG) will have germline mutations in the E-cadherin gene. Evidence suggests that stomach cancer might also be a malignant manifestation of other inherited predispositions to disease. Recently, it has been reported that the incidence of stomach cancer is significantly increased in BRCA2 gene mutation carriers. We analysed by direct sequencing the BRCA2 gene in 29 breast cancer patients derived from 29 families with an aggregation of at least one female breast cancer diagnosed before the age of 50 years and one male stomach cancer diagnosed before the age of 55 years. In all but one of these families at least one additional relative was also affected by a malignant tumour. We identified three frameshift mutations and three sequence variants -potentially missense mutations, in six unrelated patients representing 20.7% (six out of 29) of the families investigated. Our results confirm that BRCA2 gene mutations are also associated with familial aggregations of not only breast but also of stomach cancer. In comparison to the number of cancers expected in the study population compared to the general population there is an over-representation of several cancers with significant confidence intervals to suggest that the associations are real and not a selection artefact.

The NOD2 gene has been associated with susceptibility to Crohn's disease and individuals with Crohn's disease are at increased risk for cancer at a number of organ sites. We studied the association between the 3020insC allele of the NOD2 gene and cancer among 2604 cancer patients and 1910 controls from Poland. Patients were diagnosed with one of twelve types of cancer in the Szczecin region between 1994 and 2004. Significant associations were found for colon cancer (OR = 1.8; 95% CI 1.2 to 2.6), for lung cancer (OR = 1.7; 95% CI = 1.1 to 2.5) and for ovarian cancer (OR = 1.6; 95% CI 1.1 to 2.3). In addition, a significant association was found for early-onset laryngeal cancer (OR = 2.9; 95% CI 1.4 to 6.2) and for breast cancer in the presence of DCIS (OR = 2.1 95% CI = 1.2 to 3.6). The NOD2 3020insC allele is relatively common (in Poland 7.3% of individuals) and may be responsible for an important fraction of cancer cases. We estimate that the lifetime cancer risk among carriers of this allele is 30% higher than that of individuals with two wild-type alleles.