To evaluate the possible association of R117G and two germline variants reported elsewhere, R145W and I157T with breast cancer, we screened 737 BRCA1/2-negative familial breast cancer cases from 605 families, 459 BRCA1/2-positive cases from 335 families, and 723 controls from the United Kingdom, the Netherlands, and North America.
We analyzed the association between p.</span>I157T and the clinico-pathological breast cancer characteristics by comparing the p.I157T carrier tumors to non-carrier and c.1100delC carrier tumors.
Seven thousand four hundred ninety-four BRCA1 mutation-negative patients with breast cancer and 4,346 control women were genotyped for four founder mutations in CHEK2 (del5395, IVS2+1G>A, 1100delC, and I157T).
Modest increases of breast cancer risk were observed for the four analysed CHEK2 variants (I157T, 1100delC, IVS2 + 1G > A and del5395) (OR = 2.2; 95% 1.7-2.8; P = 0.0001).
The frequency, penetrance and epidemiological as well as clinical significance of the two most studied breast cancer-predisposing variants of the CHEK2 gene, 1100delC and I157T, are highlighted in more depth, and additional CHEK2 mutations and their cancer relevance are discussed as well.
In total, 26,336 cases and 44,219 controls from 18 case-control studies were used in this meta-analysis, and significant associations of the CHEK2 I157T variant with cancer susceptibility were found (OR, 1.39; 95% CI, 1.19-1.63; p<0.0001), breast cancer (OR=1.58, 95% CI=1.42-1.75, p<0.00001) and colorectal cancer (OR=1.67, 95% CI=1.24-2.26, p=0.0008).
Our study suggests that the risk of breast cancer in carriers of a deleterious CHEK2 mutation is increased if the second allele is the I157T missense variant.
Interestingly, we found no increased breast cancer risk associated with the splice site mutation IVS2+1G-->A or the most common missense mutation I157T, which account for more than half (12/21) of the variants observed in patients.
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).
Protein-truncating mutations in CHEK2 have been reported to confer higher risks of cancer of the breast and the prostate than the missense I157T variant.
Our research indicates that the CHEK2 I157T variant may be another important genetic mutation which increases risk of breast cancer, especially the lobular type.
Despite the lack of association of I157T mutation with breast cancer development in our population we deduced that the FHA domain is the subject of rare population-specific alterations that might modify risk of various cancers.
There was no significant overall association between CHEK2 and breast cancer (OR = 1.3; p = 0.30), but among those with lobular carcinoma the association with the I157T missense mutation was very strong (OR = 6.6; p > 0.0001).
Comparing the prevalence of CHEK2 mutations in BC with controls revealed that carriers of an I157T variant had OR of 1.80 for luminal A subtype and carriers of truncating mutations had OR of 6.26 for luminal B subtype of BC.
The p.H371Y mutation was significantly associated with increased breast cancer risk in unselected b</span>reast cancer (odds ratio [OR] 2.43, 95% confidence interval [CI] 1.07-5.52, P = 0.034).
We screened a cohort of 2334 Chinese women with operable primary breast cancer who received a neoadjuvant chemotherapy regimen for CHEK2 H371Y germline mutations.