Possible risk modification by polymorphisms of estrogen metabolizing genes in familial breast cancer susceptibility in an Indian population.

This case control study investigated whether polymorphisms of estrogen metabolizing genes CYP1A1 MspI, CYP17 MspAI, COMT Val(158) Met, and SULT1A1 Arg(213) His have any role in familial breast cancer susceptibility risk. Logistic regression analysis adjusted to age was used to calculate odds ratios (ORs) and 95% confidence intervals (95%CIs). Familial breast cancer risk due to CYP1A1 wt/m1 and m1/m1 genotypes was 2.3 (1.51-3.61)-fold and 7.1 (3.69-13.7)-fold, respectively. In addition to the main effects, certain first-order interactions were also significantly associated with familial breast cancer. Our results favor a possible risk modification by estrogen metabolizing gene polymorphisms in familial breast cancer susceptibility.

Contribution of XPD (Lys751Gln) and XRCC1 (Arg399Gln) polymorphisms in familial and sporadic breast cancer predisposition and survival: an Indian report.

The etiology of a significant proportion of familial breast cancers is still poorly understood, with known high penetrance gene mutations accounting for only a small proportion of the cases. The increased risk of breast cancer for the majority of women with a family history likely reflects shared minor low penetrant genetic factors. In the present case-control study undertaken to examine the influence of DNA damage repair gene polymorphisms in familial and sporadic breast cancer susceptibility, 219 Sporadic and 140 familial breast cancer patients and 367 controls were genotyped using PCRRFLP. Odds Ratios (ORs) and 95% Confidence Intervals (95%CIs) were calculated by unconditional logistic regression adjusted to age. Variant genotypes XRCC1 Arg/Gln or Gln/Gln and XPD Lys/Gln or Gln/Gln increased both familial and sporadic breast cancer susceptibility. However, when the intra group risk was compared, the risk due to the XPD polymorphic genotypes Lys/Gln or Gln/Gln was significantly lower among familial breast cancer patients compared to sporadic breast cancer patients [OR = 0.61; 95%CI = 0.39-0.94; p value = 0.024) whereas the risk implied by XRCC1 variant genotype was not significantly different between the familial and nonfamilial groups of breast cancer patients [OR = 0.97; 95%CI = 0.63-1.49; p value = 0.882]. Both these variant genotypes were not associated with the disease characteristics or survival of either familial or sporadic breast cancer patients. This study represents an addition to previous published work on GSTs from the same study population and substantiates the hypothesis that the impact of the low penetrance gene polymorphisms differ by family history of the disease.

Hereditary breast/ovarian cancer: clinicopathological characteristics and survival of BRCA2 positive and negative cases.

The clinical and pathological characteristics and prognostic outcome of patients with hereditary breast/ovarian cancer and BRCA2 mutations are poorly known. Hence, the present study aimed to correlate the BRCA2 mutation status with clinical characteristics and overall survival of 102 breast/ovarian cancer patients in Kerala, South India. All the coding regions of BRCA2 genes were PCR amplified and analyzed for mutations employing Conformation Sensitive Gel Electrophoresis and characterized by sequencing. The ORs with 95% Cls was computed to assess the association between BRCA2 gene mutation status and clinicopathologic characteristics of breast cancer patients. Survival curves were generated according to Kaplan-Meier method using Log Rank test and Cox proportional hazards regression method. Out of the 102 breast/ovarian cancer patients with known BRCA2 status, 19 were BRCA2 mutation positive. In survival analysis, BRCA2 gene mutation status (P = 0.02) and clinicopathologic parameters such as tumour size (p = 0.01), metastasis (P = 0.01), disease stage (P = 0.03) and laterality (P = 0.02) were significantly associated with poor prognosis of breast cancer patients. Patients with hereditary breast/ovarian cancer resulting from a BRCA2 mutation have been conclusively shown to have a worse survival prognosis compared to the non mutated group of patients.

Glutathione S-transferase M1, T1 and P1 polymorphisms: susceptibility and outcome in lung cancer patients.

The glutathione S-transferases (GSTs) are a superfamily of genes whose products are phase II enzymes, catalyzing the conjugation of reactive intermediates to soluble glutathione. Some of the GSTs are polymorphic and may play a role in lung cancer susceptibility. We investigated whether genetic polymorphisms of GSTM1, GSTP1 and GSTT1 genes modulated lung cancer risk and affect survival among lung cancer patients. We determined the GST genotypes in 422 study subjects, using polymerase chain reaction (PCR) and reverse PCR and restriction fragment length polymorphism (RFLP). Logistic Regression analysis was carried out to find the association of various polymorphisms and GSTs and lung cancer. The influence of the genetic polymorphisms on patient survival was estimated using the method of Kaplan-Meier survival function. Cox Proportional Hazard models were used to estimate hazard ratios (HR) for deaths. GSTT1 -/- genotype conferred a higher odds ratio of 2.9 (P = 0.001) compared to the GSTT1+/+. So also, the GSTP1 GG genotype too had higher risk compared to the GSTP1 AA genotype (OR = 2.3, P = 0.033). When the combined GST M1, GSTT1 and GSTP1 genotypes were examined, patients with the combinations GSTM1 null and GSTT1 null had a significant OR of 3.6. So also the combinations GSTT1-/- GSTP1 AA (P = 0.005) and GSTT1-/- GSTP1 AG/GG (P = 0.001) came out to be significant. There were some significant interactions between GST genotypes with tobacco smoking and also for clinicopathological factors. Regarding survival analysis, no association of GSTM1 or GSTP1 genes with survival was noted. The GSTT1 -/- genotype along with stage was significantly associated with overall survival and found to be an independent prognostic factors for shorter lung cancer survival.

Influence of germline polymorphisms of GSTT1, GSTM1, and GSTP1 in familial versus sporadic breast cancer susceptibility and survival.

Identifying genes associated with familial inheritance of breast cancer continues to be a major goal of current research as the known high penetrance genes could be attributable for only a small percentage of the risk. So, it is hypothesized that the low penetrance genes may also modify the risk for familial breast cancer. In the present case-control study, undertaken to examine the influence of polymorphisms of GSTs in familial and sporadic breast cancer susceptibility, 597 women including 222 sporadic breast cancer patients, 125 familial breast cancer patients and 250 females with no history of cancer as controls were genotyped by PCR based methods. Odds Ratios (ORs) and 95% Confidence Intervals (95%CIs) were calculated by unconditional logistic regression adjusted to age. Interestingly, GSTM1 deletion was found to be significantly associated only with familial breast cancer (OR = 2.0; 95%CI = 1.252-3.128) while GSTT1 was associated only with sporadic breast cancer (OR = 2.3; 95%CI = 1.336-3.970). GSTP1 Ile105Val polymorphism was associated neither with sporadic nor familial breast cancer susceptibility (P value > 0.05). The GST genotypes did not have any effect on the survival of both familial and sporadic breast cancer patients. However, familial breast cancer patients with GSTM1 null genotype had a relative risk of 0.42 (95%CI = 0.18-0.97) for an advanced disease stage. The results indicate that, in addition to the known high penetrance genes, certain low penetrance genes may also play a role, in the familial inheritance of breast cancer. It is also noticed that all the polymorphisms associated with sporadic breast cancer are not associated with familial breast cancer.

Prognostic importance of DNA repair gene polymorphisms of XRCC1 Arg399Gln and XPD Lys751Gln in lung cancer patients from India.

PURPOSE: Inter individual variation in lung cancer susceptibility may be modulated in part through genetic polymorphisms in the DNA repair genes, especially the genes involved in the Base Excision Repair (BER) and nucleotide excision repair (NER) pathway. Two of the genetic polymorphisms, XRCC1Arg399Gln and XPD Lys751Gln have been extensively studied in the association with lung cancer risk, although published studies have been inconclusive. METHODS: In order to verify the role of the common variant alleles in the XPD gene, we have genotyped 211 lung cancer patients and 211 healthy controls using PCR-RFLP assays in a hospital based, case-control study in an Indian population. Logistic regression models were fit to examine the relationship between the log odds of lung cancer and each covariate. Overall Survival in relation to various genotypes and clinicopathological factors were analyzed using Kaplan Meier estimates and hazard ratios were calculated using Cox Regression analysis. RESULTS: The carriers of XRCC1 399 AA genotypes were at higher risk of lung cancer (OR = 2.1, 95% CI:1.224-3.669, P = 0.007) than carriers of GG genotype. Subjects carrying 751 AC genotype were at an increased risk of carcinoma of the lung (OR = 1.8; 95% CI:1.233-2.807, P = 0.003) than subjects with AA genotypes. Compared to the XRCC1 399 GG/ XPD 751 AA reference genotype, the combined variants, XRCC1 399 GG/ XPD 751 AC+CC (OR = 1.9, 95% CI: 1.037-3.481), P = 0.03), XRCC1 399 GA+AA/ XPD 751 AA (OR = 1.7, 95% CI: 1.020-2.833, P = 0.04), XRCC1 399 GA+AA/XPD 751 AC+CC (OR = 2.7, 95% CI: 1.582-4.864, P = 0.01), had significantly higher odds ratios. Increasing numbers of either XPD or XRCC1 variant alleles were associated with shorter overall survival, the risk being significant for the XRCC1 gene polymorphism (P = 0.01 by log-rank test). The hazard of dying was significant for the XRCC1 399 AA genotype (HR = 3.04, 95%CI: 1.393-6.670, P = 0.005). Higher tumour stage also came out as significant predictors of patient death. CONCLUSIONS: These findings suggest that genetic polymorphisms in the DNA repair genes may modulate overall lung cancer susceptibility and that pathological stage and XRCC1 Arg399Gln independently predicted overall survival among Indian lung cancer patients.

Novel germline mutations in BRCA2 gene among 96 hereditary breast and breast-ovarian cancer families from Kerala, South India.

PURPOSE: Aim of the present study was to identify the genetic heterogeneity, prevalence and frequency of germline mutations of BRCA2 gene in Hereditary Breast/Ovarian cancer patients from Kerala, South India. METHODS: We analyzed 102 Breast/Ovarian cancer patients from 96 breast and/ovarian cancer families for BRCA2 gene mutations using Conformation-Sensitive Gel Electrophoresis (CSGE) followed by sequencing. RESULTS: Sequence variations in BRCA2 gene were detected in 27 (26.4%) patients. Sixteen distinct sequence variants were detected of which 11 were (69%) in exon 11. We have identified two novel disease-causing frameshift mutations (c.4642delAA and c.4926insGACC) in two unrelated patients. Apart from this, fourteen distinct sequence variants were detected in 25 breast/ovarian cancer patients of which 8 (57%) were also novel. These include nine missense mutations, one silent mutation, one-nonsense mutation and three intronic variants. CONCLUSIONS: The results of this study suggest that germline mutations of BRCA2 gene account for rather small proportion of Hereditary Breast/Ovarian cancer in Kerala, South India.