Comparison of diagnostic and prognostic performance of two assays measuring thymidine kinase 1 activity in serum of breast cancer patients

BACKGROUND

We compared two recently developed immunoassays for serum thymidine kinase 1 (TK1) activity: one manual assay (DiviTum, Biovica(®)) and one fully automated assay (Liaison, Diasorin(®)).

METHODS

The study included 368 women: 149 healthy blood donors (control), 59 patients with benign breast disease (BBD) and 160 patients with primary breast cancer (BC).

RESULTS

A regression analysis of the Liaison (y) and DiviTum (x) assays for all three groups yielded the equation y=3.93+0.03x (r=0.85, n=368). The r-value in BC was higher than in control and BBD (0.90 vs. 0.81 and 0.64). The correlation between the two assays for TK1 values above the cut-off was higher compared to that below (0.88 and 0.59). Breakdown of the BBD group into subgroups with proliferative and non-proliferative lesions was effective only with the measurement of TK1 with DiviTum assay (p=0.03). The TK1 activity determined preoperatively in BC patients with DiviTum and Liaison assays was significantly associated with T-stage (for both p=0.01), presence of vascular invasion (p=0.002 and p=0.02), lack of estrogen receptor (ER) (p=0.001 and p=0.01) and progesterone receptor (PR) (p=0.01 and p=0.03) expression. Only TK1 analyzed with the DiviTum assay was associated with tumor grade and molecular subtype of BC (p=0.02 and p=0.003). Multivariate Cox proportional hazards analyses demonstrated that T-stage, PR status and TK1 activity measured by both methods (DiviTum, RR=3.0, p=0.02 and Liaison, RR=3.1, p=0.01) were independent predictors of disease recurrence.

CONCLUSIONS

In spite of differences observed between TK1 activity measured by the DiviTum and Liaison assays, both of them may be used for recurrence prediction in preoperative evaluation of BC patients.

Abstract P4-05-08: Oncotype Dx assay in BRCA positive ER positive breast cancer patients

Background:

Oncotype DX is a 21-gene RT-PCR assay which quantifies the likelihood of breast cancer recurrence and the potential benefit of chemotherapy in patients with early stage, ER positive, Tamoxifen treated breast cancer. Breast cancer in BRCA carriers is considered more aggressive. The aim of our study was to evaluate whether Oncotype Dx recurrence score distribution is different in breast cancer patients with inherited BRCA mutation.

Methods:

The Oncotype DX assay has been used at Hadassah Medical Center since 2004 on specimens from over 450 patients. We analyzed and compared clinicopathological characteristics and Oncotype Dx recurrence scores of BRCA carriers versus non- BRCA or unknown status of BRCA patients.

Results:

Ten patients had validated inherited BRCA mutation, five of them are BRCA1 carriers and five BRCA2 carriers. There were no significant differences in the clinicopathological characteristics between the two groups. Oncotype Dx recurrence score distribution between low, intermediate and high risk groups was not significantly different. The mean recurrence score was 18.48 for the non- BRCA or unknown status of BRCA patients and 22.8 for the BRCA carriers patients. This difference was not statistically significant.

Conclusion:

Estrogen receptor positive breast cancer tumors from BRCA carriers does not display a significantly different Oncotype Dx recurrence score result distribution.

These preliminary data suggest Oncotype Dx assay might be used to help tailor treatment in this subset of patients, although further follow up is needed.

All patients evaluated for oncotype_DX  All evaluated (except BRCA+) n = 456BRCA positiveP valueAgeMean57.4557.60.7 Median5857  Range56 (25-81)34 (42-76) T stageT167.7%70%0.9 T230.7%30%  T31.6%0% Tumor sizeMean1.71.360.2 Median1.51.26  Range7.8 (0.2-8)1.3 (0.7-2) GradeGrade 1-278.8%60%0.15 Grade 321.2%40% RSLow50%40%0.57 Intermediate39.8%40%  High10.2%20% RSMean18.4822.80.16 Median17.522.5  Range64 (0-64)27 (12-39) 

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-05-08.

Increased proliferative background in healthy women with BRCA1/2 haploinsufficiency is associated with high risk for breast cancer

Previous studies indicated that BRCA haploinsufficiency was associated with activation of the EGF receptor (EGFR) signaling pathway and increased proliferative activity in mammary epithelial cells of healthy women. We hypothesized that these processes might be reflected in the expression of serologic soluble EGFR (sEGFR) and thymidine kinase 1 (TK1) activity, which signal the initial and final steps of the proliferative pathway, respectively. We found that healthy carriers of BRCA1/2 mutations (n = 80) showed a significantly higher TK1 activity than age-matched controls (P = 0.0003), and TK1 activity was similar in women with BRCA1 and BRCA2 mutations (P = 0.74). The sEGFR concentration was significantly higher in women with BRCA1 than in controls and BRCA2 mutation (P = 0.013 and 0.002, respectively). During follow-up, four of 80 BRCA1/2 mutation carriers developed breast cancer. These women showed a significantly higher TK1 activity and somewhat higher sEGFR concentrations than the other 76 BRCA1/2 carriers (P = 0.04 and 0.09, respectively). All tumors were negative for ovarian hormone receptors, but showed a high EGFR expression. This study was limited by the short-term follow-up (mean, 27 months; range, 5-45), which resulted in a small sample size. Women with BRCA1 and BRCA2 mutations that had undergone risk-reducing bilateral salpingo-oophorectomy (BSO) showed significantly lower sEGFR compared with those without surgery (P = 0.007 and 0.038, respectively). Larger, prospective studies are warranted to investigate whether TK1 and sEGFR measurements may be useful for identifying healthy BRCA1/2 carriers with high risk of developing breast cancer; moreover, sEGFR measurements may serve as effective tools for assessing risk before and after BSO.

Genetic predisposition to radiation induced sarcoma: possible role for BRCA and p53 mutations

The estimated incidence of radiation-associated sarcoma (RAS) is 0.03-0.2 % in 5 years post treatment. Most cancer predisposing genes are involved in DNA repair; therefore, elevated RAS risk in these patients is plausible. Cases of angiosarcoma post breast cancer treatment were reported in BRCA1 and BRCA2 carriers. We report the genetic evaluation of seven cases with suspected RAS from patients counseled in our cancer-genetic clinic. Of 2,885 breast cancer patient, 470 were BRCA1 or two mutation carriers and three were p53 mutation carriers. Of them seven developed sarcoma in the field of irradiation; five in the chest wall and two in other sites. Genetic evaluation revealed BRCA1 mutation in two, BRCA2 mutation in additional patient and a carrier of p53 mutation. The estimation of risk for RAS in patients with genetic predisposition is limited due to the rarity of this event, and the bias in referral to the clinic toward younger age. With these limitations the rate of RAS is 0.43 % (2/470, 95 % CI -0.17 to 1.02, SE = 0.3) in this group in a median follow-up of 8.2 years (range 1 month to 51 years). If we assume irradiation for the breast in 80 % of the patients than rate of RAS in group is proximately 0.53 % (2/376, 95 % CI -0.21 to 1.26, SE = 0.37). A BRCA1 carrier which had sarcoma after irradiation to head and neck carcinoma was not included in these analyses. In conclusion, we found a high frequency of BRCA1/2 mutation among our patients diagnosed with RAS. However, we estimated approximately twofold increase in the risk of RAS in BRCA1/2 carriers which was not significant compared to reports in general population. Therefore, RAS is a rare event in BRCA carriers as in the general population, and should not be considered in the decision regarding irradiation treatment in this population.

Ipilimumab for advanced, refractory melanoma: A report of the Israeli cohort of expanded access program

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Background: As the first agent to show survival advantage in metastatic melanoma, Ipilimumab (Yervoy, BMS) is being gradually introduced into health services worldwide. It's unique immune mediated side effects requires the incorporation of follow-up guidelines to prevent toxic sequella. We report on safety and efficacy results of refractory melanoma patients (pts) treated on an international expanded access program of Ipilimumab. Methods: Between 4/2010 and 12/2011 183 pts were treated. Pts received Ipilimumab 3 mg/kg q3w for 4 doses. Pts with evidence of clinical benefit at week 12 (CR, PR or SD), were eligible for re-induction upon progression. Results: All pts were pretreated for metastatic disease (median:1 line,range 1-5). 140 pts(77%) had M1c disease, 63 pts(34%) had brain metastasis and 84 (46%) had LDH above ULN, reflecting poor prognostic characteristics of this cohort. Patients received 3.6 doses of Ipilimumab on average. 11% received less than 4 cycles due to toxicity. Grade 3/4 immune-related adverse events were noted in 19.6% with the most common all grades toxicity being diarrhea (17.5%), pruritus (14%) rash (13%) and fatigue (8.7%). Grade 5 toxicity was noted in 4 patients (2%). Five pts were treated with anti TNF antibodies (Infliximab) for steroid resistant toxicity. Objective responses were noted in 16 pts (8.7%;4 CR, 12 PR), 26 pts(14.2%) had stable disease, overall yielding clinical benefit in 23%. Patients with stage IIIc, M1a and M1b were more likely to benefit (52% Vs 23% of the group, p<0.001) as well as patients previously treated by immunotherapy (p=0.026). Median OS was 9.2 months with 1 year survival of 42%. 34 pts (18.6%) are alive beyond 20 months, the majority of them received no further treatment. Factors favoring survival included stage IIIc, M1a and M1b, LDH below ULN and lymphocyte count at week 6 above 1000/ml (p values: <0.001,<0.001, 0.03 respectively). None of the 14 ocular melanoma pts exhibited clinical benefit. Conclusions: Our cohort reflects rapid adoption of this new modality. Ipilimumab had significant clinical benefit, comparable with previous reports, in a heterogenous group of patients, including those with poor prognostic factors.

Tumor STAT3 tyrosine phosphorylation status, as a predictor of benefit from adjuvant chemotherapy for breast cancer

Signal transducer and activator of transcription 3 (STAT3) is a point of convergence for numerous oncogenic signaling pathways. In breast cancer cell lines and xenograft models activated STAT3 participates in breast tumorigenesis, while studies in humans have demonstrated that phosphorylated (tyrosine705)-STAT3 is a marker of good prognosis in breast cancer. In order to resolve this paradox we hypothesized that in clinic, phospho-STAT3 has a predictive role of benefit from adjuvant chemotherapy; therefore the goal of this study was to determine the usefulness of phospho-STAT3 status as a predictor of benefit from adjuvant chemotherapy in breast cancer patients. Immunohistochemical analysis of phospho-STAT3 was performed on a tissue microarray of breast cancer specimens. The expression pattern of phospho-STAT3 was retrospectively correlated with pathological parameters and overall survival in patients who were or were not treated with adjuvant chemotherapy. Of 375 tissue specimens interpretable for phospho-STAT3, 134 (36 %) exhibited positive phospho-STAT3 nuclear expression. Among 234 patients who received adjuvant therapy, those with tumors displaying positive phospho-STAT3 nuclear expression had a better ten-year rate of overall survival than patients with tumors displaying negative phospho-STAT3 nuclear expression (P = 0.001). Among patients who did not received adjuvant chemotherapy, positive phospho-STAT3 nuclear status was not correlated with increased overall survival (P = 0.54). Positive phospho-STAT3 was correlated with improved overall survival only among patients who received adjuvant chemotherapy in a multivariate analysis adjusted for stage, grade, hormonal status, Her2 status, and age, irrespective of the chemotherapy regimen received (hazard ratio for death, 0.35 [95 % CI 0.188-0.667]; P = 0.001). These findings support the role of phospho-STAT3 as a marker of favorable outcome in breast cancer patients treated with adjuvant chemotherapy. Whether phospho-STAT3 has a predictive role of benefit from adjuvant chemotherapy has to be validated on prospective, randomized, controlled studies.

The prognostic significance of LIAISON(R) CA15-3 assay in primary breast cancer

AIM

To investigate the prognostic significance of cancer antigen 15-3 (CA15-3) in primary breast cancer (BC).

PATIENTS AND METHODS

This prospective study included 368 women: 62 patients with benign breast disease (BBD), 159 patients with invasive BC and 88 healthy blood donors (control). The median follow-up was 76 months (range, 43-99 months). Serum CA15-3 was measured with LIAISON® CA15-3® chemilluminescence immunoassay.

RESULTS

Significantly high levels of CA15-3 were found in patients with BC compared to controls (p=0.029), but not to the BBD group (p=0.16). Preoperative CA15-3 in patients with BC was significantly associated with tumor size (p=0.003), TNM stage (p=0.005), vascular invasion (p=0.018) and tumor necrosis (p<0.05). Increased CA15-3 (>30 U/ml) concentrations were more often found in patients with larger tumors (p<0.05), advanced stage (p=0.004) and node-positive disease (p=0.007). Patients with normal levels of CA15-3 had better recurrence-free survival (RFS) than those with elevated levels (p<0.001). After adjustment for T-stage, grade, tumor necrosis, estrogen receptor (ER) and progesterone receptor (PR) status, CA15-3 remained an important preoperative characteristic with independent impact on RFS (hazard ratio=4.4, 95% confidence interval=1.5-13.1, p=0.007). The independent prognostic contribution of CA15-3, considered on a continuous scale was significant among subgroups of the BC patients with ER/PR-positive (p=0.002), node-positive (p=0.028), node-negative (p=0.003), T1-stage node-negative (p=0.017), luminal-A (p=0.003), luminal-B (p=0.028) and human epidermal growth factor receptor-2 (HER2)/non-luminal disease (p=0.045).

CONCLUSION

Preoperative measurement of CA15-3 allowed identifying high-risk of recurrence for patients with primary BC and might be combined with existing prognostic factors in planning adjuvant treatment.

Control of breast cancer growth and initiation by the stem cell-associated transcription factor TCF3

Regulatory factors controlling stem cell identity and self-renewal are often active in aggressive cancers and are thought to promote their growth and progression. TCF3 (also known as TCF7L1) is a member of the TCF/LEF transcription factor family that is central in regulating epidermal and embryonic stem cell identity. We found that TCF3 is highly expressed in poorly differentiated human breast cancers, preferentially of the basal-like subtype. This suggested that TCF3 is involved in the regulation of breast cancer cell differentiation state and tumorigenicity. Silencing of TCF3 dramatically decreased the ability of breast cancer cells to initiate tumor formation, and led to decreased tumor growth rates. In culture, TCF3 promotes the sphere formation capacity of breast cancer cells and their self-renewal. We found that in contrast to ES cells, where it represses Wnt-pathway target genes, TCF3 promotes the expression of a subset of Wnt-responsive genes in breast cancer cells while repressing another distinct target subset. In the normal mouse mammary gland, Tcf3 is highly expressed in terminal end buds, structures that lead duct development. Primary mammary cells are dependent on Tcf3 for mammosphere formation, and its overexpression in the developing gland disrupts ductal growth. Our results identify TCF3 as a central regulator of tumor growth and initiation, and a novel link between stem cells and cancer.

Tissue microarray-based study of patients with lymph node-positive breast cancer shows tyrosine phosphorylation of signal transducer and activator of transcription 3 (tyrosine705-STAT3) is a marker of good prognosis

BACKGROUND

Although lymph node-positive breast cancers are associated with poorer prognosis, individual patients may have different clinical outcomes. Signal transducer and activator of transcription 3 (STAT3) is a point of convergence for numerous oncogenic signalling pathways. The goal of this study was to determine the prognostic value of phosphorylated (tyrosine705)-STAT3 in node-positive breast cancer patients.

METHODS

Immunohistochemical analysis of Phospho- STAT3 was performed on a tissue microarray of breast cancer specimens. The expression pattern of Phospho-STAT3 was correlated with survival outcome, and clinical and pathological parameters.

RESULTS

Out of 125 interpretable tumours, positive Phospho- STAT3 nuclear expression was seen in 35 (28%) of tumours. There was no significant relationship between Phospho-STAT3 expression and clinical-pathological parameters including age, hormonal receptor status, grade and tumour size. Interestingly positive tumours had a significantly improved disease-free survival at 5 years (p=0.035). Additionally, positive Phospho-STAT3 nuclear expression was correlated with significantly improved survival at both 5 years (p=0.023) and 10 years (p=0.026). Finally, in multivariate analyses Phospho-STAT3 was found to be an independent prognostic marker of overall survival in node-positive breast cancer patients.

CONCLUSION

These findings support the role of Phospho- STAT3 as an important independent prognostic marker in node-positive breast cancer patients.

Regulation of human protease-activated receptor 1 (hPar1) gene expression in breast cancer by estrogen

A pivotal role is attributed to the estrogen-receptor (ER) pathway in mediating the effect of estrogen in breast cancer progression. Yet the precise mechanisms of cancer development by estrogen remain poorly understood. Advancing tumor categorization a step forward, and identifying cellular gene fingerprints to accompany histopathological assessment may provide targets for therapy as well as vehicles for evaluating the response to treatment. We report here that in breast carcinoma, estrogen may induce tumor development by eliciting protease-activated receptor-1 (PAR(1)) gene expression. Induction of PAR(1) was shown by electrophoretic mobility shift assay, luciferase reporter gene driven by the hPar(1) promoter, and chromatin-immunoprecipitation analyses. Functional estrogen regulation of hPar1 in breast cancer was demonstrated by an endothelial tube-forming network. Notably, tissue-microarray analyses from an established cohort of women diagnosed with invasive breast carcinoma exhibited a significantly shorter disease-free (P=0.006) and overall (P=0.02) survival of patients that were positive for ER and PAR(1), compared to ER-positive but PAR(1)-negative patients. We propose that estrogen transcriptionally regulates hPar(1), culminating in an aggressive gene imprint in breast cancer. While ER(+) patients are traditionally treated with hormone therapy, the presence of PAR(1) identifies a group of patients that requires additional treatment, such as anti-PAR(1) biological vehicles or chemotherapy.

Serum thymidine kinase 1 activity in breast cancer

AIMS

Thymidine kinase 1 (TK1) is an enzyme involved in DNA synthesis and an important proliferation marker. We explored the association of preoperative serum TK1 activity with clinicopathological parameters and prognosis in terms of recurrence-free survival (RFS) in breast cancer (BC) patients.

PATIENTS AND METHODS

TK1 activity in serum of 120 healthy women and 161 BC patients was measured by quantitative ELISA.

RESULTS

Serum TK1 activity in BC patients was significantly higher than in healthy women (P < 0.0001). In BC patients elevated TK1 activity was significantly associated with advanced T stage (P = 0.015), higher grade (P = 0.013), presence of tumor necrosis (P = 0.006), vascular invasion (P = 0.002), and lack of estrogen receptor (ER) and progesterone receptor (PR) expression (P = 0.0004 and P = 0.003). Higher TK1 activity was found in patients with BRCA1/2 mutations compared to those without the mutation (P = 0.004). Multivariate Cox proportional hazards analyses demonstrated that TK1, adjusted for stage, grade, necrosis, ER and PR negativity was retained as an independent predictor of disease recurrence (Hazard Ratio = 3.9, 95%CI 1.3-11.6, P = 0.013).

CONCLUSION

Elevated serum TK1 is an important risk factor indicating a high proliferation potential of tumors at the time of excision. In multivariate analysis TK1 activity was found to be an independent prognostic factor for RFS.

Fertility and pregnancy in patients under age 38 following chemotherapy for breast cancer

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Background: Chemotherapy improves breast cancer outcome, but may impact fertility. Post chemotherapy fertility rates range between 10–90% among studies. Fertility post chemotherapy is most often assessed by rate of menstruation resumption- an indirect method of evaluating childbearing potential. It is noteworthy that future pregnancy is a woman's first concern not menses preservation. Variability in fertility rates along with limited data on post chemotherapy pregnancies led us to undertake this single institute retrospective study evaluating fertility and pregnancy post chemotherapy in ≤ 38 y old breast cancer patients. Methods: We reviewed medical records of 222 consecutive stage II-IIIB breast cancer patients diagnosed, treated and followed at Sharette Institute of Hadassah-Hebrew University Medical Center from 1990–2004. Inclusion criteria included age ≤ 38 years, ≥3 cycles of standard metothrexate or adriamycine based chemotherapy, metastasis-free 12 months post chemotherapy initiation or one year following GnRH analog withdrawal. Patients diagnosed with infertility prior to breast cancer diagnosis (data present for part of patients), bilateral oophorectomy or patients surviving ≤3 years from diagnosis were excluded. Patient pregnancy preference was not recorded. Fertility was defined as resumption of recurrent menses or pregnancy anytime during follow up. In case of recurrence, date of recurrence diagnosis was assigned as date of last follow up. Results: Cohort included 65 patients. Mean age 32.5±4 ys (20.3–38.5) Almost all patients (95.4%), 38 ys or younger, preserve menses following chemotherapy, and 33.9% become pregnant. Most of patients who did not conceive post chemotherapy (66.1%), were under a familial status not promoting pregnancy; 44% of all women who did not give birth post chemotherapy had at least 3 offspring at the time of diagnosis and 83% out of all women who did not have any offspring by the end of follow up were single. Conclusions: This data suggest that pregnancy potential may be even higher than our actual finding, since pregnancy is most probably not attempted by multiparous or most single patients, whom cultural constrains affect their decisions. It seems prudent to offer the subgroup of unmarried women fertility preservation.

No significant financial relationships to disclose.

Application of a novel severity grading system for surgical complications after colorectal resection

BACKGROUND

Uniform and accurate reporting of surgical complications is the basis for quality control. We developed a computerized system for reporting and grading surgical complications in colorectal surgery. This study was conducted to evaluate this computerized reporting system.

STUDY DESIGN

A retrospective chart review was conducted of all surgical complications in patients who underwent resection of the colon or rectum at our institution between the years 1999 and 2004 (n = 408). All complications were recorded using the computerized reporting system and compared with complications reported in the literature.

RESULTS

Elective operations were performed in 75.7% of patients, and 24.3% required emergency operations. Of the 408 patients in the study, 239 (58.6%) had an uneventful recovery without complications. At least 1 complication was recorded in 169 (41.4%) patients. Grades 1 and 2 complications were recorded in 83 (20.3%) and 105 (25.7%) patients, respectively, requiring observation or medical treatment only, and 59 patients (14.5%) had grades 3 to 5 complications. The three leading complications were surgical site infection, intraabdominal abscess, and hemorrhage requiring blood transfusion. The grades 3 to 5 complication rate was within the range described in the literature, and the rate of grades 1 and 2 complications was substantially higher. These grades 1 and 2 complications were associated with a substantially longer hospital stay.

CONCLUSIONS

This novel complication reporting system was found feasible and proved to have a higher sensitivity for recording minor but meaningful complications that tend to prolong hospital stay.

Effects of the single nucleotide polymorphism at MDM2 309 on breast cancer patients with/without BRCA1/2 mutations

BACKGROUND

A germ line single nucleotide polymorphism (SNP) in the first intron of the gene encoding MDM2 at position 309, an important modulator of p53, has been described. BRCA1/2 mutation have been associated with increased rates of breast cancers with mutated P53. It was shown that the presence of MDM2 309 SNP correlated with younger cancer onset age in individuals with a p53 mutations. The differential effects of this SNP were also linked to estrogen receptor activation. Here we report on our study of 453 Ashkenazi breast cancer patients of whom 180 were positive for the known Ashkenazi BRCA1/2 mutations

METHODS

DNA from breast cancer patients was obtained for analysis of one of the three common BRCA1/2 mutations and MDM2 SNP309. Data regarding cancer onset and death ages was obtained from our database and Statistical analysis was performed using the SPSS statistical package (SPCC Inc., Chicago, IL), and JMP software (SAS Institute, Cary, NC).

RESULTS

The percentage of MDM2 SNP309 in control and BRCA 1/2 population which is similar to that reported for other Jewish Ashkenazi populations at 52.2% for the heterozygotes and 25.0% for MDM2SNP309G/G and 22.8% for MDM2SNP309T/T.There was not a statistical significant difference in median age of disease onset in the different MDM2 SNP309 subgroups of the BRCA1/2 carriers. When we further divided the group into under and above 51 years old ( presumed menopause age) in the BRCA1 positive subset we found that there were less patients of the MDM2SNP309 G/G versus the MDM2SNP309 T/T in the over 51 patient group (p = 0.049). This result has been obtained in a relatively small subgroup and is of borderline statistical significance. Interestingly, in the BRCA1/2 mutation carriers, we found a survival advantage for patients harboring the SNP309 G/G genotype (p = 0.0086) but not for the 272 patients not harbouring this mutations.

CONCLUSION

MDM2SNP309G/G main effect on BRCA1/2 positive mutation carriers is linked to its effect on patients survival. Further research is needed in order to understand the reason for this difference.

Glutathione-S-transferase M1, T1 and P1 polymorphisms, and breast cancer risk, in BRCA1/2 mutation carriers

Variation in penetrance estimates for BRCA1/2 carriers suggests that other environmental and genetic factors may modify cancer risk in carriers. The GSTM1, T1 and P1 isoenzymes are involved in metabolism of environmental carcinogens. The GSTM1 and GSTT1 gene is absent in a substantial proportion of the population. In GSTP1, a single-nucleotide polymorphism that translates to Ile112Val was associated with lower activity. We studied the effect of these polymorphisms on breast cancer (BC) risk in BRCA1/2 carriers. A population of 320 BRCA1/2 carriers were genotyped; of them 262 were carriers of one of the three Ashkenazi founder mutations. Two hundred and eleven were affected with BC (20 also with ovarian cancer (OC)) and 109 were unaffected with BC (39 of them had OC). Risk analyses were conducted using Cox proportional hazard models adjusted for origin (Ashkenazi vs non-Ashkenazi). We found an estimated BC HR of 0.89 (95% CI 0.65-1.12, P=0.25) and 1.11 (95% CI 0.81-1.52, P=0.53) for the null alleles of GSTM1 and GSTT1, respectively. For GSTP1, HR for BC was 1.36 (95% CI 1.02-1.81, P=0.04) for individuals with Ile/Val, and 2.00 (95% CI 1.18-3.38) for carriers of the Val/Val genotype (P=0.01). An HR of 3.20 (95% CI 1.26-8.09, P=0.01), and younger age at BC onset (P=0.2), were found among Val/Val, BRCA2 carriers, but not among BRCA1 carriers. In conclusion, our results indicate significantly elevated risk for BC in carriers of BRCA2 mutations with GSTP1-Val allele with dosage effect, as implicated by higher risk in homozygous Val carriers. The GSTM1- and GSTT1-null allele did not seem to have a major effect.