To discover a set of markers predictive for the type of response to endocrine therapy with the antiestrogen tamoxifen using gene expression profiling.
The study was performed on 112 estrogen ...receptor-positive primary breast carcinomas from patients with advanced disease and clearly defined types of response (ie, 52 patients with objective response v 60 patients with progressive disease) from start of first-line treatment with tamoxifen. Main clinical end points are the effects of therapy on tumor size and time until tumor progression (progression-free survival PFS). RNA isolated from tumor samples was amplified and hybridized to 18,000 human cDNA microarrays.
Using a training set of 46 breast tumors, 81 genes were found to be differentially expressed (P < or = .05) between tamoxifen-responsive and -resistant tumors. These genes were involved in estrogen action, apoptosis, extracellular matrix formation, and immune response. From the 81 genes, a predictive signature of 44 genes was extracted and validated on an independent set of 66 tumors. This 44-gene signature is significantly superior (odds ratio, 3.16; 95% CI, 1.10 to 9.11; P = .03) to traditional predictive factors in univariate analysis and also significantly related with a longer PFS in univariate (hazard ratio, 0.54; 95% CI, 0.31 to 0.94; P = .03) as well as in multivariate analyses (P = .03).
Our data show that gene expression profiling can be used to discriminate between breast cancer patients with progressive disease and objective response to tamoxifen. Additional studies are needed to confirm if the predictive signature might allow identification of individual patients who could benefit from other (adjuvant) endocrine therapies.
Mutations in the breast cancer susceptibility genes BRCA1, BRCA2, and CHEK2 are known risk factors for female breast cancer. Mutations in BRCA1 and BRCA2 also are associated with male breast cancer ...(MBC). Similarly, it had been suggested in the original CHEK2 identification report that the CHEK2 1100delC mutation confers an increased risk for MBC. Here, we have evaluated the risk of CHEK2 1100delC for MBC by genotyping CHEK2 1100delC in 23 familial and 71 unselected Dutch MBC cases. None of the 23 familial MBC cases carried the CHEK2 1100delC mutation. In contrast, CHEK2 1100delC was present in 3 of the 71 (4.2%) unselected MBC cases, which was significantly more prevalent than the 1.1% Dutch population frequency assessed in 1,692 individuals (P = 0.05, OR = 4.1, 95% CI 1.2-14.3). Our data suggest that, in the Netherlands, CHEK2 1100delC is associated with an increased risk for MBC.
Background
Molecular signatures that predict outcome in tamoxifen treated breast cancer patients have been identified. For the first time, we compared these response profiles in an independent cohort ...of (neo)adjuvant systemic treatment naïve breast cancer patients treated with first-line tamoxifen for metastatic disease.
Methods
From a consecutive series of 246 estrogen receptor (ER) positive primary tumors, gene expression profiling was performed on available frozen tumors using 44K oligoarrays (n = 69). A 78-gene tamoxifen response profile (formerly consisting of 81 cDNA-clones), a 21-gene set (microarray-based Recurrence Score), as well as the HOXB13-IL17BR ratio (Two-Gene-Index, RT-PCR) were analyzed. Performance of signatures in relation to time to progression (TTP) was compared with standard immunohistochemical (IHC) markers: ER, progesterone receptor (PgR) and HER2.
Results
In univariate analyses, the 78-gene tamoxifen response profile, 21-gene set and HOXB13-IL17BR ratio were all significantly associated with TTP with hazard ratios of 2.2 (95% CI 1.3–3.7,
P
= 0.005), 2.3 (95% CI 1.3–4.0,
P
= 0.003) and 4.2 (95% CI 1.4–12.3,
P
= 0.009), respectively. The concordance among the three classifiers was relatively low, they classified only 45–61% of patients in the same category. In multivariate analyses, the association remained significant for the 78-gene profile and the 21-gene set after adjusting for ER and PgR.
Conclusion
The 78-gene tamoxifen response profile, the 21-gene set and the HOXB13-IL17BR ratio were all significantly associated with TTP in an independent patient series treated with tamoxifen. The addition of multigene assays to ER (IHC) improves the prediction of outcome in tamoxifen treated patients and deserves incorporation in future clinical studies.
To understand the biological basis of resistance to endocrine therapy is of utmost importance in patients with steroid hormone receptor-positive breast cancer. Not only will this allow us prediction ...of therapy success, it may also lead to novel therapies for patients resistant to current endocrine therapy. DNA methylation in the promoter regions of genes is a prominent epigenetic gene silencing mechanism that contributes to breast cancer biology. In the current study, we investigated whether promoter DNA methylation could be associated with resistance to endocrine therapy in patients with recurrent breast cancer. Using a microarray-based technology, the promoter DNA methylation status of 117 candidate genes was studied in a cohort of 200 steroid hormone receptor-positive tumors of patients who received the antiestrogen tamoxifen as first-line treatment for recurrent breast cancer. Of the genes analyzed, the promoter DNA methylation status of 10 genes was significantly associated with clinical outcome of tamoxifen therapy. The association of the promoter hypermethylation of the strongest marker, phosphoserine aminotransferase (PSAT1) with favorable clinical outcome was confirmed by an independent quantitative DNA methylation detection method. Furthermore, the extent of DNA methylation of PSAT1 was inversely associated with its expression at the mRNA level. Finally, also at the mRNA level, PSAT1 was a predictor of tamoxifen therapy response. Concluding, our work indicates that promoter hypermethylation and mRNA expression of PSAT1 are indicators of response to tamoxifen-based endocrine therapy in steroid hormone receptor-positive patients with recurrent breast cancer.
To explore long-term psychosocial consequences of carrying a BRCA1/2 mutation and to identify possible risk factors for long-term psychological distress.
Five years after genetic test disclosure, 65 ...female participants (23 carriers, 42 noncarriers) of our psychological follow-up study completed a questionnaire and 51 participants were interviewed. We assessed general and hereditary cancer-related distress, risk perception, openness to discuss the test result with relatives, body image and sexual functioning.
Carriers did not differ from noncarriers on several distress measures and both groups showed a significant increase in anxiety and depression from 1 to 5 years follow-up. Carriers having undergone prophylactic surgery (21 of 23 carriers) had a less favorable body image than noncarriers and 70% reported changes in the sexual relationship. A major psychological benefit of prophylactic surgery was a reduction in the fear of developing cancer. Predictors of long-term distress were hereditary cancer-related distress at blood sampling, having young children, and having lost a relative to breast/ovarian cancer. Long-term distress was also associated with less open communication about the test result within the family, changes in relationships with relatives, doubting about the validity of the test result, and higher risk perception.
Our findings support the emerging consensus that genetic predisposition testing for BRCA1/2 does not pose major mental health risks, but our findings also show that the impact of prophylactic surgery on aspects such as body image and sexuality should not be underestimated, and that some women are at risk for high distress, and as a result, need more attentive care.
To assess long-term cause-specific mortality in breast cancer patients.
We studied mortality in 7425 patients treated for early breast cancer between 1970 and 1986. Follow-up was 94% complete until ...January 2000. Treatment-specific mortality was evaluated by calculating standardized mortality ratios (SMRs) based on comparison with general population rates and by using Cox proportional hazards regression.
After a median follow-up of 13.8 years, 4160 deaths were observed, of which 76% were due to breast cancer. Second malignancies showed a slightly increased SMR of 1.2 (95% confidence interval CI, 1.0-1.3). Radiotherapy (RT) as compared with surgery was associated with a 1.7-fold (95% CI, 1.2-2.5) increased mortality from cardiovascular disease (CVD). After postlumpectomy RT, no increased mortality from CVD was observed (hazard ratio, 1.0; 95% CI, 0.5-1.9). Postmastectomy RT administered before 1979 and between 1979 and 1986 was associated with a 2-fold (95% CI, 1.2-3.4) and 1.5-fold (95% CI, 0.9-2.7) increase, respectively. Patients treated before age 45 experienced a higher SMR (2.0) for both solid tumors (95% CI, 1.6-2.7) and CVD (95% CI, 1.3-3.1).
Currently, a large population of breast cancer survivors is at increased risk of death from CVDs and second cancers, especially when treated with RT at a young age. Patients irradiated after 1979 experience low (postmastectomy RT) or no (postlumpectomy RT) excess mortality from CVD.
The aim of this study was to investigate whether expression of particular drug resistance genes in primary operable breast cancer correlates with response to first-line chemotherapy in advanced ...disease.
We determined mRNA levels of BCRP, LRP, MRP1, MRP2, and MDR1 in 59 primary breast tumor specimens of patients who received chemotherapy as first-line systemic treatment after diagnosis of advanced disease. The relative expression levels were measured by quantitative real-time reverse transcription-PCR and subsequently analyzed in relation to the type of response to chemotherapy, the length of progression-free survival (PFS), and post-relapse overall survival.
For each of these drug resistance genes, a large variation in expression level was observed among the tumors of the different patients. When analyzing mRNA expression in relation to overall response, it was found that the median expression level of these five drug resistance genes in the responding tumors, as compared with nonresponding tumors, was markedly lower. Classification of tumors as high versus low with respect to the expression level of these genes showed that the overall response in the MDR1-high subset (17%), as compared with the MDR1-low subset (68%), was significantly lower (P = 0.005). Although similar differences in response rate were found for subsets of tumors stratified by the expression level of the other drug resistance genes, none of the observed differences were statistically significant. However, in the subgroup of patients treated with anthracycline-based chemotherapy (5-fluorouracil, Adriamycin/epirubicin, and cyclophosphamide), a correlation between response and the expression of BCRP and MRP1 (only PFS) was found, whereas such an association was not present in the cyclophosphamide, methotrexate, and 5-fluorouracil-treated group of patients. Furthermore, high expression of LRP as well as MDR1 was found to be significantly associated with a poor PFS (P = 0.04 and P < 0.001, respectively). For lung resistance-related protein, this association was limited to 5-fluorouracil, Adriamycin/epirubicin, and cyclophosphamide. Expression levels of BCRP, MRP1, or MRP2 were not related with the length of PFS. Furthermore, no correlation between the expression level of these drug resistance genes and post-relapse overall survival was found.
In this pilot study, MDR1 expression in primary breast tumors was inversely related with the efficacy of first-line chemotherapy, and high expression level was a significant predictor of poor prognosis for patients with advanced disease. Apart from MDR1, the expression levels of BCRP, LRP, and MRP1 might have some additional predictive value for clinical outcome.
Radiation exposure at a young age is one of the strongest risk factors for breast cancer. Germline mutations in genes involved in the DNA-damage repair pathway (DDRP) may render women more ...susceptible to radiation-induced breast cancer.
We evaluated the contribution of germline mutations in the DDRP genes BRCA1, BRCA2, CHEK2 and ATM to the risk of radiation-induced contralateral breast cancer (CBC). The germline mutation frequency was assessed, in a case-only study, in women who developed a CBC after they had a first breast cancer diagnosed before the age of 50 years, and who were (n = 169) or were not (n = 78) treated with radiotherapy for their first breast tumour.
We identified 27 BRCA1, 5 BRCA2, 15 CHEK2 and 4 truncating ATM germline mutation carriers among all CBC patients tested (21%). The mutation frequency was 24.3% among CBC patients with a history of radiotherapy, and 12.8% among patients not irradiated for the first breast tumour (odds ratio 2.18 (95% confidence interval 1.03 to 4.62); p = 0.043). The association between DDRP germline mutation carriers and risk of radiation-induced CBC seemed to be strongest in women who developed their second primary breast tumour at least 5 years after radiotherapy. Those patients had an odds ratio of 2.51 (95% confidence interval 1.03 to 6.10; p = 0.049) of developing radiation-induced breast cancer, in comparison with non-carriers.
This study shows that carriers of germline mutations in a DDRP gene have an increased risk of developing (contralateral) breast cancer after radiotherapy; that is, over and above the risk associated with their carrier status. The increased risk indicates that knowledge of germline status of these DDRP genes at the time of breast cancer diagnosis may have important implications for the choice of treatment.
Germline mutations in the mismatch repair genes MLH1, MSH2, MSH6, and PMS2 predispose to Lynch syndrome (also known as hereditary non-polyposis colorectal cancer). Recently, we have shown that the ...CHEK2 1100delC mutation also is associated with Lynch syndrome/Lynch syndrome-associated families albeit in a polygenic setting. Two of the ten CHEK2 1100delC positive Lynch syndrome families additionally carried a pathogenic MLH1 or MSH6 mutation, suggesting that mutations in mismatch repair genes may be involved in CHEK2 1100delC-associated cancer phenotypes. A phenotype of importance is hereditary breast and colorectal cancer (HBCC), with the CHEK2 1100delC mutation present in almost one-fifth of the families—again in a polygenic setting. In order to evaluate the involvement of MSH6 in polygenic CHEK2 cancer susceptibility, we, here, have analyzed the entire MSH6 coding sequence for genetic alterations in 68 HBCC breast cancer families. Rare MSH6 variants, with population frequencies below 1%, were identified in 11.8% of HBCC breast cancer families, whereas the same variants were identified in only 1.5% of population controls, suggesting that rare MSH6 variants are associated with HBCC breast cancer (P ≤ 0.00001). However, screening of the entire MSH6 coding sequence in 68 non-HBCC breast cancer families showed a similar association (8.8 vs. ~1.4% in controls, P ≤ 0.001), suggesting that rare MSH6 variants are not confined to HBCC breast cancer. Together, our data suggest that rare MSH6 variants may predispose to familial breast cancer. However, none of the rare MSH6 variants are obviously pathogenic, suggesting that a more subtle disease mechanism may operate in breast carcinogenesis.
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