BackgroundCyclooxygenase-2 (COX-2) is up-regulated in several types of cancer, and it is hypothesized that COX-2 expression may be genetically influenced. Here, we evaluate the association between single-nucleotide polymorphisms (SNPs) in the COX-2 gene (PTGS2) and the occurrence of breast cancer among Brazilian women.MethodsThe study was conducted prospectively in two steps: First, we screened the promoter region and three fragments of the 3'-untranslated region of PTGS2 from 67 healthy Brazilians to identify SNPs and to select those with a minor allele frequency (MAF) of at least 0.10. The MAF of these selected SNPs was further characterized in 402 healthy volunteers to evaluate potential differences related to heterogeneous racial admixture and to estimate the existence of linkage disequilibrium among the SNPs. The second step was a case-control study with 318 patients and 273 controls designed to evaluate PTGS2 genotype- or haplotype-associated risk of breast cancer.ResultsThe screening analysis indicated nine SNPs with the following MAFs: rs689465 (0.22), rs689466 (0.15), rs20415 (0.007), rs20417 (0.32), rs20419 (0.015), rs5270 (0.02), rs20424 (0.007), rs5275 (0.22) and rs4648298 (0.01). The SNPs rs689465, rs689466, rs20417 and rs5275 were further studied: Their genotypic distributions followed Hardy-Weinberg equilibrium and the MAFs were not affected by gender or skin color. Strong linkage disequilibrium was detected for rs689465, rs20417 and rs5275 in the three possible pairwise combinations. In the case-control study, there was a significant increase of rs5275TC heterozygotes in cases compared to controls (OR = 1.44, 95% CI = 1.01-2.06; P = 0.043), and the haplotype formed by rs689465G, rs689466A, rs20417G and rs5275C was only detected in cases. The apparent association with breast cancer was not confirmed for rs5275CC homozygotes or for the most frequent rs5275C-containing haplotypes.ConclusionsOur results indicate no strong association between the four most frequent PTGS2 SNPs and the risk of breast cancer.

Cyclooxygenase-2 (COX-2) overexpression is associated with worse prognosis in breast cancer. COX-2 is encoded by a polymorphic gene, called PTGS2, and its expression may be genetically influenced. In this article, we investigate the association between PTGS2 haplotypes and histopathological parameters with prognostic value on the clinical outcome of breast cancer. The study involved 606 women under current treatment for non-metastatic breast cancer. Patients were genotyped for rs689465, rs689466, rs20417, and rs5275, and their haplotypes were inferred. The distribution of PTGS2 genotypes and haplotypes was evaluated according to histopathological categorical groups used for prognostic determination of low/intermediate versus high risk of tumor recurrence. Our results indicate positive associations between variant genotypes of rs689465 and estrogen receptor negativity (OR: 1.59, 95% CI: 1.04-2.44, P: 0.02) or HER2 positivity (OR: 1.79, 95% CI: 1.00-3.18, P: 0.03), and between variant genotypes of rs20417 and estrogen receptor negativity (OR: 1.75, 95% CI: 1.15-2.57, P: 0.005), progesterone receptor negativity (OR: 1.56, 95% CI: 1.09-2.22, P: 0.01) or HER2 positivity (OR: 1.80, 95% CI: 1.04-3.13, P: 0.02). In contrast, variant genotypes of rs689466 are negatively associated with estrogen receptor negativity (OR: 0.57, 95% CI: 0.33-0.98, P: 0.03). A total of eight haplotypes were inferred, and there was a significant difference in their distribution as a function of tumor size (P: 0.011), estrogen receptor status (P: 0.018), and HER2 status (P: 0.025). PTGS2 haplotype *7 (formed by rs689465G, rs689466A, rs20417C, and rs5275T) is positively associated with higher tumor size (OR: 3.72, 95% CI: 1.19-11.22, P: 0.006), estrogen receptor negativity (OR: 2.43, 95% CI: 0.97-5.98, P: 0.032), progesterone receptor negativity (OR: 2.58, 95% CI: 1.05-6.39, P: 0.02), and HER2 positivity (OR: 4.17, 95% CI: 1.19-14.44, P: 0.007). Our results suggest that PTGS2 haplotype *7 may contribute to higher growth of untreated breast cancer and that PTGS2 haplotypes need to be considered in the characterization of breast cancer prognosis.

BackgroundThe epidermal growth factor receptor (EGFR) is differently expressed in breast cancer, and its presence may favor cancer progression. We hypothesized that two EGFR functional polymorphisms, a (CA)n repeat in intron 1, and a single nucleotide polymorphism, R497K, may affect EGFR expression and breast cancer clinical profile.MethodsThe study population consisted of 508 Brazilian women with unilateral breast cancer, and no distant metastases. Patients were genotyped for the (CA)n and R497K polymorphisms, and the associations between (CA)n polymorphism and EGFR transcript levels (n = 129), or between either polymorphism and histopathological features (n = 505) were evaluated. The REMARK criteria of tumor marker evaluation were followed.Results(CA)n lengths ranged from 14 to 24 repeats, comprehending 11 alleles and 37 genotypes. The most frequent allele was (CA)16 (0.43; 95% CI = 0.40–0.46), which was set as the cut-off length to define the Short allele. Variant (CA)n genotypes had no significant effect in tumoral EGFR mRNA levels, but patients with two (CA)n Long alleles showed lower chances of being negative for progesterone receptor (ORadjusted = 0.42; 95% CI = 0.19–0.91). The evaluation of R497K polymorphism indicated a frequency of 0.21 (95% CI = 0.19 – 0.24) for the variant (Lys) allele. Patients with variant R497K genotypes presented lower proportion of worse lymph node status (pN2 or pN3) when compared to the reference genotype Arg/Arg (ORadjusted = 0.32; 95% CI = 0.17–0.59), which resulted in lower tumor staging (ORadjusted = 0.34; 95% CI = 0.19-0.63), and lower estimated recurrence risk (OR = 0.50; 95% CI = 0.30-0.81). The combined presence of both EGFR polymorphisms (Lys allele of R497K and Long/Long (CA)n) resulted in lower TNM status (ORadjusted = 0.22; 95% CI = 0.07-0.75) and lower ERR (OR = 0.25; 95% CI = 0.09-0.71). When tumors were stratified according to biological classification, the favorable effects of variant EGFR polymorphisms were preserved for luminal A tumors, but not for other subtypes.ConclusionsThe data suggest that the presence of the variant forms of EGFR polymorphisms may lead to better prognosis in breast cancer, especially in patients with luminal A tumors.

Breast cancer is the top cancer among women, and its incidence is increasing worldwide. Although the mortality tends to decrease due to early detection and treatment, there is great variability in the rates of clinical response and survival, which makes breast cancer one of the most appealing targets for pharmacogenomic studies. The recognition that functional CYP2D6 polymorphisms affect tamoxifen pharmacokinetics has motivated the attempts of using CYP2D6 genotyping for predicting breast cancer outcomes. In addition to tamoxifen, the chemotherapy of breast cancer includes combinations of cytotoxic drugs, which are substrates for various xenobiotic metabolizing enzymes. Because of these drugs’ narrow therapeutic window, it has been postulated that impaired biotransformation could lead to increased toxicity. In the present review, we performed a systematic search of all published data exploring associations between polymorphisms in xenobiotic metabolizing enzymes and clinical outcomes of breast cancer. We retrieved 43 original articles involving either tamoxifen or other chemotherapeutic protocols, and compiled all information regarding response or toxicity. The data indicate that, although CYP2D6 polymorphisms can indeed modify tamoxifen pharmacokinetics, CYP2D6 genotyping alone is not enough for predicting breast cancer outcomes. The studies involving other chemotherapeutic protocols explored a great diversity of pharmacogenetic targets, but the number of studies for each functional polymorphism is still very limited, with usually no confirmation of positive associations. In conclusion, the application of pharmacogenetics to predict breast cancer outcomes and to select one individual’s chemotherapeutic protocol is still far from clinical routine. Although some very interesting results have been produced, no clear practical recommendations are recognized yet.

Introduction: Cycloxygenase-2 (COX-2) overexpression in breast cancer is associated with parameters of aggressiveness, including great tumor size, positive nodal status and lower survival. COX-2 is encoded by a polymorphic gene, PTGS2, with variant alleles in regulatory sites of the promoter and of the 3′-untranslated regions. Aim: To investigate the association between the haplotypes formed by the for most frequent PTGS2 SNPs (rs689465, rs689466, rs20417 and rs5275) and: 1) histopathological parameters with prognostic value on clinical outcome of breast cancer; 2) COX-2 expression in breast tumors. Methods: The study was conducted at the Brazilian National Cancer Institute with 606 women with non-metastatic breast cancer (Protocols #116/07 and #129/08). Recruitment occurred between Jan/ 2008 and Dec/2010 and all patients were genotyped using PCR-RFLP or Real Time-PCR. PTGS2 haplotypes were inferred using the computer software Haploview 4.2, and the individual histopathological profiles were obtained from data available in electronic medical records. The expression of PTGS2 gene in breast tumors was evaluated by the amounts of mRNA transcripts determined with Real Time RT-PCR and by the amounts of COX-2 determined with immunohistochemistry (IHC) in paraffin-embedded tissues. Results: A total of 8 PTGS2 haplotypes were inferred, whose distribution varied as a function of tumor size (P: 0.011), estrogen receptor (ER) status (P: 0.018) and HER2 status (P: 0.025). PTGS2 haplotype *7 (formed by rs689465G, rs689466A, rs20417C, rs5275T) was positively associated with higher tumor size (OR: 3.72, 95%CI: 1.19-11.22, P: 0.006), ER negativity (OR: 2.43, 95%CI: 0.97-5.98, P: 0.032), progesterone receptor (PR) negativity (OR: 2.58, 95%CI: 1.05-6.39, P: 0.02), and HER2 positivity (OR: 4.17, 95%CI:1.19-14.44, P: 0.007). The results also indicated positive associations between variant genotypes of rs689465 and ER negativity (OR: 1.59, 95%CI: 1.04-2.44, P: 0.02) or HER2 positivity (OR: 1.79, 95%CI: 1.00-3.18, P: 0.03), and between variant genotypes of rs20417 and ER negativity (OR: 1.75, 95%CI: 1.15-2.57, P:0. 005), PR negativity (OR: 1.56, 95%CI: 1.09-2.22, P: 0.01) or HER2 positivity (OR: 1.80, 95%CI: 1.04-3.13, P: 0.02). In contrast, variant genotypes of rs689466 were negatively associated with ER negativity (OR: 0.57, 95%CI: 0.33-0.98, P: 0.03). The analyses of PTGS2 expression in breast tumors are currently under course, with 166 tumor species submitted to IHC and 100 submitted to Real Time RT-PCR. Conclusion: Our results suggest that PTGS2 haplotype *7 may contribute to higher growth of untreated breast cancer. We expect that the results regarding the regulation of PTGS2 expression may help understanding the prognostic value of PTGS2 SNPs in breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4503. doi:1538-7445.AM2012-4503