Hereditary Renal Cancer Syndromes

Familial kidney tumors represent a rare variety of hereditary cancer syndromes, although systematic gene sequencing studies revealed that as many as 5% of renal cell carcinomas (RCCs) are associated with germline pathogenic variants (PVs). Most instances of RCC predisposition are attributed to the loss-of-function mutations in tumor suppressor genes, which drive the malignant progression via somatic inactivation of the remaining allele. These syndromes almost always have extrarenal manifestations, for example, von Hippel-Lindau (VHL) disease, fumarate hydratase tumor predisposition syndrome (FHTPS), Birt-Hogg-Dubé (BHD) syndrome, tuberous sclerosis (TS), etc. In contrast to the above conditions, hereditary papillary renal cell carcinoma syndrome (HPRCC) is caused by activating mutations in the MET oncogene and affects only the kidneys. Recent years have been characterized by remarkable progress in the development of targeted therapies for hereditary RCCs. The HIF2aplha inhibitor belzutifan demonstrated high clinical efficacy towards VHL-associated RCCs. mTOR downregulation provides significant benefits to patients with tuberous sclerosis. MET inhibitors hold promise for the treatment of HPRCC. Systematic gene sequencing studies have the potential to identify novel RCC-predisposing genes, especially when applied to yet unstudied populations.

Ethnicity-specific BRCA1, BRCA2, PALB2, and ATM pathogenic alleles in breast and ovarian cancer patients from the North Caucasus

BACKGROUND

Mountain areas of the North Caucasus host several large ethnic communities that have preserved their national identity over the centuries.

METHODS

This study involved high-grade serous ovarian cancer (HGSOC) and breast cancer (BC) patients from Dagestan (HGSOC: 37; BC: 198), Kabardino-Balkaria (HGSOC: 68; BC: 155), North Ossetia (HGSOC: 51; BC: 104), Chechnya (HGSOC: 68; BC: 79), Ingushetia (HGSOC: 19; BC: 103), Karachay-Cherkessia (HGSOC: 13; BC: 47), and several Armenian settlements (HGSOC: 16; BC: 101). The group of BC patients was enriched by young-onset and/or family history-positive and/or bilateral and/or receptor triple-negative cases. The entire coding region of BRCA1, BRCA2, PALB2, and ATM genes was analyzed by next-generation sequencing.

RESULTS

A significant contribution of BRCA1/2 pathogenic variants (PVs) to HGSOC and BC development was observed across all North Caucasus regions (HGSOC: 19-39%; BC: 6-13%). Founder alleles were identified in all ethnic groups studied, e.g., BRCA1 c.3629_3630delAG in Chechens, BRCA2 c.6341delC in North Ossetians, BRCA2 c.5351dupA in Ingush, and BRCA1 c.2907_2910delTAAA in Karachays. Some BRCA1/2 alleles, particularly BRCA2 c.9895C > T, were shared by several nationalities. ATM PVs were detected in 14 patients, with c.1673delG and c.8876_8879delACTG alleles occurring twice each. PALB2 heterozygosity was observed in 5 subjects, with one variant seen in 2 unrelated women.

CONCLUSION

This study adds to the evidence for the global-wide contribution of BRCA1/2 genes to HGSOC and BC morbidity, although the spectrum of their PVs is a subject of ethnicity-specific variations. The data on founder BRCA1/2 alleles may be considered when adjusting the BRCA1/2 testing procedure to the ethnic origin of patients.

Monitoring of the presence of EGFR-mutated DNA during EGFR-targeted therapy may assist in the prediction of treatment outcome

The aim of our trial was to evaluate the prognostic significance of qualitative ctDNA analysis on different stages of EGFR mutated non-small cell lung cancer (NSCLC) treatment. We included 99 patients amendable for the first line treatment with either gefitinib/erlotinib (n = 87), afatinib (n = 10) or osimertinib (n = 2). Sequential qualitative analysis of ctDNA with cobas® EGFR Mutation Test v2 were performed before first dose, after 2 and 4 months of treatment, and on progression. Our analysis showed clinically significant heterogeneity of EGFR-mutated NSCLC treated with 1st line tyrosine kinase inhibitors (TKIs) in terms of progression-free and overall survival. When treated with conventional approach, i.e. monotherapy with TKIs, the patients falls into three subgroups based on ctDNA analysis before and after 2 months of treatment. Patients without detectable ctDNA at baseline (N = 32) possess the best prognosis on duration of treatment (PFS: 24.07 [16.8-31.3] and OS: 56.2 [21.8-90.7] months). Those who achieve clearance after two months of TKI (N = 42) have indistinguishably good PFS (19.0 [13.7 - 24.2]). Individuals who retain ctDNA after 2 months (N = 25) have the worst prognosis (PFS: 10.3 [7.0 - 13.5], p = 0.000). 9/25 patients did not develop ctDNA clearance at 4 months with no statistical difference in PFS from those without clearance at 2 months. Prognostic heterogeneity of EGFR-mutated NSCLC should be taken into consideration in planning further clinical trials and optimizing the outcome of patients.

Molecular predictors of the outcome of paclitaxel plus carboplatin neoadjuvant therapy in high-grade serous ovarian cancer patients

BACKGROUND

Patients with advanced high-grade serous ovarian cancer (HGSOC) are usually treated with paclitaxel and carboplatin; however, predictive markers for this drug combination are unknown.

METHODS

Tumor samples from 71 consecutive HGSOC patients, who received neoadjuvant chemotherapy with paclitaxel and carboplatin, were subjected to molecular analysis.

RESULTS

BRCA1/2 germline mutation carriers (n = 22) had longer treatment-free interval (TFI) than non-carriers (n = 49) (9.5 months vs. 3.8 months; P = 0.007). Fifty-one HGSOCs had sufficient quality of tumor DNA for the next-generation sequencing (NGS) analysis by the SeqCap EZ CNV/LOH Backbone Design panel. All 13 tumors obtained from BRCA1/2 germline mutation carriers and 12 sporadic HGSOCs showed a high number of evenly spread chromosomal breaks, which was defined as a BRCAness phenotype; median TFI for this combined group approached 9.5 months. The remaining 26 HGSOCs had similarly high global LOH score (above 20%); however, in contrast to BRCAness tumors, LOH involved large chromosomal segments; these patients had significantly lower TFI (3.7 months; P = 0.006). All patients with CCNE1 amplification (n = 7), TP53 R175H substitution (n = 6), and RB1 mutation (n = 4) had poor response to paclitaxel plus carboplatin.

CONCLUSION

This study describes a cost-efficient method of detecting the BRCAness phenotype, which is compatible with the laboratory-scale NGS equipment. Some molecular predictors allow the identification of potential non-responders to paclitaxel plus carboplatin, who may need to be considered for other treatment options.

Abstract 717: Presence of distant metastases and disease progression but not tumor size, lymph node involvement, circadian rhythms, prior physical exercise or recent food consumption influence the concentration of circulating tumor DNA in cancer patients

Liquid biopsy is potentially useful for early tumor detection, monitoring of cancer disease during treatment and diagnosis of therapy-related secondary mutations. Despite significant advantages, it cannot be routinely used in cancer medicine until the standardization of pre-analytical procedures is agreed. It is well known that the results of some blood-based diagnostic tests depend on the time of the day, prior fasting and recent physical exercise. We addressed the question whether these factors could influence the efficacy of the detection of actionable mutations in circulating tumor DNA (ctDNA). 437 plasma samples obtained from 88 patients (KRAS/NRAS/BRAF-mutated colorectal cancer (CRC): n= 57; EGFR-mutated lung adenocarcinomas (LC): n = 14; BRAF-mutated melanoma: n = 17) were analyzed by ddPCR for the presence of corresponding mutations in ctDNA. Patients provided their blood at 9 am (morning), at 1 pm (noon) and at 4 pm (afternoon). In addition, blood-takes were performed before and 15 minutes after the usual breakfast as well as before and 15 minutes after moderate physical exercise. Presence of tumor-specific mutations in plasma was confirmed in 32/57 (56%) CRC, 7/14 (50%) LC, and 4/17 (31%) melanoma cases. The amount of circulating mutant DNA did not correlate with the tumor size, presence of regional lymph node metastases or described above circumstances of blood-take. The proportion of mutation-positive plasma cases was significantly higher in the group of patients with distant metastases compared to subjects with localized disease [31/48 (65%) vs. 8/23 (35%), р = 0.023]. 48 patients were subjected to plasma analysis at the time of disease progression (PD), 37 individuals demonstrated disease control and 3 patients were in clinical remission with no radiologically detectable cancer lumps. Mutant gene copies were observed significantly more frequently in plasma specimens obtained from patients experiencing treatment failure [33/48 (68.8%) vs. 10/40 (25.0%), p = 0.00043]. The obtained data confirm the potential role of ctDNA testing for monitoring the course of cancer disease. The research is supported by RSF grant 18-75-10070.

Citation Format: Ekaterina Sh Kuligina, Roman Meerovich, Kirill A. Zagorodnev, Maxim M. Kholmatov, Tatiana A. Laidus, Aleksandr S. Martianov, Tatyana N. Sokolova, Maria O. Anisimova, Grigoriy A. Yanus, Evgeny N. Imyanitov. Presence of distant metastases and disease progression but not tumor size, lymph node involvement, circadian rhythms, prior physical exercise or recent food consumption influence the concentration of circulating tumor DNA in cancer patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 717.

Molecular profiles of BRCA1-associated ovarian cancer treated by platinum-based therapy: Analysis of primary, residual and relapsed tumors

Our study aimed to analyze the evolution of molecular portraits of BRCA1-driven ovarian cancer (OC) during treatment. BRCA1 loss-of-heterozygosity status (LOH) and exome profiles were investigated in serial OC samples from 13 patients, which included primary tumors (n = 11) obtained before neoadjuvant therapy (NACT) or at primary debulking surgery, residual post-NACT cancer tissues (n = 13) and tumor relapses (16 samples from 13 patients). Loss of the wild-type BRCA1 allele was detected in 11/11 (100%) primary tumors, 6/13 (46%) residual post-NACT OC samples and 15/16 (94%) OC relapses. Full tumor triplets were available for four patients undergoing NACT; whereas primary carcinomas from these patients demonstrated BRCA1 LOH, the retention of the wild-type allele was detected in all four post-NACT residual tumors. These four women provided to the study 5 recurrent OC samples; 4 out of 5 tumor relapses had BRCA1 LOH thus resembling BRCA1 status observed in primary but not residual OC tissues. TP53 mutation was detected in 12 out of 13 patients and was retained across all serial samples. OC relapses tended to acquire additional intragenic mutations in genes involved in cell migration, adhesion and cell junction assembly. BRCA1-driven OCs demonstrate the plasticity of BRCA1 status during the treatment course. NACT results in rapid selection of pre-existing BRCA1-proficient cells. However, BRCA1 proficiency appears to be disadvantageous in the absence of platinum exposure, as tumor relapses usually re-acquire BRCA1 LOH during therapy holidays.

The spectrum of Lynch syndrome-associated germ-line mutations in Russia

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome (LS), is a common cancer-predisposing syndrome. This study aimed to investigate the spectrum of germ-line mutations in Russian LS patients. LS-related mismatch repair (MMR) genes were analyzed in 16 patients, who were forwarded to genetic testing due to strong clinical features of LS and had high-level microsatellite instability (MSI-H) in the tumor (n = 14) or unknown MSI status (n = 2). In addition, 672 consecutive colorectal cancer (CRC) cases were screened for family history; 15 patients were younger than 50 years and reported 2 or more instances of LS-related cancers in 1st- or 2nd-degree relatives. Seven of these cases demonstrated MSI-H and therefore were subjected to DNA germ-line testing. Overall, 17/23 (74%) subjects carried LS-associated gene variants (MLH1: 10; MSH2: 4; MSH6: 2; PMS2: 1), with 2 alleles (MLH1 c.677G > T and MSH2 с.1906G > C) detected twice. Testing for recurrent mutations of 30 consecutive MSI-H CRCs led to the identification of 2 additional subjects with LS. The analysis of all relevant publications identified 28 unrelated LS patients presented in Russian medical literature and 3 unrelated Russian LS subjects described in international journals. Overall, 15/49 (31%) genetic defects revealed in Russian LS patients were represented by six recurrent alleles (MLH1: c.350C > T, c.677G > T, c.1852_1854del; MSH2: c.942+3A > T, c.1861C > T, с.1906G > C). We conclude that the founder effect for LS in Russia is seemingly less pronounced than the one for hereditary breast-ovarian cancer syndrome, however testing for recurrent LS mutations may be considered feasible in some circumstances.

Abstract 4160: PZP as a new gene associated with increased breast cancer risk

Germline mutations in known breast cancer (BC) predisposing genes account for only 20 - 25% of hereditary breast cancer susceptibility. In this study, we anticipated that application of exome analysis to a series of genetically homogeneous Slavic BC patients will allow to identify novel recurrent BC predisposing mutations. 49 BRCA1/2-negative BC patients with evident clinical signs of the hereditary disease (family history and/or BC bilaterality and/or young onset) were subjected to Illumina-based whole exome sequencing. Two patients were found to carry a rare nonsense mutation in pregnancy zone protein (PZP) gene (p.Arg680*, rs145240281). This mutation was further analyzed in a case-control study involving 1046 high-risk BRCA1/2-negative BC cases, 1608 consecutive BC and 1082 middle-aged tumor-free women. Distribution of PZP p.Arg680* alleles was in agreement with its putative BC-predisposing role: 4/1046 (0.38%) and 9/1608 (0.56%) BC cases vs. 1/1082 (0.09%) controls, producing risk estimates in consecutive BC group equal to 6.08 (95% CI 0.770 to 48.096, P = 0.087]. 5/15 heterozygous for PZP p.Arg680* variant patients were diagnosed with multiple primary tumors (2 bilateral BCs, BC + colorectal cancer, bilateral BC + gastric cancer, BC + basal-cell like skin cancer). To the best of our knowledge, no reports associating gene PZP to cancer pathogenesis are available. In order to evaluate the functional effects of PZP p.Arg680*, we obtained two heterozygous mutant clones of CRISPR/Cas9-modified MCF7 cells containing 10-bp and 4-bp deletions adjacent to the desired targeted location. The real-time quantitative PCR confirmed significant down-regulation of PZP transcript in the clones carrying CRISPR/Cas9 induced deletions. Since this mutation results in a truncated protein, we also performed shRNA mediated knock-down of PZP. To study the effects of PZP mutation on cell proliferation and apoptosis, CRISPR/Cas9- and shRNA-modified clones were treated with tamoxifen and etoposide for 72 hours. The results have shown a significantly higher inhibitory concentration (IC50) for both drugs and higher clonogenic potential in CRISPR/Cas9-modified PZP clones compared to control MCF7 cells. Apoptosis induction was quantified using AnnexinV/PI staining; the reduced apoptosis in PZP-defective clones was documented. Taken together, obtained data argue that PZP may function as a tumor suppressor gene, and truncating variant p.Arg680* can represent a moderate-risk breast cancer susceptibility allele. This work has been supported by the Russian Science Foundation (grant 17-15-01384) and DST/INT/RUS/RSF/P-11

Citation Format: Ekaterina Sh Kuligina, Anna P. Sokolenko, Rohit Kumar, Ilya V. Bizin, Aglaya G. Iyevleva, Kirill Zagorodnev, Syed K. Hasan, Aleksandr A. Romanko, Ashok K. Varma, Evgeny N. Imyanitov. PZP as a new gene associated with increased breast cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4160.

Abstract 2283: PCR-based validation of novel cancer-predisposing mutations identified upon exome sequencing: An emphasis on primer design

Whole exome sequencing (WES) is a robust instrument for the identification of novel genes for hereditary diseases. WES experiments usually produce hundreds or thousands of candidates, which require validation in primary DNA samples and subsequent case-control studies. The analysis of each candidate includes individual primer design for allele-specific polymerase chain reaction (PCR) assay or high-resolution melting (HRM) coupled with Sanger sequencing. For the time being, the selection of primers for PCR remains a time-consuming procedure. None of the available software instruments allows to generate a pool of primers for the entire coding region of the gene, therefore each coding fragment has to be selected and analyzed manually. Furthermore, the existing tools have limited capability to ensure that primers will not amplify a non-target fragment of the genome. The consideration of single nucleotide polymorphisms located within primer sequence is usually done without adjustment for their frequency. We developed a pipeline, which facilitates the process of large-scale primer design in an automatic mode. We named the tool PrimerWay and made it available at http://github.com/zoldrax/primer-way under the GNU General Public License. The developed pipeline is provided as a standalone python-based script which requires installed Primer3, tntBLAST and HTSlib. We created automatic upload of the sequence of interest with flanking regions using protein_id or genome coordinates from the reference genome. We utilized the ThermonucleotideBLAST (tntBLAST) instrument in order to ensure PCR specificity. While other computer tools focus mainly on the heuristic definition of sequence similarity, this software runs in-silico PCR based on the thermodynamic similarity and minimizes the risk of the amplification form a non-target template. Our pipeline detects polymorphic sites within the potential primer (5'-end or 3'-end) using a common subset of the dbSNP public database. If the SNP is rare and located at the 5'-end of the primer, it is highly unlikely to compromise further experiments. PrimerWay is capable to suggest the design for the analysis of long DNA sequences. It breaks the sequence for short consecutive fragments and generates a pool of candidate primers for each fragment. It suggests, which of the chosen fragments and primer pairs are most reliable for analysis, by considering the risks of forming dimers, recognizing the non-target sequences, or being compromised by SNPs; these risks are measured by the comprehensive penalty scores. Subsequently, it considers several variants of breaking the entire sequence for overlapping DNA fragments. The utility of PrimerWay tool was validated in a WES study for hereditary breast cancer, which utilized, inter alia, 23 candidate mutations and entire coding regions of two candidate genes. The research is supported by RSF grant 16-45-02011.

Citation Format: Ekaterina Sh Kuligina, Anna P. Sokolenko, Ilya V. Bizin. PCR-based validation of novel cancer-predisposing mutations identified upon exome sequencing: An emphasis on primer design [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2283.

Abstract 2928: Accumulation of tumor cells with retained heterozygous BRCA1 status during platinum therapy: A probable mechanism of attenuation of tumor response in BRCA1-driven ovarian cancer

Approximately 15-25% ovarian cancer (OC) patients carry germ-line mutation in BRCA1 or BRCA2 genes. BRCA deficiency underlies the pronounced sensitivity of tumor cells to platinum-containing cytotoxic therapy. However, significant variations in platinum sensitivity are observed even within BRCA1/2 mutation-driven carcinomas. It has been shown, that chemoresistant tumor tissues could be characterized by the restoration of the BRCA1 function via additional somatic genetic events. This investigation aimed to analyze the role of BRCA status within the group of patients receiving preoperative platinum-based therapy. We addressed the question, whether intratumoral LOH status of BRCA1 gene may be altered during neoadjuvant therapy.

At first, we tested for Slavic founder BRCA mutations 225 ovarian cancer patients, who started their treatment with a few cycles of platinum-based therapy, and underwent debulking surgery afterwards. 34 BRCA1 and 1 BRCA2 mutation carriers were identified. Complete clinical response was documented in 12/35 (34%) mutation carriers and 8/190 (4%) non-carriers (P  =  0.000002). Histopathologic response was observed in 16/35 (46%) women with the germ-line mutation versus 42/169 (25%) patients with the wild-type genotype (P  =  0.02). Surprisingly, somatic loss of heterozygosity (LOH) for the remaining wild-type BRCA1 allele was detected only in 7/24 (29%) post-neoadjuvant therapy residual tumor tissues as compared to 9/11 (82%) BRCA1-associated OC, which were not exposed to systemic treatment before the surgery (P  =  0.009). We hypothesize that the low frequency of LOH is related to the selection of tumor clones with somatically preserved BRCA1 gene during the therapy. We obtained for the LOH-analysis paired biological specimens from 8 patients; the pairs included cytological slides prepared at diagnosis and corresponding surgical material removed after neoadjuvant therapy. The restoration of BRCA1 heterozygosity was revealed in 4 out of 6 post-treatment tumor samples presenting with LOH at diagnosis. Another two ovarian carcinomas did not demonstrate somatic LOH before the treatment, and their status did not change during the neoadjuvant therapy. Thus, even though chemonaive OC specimens demonstrate somatic loss of the wild-type BRCA1 allele, the intratumoral BRCA1 heterozygosity could be restored in the platinum-exposed tissue, probably via expansion of LOH-negative clones.

Conclusion: The obtained data confirm high sensitivity of BRCA-driven ovarian cancer to platinating agents and provide evidence for a rapid selection of tumor cell clones without LOH during the platinum-based therapy.

Citation Format: Ekaterina Sh. Kuligina, Tatyana V. Gorodnova, Anna P. Sokolenko, Aleksandr O. Ivantsov, Aglaya G. Iyevleva, Evgeny N. Imyanitov. Accumulation of tumor cells with retained heterozygous BRCA1 status during platinum therapy: A probable mechanism of attenuation of tumor response in BRCA1-driven ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2928.

Abstract 2597: Identification of new genes for hereditary breast cancer

Major hereditary breast cancer (BC) genes, BRCA1 and BRCA2, contribute to no more than 20-25% of familial BC clustering; therefore the majority of BC-predisposing mutations remain to be identified. We have selected for the study 95 BC cases, which showed accumulation of clinical signs of the genetic disease (e.g., occurrence of BC among multiple relatives and/or bilaterality and/or young age at onset), but could not be explained either by BRCA1/2 sequence alterations or by Russian founder mutations in CHEK2 (c.1100delC, c.444+1G>A, del5395) or NBN (657del5) genes. The entire coding regions of DNA repair genes were examined using high resolution melting (HRM) analysis and DNA sequencing. Three of 16 genes selected for the study (CHEK2, NBN, PALB2, BRIP1, BARD1, RAD51C, BLM, FANCG, CHEK1, PARP1, PARP2, ERCC1, XPE, BRD7, RNF8, RAD51A) contained potentially deleterious mutations. Two patients carried inactivating lesion in the PALB2 gene (p.R414X and p.Q921X); both these carriers had the bilateral form of BC disease. 1 woman harbored mutation in the FANCG gene (c.520_524delTCTAinsC), which resulted in the loss of serine at position 174 and lysine to glutamine substitution at position 175. The analysis of the BLM gene revealed two heterozygous carriers of the c.1642 C>T (Q548X) allele. This mutation was subjected to the extended study, which confirmed its recurrent character and strong association with BC risk: BLM c.1642 C>T (Q548X) heterozygotes were detected in 17/1,498 (1.1%) BC patients as compared to 2/1,093 (0.2%) healthy females (p = 0.004). As expected for BC-predisposing gene, the BLM 1670 C>T allele tended to be associated with first-degree family history of BC, early onset and bilateral appearance of the disease. This is the first demonstration of the role of the BLM heterozygosity in the determination of BC risk. The impact of constitutional BLM mutations in hereditary cancer predisposition deserves to be tested in other ethnic groups as well as in other tumor types.

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 2597. doi:1538-7445.AM2012-2597

Distinct prevalence of the CYP19 Delta3(TTTA)(7) allele in premenopausal versus postmenopausal breast cancer patients, but not in control individuals

The CYP19 gene encodes the enzyme aromatase, which plays a key role in the conversion of androgens to oestrogens. A polymorphism in CYP19 in intron 4 (TTTA)n has been reported to be associated with breast cancer (BC) risk, although conflicting evidence has also been published. Here, we employ a non-traditional, highly demonstrative design of a molecular epidemiological study, where the comparison of BC cases and healthy middle-aged female donors was supplemented by an analysis of groups with extreme characteristics of either BC risk (bilateral breast cancer (biBC) patients) or cancer tolerance (tumour-free elderly women aged >or=75 years). None of the (TTTA)n polymorphic variants was significantly overrepresented among the affected women compared with any of the control groups. However, a 3-bp deletion/insertion CYP19 polymorphism, which is located in the same intron approximately 50 bp upstream to the (TTTA)n repeat, was evidently associated with the menopausal status in both the BC and biBC cohorts. In particular, the Delta3(TTTA)(7) allele occurred significantly more frequently in premenopausal than in postmenopausal BC patients (65/172 (38%) versus 67/310 (22%); P=0.0001; Odds Ratio (OR)=2.20 (95% Confidence Interval (CI) 1.46-3.32)), while the perimenopausal cases demonstrated an intermediate value (9/34 (26%)). In the biBC cohort, women who developed both tumours during their premenopausal period had a significantly higher prevalence of the Delta3(TTTA)(7) allele than patients with a postmenopausal onset of bilateral disease (16/46 (35%) versus 8/50 (16%); P=0.035; OR=2.80 (1.08-7.23)); those biBC patients, whose tumours were diagnosed before and after the cessation of menses, displayed an intermediate occurrence of the Delta3(TTTA)(7) allele (7/32 (22%)). Similar tendencies in the Delta3(TTTA)(7) allele distribution in BC and biBC patients suggest that its association with the menopausal status of the patients is truly non-random and thus this observation deserves further detailed investigation.

CYP17 polymorphism in the groups of distinct breast cancer susceptibility: comparison of patients with the bilateral disease vs. monolateral breast cancer patients vs. middle-aged female controls vs. elderly tumor-free women

The CYP17 gene encodes an enzyme involved in several critical steps of steroidogenesis. The promoter region of the CYP17 displays a single-nucleotide polymorphism, which is suspected to modulate the expression of the gene and thus may contribute in the interindividual variations of hormonal background. In agreement with this functional hypothesis, the MspA1+ allele (designated as A2) of the CYP17 was shown to render an increased risk of breast cancer (BC). However, the latter observation was disputed by a series of negative reports. Here, we re-evaluated the role of CYP17 MspA1 polymorphism in the BC susceptibility, using a non-traditional design of a case-control study. In addition to randomly selected 183 BC patients and 107 female middle-aged donors, we examined the groups with apparently extreme characteristics of either BC risk or BC resistance, namely the 57 bilateral breast cancer (biBC) patients and 75 elderly (>/=75 years old) tumor-free women. Neither BC nor biBC patients showed increased prevalence of 'unfavorable' A2 allele as compared with the non-affected cohorts. Moreover, the A2 variant was not significantly associated with the tumor size, nodal involvement and menopausal status in the patients either with the monolateral or bilateral disease. Thus, our data argue against the earlier reported role of the CYP17 in BC predisposition and progression. In addition, usual distribution of the CYP17 alleles in the elderly group indicates a neutral effect of this polymorphism on the longevity in females.