Aleksandra Tołoczko-Grabarek

A high proportion of founder BRCA1 mutations in Polish breast cancer families

Three mutations in BRCA1 (5382insC, C61G and 4153delA) are common in Poland and account for the majority of mutations identified to date in Polish breast and breast–ovarian cancer families. It is not known, however, to what extent these 3 founder mutations account for all of the BRCA mutations distributed throughout the country. This question has important implications for health policy and the design of epidemiologic studies. To establish the relative contributions of founder and nonfounder BRCA mutations, we established the entire spectrum of BRCA1 and BRCA2 mutations in a large set of breast–ovarian cancer families with origins in all regions of Poland. We sequenced the entire coding regions of the BRCA1 and BRCA2 genes in 100 Polish families with 3 or more cases of breast cancer and in 100 families with cases of both breast and ovarian cancer. A mutation in BRCA1 or BRCA2 was detected in 66% of breast cancer families and in 63% of breast–ovarian cancer families. Of 129 mutations, 122 (94.6%) were in BRCA1 and 7 (5.4%) were in BRCA2. Of the 122 families with BRCA1 mutations, 119 (97.5%) had a recurrent mutation (i.e., one that was seen in at least 2 families). In particular, 111 families (91.0%) carried one of the 3 common founder mutations. The mutation spectrum was not different between families with and without ovarian cancer. These findings suggest that a rapid and inexpensive assay directed at identifying the 3 common founder mutations will have a sensitivity of 86% compared to a much more costly and labor‐intensive full‐sequence analysis of both genes. This rapid test will facilitate large‐scale national epidemiologic and clinical studies of hereditary breast cancer, potentially including studies of chemoprevention.

Breast cancer predisposing alleles in Poland

SummaryMutant alleles of several genes in the DNA repair pathway have been found to predispose women to breast cancer. From a public health perspective, the importance of a given allele in a population is determined by the frequency of the allele and by the relative risk of breast cancer that it confers. In Poland founder alleles of the BRCA1, CHEK2 and NBS1 genes have been associated with an increased risk of breast cancer, but the relative contribution of each of these alleles to the overall breast cancer burden has not yet been determined. We screened 2012 unselected cases of breast cancer and 4000 population controls for 7 different mutations in these genes. Overall, a mutation was found in 12% of the cases and in 6% of the controls. Mutations in BRCA1 and CHEK2 contributed in approximately equal measure to the burden of breast cancer in Poland. A BRCA1 mutation was present in 3% of the cases. The missense BRCA1 mutation C61G was associated with a higher odds ratio for breast cancer (OR=15) than were either of the truncating BRCA1 mutations 4153delA (OR=2.0) and 5382insC (OR=6.2). In contrast, a higher odds ratio was seen for truncating CHEK2 mutations (OR=2.1) than for the missense mutation I157T (OR=1.4). This study suggests that cancer risks may be specific for particular alleles of a susceptibility gene and that these different risks should be taken into account by genetic counselors.

BRCA1-associated breast and ovarian cancer risks in Poland: no association with commonly studied polymorphisms

Polymorphisms in genes involved in DNA repair, steroid hormone biosynthesis/metabolism/signaling, folate metabolism as well as cell growth are prime candidates for possible associations with breast and ovarian cancer risk in women with an inherited predisposition. We investigated 29 polymorphisms in 20 genes encoding key proteins of the above four biological pathways for their breast and ovarian cancer risk modifying effect in Polish women harboring BRCA1 founder mutations. Of the analyzed genes, ERCC2, XRCC1, XRCC2, XRCC3 and Lig4 participate in DNA repair, TP53 in cell cycle check point control, AIB1, AR, COMT, CYP11A1, CYP17A1, CYP19A1, HSD17 and PGR in steroid hormone biosynthesis/metabolism/signaling, TYMS in folate metabolism and HER2, IL6, LRP1, TGFB and TGFBR1 affect cell growth. Using validated methods, we genotyped 319 breast cancer cases, 146 ovarian cancer cases and 290 unaffected controls, all of whom harbored one of three causative mutations in BRCA1. Our results revealed no association of any of the investigated polymorphisms with BRCA1-associated breast or ovarian cancer risk. Thus, it appears that these polymorphisms do not influence disease risk in Polish women carrying one of the three common BRCA1 founder mutations.

Premature Menopause in Patients with BRCA1 Gene Mutation

This study was undertaken with regard to the gonadotropin theory of ovarian cancer advocated in the literature and was designed to disclose specific features of ovarian morphology in carriers of the BRCA1 gene mutation. We enrolled 171 patients and divided them into two groups: A (n=90)—operated for breast cancer (30 patients with and 60 without the BRCA1 mutation); B (n=81)—with the BRCA1 mutation qualified for preventive adnexectomy. According to the authors’ classification described herein, some patients without the BRCA1 mutation retained “signs of estrogenization” in menopausal ovaries, revealing the role of estrogens as a factor promoting mammary carcinogenesis in these patients. A tendency to premature menopause was observed in BRCA1 mutation carriers of groups A and B as evidenced by the final menorrhea appearing at a younger age and almost total absence of “signs of estrogenization” in menopausal ovaries. It is concluded from these findings that earlier menopause in carriers of the BRCA1 mutation is associated with hypergonadotropic activity and may predispose to ovarian cancer at younger age.

Smoking related cancers and loci at chromosomes 15q25, 5p15, 6p22.1 and 6p21.33 in the Polish population.

Genetic factors associated with the risk of smoking related cancers have until recently remained elusive. Since the publication of a genome-wide association study (GWAS) on lung cancer new genetic loci have been identified that appear to be associated with disease risk. In this replication study we genotyped 14 single nucleotide polymorphisms (SNPs) located at the 5p12.3-p15.33, 6p21.3-p22.1, 6q23-q27 and 15q25.1 loci in 874 lung, 450 bladder, 418 laryngeal cancer cases and cancer-free controls, matched by year of birth and sex to the cases. Our results revealed that loci in the chromosome region 15q25.1 (rs16969968[A], rs8034191[G]) and 5p15 (rs402710[T]) are associated with lung cancer risk in the Polish population (smoking status adjusted OR = 1.45, 1.35, 0.77; p≤0.0001, 0.0005, 0.002; 95%CI 1.23–1.72, 1.14–1.59, 0.66–0.91 respectively). None of the other regions analyzed herein were implicated in the risk of lung, bladder or laryngeal cancer. This study supports previous findings on lung cancer but fails to show association of SNPs located in 15q25.1 and 5p15 region with other smoking related cancers like bladder and laryngeal cancer.

An evaluation of the polymorphisms Ins16bp and Arg72Pro in p53 as breast cancer risk modifiers in BRCA1 and BRCA2 mutation carriers

The close functional relationship between p53 and the breast cancer susceptibility genes BRCA1 and BRCA2 has promoted the investigation of various polymorphisms in the p53 gene as possible risk modifiers in BRCA1/2 mutation carriers. Specifically, two polymorphisms in p53, c.97-147ins16bp and p.Arg72Pro have been analysed as putative breast cancer susceptibility variants, and it has been recently reported that a p53 haplotype combining the absence of the 16-bp insertion and the presence of proline at codon 72 (No Ins-72Pro) was associated with an earlier age at the onset of the first primary tumour in BRCA2 mutation carriers in the Spanish population. In this study, we have evaluated this association in a series of 2932 BRCA1/2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1 and BRCA2.

Population Screening for Cancer Family Syndromes in the West Pomeranian Region of Poland

The largest worldwide population screening for cancer family syndromes was initiated in January 2001 in the West Pomeranian Region of Poland with 1.7 m inhabitants. In the first step in the period January 2001 - May 2002 family doctors and nurses collected questionnaires asking about cancer family history among 1st and 2nd degree relatives from 1,258,401 of 1.5 m individuals (87%) who were insured in the West Pomeranian Regional Health Foundation. Up to now about 1.15 m questionnaires have been evaluated by geneticists/oncologists. According to questionnaire data around 2% of families fulfilled criteria to be suspected for cancer family syndrome. Family members (usually 1-2 representatives per family) from suspected families were invited for detailed examination. After pedigree and clinical examination as well as DNA/RNA analyses, high genetic predisposition to neoplasms was diagnosed in 10,525 families. Diagnosis of the following syndromes was established definitively or with high probability: 1. Hereditary breast/ovarian cancer syndrome - 4121 families including 438 families with diagnosed BRCA1/2 mutation. 2. Familial syndromes of colorectal cancer: a) HNPCC - 568 families including 63 families with diagnosed MSH2/MLH1 mutation, b) FAP - 22 families, c) Late onset colorectal cancer aggregations - 459 families. 3. Other hereditary organ specific syndromes: a) hereditary stomach cancer - 1250 families, b) hereditary renal cancer - 565 families, c) hereditary laryngeal cancer - 206 families, d) hereditary prostate cancer - 170 families, e) NFI - 66 families, f) VHL - 36 families, g) Retinoblastoma - 4 families, h) Peutz Jeghers syndrome - 3 families, i) juvenile polyposis - 2 families. 4. Organ-specific familial aggregations: a) familial lung cancer - 242 families, b) familial leukaemia/lymphoma - 77 families, c) familial liver cancer - 68 families, d) familial cervical cancer - 30 families, e) familial pancreatic cancer - 73 families, f) familial melanoma - 44 families, g) familial bladder - 19 families. 5. Unspecified cancer family aggregations - 3319 families. Appropriate management has been introduced in all identified families with high predisposition to malignancies.

CDH1 gene mutations do not contribute in hereditary diffuse gastric cancer in Poland

Hereditary diffuse gastric cancer (HDGC) is a cancer susceptibility syndrome characterized by a high risk of diffuse stomach cancer and lobular breast cancer. HDGC is caused by germline mutations in the CDH1 gene encoding the E-cadherin which is a member of the transmembrane glycoprotein family responsible for calcium-dependent, cell-to-cell adhesion and plays a fundamental role in the maintenance of cell differentiation and the normal architecture of epithelial tissues. Mutations in the CDH1 gene are detected in 30–46% of families that fulfil strong clinical criteria for HDGC and in about 11% of families fulfilling the modified criteria. In the present study, we investigated germline mutations in the CDH1 gene in Polish patients with HDGC. The entire coding sequence of CDH1 gene was analyzed by sequencing in 86 Polish cancer patients from families fulfilling the modified criteria of HDGC. We found several silent mutations including one common variant (c.2076T>C) present in 56 patients, and three rare variants (c.2253C>T, c.1896C>T, c.2634C>T) detected in 2 patients. In addition, we found four rare sequence variants of unknown significance localized in introns. We did not detect any deleterious mutations of the CDH1 gene. CDH1 gene mutations are not present in Polish families with HDGC defined by the modified clinical criteria. Further studies of families with HDGC matching the restrictive criteria for HDGC are needed.

Low-risk Genes and Multi-organ Cancer Risk in the Polish Population

Keywords: CDKN24, CHEK2, NOD2, cancer risk There is continuing interest in identifying low-penetrance genes which are associated with increased susceptibility to common types of cancer. There are several approaches to this problem, including the use of chip-based single nucleotide polymorphism (SNP) arrays to interrogate a large number of genes simultaneously and pre-selecting candidate genes of interest. Candidate genes for cancers of a particular site may be selected because they are known to predispose to malignancies of other organs, or because they are mutated somatically in the cells from the cancer of interest. It is possible that missense variants of genes for which truncating mutations are clearly pathogenic may also be deleterious, but with reduced penetrance. In this situation the association may be overlooked unless large numbers of cancers are studied. In our centre we performed population-based studies of common variants of three genes: a tumour-suppressor gene CDKN2A (OMIM 600160), NOD2 (OMIM 605956) involved in the chronic inflammation process, and CHEK2 (OMIM 604373) participating in the DNA damage response. To determine whether CDKN2A common variant A148T may be associated with an increased risk of malignancies at different sites of origin we genotyped a series of 8,263 unselected cancer cases and compared the frequency of the change observed in this population to 3,000 controls in Poland. To establish the range of cancer types associated with three CHEK2 mutations (VS2+1G → A, 1100delC, and I157T) we genotyped 4,008 unselected cases of cancer and 4,000 controls in Poland. In order to define the range of cancer phenotypes associated with the NOD2 3020insC mutation we examined 2,604 unselected invasive cancers of 12 different types and 1,910 controls from Poland.

Selenium as marker for cancer risk and prevention.

MARCIN LENER1*, KATARZYNA JAWORSKA1,3*, MAGDALENA MUSZYnSKA1,2, GRZEGORZ SUKIENNICKI1,2, KATARZYNA DURDA1, SATISH GUPTA1,3, ELŻBIETA ZŁOWOCKA-PERŁOWSKA1, JoZEF KŁADNY4, ANNA WIECHOWSKA-KOZŁOWSKA5, TOMASZ GRODZKI6, EWA JAWOROWSKA7, JAKUB LUBInSKI7, BARBARA GoRECKA-SZYLD8, GRAŻYNA WILK8, MIECZYSŁAW SULIKOWSKI9, TOMASZ HUZARSKI1, TOMASZ BYRSKI1, CEZARY CYBULSKI1, JACEK GRONWALD1, TADEUSZ DeBNIAK1, OLGIERD ASHURYK1, ALEKSANDRA TOŁOCZKO-GRABAREK1, ANNA JAKUBOWSKA1, ANTONI MORAWSKI10, JAN LUBInSKI1,2