Hereditary truncating mutations of DNA repair and other genes in BRCA1/BRCA2/PALB2-negatively tested breast cancer patients.

Hereditary breast cancer comprises a minor but clinically meaningful breast cancer (BC) subgroup. Mutations in the major BC-susceptibility genes are important prognostic and predictive markers; however, their carriers represent only 25% of high-risk BC patients. To further characterize variants influencing BC risk, we performed SOLiD sequencing of 581 genes in 325 BC patients (negatively tested in previous BRCA1/BRCA2/PALB2 analyses). In 105 (32%) patients, we identified and confirmed 127 truncating variants (89 unique; nonsense, frameshift indels, and splice site), 19 patients harbored more than one truncation. Forty-six (36 unique) truncating variants in 25 DNA repair genes were found in 41 (12%) patients, including 16 variants in the Fanconi anemia (FA) genes. The most frequent variant in FA genes was c.1096_1099dupATTA in FANCL that also show a borderline association with increased BC risk in subsequent analysis of enlarged groups of BC patients and controls. Another 81 (53 unique) truncating variants were identified in 48 non-DNA repair genes in 74 patients (23%) including 16 patients carrying variants in genes coding proteins of estrogen metabolism/signaling. Our results highlight the importance of mutations in the FA genes' family, and indicate that estrogen metabolism genes may reveal a novel candidate genetic component for BC susceptibility.

[CZECANCA: CZEch CAncer paNel for Clinical Application-- Design and Optimization of the Targeted Sequencing Panel for the Identification of Cancer Susceptibility in High-risk Individuals from the Czech Republic]. / CZECANCA: CZEch CAncer paNel for Clinical Application -  návrh a príprava cíleného sekvenacního panelu pro identifikaci nádorové predispozice u rizikových osob v Ceské republice.

Individuals with hereditary cancer syndromes form a minor but clinically important subgroup of oncology patients, comprising several thousand cases in the Czech Republic annually. In these patients, the identification of pathogenic mutations in cancer susceptibility genes has an important predictive and, in some cases, prognostic value. It also enables rational preventive strategies in asymptomatic carriers from affected families. More than 150 cancer susceptibility genes have been described so far; however, mutations in most of them are very rare, occurring with substantial population variability, and hence their clinical interpretation is very complicated. Diagnostics of mutations in cancer susceptibility genes have benefited from the broad availability of next-generation sequencing analyses using targeted gene panels. In order to rationalize the diagnostics of hereditary cancer syndromes in the Czech Republic, we have prepared the sequence capture panel "CZECANCA", targeting 219 cancer susceptibility genes. Besides more than 50 clinically important high- and moderate-penetrance susceptibility genes, the panel also targets less common candidate genes with uncertain clinical relevance. Alongside the panel design, we have optimized the analytical and bioinformatics pipeline, which will facilitate establishing a collective nationwide database of genotypes and clinical data from the analyzed individuals. The key objective of this project is to provide diagnostic laboratories in the Czech Republic with a reliable procedure and collective database improving the clinical utility of next-generation sequencing analyses in high-risk patients, which would help improve the interpretation of rare or population-specific variants in cancer susceptibility genes.

[PALB2 as Another Candidate Gene for Genetic Testing in Patients with Hereditary Breast Cancer in Czech Republic]. / PALB2 jako dalsí kandidátní gen pro genetické testování u pa-cientu s hereditárním karcinomem prsu v Ceské republice.

BACKGROUND: The PALB2 (FANCN) gene was identified as a component of endogenous BRCA2 complex that encodes a DNA repair protein participating along with BRCA1 and BRCA 2 proteins in DNA double-strand break repair. Hereditary PALB2 mutations are associated with an increased risk of breast and pancreatic cancers in heterozygotes. Breast cancer risk for PALB2 mutation carriers has recently been estimated at 33-58% depending on family history of breast cancer; pancreatic cancer risk in carriers of PALB2 mutations has not been precisely quantified, yet. MATERIALS AND RESULTS: Results of a study identifying PALB2 mutations in high-risk, BRCA1/2-negative, breast and/or ovarian cancer patients in the Czech Republic indicate that the frequency of hereditary PALB2 mutations in our population is quite high. Interestingly, almost 20% of all recognized mutations comprised large genomic rearrangements. The highest proportion of PALB2 mutations (comparable with the number of mutations reported for BRCA2) was found in a subgroup of hereditary breast cancer patients (5.5%). Frequency of mutations in an independent group of Czech unselected pancreatic cancer patients was approximately 1.3%. CONCLUSION: Considering the frequency of pathogenic, hereditary PALB2 mutations in our population, their phenotypic similarity to BRCA2, and expected risk of breast cancer associated with PALB2 mutations, its screen-ing (including large genomic rearrangements) should be encouraged in patients from hereditary breast cancer families. The follow-up of pathogenic PALB2 mutation carriers should be similar to that in BRCA2 mutation carriers, enabling early diagnosis, prevention, and possible targeted therapy. Preventive surgical interventions for the carriers could be considered in case of strong family cancer history and evident segregation of a pathogenic mutation with a tumor phenotype. Additional analysis of various cancer patient populations and further meta-analyses will be necessary for accurate assessment of PALB2 gene penetrance and its significance for the risk of pancreatic and other cancers.

Polygenic risk score (PRS) and its potential for breast cancer risk stratification.

BACKGROUND: Breast cancer is a complex, multifactorial disease influenced by many genetic factors. Besides the relatively rare pathogenic variants in high or moderate penetrant cancer predisposition genes, breast cancer risk is modified by numerous low risk alleles considered to be polygenic genetic factors. While the risks associated with individual polygenic loci are negligible, its cumulative effect can reach clinically significant values and it can be expressed as a polygenic risk score (PRS). PRS is recently considered to be a possible tool improving assessment of absolute and cumulative risks at the individual level. PURPOSE: Several single nucleotide polymorphism sets for PRS assessment have recently been developed and prepared for their implementation into clinical practice. The following text aims to explain the fundamental principles of the PRS assessment and its interpretation as a candidate prediction tool. The use of the PRS should always depend on genetic analysis of pathogenic variants in cancer predisposition genes including its current limitations.

Classification of germline variants identified in cancer predisposition genetic testing - consensus of the CZECANCA consortium.

BACKGROUND: Hereditary cancer syndromes are an important subset of malignant cancers caused by pathogenic variants in one of many known cancer predisposition genes. Diagnosis of cancer predisposition is based on genetic testing using next-generation sequencing. This allows many genes to be analysed at once, increasing the number of variants identified. The correct classification of the variants found is essential for the clinical interpretation of genetic test results. PURPOSE: The aim of this study is to summarise the rules for classifying identified variants within individual laboratories and to present the process for creating a common classification. In the Czech Republic, the sharing of identified genetic variants and the development of their consensus classification among national laboratory diagnostic communities is carried out within the Czech Cancer Panel for Clinical Application (CZECANCA) consortium of scientific and diagnostic oncogenetic laboratories. Consensus for variant classification follows a defined protocol. Sharing the results and consensus classification accelerates and refines the release of genetic test results, harmonises results between laboratories and thus contributes to improving the care of individuals at high risk of cancer and their relatives.

[The clinical importance of a genetic analysis of moderate-risk cancer susceptibility genes in breast and other cancer patients from the Czech Republic]. / Klinický význam analýz genu stredního rizika pro hodnocení rizika vzniku karcinomu prsu a dalsích nádoru v Ceské republice.

BACKGROUND: Analysis of the major breast cancer (BC) predisposition genes BRCA1 and BRCA2 enables identification of high-risk individuals. Specialized programs enrolling the carriers of BRCA1/2 mutations facilitate an improvement in prevention and early diagnostics in asymptomatic individuals and rationalize the selection of individualized treatment in case of a BC onset. However, the carriers of mutations in the major predisposition genes represent only approximately 25% of cases among high-risk BC patients. Numerous candidate predisposing genes for breast and other cancers have recently been identified. The risk of cancer development associated with alterations in these genes is lower, and there is a considerable population variability in different regions worldwide. AIM: We have performed mutation analyses of moderate-risk cancer susceptibility genes to evaluate their clinical importance for genetic counseling in high-risk patients suffering from breast and other cancers in the Czech population. RESULTS: Czech oncological patients were analysed for mutation in ATM, CHEK2, NBS1 (NBN) and PALB2 genes. The majority of analyzed individuals represent the population of high-risk BRCA1/2-negative BC patients. CONCLUSIONS: Based on results of this study, we recommend an analysis of recurrent truncating mutations in the CHEK2 gene (the c.1100delC mutation and a large deletion affecting exons 9-10) in BRCA1/2-negative patients from high-risk BC families. A clinical assessment of missense variants in CHEK2 is not suitable. A routine mutation analysis of the ATM and NBS1 (NBN) genes is not recommended in BC patients due to the low frequency of alterations in these genes in the Czech Republic. An identification of truncating mutations in the PALB2 gene is important in BRCA1/2-negative BC patients from families with a strong history of BC (HBC families). The frequency of PALB2 mutations may be comparable to the frequency of mutations in the BRCA2 gene in Czech HBC families.

Alterations of CHEK2 forkhead-associated domain increase the risk of Hodgkin lymphoma.

Checkpoint kinase 2 gene (CHEK2) codes for an important mediator of DNA damage response pathway. Mutations in the CHEK2 gene increase the risk of several cancer types, however, their role in Hodgkin lymphoma (HL) has not been studied so far. The most frequent CHEK2 alterations (including c.470T>C; p.I157T) cluster into the forkhead-associated (FHA) domain-coding region of the CHEK2 gene. We performed mutation analysis of the CHEK2 gene segment coding for FHA domain using denaturing high-performance liquid chromatography in 298 HL patients and analyzed the impact of characterized CHEK2 gene variants on the risk of HL development and progression-free survival (PFS). The overall frequency of CHEK2 alterations was significantly higher in HL patients (17/298; 5.7%) compared to the previously analyzed non-cancer controls (19/683; 2.8%; p= 0.04). Presence of any alteration within the analyzed region of the CHEK2 gene was associated with increased risk of HL development (OR = 2.11; 95% CI = 1.08 - 4.13; p= 0.04). The most frequent I157T mutation was found in 4.0% of HL patients and 2.5% of controls (p = 0.22), however, the frequency of 5 other alterations (excluding I157T) was significantly higher in HL cases and associated with increased risk of HL development (OR = 5.81; 95% CI = 1.12 - 30.12; p= 0.03). PFS in HL patients did not differ between CHEK2 mutation carriers and non-carriers. The predominant I157T mutation together with other alterations in its proximity represent moderate genetic predisposition factor increasing the risk of HL development.

Population-based study of BRCA1/2 mutations: family history based criteria identify minority of mutation carriers.

The two major susceptibility genes, BRCA1 and BRCA2, are involved in hereditary breast and ovarian cancer syndrome. Early detection of mutation carriers has crucial clinical importance, as it allows identification of women who may benefit from intensive clinical follow-up or prophylactic surgery. Generally accepted inclusion criteria for BRCA1/2 mutation testing are based either upon family history of breast or ovarian cancer or young age at cancer diagnosis. In order to analyze the impact of BRCA1/2 mutations on breast cancer development in the Czech population and to confront the clinical and histopathological data of mutation carriers with current criteria for mutation testing we examined the frequency of mutations in unselected breast cancer cases. Mutational analysis of BRCA1/2 genes performed in 679 unselected female breast cancer patients included all recurrent deleterious alterations previously identified in the Prague area and truncating mutations in the whole exon 11 of BRCA1. Within analyzed gene sequences more than 80% of mutations were identified previously in high-risk patients. A total of 16 breast cancer patients (2.4%) carried a mutation. BRCA1 mutations were identified in 14 (2.1%) whereas BRCA2 in 2 (0.3%) women. Family history of ovarian cancer was a strong predictor of a BRCA1/2 mutation (OR = 8.3; p = 0.01), however, family history of breast cancer was not indicative of carrier status. A significant association between medullary breast cancer and mutation status was observed. Current criteria for BRCA1/2 mutation testing would distinguish only 6 out of 16 (37.5%) carriers identified in our study. Ten breast cancer patients with confirmed BRCA1/2 germ-line mutation exhibited no clinical characteristics that would predict their carrier status. Therefore, we believe that the testing for BRCA1/2 mutations in the Czech Republic may not be restricted only to high-risk patients. Our results indicate that analysis of locally prevalent BRCA1/2 mutations in all breast cancer patients might extend substantially the percentage of identified mutation carriers.

Influence of dihydropyrimidine dehydrogenase gene (DPYD) coding sequence variants on the development of fluoropyrimidine-related toxicity in patients with high-grade toxicity and patients with excellent tolerance of fluoropyrimidine-based chemotherapy.

Alterations in dihydropyrimidine dehydrogenase gene (DPYD) coding for the key enzyme (DPD) of fluoropyrimidines (FPs) catabolism contribute to the development of serious FPs-related toxicity. We performed mutation analysis of DPYD based on cDNA sequencing in 76 predominantly colorectal cancer patients treated by FPs with early development of high (grade 3-4) hematological and/or gastrointestinal toxicity. Six previously described [85T>C (C29R), 496A>G (M166V), 775A>G (K259E), 1601G>A (S534N), 1627A>G (I543V), IVS14+1G>A, 2194G>A (V732I)] and two novel [187A>G (K63E) and 1050 G>A (R357H)] non-synonymous DPYD variants were found in 56/76 (73.7%) high-toxicity patients. Subsequently, these alterations were analyzed in 48 patients with excellent long-term tolerance of FPs and in 243 controls and were detected in 37/48 (77.1%) and 166/243 (68.3%) cases, respectively. Analysis of these alterations as risk factors for development of toxicity in pooled FPs-treated population demonstrated that C29R negatively correlated with overall gastrointestinal toxicity (OR = 0.48; 95%CI 0.23-1.0) and M166V in women protected against overall hematological toxicity and neutropenia (both OR = 0.26; 95%CI 0.07-0.89), whereas IVS14+1G>A (found in five high-toxicity patients only) increased risk of mucositis in overall population (OR = 7.0; 95%CI 1.1-44.53), and thrombocytopenia in women (OR = 10.8; 95%CI 1.24-93.98). Moreover, we identified a strong association of V732I with leucopenia (OR = 8.17; 95%CI 2.44 - 27.31) and neutropenia (OR=2.78; 95% CI 1.03-7.51). Our data enabled characterization of "high risk" haplotypes (carriers of IVS14+1G>A or V732 lacking M166V) representing small (22% female and 11% male patients), population in high risk of serious hematological toxicity development, and in patients with "lower risk" that unlikely develop serious hematological toxicity [carriers of M166V without IVS14+1G>A and V732I in females (32% women), and non-carriers of C29R, M166V, IVS14+1G>A, and V732I in males (46% men)]. Our results indicate that genotyping of several DPYD variants may lead to stratification of patients with respect to the risk of serious hematological toxicity development during FPs treatment.

[Prerequisites for preimplantation genetic diagnosis (PGD in carriers of mutations responsible for hereditary cancers]. / Predpoklady pro preimplantacní genetickou diagnostiku (PGD) u nosicu mutací v nádorových predispozicních genech.

BACKGROUNDS: Carriers of hereditary mutations in cancer susceptibility genes represent a limited but high-risk population characterized by a high probability of cancer development, frequently with its manifestation in early age and with a 50% chance of pathogenic allele inheritance by offspring. In case of monogenic disorders, preimplantation genetic diagnosis (PGD) could be used for characterization of the DNA region affected by pathogenic mutation in the early stages of an embryo created by in vitro fertilization (IVF). Therefore, the transfer of unaffected embryos could be performed based on the results of PGD genotyping, enabling the development of offspring not carrying the pathogenic alteration. AIM: Here we present the consensus of the collaborative group of the Society for Medical Genetics, the Czech Society for Oncology and other professionals for use of PGD in the Czech Republic for carriers of mutations in cancer susceptibility genes. We address the conditions, prerequisites, and limits of practical application of this method. We also point out specific issues of ovarian hyperstimulation in carriers of mutations in BRCA1, BRCA2, and p53, anticipating the increased risk of hormonally dependent breast and ovarian cancers development. CONCLUSIONS: We assume that a narrow but non-negligible subgroup of cancer susceptibility gene mutation carriers may benefit from PGD.They are mainly individuals deciding to undergo IVF and PGD recruited from mutation carriers with extreme concerns about transmitting the mutation to their children. The PGD in these individuals should be managed by a closely cooperating multidisciplinary team of professionals responsible for indication of PGD, giving complete information regarding the IVF and PGD procedures including their limits, evaluating individual risks and performing instrumental and laboratory procedures with respect to up-to-date good laboratory and clinical practice.

Long-term BRCA1 down-regulation by small hairpin RNAs targeting the 3' untranslated region.

Mutations in the BRCA1 gene are responsible for the majority of hereditary breast/ovarian cancers. The functional significance of many mutations/splicing variants identified during the screening of high-risk individuals is difficult to predict due to the lack of in vitro functional tests correlating sequence variants with a risk of cancer development. RNA interference is a promising tool in analyzing functional properties of BRCA1 mutations. Here we designed and functionally analyzed shRNAs directed to 3'-UTR of BRCA1 mRNA that may be used to knock-down expression of endogenous BRCA1. Using retroviral infection, we achieved long-term down-regulation of BRCA1 in a cell-type specific manner. We propose that 3'-UTR-directed shRNAs, coupled with up-regulation of exogenous mutated BRCA1 variants, may constitute a versatile system for the functional analysis of BRCA1 gene alterations.

Mutation analysis of the MYH gene in unrelated Czech APC mutation-negative polyposis patients.

Some of the APC negative FAP and AFAP cases have recently been found to be attributable to MYH associated polyposis (MAP). MAP is an autosomal recessive syndrome associated with 5-100 colorectal adenomas and caused by mutation in the MYH gene. Here, we screened for germline MYH mutations in 82 APC-mutation-negative probands with classical and attenuated familial adenomatous polyposis using the denaturing high performance liquid chromatography (DHPLC) method in combination with sequencing. Altogether 12 previously reported changes and four novel genetic alterations, mostly in intronic sequences, were identified. The results revealed the presence of biallelic germline MYH mutations in two patients. These patients were compound heterozygotes for two of the most common germline mutations c.494 A>G (p.Y165C); c.1,145 G>A (p.G382D). These variants are established to be associated with adenomatous polyposis and colorectal cancer. No novel pathogenic mutation has been identified in our study.

[Evaluation of DHPLC analysis for mutation detection in haemophilia A]. / Testování DHPLC analýzy pro detekci mutací u hemofilie A.

BACKGROUND: Haemophilia A is one of the most prevalent inherited bleeding disorders. Causal mutations in the factor VIII gene are detected to facilitate the genetic counselling and to estimate the risk of serious complication associated with standard treatment (factor VIII inhibitor). Wide range of mutations located across the entire length of the factor VIII gene underlies the factor VIII deficiency of variable severity. The only two common recurrent mutations in the factor VIII gene are intron 22 and intron I inversions. In the remaining cases it is necessary to screen all 26 exons encoding 9kb mRNA together with adjacent nonncoding sequences. In order to speed up genotyping in haemophilia A families in the Czech Republic we evaluated DHPLC-based screening technique. METHODS AND RESULTS: We tested sensitivity of the analysis on a panel of DNA samples containing 49 different sequence variations distributed over 21 exons. All the genetic alterations were readily detected. Analysis of family members has shown good reproducibility of the respective elution patterns. DHPLC analysis detected mutations in 4 out of 5 samples from apparently unrelated haemophilia patients, where previously applied multiplex CSGE was not successful. CONCLUSIONS: Establishing of DHPLC analysis will substantially speed up the genotyping of haemophilia A families in the Czech Republic.

[Hereditary forms of colorectal adenomatous polyposis]. / Hereditární formy kolorektální adenomatózní polypózy.

BACKGROUND: Hereditary colorectal adenomatous polyposis syndromes are a predisposition to colorectal carcinoma development. The familial adenomatous polyposis is the most common analyzed syndrome that results from germline mutations in the APC gene. In addition to, the autosomal recessive form of polyposis has been recently reported. This disease is caused by germ-line mutations in the base excision repair MYH gene. The goal of this study is the identification of genetic causes of the colorectal polyposis, the determination of the frequency and type of the APC and MYH germ-line mutations in the set of families with colorectal polyposis in Czech population. METHODS AND RESULTS: The set of 103 probands with FAP was screened for germ-line APC mutations using the Protein Truncation Test and Denaturing Gradient Gel Electrophoresis. The MYH mutational screening was performed on 60 unrelated patients without detected APC mutations using the Denaturing High Performance Liquid Chromatography. Automated sequencing was carried out to identify found mutations. Totally, the 51 germ-line APC mutations (69,9%) are reported in the set of 72 probands including 31 novel mutations unique for Czech population. Molecular genetic analysis of the MYH gene revealed 15 DNA variations (25 %) including two patients identified as p.Y 165C/p.G382D compound heterozygotes (3,3%) and 13 polymorphisms or intronic changes (21,7%). The novel variants were detected in the 5 patients. CONCLUSION: Present study reflects the extremely heterogenous spectrum of the APC mutations in Czech population and confirms the previously reported data. However, the changes found in the MYH gene still need more extensive studies. Our results are important for genetic counselling and further clinical management among at-risk family members. It also enables distinction among different types of the colorectal polyposis.

Mutation analysis of the PALB2 gene in unselected pancreatic cancer patients in the Czech Republic.

Pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis among common solid cancer diagnoses. It has been shown that up to 10% of PDAC cases have a familial component. Characterization of PDAC-susceptibility genes could reveal high-risk individuals and patients that may benefit from tailored therapy. Hereditary mutations in PALB2 (Partner and Localizer of BRCA2) gene has been shown to predispose, namely to PDAC and breast cancers; however, frequencies of mutations vary among distinct geographical populations. Using the combination of sequencing, high-resolution melting and multiplex ligation-dependent probe amplification analyses, we screened the entire PALB2 gene in 152 unselected Czech PDAC patients. Truncating mutations were identified in three (2.0%) patients. Genotyping of found PALB2 variants in 1226 control samples revealed one carrier of PALB2 truncating variant (0.08%; P = 0.005). The mean age at PDAC diagnosis was significantly lower among PALB2 mutation carriers (51 years) than in non-carriers (63 years; P = 0.016). Only one patient carrying germline PALB2 mutation had a positive family breast cancer history. Our results indicate that hereditary PALB2 mutation represents clinically considerable genetic factor increasing PDAC susceptibility in our population and that analysis of PALB2 should be considered not only in PDAC patients with familial history of breast or pancreatic cancers but also in younger PDAC patients without family cancer history.

Mammaglobin A, a novel marker of minimal residual disease in early stages breast cancer.

Mammaglobin A, in contrast to other factors, is a breast specific member of uteroglobin gene family. Expression is restricted to normal and neoplastic breast epithelium. A highly homologous mammaglobin B is not specific to breast tissue. In this pilot feasibility study we examined expression of both markers for minimal residual disease in the bone marrow of patients with breast cancer. We obtained bone marrow aspirates of 34 patients with stage I (41%), II (56%) and III (3%) breast cancer who underwent either immediate complete resection of the tumor or neoadjuvant therapy with subsequent curative surgery. mRNA was isolated using QIAamp RNA blood mini kit (Qiagen). Subsequently two-step nested RT-PCR for the expression of mammaglobin A and mammaglobin B was performed. Mammaglobin A was detected in samples from 4 (12%) out of 34 patients. None of the specimens was positive for mammaglobin B. With a median follow-up of 21 month we observed only 2 recurrences, one in patient with mammaglobin A positive bone marrow.RT-PCR assay for mammaglobin A may be a useful tool for detection of occult breast cancer cells in the bone marrow. Clinical and prognostic relevance of minimal residual disease should be further investigated.

Prognostic significance of c-erbB-2 gene expression in pancreatic cancer patients.

Molecular methods tend to belong to the standard armamentarium of modern pathology. In some instances, these methods are able to identify nosological entities with better accuracy than conventional technique. These methods give useful complementary information to choose appropriate therapeutic strategy. C-erbB-2 overexpression in pancreatic cancer vary widely between 17 to 82%. C-erbB-2 gene is perspective target of anticancer therapies. 57 histologically confirmed tumors (51 pancreatic adenocarcinoma, 5 pancreatic neuroendocrine tumors and 1 carcinoma of Vater's ampullae) were analyzed for the presence of c-erbB-2 expression by immunohistochemistry. Correlation with time from initial symptoms until diagnosis, tumor size and TNM stage at diagnosis, tumor grade, type of operation and overall survival were investigated. C-erbB-2 overexpression was detected in 19.6% samples of pancreatic adenocarcinoma and in one case of Vater's ampullae carcinoma. C-erbB-2 overexpression was found in two of four insulinomas. Univariate statistical correlation stage between c-erbB-2 overexpression and time from initial symptoms until diagnosis, tumor size and TNM at diagnosis, tumor grade, type of operation and overall survival did not reach statistical significans in any parameter studied. C-erbB-2 oncogene was not found to be prognostic factor in pancreatic cancer. Its value to predict therapeutical response remains to be determined in prospective clinical trials.

Relationship between K-ras mutation and the expression of p21WAF1/CIP1 and p53 in chronic pancreatitis and pancreatic adenocarcinoma.

Overexpression of p21WAF1/CIP1 was recently described as an early event in the development of pancreatic intraepithelial neoplasia. Since activating K-ras mutations are described in more than 80% of pancreatic cancers and are known to increase intracellular levels of p21WAF1/CIP1 in experimental models, the possible role of activating K-ras mutations in an induction of the p21WAF1/CIP1 expression was investigated in our study. We examined 71 surgical specimens, 29 of chronic pancreatitis and 42 of invasive ductal adenocarcinoma both having a large spectrum of PanIN (pancreatic intraepithelial neoplasia) lesions. Expression of p53 and p21WAF1/CIP1 was examined immunohistochemically and codon 12 K-ras mutational analysis was performed using the very sensitive mutant-enriched PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) analysis. Our study demonstrated the overexpression of p21WAF1/CIP1 as an early event in the development of pancreatic intraepithelial neoplasia in the group of chronic pancreatitis and invasive adenocarcinoma as well. Overexpression of p21WAF1/CIP1 increased progressively from normal ducts through the spectrum of PanIN lesions to invasive carcinomas. The p53 overexpression increased again progressively according to the severity of the lesion and seems to be a later event in the development of pancreatic intraepithelial neoplasia if compared to p21WAF1/CIP1 expression. Our results confirmed also the possible p53 independent p21WAF1/CIP1 expression in some PanIN2, PanIN3 lesions and invasive carcinomas. K-ras mutations were not revealed in samples with only low grade PanIN lesions (PanIN1a and PanIN1b). K-ras mutations were detected in 69,4% adenocarcinomas and in only one case of chronic pancreatitis. Two codon 12 K-ras positive pancreatic carcinomas showed K-ras mutations in the surrounding normal pancreatic tissue. In adenocarcinomas, no statistically significant correlation was found between K-ras mutational status and p21WAF1/CIP1 and p53 expression, respectively. The possible role of activating K-ras mutations in an induction of p21WAF1/CIP1 expression was not confirmed in this study.

[Hereditary predisposition for the development of breast and ovarian carcinoma]. / Hereditární dispozice ke vzniku karcinomu prsu a ovaria.

Part of breast and ovarian cancer cases develops on the hereditary predisposition, i.e. mutation in one of predisposing genes. Although this proportion is relatively small, 5-10% of all breast and ovarian carcinomas, it represents a group with clearly defined etiologic factor. Predictive analysis of unaffected family members allows to identify individuals at high risk of cancer and to include them into the programme of primary and secondary cancer prevention. Following article presents basic review of the hereditary predisposition to breast and ovarian cancer focusing especially on BRCA1 and BRCA2 genes, which are responsible for almost three-quarters of those hereditary tumours.