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Lynch syndrome (formerly known as hereditary non-polyposis colorectal cancer) is the most com-mon hereditary colorectal cancer syndrome. The syndrome is caused by a germline mutation of one of the mismatch repair (MMR) genes responsible for DNA replication error repair. Impaired function of the proteins encoded by these genes leads to microsatellite instability (MSI), which is associated with increased incidence of neoplasms: mainly colorectal cancer. According to recent estimates, up to 5% of all colorectal cancers are associated with Lynch syndrome. Due to this relatively high frequency, familial occurence, absence of premorbid phenotype, and development of malignant tumors at a reproductive age, a correct diagnosis is important not only from an ethical but also from an economical point of view. Unfortunately, clinical means of diagnosis, namely, the revised Bethesda guidelines designed to detect patients suitable for genetic testing for Lynch syndrome, lack sufficient sensitivity. The methods associated with modern pathology are more sensitive than the clinical criteria used to detect patients suspected of having Lynch syndrome. Pathological diagnostics are based on direct or indirect detection of MSI. Indirect methods include analysis of morphological signs associated with MSI in histological samples from colorectal carcinoma patients and immunohistochemical investigation of MMR protein expression. To rule out sporadic cases caused by epigenetic inactivation of an MMR gene, molecular genetic investigation of the BRAF gene and methylation analysis of the MLH1 promoter are performed during diagnostic workup. A suspicion of Lynch syndrome based on the results of the methods mentioned above should be proven by detection of a germline mutation in an MMR gene in peripheral blood leukocytes.

Lynch syndrome (formerly hereditary non-polyposis colorectal cancer) is the most common familial colorectal cancer syndrome with a known molecular genetic background. The syndrome is caused by a germline mutation of one of the genes encoding mismatch repair (MMR) proteins that are responsible for DNA replication errors repair. Impaired function of these proteins leads to microsatellite instability (MSI) and forms a suitable background for the development and progression of tumors, mainly colorectal cancer. Traditionally, Lynch syndrome was regarded to be responsible for 2 % of all cases of colorectal cancer, however recent estimates reach even 5 %. Due to this relatively high frequency, familial occurence, the absence of the premorbid phenotype and the development of malignant tumors during the productive years of life, the correct diagnosis becomes not only a medical, but also a socioeconomical problem. Unfortunately, clinical means of diagnostics of Lynch syndrome (like the Amsterdam criteria and Bethesda guidelines) lack sensitivity. It was shown that predictive models based on histological signs of MSI are more sensitive than the clinical criteria used to detect patients suspicious of Lynch syndrome. Of all MSI-H colorectal cancers, 1/5 is caused by Lynch syndrome, the rest being only sporadic cancers caused by epigenetic inactivation of a MMR protein. To rule out the sporadic cases, molecular genetic investigation of the BRAF gene and methylation analysis of MLH1 is used in the diagnostic workup of Lynch syndrome. The suspicion of Lynch syndrome, based on the results of the assortment of diagnostic methods mentioned above, should be proven by detection of a germline mutation of an MMR gene in peripheral blood, and followed by screening of family members, which is a necessary condition for efficient prevention.

Introduction: Optimized staging of colorectal carcinoma (CRC) is essential for treatment planning and for estimating the prognosis of the disease. In addition to tumour size and the depth of bowel wall infiltration, the lymph node status is very important for the determination of the disease stage. For this reason, detection and assessment of the maximum number of lymph nodes is emphasized in the examination of resected segments of the large bowel. The number of lymph nodes (LNs) found in the segments resected depends on various circumstances. In our study, we focused on factors which could influence the number of pericolic LNs., Material and Methods: We examined two groups of CRC patients. The first group included 30 patients within the age range of 32-50 years (average: 47.5 years) and the second group consisted of 90 patients aged between 51 and 87 years (average: 68 years). The tumours were localized in various parts of the colon, predominantly in the descending colon and the sigmoid colon. Rectal tumour was present in 23 patients; 13 of them underwent preoperative chemoradiation therapy and 10 of them received no preoperative therapy. The length of the resected colon segments (radical intervention) ranged from 6 to 51 cm. The size of CRC ranged from 0.5 to 15 cm (average: 4.5 cm). The maximum tumour invasion depth reached into the subserosal tissue and pericolic adipose tissue., Results: The number of LNs found in 120 resected colon segments ranged from 1 to 60 LNs per case. The number of LNs showed differences among the patients and also depended on the location of CRC within the large intestine. In the resected segments of the ceacum with CRC, the average number of LNs was 11.5, whereas it was only 7 in rectal CRC. The largest volume of pericolic adipose tissue was found in the caecum, whereas the smallest volume was seen on the rectal circumference. In CRC patients aged 50 years or younger, the number of LNs was from 2 to 60 (average: 17). In contrast, the number of LNs ranged from 1 to 46 (average: 11) in patients older than 50 years. In resected segments that were 6 to 12 cm long, the number of LNs ranged from 1 to 18 (average: 8). In resected segments that were 12 to 51 cm long, the number of LNs was from 1 to 60 (average: 13.8). In 13 cases of rectal CRC with preoperative chemoradiation therapy, small LNs of an average length of 1-3 mm predominated, and the number of LNs ranged between 1 and 13 (average: 5). The required number of 12 LNs was reached in 4 resected parts of the rectum (31%)., Conclusion: The number of pericolic LNs found in the resected segments of the colon and the rectum with CRC depends on various factors. Besides individual differences, the number of LNs is influenced by the CRC location in the colon, the extent of the resected pericolic adipose tissue, the patients age and the length of the segment resected. In cases of rectal CRCs, it is also influenced by preoperative chemoradiation therapy.