Introduction: Colorectal carcinoma is the second frequently occurring malignant neoplasm in human beings. Out of its many causes, hereditary predisposition comprises 10-20% of all colorectal carcinomas.
Material and methods: The study group comprised 170 patients with colorectal carcinoma who had been operated upon in The Department of General Surgery, Medical Academy, Bydgoszcz, between 1994 and 1997. Patients with familial polyposis, ulcerative colitis and those previously treated for colorectal cancer were excluded from the study. Prior to surgical intervention, all patients submitted a thorough history concerning familial colorectal cancer or other neoplasms. The following groups underwent further analysis: Group I - families with HNPCC features (hereditary non-polyposis colorectal cancer) according to ICG-HNPCC criteria(International collaborative group on hereditary non-polyposis colorectal cancer). Group II - HNPCC suspicion in the family, according to LubiÄski and K¸adny criteria. Group III - sporadic colorectal cancer cases - singular colorectal cancer cases in the family.
Results: Out of the 170 patients with colorectal cancer that underwent surgery, we noted 4 families complying with ICG-HNPCC criteria (2.4%) and 21 families with suspicion of HNPCC (12.3%). The remaining 145 patients (85.3%) presented with sporadic colorectal cancer cases. These results demonstrate, that nearly 15 % of colorectal cancer patients operated upon in our clinic are of familial origin. The percentage of families with HNPCC amounts to 2.4%.
Conclusions:
1. Family history is the basis of a proper hereditary non-polyposis colorectal cancer diagnosis.
2. The incidence of HNPCC in the Bydgoszcz region does not differ from literature data.

Keywords: Colorectal Carcinoma, hereditary non-polyposis colorectal cancer (HNPCC)