OBJECTIVE: To identify the most predominant types of human papillomavirus (HPV) in carriers of the anal canal carcinoma (ACC), relating them to the cell differentiation and lesion staging degree, in patients from Belém, Pará, Brazil, between 1998 and 2000. METHODS: A case-control study was conducted with 75 patients, divided into Test Group, with 33 carriers of the anal canal carcinoma, and Control Group, with 42 carriers of non-neoplastic diseases of the anal canal. The methods employed to identify the viral types were the polymerase chain reaction and the dot blot. The Fisher's exact test was used to assess the HPV occurrence. The distribution of HPV types was analyzed by 3x2 contingency tables, representing the distribution of HPV types. For hypothesis testing, the significance level α=0.05 was previously established for rejection of the null hypothesis. RESULTS: HPV was significantly prevalent (p=0.0027) in the Test (60.6%) and Control Groups (26.2%) (p=0.0027). The most prevalent viral types were HPV 16 (42.4%) and 18 (15.2%). Significant differences related to the prevalence of HPV 16 and 18 were verified between both groups (p=0.027 and p=0.043, respectively). In the Control Group, HPV 16 was found in 19.0%, whereas HPV 18 was observed in 2.4%. In the Test Group, we evaluated the distribution of HPV types according to the staging and degree of cell differentiation, and found no significant differences between the results of the different groups. CONCLUSION: Squamous cell carcinoma of the anal canal is associated with the HPV presence, and the 16 and 18 types are the most frequently found
papillomavirus infections; carcinoma; squamous cells; anal canal; papilloma
