we conducted a study of 126 patients with anal and rectal squamous cell carcinoma and 372 randomly selected control subjects in the san francisco bay area ( ca ) to test the hypothesis that these tumors are related to a history of anal intercourse , the presence of sexually transmitted diseases and other conditions of the anal area , treatment of these diseases or conditions , and history of use of cigarettes or other substances .
C0027651
tumors
C0012634
diseases