Purpose: Infection with human papillomaviruses (HPVs) is associated with the development of cervical cancer, but whether HPVs have a role in colorectal cancer remains controversial.
Experimental Design: To determine the relationship between HPV and colorectal cancer, we performed a retrospective, controlled study using tumor and tumor-adjacent colorectal tissues dissected from patients with colorectal cancer, as well as colorectal tissues from control individuals with no cancer. The samples were processed in a blinded fashion for nested PCR and in situ PCR detection of HPV DNAs. The PCR products were gel purified and sequenced for HPV genotyping.
Results: We found that colorectal tissues from 28 (51%) of 55 patients with colorectal cancer were positive for HPV DNA. Colorectal tissues from all 10 control individuals were negative for HPV DNA (P=0.0034). Of the 107 usable (GAPDH+) samples collected as paired colorectal tissues (tumor and tumor-adjacent tissues) from the patients, 38 (36%) had HPV16 (n=31), HPV18 (n=5), or HPV45 (n=2), with HPV DNA in both tumor and tumor-adjacent tissues of 10 paired samples, 13 in only the tumor, and 5 in only tumor-adjacent tissues. In situ PCR detection of the tumor tissues confirmed the presence of HPV DNA in tumor cells.
Conclusion: Our results suggest that colorectal HPV infection is common in patients with colorectal cancer, albeit at a low DNA copy number, with HPV16 being the most prevalent type. HPV infection may play a role in colorectal carcinogenesis.