Meta-analysis Suggests Possible Relationship Between HPV and Colorectal Cancer
Posted: Monday, November 12, 2018
The involvement of human papillomavirus (HPV) in the carcinogenesis of colorectal cancer has been an issue of much debate. Marina K. Ibragimova, MD, of the Cancer Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, Tomsk, Russia, and her colleagues conducted a meta-analysis on current research to provide some clarity about this topic. Their analysis, published in Medical Oncology, revealed a “low but statistically significant level of the prevalence of HPV infection in the colorectal cancer tumor tissue and the association of HPV with colorectal cancer.”
In total, the investigators analyzed 19 studies that presented 2,049 samples of colorectal cancer tumor tissue and 830 samples of normal mucosal tissue from the large intestine. High variability was manifested, depending on the studied population. The highest incidence of HPV infection was shown in a sample of patients from Argentina and Turkey. Other studies from these countries showed lower levels of HPV infection in the tumor tissue of the large intestine. Thus, the researchers concluded that regional and ethnic features seem to play a little role in the prevalence of HPV in the large intestine tumor.
Immunohistochemical analysis showed that 8 of 11 DNA-HPV16–positive tumors had increased expression of the E6 oncoprotein. In addition, adjacent normal tissues, including endothelial cells, lymphocytes, fibroblasts, and mucosal cells in E6-positive tumors, had high expression of the E6 oncoprotein in 75% of cases. According to the authors, similar observations of expression of the E6 oncoproteins in neighboring normal cells seem to confirm the possibility that HPV infection in colorectal tumors may be mediated by blood circulation.
“To prove the role of HPV in colorectal cancer development, additional studies on the presence and physical status of HPV—in the premalignant large intestine tissue, in adenomatous polyps of the colon, and in inflammatory bowel diseases—are necessary,” the investigators noted.