Background and Aims: Human papillomavirus (HPV) is considered a major risk factor in the development of squamous call cancer of the anus. There are believed to be over 100 subtypes of the virus with varying pathogenicity; however subtypes HPV 16 and 18 are considered “high risk” as they are seen in the majority of cervical cancer specimens. Little data exists confirming the presence of these subtypes in squamous cell cancer of the anus. We have developed and utilized a novel technique using microarray technology to examine DNA for HPV sub-typing in anal carcinomas.
Methods: We have built a sensitive microarray platform to classify 37 types of mucosal HPVs, which includes 14 known high-risk and 23 low-risk types. The estimated detection sensitivity of our protocol is 1-2 copies of HPV16 genome, based upon standardization experiments using the SiHa cell line, which contains 1-2 copies of integrated HPV16 per cell. Results. We collected twenty cases of anal carcinoma from our local hospitals. HPV was detected in 18/20 (90%) cases. HPV 16 and 18 was present in the majority of our specimens, with HPV 16 being the most common. However, HPV serotypes 11, 43 and 81 were detected in the background of HPV 16 and 18 in a minority of cases. In 2/20 (10%) of anal carcinomas that tested negative using our microarray platform, further DNA sequencing confirmed the lack of presence of HPV DNA in these samples.
Conclusion: Microarray technology is a novel and accurate way to screen for the various subtypes of HPV in anal cancer. In our study the majority of anal cancers were associated with HPV subtypes 16 and/or 18, and like cervical cancer may be the driving forced for carcinogenesis. Other HPV subtypes can be present in anal cancers, and might contribute to its pathogenesis.