The "Cancer Connection"

One group of HPVs cause "benign" warty growths that rarely, if ever, cause cancerous tumors. These viruses are frequently referred to as "non-oncogenic" HPVs. Non-oncogenic HPVs can infect the outer skin (cornified squamous epithelium), smooth moist tissues (vagina, labia or the underside of the foreskin) and mucous membranes (nasal passages and oral cavity). HPVs infect particular tissues with high specificity; besides a few notable exceptions, HPVs that infect the genital tract do not tend to infect non-genital tissues or vice versa. Examples of these genital ‘tropic’ viruses would include HPV-6 , -11, -16 and -18. HPV-1, the virus that causes plantar warts, exclusively infects the outer skin layer of the body.

"Oncogenic HPVs" have earned their title by their associations with cancers. These HPVs appear to be different from non-oncogenic HPVs in that they seem to dysregulate normal cell division in infected cells; making it easier for cells to reproduce unchecked in the fashion that typically happens in cancer cells. Oncogenic HPVs are not normally cancer-associated because not everybody who becomes infected with these viruses develops cancer. Rather, particular cancers that develop are most often associated with these HPV types. Each year, 5,000 U.S. women die from invasive cervical cancer. HPV-16 is associated with about half of the cervical cancer tumors worldwide. Other oncogenic genital HPV types include type-18, -31, -33, and -35. Also, HPV type-39 is an example of an oncogenic, non-genital HPV virus.

Genital Warts and Cervical or Anal Cancer:

The (HPV) virus types that cause genital warts rarely, if ever, cause cancer. However, women diagnosed with genital warts should receive routine cervical cancer screening using Pap tests. Similarly, men and women who have internal anal warts should be screened for anal cancer. These recommendations are based upon the fact that women with external genital warts and men and women with internal anal warts are more likely (than those without these diagnoses) to have been exposed to HPV viruses that are "oncogenic," or cancer-causing virus types.

Also, men and women who have ever had receptive anal intercourse should be screened for anal cancer at least once. The same HPV types that cause cervical cancer can also cause anal cancers. However, like cervical cancer, these viruses need to be ‘delivered’ to anal/rectal area before they can cause the cancers for which they are responsible. Unfortunately, anal receptive intercourse is sometimes not considered ‘sex’ in some cultures, is difficult for many people to discuss with their doctors or nurses, and is frequently considered a social or sexual taboo. All of these factors make it difficult for us to know who to screen for anal cancer, and in light of this ignorance, we tend to not diagnose precancerous changes in the anal tissues of at-risk men and women.