Monday July 28, 2014 (foodconsumer.org) -- A study suggests that practicing oral sex or having multiple sexual partners can increase risk of cancers of the oral cavity and the oropharynx because the sexually transmitted infection called human papillomavirus (HPV) infection that causes cervical cancer can be transmitted to the mouth through mouth to mouth kissing or oral sex, and increase risk of oral cavity cancer and oropharynx cancer.

This case control study involved 1,670 cases of patients with 1,415 diagnosed with oral cavity cancer and 255 with cancer of the oropharynx, and 1,732 controls.

In the study, HPV DNA was detected in 3.9% of oral cavity cancer cases and 18.3% of the oropharynx cancers and tonsil cancers.

Among the cancer patients, tobacco smokers and paan chewers were less likely to be HPV DNA carriers while those who reported more than one sexual partners or who practiced oral sex were more likely to be HPV DNA carriers.   Tobacco smoking and paan chewing can increase the risk of oral cavity cancer, which explains why smokers and paan chewers were less likely to be HPV carriers.

Of the HPV DNA positive cancer patients, 95% were found to carry HPV 16 DNA.

Antibodies against HPV 16 L1 were found associated with 50% increased risk for oral cavity cancer and 250% increased risk of oropharynx cancer.

HPV 16 E6 or E7 seemed to be more virulent in terms of their potency to cause cancers of the oral cavity and the oropharynx.  Antibodies against 16 E6 or E7 were correlated with 190% and 820% increased risk for cancers of the oral cavity and the oropharynx, respectively.

The study concluded "HPV appears to play an etiologic role in many cancers of the oropharynx and possibly a small subgroup of cancers of the oral cavity" and "The most common HPV type in genital cancers (HPV16) was also the most common in these tumors." 

Comment:  HPV can spread not only through sexual contact, but also through mouth to mouth kissing.  Saliva can carry the virus even if there are no clinical symptoms of the infection or lesion.    

HPV is extremely common among adults.  An estimated about 50% men and women will acquire the virus in their lifetime.  HPV can be cleared in 80 percent of infection cases without any medical intervention.  The virus can cause lesion in some carriers, which may or may not lead to the development of cervical cancer, oral cavity cancer or oropharynx cancer.

News report says that Michael Douglas, the famous actor, claimed that his throat cancer was caused by HPV infection.  (David Liu)

Reference: Rolando Herrero, Xavier Castellsagué, Michael Pawlita, Jolanta Lissowska, Frank Kee, Prabda Balaram, Thangarajan Rajkumar, Hema Sridhar, Barbara Rose, Javier Pintos, Leticia Fernández, Ali Idris, María José Sánchez, Adoración Nieto, Renato Talamini, Alessandra Tavani, F. Xavier Bosch, Ulrich Reidel, Peter J. F. Snijders, Chris J. L. M. Meijer, Raphael Viscidi, Nubia Muñoz, Silvia Franceschi and For the IARC Multicenter Oral Cancer Study Group, Human Papillomavirus and Oral Cancer: The International Agency for Research on Cancer Multicenter Study,  Journal of National Cancer Institute, 2003, Volume 95, Issue 23Pp. 1772-1783.