Molecular etiology of second primary tumors in contralateral tonsils of human papillomavirus-associated index tonsillar carcinomas

For the small subset of patients with tonsillar carcinomas who develop SPTs in the contralateral tonsil, the index case and the SPT consistently harbored the same HPV variant. This finding suggests that HPV-related tumor multi-focality can be attributed either to independent inoculation events by the same virus, or by migration of HPV-infected cells from a single inoculation site to other regions of Waldeyer's ring.