Single or multiple HPV types in cervical cancer and associated metastases

Almost all cervical cancers are human papillomavirus (HPV)-positive. Some aspects of HPV carcinogenesis, such as factors involved in the transformation process and the mono- or polyclonal origin of the carcinogenic process, need to be defined. The latter aspect is addressed in our study. Cervical samples were collected from 102 patients with squamous cell carcinoma. The HPV positivity was established by PCR analysis performed using consensus and specific primers for the L1 and E6/E7 regions, respectively. Eighty-seven samples were positive for the L1 gene and 5 for the E6/E7 genes. Overall, 92 samples contained segments of HPV-DNA (90.2%). HPV-16 was most frequently found either alone or associated with other genotypes (63%). All genotypes identified as a single infection, except HPV-73, belonged to the high-risk HPV group. Among multiple infections, the HPV-31+54 couple was the most frequent. The presence of two genotypes in a primary tumor raises the question of their distribution in a single tumor cell. We attempted to answer this question by comparing the HPV patterns in primary tumors and metastases, considering that metastases derive from cell clones released from the primary tumor. The HPV patterns of primary tumors and metastases overlapped in most patients, even when primary tumors contained a double genotype, thus suggesting that single tumor cells may contain multiple HPV genotypes.