Types and variants of human papillomavirus in patients with cervical cancer submitted to radiotherapy

ABSTRACT

INTRODUCTION: high risk HPV infections and variants presence has been associated to increase the risk of cervical cancer. However, there are few studies that analyze the presence of them in patients with cervical cancer before and alter radiotherapy treatment. OBJECTIVES: to analyse the human papilloma virus presence and E7/HPV16 variants in 60 women with cervical cancer before and after radiotherapy. MATERIALS AND METHODS: HPV detection and typing were based on a GP5+/GP6+ PCR – Enzyme immune assay. E7/HPV16 variants were detected by PCR -Single strand conformation polymorphism (SSCP) and confirmed by direct sequence. RESULTS: before radiotherapy, 50/60 patients (83.3 percent) were HPV positive and HPV16 (53.3 percent) was the most prevalent type. After 3 months of radiotherapy, 55 patients attended to consult; of them, 19 (34.6 percent) were HPV positive, this decrease in the HPV detection was significant (p<0.0005). The E7/HPV16 analysis showed that 20 samples (62.5 percent) amplified before radiotherapy, 18 of them (90 percent) had identical SSCP pattern to the prototype and 2 showed a different SSCP pattern. The sequence of these two samples showed silent mutations at nt. 732 (T-to-C), 789 (T-to-C) and 795 (T-to-G). After radiotherapy, the was not detection of new mutations, 6 patients showed persistent HPV16 infection with the same SSCP pattern to the prototype, and samples that initially showed a different SSCP pattern were negative to E7/ HPV16 after radiotherapy. CONCLUSION: few E7/HPV16 variants were detected before radiotherapy and it seems that the treatment did not cause mutations in this gene