Most cervical cancer develops as a result of a permanent infection with human papillomavirus virus (HPV). Despite the common perception that HPV is a requirement for the development of cervical cancer, a smaller proportion of HPV negative cervical cancer is often found in larger studies.
The aim of this study was to reinvestigate a proportion of HPV-negative tumors in a Swedish cohort (n=209) of patients diagnosed with cervical cancer, previously analyzed for detection of HPV where 14.4 % of the tumors were found to be negative.
Cervical cancer tumors with a HPV negative or invalid result from genotyping with AnyplexTM II HPV28 (Seegene) were included (n=37). This real time PCR method targets 28 genotypes using the viral L1 gene together with the human gene HBB. Second approach included an in house real time PCR protocol instead targeting the viral oncogenes E6 or E7 for 12 high-risk and two low-risk genotypes.
Samples with HPV negative results with both real-time PCR methods were assessed by pathologist and tumors with lacking amount and quality were excluded. Remaining HPV-negative samples were investigated with immunohistochemistry (p16, Vim, ER, PR, CD10, CEA, CK5, P63 and MUC2) to exclude the inclusion of tumors of non-cervical origin.
The initial results showed a proportion of 14.4 % negativity. With repetitive analysis (Anyplex) and second approach with alternative genotyping method the HPV-negativity was 9.6 %. After assessment of tumor material together with immunohistochemistry, five samples were excluded due to lack of tumor material or suspicion of other than cervical origin. This resulted in a HPV-negative proportion of 7.2 % in this Swedish cohort of cervical cancer. HPV-negativity was significantly (Pearson chi-square test; p < 0.0001) associated with adenocarcinoma (AC) histology and worse cancer-specific survival rate at 5 years (log-rank test; p = 0.010).
Reinvestigation of HPV-negative samples led to a drop of the total proportion of HPV negative tumors from 14.4 % to 7 %. HPV negativity in this group was associated with poor prognosis.