In Kazakhstan, cervical carcinoma (CC) is the most common cancer in women aged 15 to 44 years, ranking second as the leading cause of female cancers. According to the National Cancer Registry, the incidence rate of CC in Kazakhstani women is very high. In 2012, the estimated crude incidence rate of CC was 22.8 per 100,000 women with a mortality rate of 9.8 per 100,000 women. Unfortunately, data regarding the prevalence and distribution of high-risk HPV (hrHPV) types in CC in Kazakhstan are scarce. Hence, the aim of our study was to evaluate the distribution of hrHPV types in invasive CC samples obtained from Kazakhstani women.
A total of 99 archival formalin-fixed paraffin-embedded (FFPE) tissue samples, obtained from the same number of Kazakhstani women with histologically confirmed invasive CC, were included in the study. Total DNA was extracted from three 10 μm tissue sections of each FFPE block using a DNA Mini Kit (Qiagen, Hilden, Germany), following our in-house protocol for DNA extraction from FFPE tissues. Detection of hrHPV types was performed using a RealTime High Risk HPV Test (Abbott, Wiesbaden, Germany), which enables concurrent separate genotyping of HPV16 and HPV18 and pooled detection of 12 other hrHPV types: HPV31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68. Up to 200 ng of each DNA isolate was used per PCR reaction to allow efficient PCR amplification.
Out of 99 samples tested, two (2.0%) were excluded from the analysis due to invalid results for amplification of beta-globin. In total, 77/97 (79.4%) samples tested positive for the presence of hrHPV types. HPV16, HPV18, and other hrHPV types were present in 69/77 (89.6%), 3/77 (3.9%), and 6/77 (7.8%) samples, respectively. An infection with a single hrHPV type was detected in the majority of samples (98.7%).
To the best of our knowledge, this is the first study to evaluate the distribution of hrHPV types among Kazakhstani women with invasive CC. The prevalence of hrHPV types in FFPE CC samples was slightly lower compared to previous studies, most likely due to the fixation process and/or storage conditions. However, approximately 80% of samples tested positive for the presence of hrHPV types, of which HPV16 was detected in almost 90% of cases. Nevertheless, further studies evaluating the distribution of hrHPV types in fresh tissue samples are needed to confirm our observations. Our data suggest that the implementation of HPV vaccination could have an enormous impact on the incidence rate of CC in Kazakhstan.