Frequency and genotype distribution of high risk human papillomavirus in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a dismal disease exhibiting striking geographical differences in its incidence. It is multifactorial in origin. Among infectious agents, human papillomavirus (HPV) was introduced as a possible causative agent in the development of ESCC in 1982. Subsequent studies using various methods have confirmed the presence of HPV in ESCC. We aimed to determine the frequency of HPV in ESCC in northwest Pakistan which is part of high risk belt for this disease.

This study was conducted on two hundred and forty-three (243) diagnosed cases of ESSC at two tertiary care hospitals of Peshawar, Pakistan, from 2011 to 2016. DNA was extracted from all specimens. Polymerase chain reaction (PCR) was used to check the quality of DNA using β-globin primers and frequency and genotypes of HPV using HPV general primers and type-specific primers respectively. HPV and its genotypes were confirmed through the sequencing of a few selected cases.

Two hundred and three (203) tissue specimens had adequate DNA and were further analyzed. HPV positivity with general primers alone was 15.7% (32/203). Using HPV general primers and type-specific primers (HPV 16 or HPV 18), the overall positivity of HPV was 31% (63/203). For type-specific primers, frequency of HPV types 16 and 18 was 20.19% (41) and 7.8% (16) respectively where 6 cases were positive for both HPV 16 and 18.

The overall high prevalence of HPV indicates it as a possible risk factor for ESSC.