Published online Oct 21, 2013. doi: 10.3748/wjg.v19.i39.6598
Revised: August 3, 2013
Accepted: August 17, 2013
Published online: October 21, 2013
Processing time: 150 Days and 3.1 Hours
AIM: To investigate the association between human papillomavirus (HPV) and esophageal squamous cell carcinoma (ESCC) in southern Brazil.
METHODS: We studied 189 esophageal samples from 125 patients from three different groups: (1) 102 biopsies from 51 patients with ESCC, with one sample from the tumor and another from normal esophageal mucosa distant from the tumor; (2) 50 esophageal biopsies from 37 patients with a previous diagnosis of head and neck squamous cell carcinoma (HNSCC); and (3) 37 biopsies from esophageal mucosa with normal appearance from 37 dyspeptic patients, not exposed to smoking or alcohol consumption. Nested-polymerase chain reaction (PCR) with the MY09/11 and GP5/6 L1 primers was used to detect HPV L1 in samples fixed in formalin and stored in paraffin blocks. All PCR reactions were performed with a positive control (cervicovaginal samples), with a negative control (Human Genomic DNA) and with a blank reaction containing all reagents except DNA. We took extreme care to prevent DNA contamination in sample collection, processing, and testing.
RESULTS: The histological biopsies confirmed the diagnosis of ESCC in 52 samples (51 from ESCC group and 1 from the HNSCC group) and classified as well differentiated (12/52, 23.1%), moderately differentiated (27/52, 51.9%) or poorly differentiated (7/52, 13.5%). One hundred twenty-eight esophageal biopsies were considered normal (51 from the ESCC group, 42 from the HNSCC group and 35 from dyspeptic patients). Nine had esophagitis (7 from the HNSCC and 2 from dyspeptic patients). Of a total of 189 samples, only 6 samples had insufficient material for PCR analysis: 1 from mucosa distant from the tumor in a patient with ESCC, 3 from patients with HNSCC and 2 from patients without cancer. In 183 samples (96.8%) GAPDH, G3PDH and/or β-globin were amplified, thus indicating the adequacy of the DNA in those samples. HPV DNA was negative in all the 183 samples tested: 52 with ESCC, 9 with esophagitis and 122 with normal esophageal mucosa.
CONCLUSION: There was no evidence of HPV infection in different ESCC from southern Brazil.
Core tip: This paper gives additional evidence related to the controversy on the potential role of human papillomavirus (HPV) in the pathogenesis of esophageal squamous cell carcinoma (ESCC). Taking great care to avoid contamination by environmental HPV and using a very sensitive HPV DNA detection technique, we found no evidence of HPV neither in ESCC tumor tissue, nor in esophageal non-tumoral tissue from ESCC patients, or from head and neck squamous cell carcinoma patients or from dyspeptic controls without cancer. These data convincingly argue that when environmental contamination is carefully controlled, there is no evidence that HPV is involved in ESCC carcinogenesis in southern Brazil.