Extremely High Tp53 Mutation Load in Esophageal Squamous Cell Carcinoma in Golestan Province, Iran

Background: Golestan Province in northeastern Iran has one of the highest incidences of esophageal squamous cell carcinoma (ESCC) in the world with rates over 50 per 100,000 person-years in both sexes. We have analyzed TP53 mutation patterns in tumors from this high-risk geographic area in search of clues to the mutagenic processes involved in causing ESCC. Methodology/Principal Findings: Biopsies of 119 confirmed ESCC tumor tissue from subjects enrolled in a case-control study conducted in Golestan Province were analyzed by direct sequencing of TP53 exons 2 through 11. Immunohistochemical staining for p53 was carried out using two monoclonal antibodies, DO7 and 1801. A total of 120 TP53 mutations were detected in 107/119 cases (89.9), including 11 patients with double or triple mutations. The mutation pattern was heterogeneous with infrequent mutations at common TP53 "hotspots" but frequent transversions potentially attributable to environmental carcinogens forming bulky DNA adducts, including 40 at bases known as site of mutagenesis by polycyclic aromatic hydrocarbons (PAHs). Mutations showed different patterns according to the reported temperature of tea consumption, but no variation was observed in relation to ethnicity, tobacco or opium use, and alcoholic beverage consumption or urban versus rural residence. Conclusion/Significance: ESCC tumors in people from Golestan Province show the highest rate of TP53 mutations ever reported in any cancer anywhere. The heterogeneous mutation pattern is highly suggestive of a causative role for multiple environmental carcinogens, including PAHs. The temperature and composition of tea may also influence mutagenesis

Accuracy and cut-off values of pepsinogens I, II and gastrin 17 for diagnosis of gastric fundic atrophy: influence of gastritis.

BACKGROUND: To establish optimal cutoff values for serologic diagnosis of fundic atrophy in a high-risk area for oesophageal squamous cell carcinoma and gastric cancer with high prevalence of Helicobacter pylori (H. pylori) in Northern Iran, we performed an endoscopy-room-based validation study. METHODS: We measured serum pepsinogens I (PGI) and II (PGII), gastrin 17 (G-17), and antibodies against whole H. pylori, or cytotoxin-associated gene A (CagA) antigen among 309 consecutive patients in two major endoscopy clinics in northeastern Iran. Updated Sydney System was used as histology gold standard. Areas under curves (AUCs), optimal cutoff and predictive values were calculated for serum biomarkers against the histology. RESULTS: 309 persons were recruited (mean age: 63.5 years old, 59.5% female). 84.5% were H. pylori positive and 77.5% were CagA positive. 21 fundic atrophy and 101 nonatrophic pangastritis were diagnosed. The best cutoff values in fundic atrophy assessment were calculated at PGI<56 µg/l (sensitivity: 61.9%, specificity: 94.8%) and PGI/PGII ratio<5 (sensitivity: 75.0%, specificity: 91.0%). A serum G-17<2.6 pmol/l or G-17>40 pmol/l was 81% sensitive and 73.3% specific for diagnosing fundic atrophy. At cutoff concentration of 11.8 µg/l, PGII showed 84.2% sensitivity and 45.4% specificity to distinguish nonatrophic pangastritis. Exclusion of nonatrophic pangastritis enhanced diagnostic ability of PGI/PGII ratio (from AUC = 0.66 to 0.90) but did not affect AUC of PGI. After restricting study samples to those with PGII<11.8, the sensitivity of using PGI<56 to define fundic atrophy increased to 83.3% (95%CI 51.6-97.9) and its specificity decreased to 88.8% (95%CI 80.8-94.3). CONCLUSIONS: Among endoscopy clinic patients, PGII is a sensitive marker for extension of nonatrophic gastritis toward the corpus. PGI is a stable biomarker in assessment of fundic atrophy and has similar accuracy to PGI/PGII ratio among populations with prevalent nonatrophic pangastritis

Proportion of PPI use, <i>H. pylori</i> infection and fundic atrophy among categories generated by G-17 cutoff values.

<p>G-17: gastrin-17, PPI: proton pump inhibitor, IQR: interquartile range.</p><p>*Fundic atrophy was defined by histology gold standard.</p

Levels of pepsinogens, gastrin, and percentage of subjects seropositive for <i>H. pylori</i>, and CagA according to the topography of moderate/marked gastritis and atrophy.

<p>SD: Standard deviation, IQR: interquartile range, PGI: pepsinogen I, PGII: pepsinogen II, CagA: cytotoxin-associated gene A, PPI (proton pump inhibitor).</p><p>*<i>H. pylori</i> status was determined according to the results of histology examination, ELISA IgA/IgG, and Western blot.</p

Screening characteristics of PGI and PGI/PGII ratio for diagnosis of fundic atrophy and nonatrophic pangastritis.

<p>CI: confidence interval, AUC: area under curve, PPV: positive predictive value, NPV: negative predictive value, PGI: pepsinogen I, PGII: pepsinogen II, G-17: gastrin-17.</p

AUCs for discrimination of fundic atrophy (dark bar), and nonatrophic pangastritis (dotted bar represents the study population after exclusion of fundic atrophy from reference group, diagonal lined bar represents whole study population).

<p>AUC: Area under curve, PGI: pepsinogen I, PGII. pepsinogen II, PGI/PGII ratio: pepsinogen I/pepsinogen II ratio, G-17: gastrin-17.</p