Association between HIV infection and Gastric Cancer in an African Population

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Kayamba, Violet Jolezya
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Introduction There is a shortage of systematically collected data on gastric cancer in Zambia. An audit carried out as preliminary work showed that there was a change in the epidemiology of gastric cancer since the early 1980s, and it was hypothesised that this change was linked to HIV infection. The aim of this study was to evaluate a possible association between gastric cancer and HIV infection in patients seen at the University Teaching Hospital (UTH), Lusaka. Other well known risk factors such as infection with Helicobacter pylori (H. pylori), presence of CagA, serum pepsinogen 1 to 2 ratios, smoking, alcohol intake and low income were also evaluated. Methods This was a prospective case-control study conducted over one year. Cases were patients with gastric adenocarcinoma confirmed by histopathology while controls were patients with no visible mucosal abnormality in the upper gastrointestinal tract. Two controls were enrolled for each case after matching for age and sex. The presence of HIV infection was determined by testing for HIV antibodies in each group and odds ratios (OR) was calculated to determine the presence of any association. The presence of antibodies to H.pylori, the virulence factor CagA and serum pepsinogen 1 and 2 levels were determined using ELISA. Also collected was data on other life style risk factors using an interviewer administered questionnaire. Results were analysed using STATA 10. Results A total of 38 cases and 76 controls were enrolled. There was no association between gastric cancer and HIV infection (OR 1.4, 95%CI 0.3-6.4; P=0.73). Smoking and alcohol were found to increase the odds of developing gastric cancer in both univariate and multivariate analysis (multivariate P=0.04 and P=0.02 respectively). Overall, 81% of the patients were found to be positive for H. pylori infection, with no significant difference between the cases and the controls (P=0.24). The presence of antibodies to CagA was also not different between the two groups (P=0.79). A small proportion of cases and controls had low serum levels of pepsinogen 1, (11% and 6% respectively) but this was not significantly different (P=0.45). vii However, the presence of a low pepsinogen 1 to 2 ratio was more discriminating, with a higher proportion among the cases (P=0.009). Conclusions No association was found between HIV infection and gastric cancer in the patients seen at the endoscopy unit, UTH, Lusaka. Alcohol and smoking were shown to increase the odds of developing gastric cancer. Patients with gastric cancer have a lower ratio of pepsinogen 1 to 2, although there was no significant difference in the levels of pepsinogen 1, H.pylori infection or CagA between gastric cancer patients and healthy controls. In conclusion, the reason for the apparent change in epidemiology of gastric cancer has not been established and therefore, more work still needs to be done to answer this question
Stomach--Diseases(HIV and AIDS) , HIV infections--Zambia , AIDS -related complex