Differences in Cancer Risks in the South and North of Viet Nam.

Background: As there are few available data regarding cancers in Viet Nam, the aim of the present study was to evaluate cancer risk ratios and geographical differences in cancer incidences between the south and north populations in the 1990s. Methods: Data for cancer incidences in Ho Chi Minh (HCM) and Hanoi were derived from published reports. The method for comparison of cancer incidence in two groups used in the present study was the Mantel-Haenszel test. Results: In HCM, all cancers were observed to be lower in males, (RR = 0.87, 95% CI = 0.83-0.91) but higher in females, (RR = 1.06, 95% CI = 1.01-1.12) than in Hanoi. For males, significantly higher incidences in HCM were observed for cancers of the oesophagus (RR = 1.66, 95% CI = 1.19-2.32), liver (RR = 1.22, 95% CI = 1.09-1.36), gall bladder (RR = 5.95, 95% CI = 2.49-14.23), and larynx (RR = 3.54, 95% CI = 2.26-5.55). In contrast, there were much lower incidences in HCM for cancers of the nasopharynx (RR = 0.5, 95% CI = 0.41-0.61), stomach (RR = 0.76, 95% CI = 0.67-0.86), and lung (RR = 0.7, 95% CI = 0.64-0.78). For females, breast cancer incidence was much lower (RR = 0.65, 95% CI = 0.57-0.73) but that of cervical cancer was significantly higher in HCM than in Hanoi, (RR = 3.94, 95% CI = 3.36-4.62), especially for the age group 55-64, (RR = 8.7, 95% CI = 5.9-13.3). Conclusion: The present findings show that cancer risk is quite different in the south and north populations within Viet Nam.