Time Trend of Liver Cancer Among Subpopulation of Ages Less Than 40 During 2005-2014 in Nghe An, Viet Nam

Background: Liver cancer has been leading cancer mortality nationwide in Viet Nam. Aim: The aim was to examine time trends of liver cancer mortality by performing population-based mortality registration in Nghe An province, 2005-2014. Methods: We yearly collected data from all 480 Commune Health Stations from 2005 to 2014 using the designed form of “Mortality Registration” with a guideline of underlying-, immediate, - and contribute cause of death. Five variables were included name, age, sex, date of death and cause of death. Average residents of each commune were also yearly reported. All cases were coded ICD-10, then liver cancer (C22) was derived. Age-standardized rate (ASR) was estimated. Trend of liver cancer was observed by estimated mortality rates ratio and 95% confident interval (MRR) for 5-period of 2005-2006 (reference), 2007-2008, 2009-2010, 2011-2012, 2013-2014, adjusted for total mortality rate and proportion of cases with unknown causes of death, for total, subgroup of ages 40 or older, and ages less than 40. Results: Among registered 7,667 cases of liver cancer, there were 855 cases aged less than 40. Mortality rates per 100,000 (ASR) were increased from 37.4 to 52.8 in men and 9.2 to 12.6 in women, from 2005 to 2014, respectively. The increased trends were significantly seen for the subpopulation ages 40 or older only, MRR=1.56, 95% CI: 1.38-1.76 in men and MRR=1.67, 95% CI: 1.36-2.04 in women, all P trend < 0.05. In contrast, the decreased trends were significantly observed for the subpopulation ages less than 40, MRR=0.72, 95% CI: 0.54-0.97 in men and MRR=0.47, 95% CI: 0.22-0.99 in women, all P trend < 0.05. Conclusion: The significant decline risks of death from liver cancer for the subpopulation ages less than 40 during 2005-2014 might be explained by HBV vaccine nationwide from 1998 to date and reduction of environmental factors induced this cancer sites in improving healthy environments after the war ended in 1975. Key-words: Liver-cancer, population-based mortality registration, Viet Nam, HBV-vaccine.