HBV infection and extra-hepatic cancers in adolescents and 20s: A retrospective study in China

Background: The mean age at cancer diagnosis is younger in hepatitis B virus (HBV) infected than non-infected patients. It remains unknown whether this association reflects an increase in the incidence rates of extra-hepatic cancers in adolescents and younger. Methods: We examined 10 common extra-hepatic cancers (lung, breast, gastric, prostate, esophageal, rectal, cervical, nasopharyngeal, lymphatic, and urinary bladder) among patients diagnosed at three Chinese hospitals during 2007-2016. We compared the percentage distribution (frequencies at each age point are shown as a percentage of the total frequency) of HBsAg + with HBsAg(-) patients, and calculated the standardized incidence ratio for each age group. Results: A total of 60,323 patients were identified. The mean age at cancer diagnosis was 1.5-5.5 years younger in hepatitis B surface antigen (HBsAg) positive patients compared to HBsAg(-) patients (p <= 0.001). Lymphoma patients had the highest prevalence rate of HBV infection (20.7%). Among the pooled HBsAg + cancer patients, 14.8% (1138/7666) were aged <= 39 years; by contrast, 9.7% (5122/52657) of HBsAg - cancer patients were in the same age range, giving an odds ratio of 1.6 [95%C11.509-1.733)]. The observations were similar when each cancer was considered individually. The odds ratio was greater in pooled male patients aged <= 39 years [1.9(95%C11.705-2.085)] compared with females [1.6(95%CI1.382-1.83)]. The ratio of the observed to the expected number of HBsAg + patients aged 15-19, 20-24, and 25-29 years were 3.3, 4.8 and 2.0, respectively, higher than 1.2-1.7 observed for older age-groups. Conclusion: HBV infection is a risk factor for diverse extra-hepatic cancers in adolescents and 20s.