The objective of this study was to determine whether immunologic competence, as measured by lymphocyte stimulation indices from three different ex vivo challenges, is associated with subsequent risk of
cancer or total mortality in Linzhou, China, a population at high risk for upper
gastrointestinal cancers. Cellular immune function tests were conducted on a subgroup of 381 trial participants after 5.25 years of intervention to evaluate whether nutrient supplementation affected the cellular immune system and found significantly higher T-lymphocyte mitogenic responsiveness to
phytohemagglutinin-M among men receiving daily supplementation of
beta-carotene (15 mg) plus
selenium (50 mug) plus
alpha-tocopherol (30 mg) (supplementation
factor D) compared with those who did not receive this supplement (P<0.05). The current analysis reports 10 years of post-trial prospective follow-up of these 381 trial participants and identifies 53 incident
cancers, 48 (92%) of which were upper
gastrointestinal cancers, including 22
esophageal cancers, 22 gastric cardia
cancers, and four noncardia
gastric cancers. Ninety-one deaths occurred among the 381 participants, including 33 upper
gastrointestinal cancer deaths, 23
heart disease deaths, 16
stroke deaths, and seven fatal accidents. Multivariate Cox proportional hazards models including variables for age at time of tests, sex, tobacco smoking, alcohol drinking, and original trial treatment group showed no significant associations between
phytohemagglutinin-M,
concanavalin-A, or anti-CD3 stimulation indices and subsequent
cancer incidence or total mortality. This implies that immune competence, as measured by these stimulation indices, is not associated with incident
cancer or total mortality in this population.