ABSTRACT
Serologic screening of gastric cancer [GC] by serum pepsinogens [sPG] levels and Helicobacter pylori [Hp] sero-status, though highly informative, has provided heterogeneous results. Here, we have evaluated the modifying effects of demographic factors on the risk impact of Hp sero-status/sPG levels in gastric cancer, with particular emphasis on age. A cross-sectional study was carried out on 1341 individuals [GC = 578, healthy = 763], who were stratified into two age groups: 35-59 years [middle-aged, n = 830] and >/= 60 years [60 years-plus, n = 511]. Demographic factors and serological states [Hp sero-staus and sPG levels] were recorded by subject interview and serum ELISAs, respectively. Covariate-specific odds ratios were calculated by multivariable logistic regression. Hp infection was consistently associated with increased sPGI and sPGII levels in the 60 year-plus, but not the middle-aged group. The joint examination of the variable states of the three serum biomarkers [Hp serology, sPGI, and sPGI/II ratio], in the 60 year-plus age group, demonstrated a stepwise escalation of risk from the single [sPGI[low]; OR = 2.6], to double [sPGI[low]/sPGI/II[low]; OR = 3.55, and Hp[positive]/sPGI[low]; OR = 5.0] and ultimately triple [Hp[positive]/PGI[low]/PGI/II[low]; OR = 10.48] positive states, in reference to the triple negatives. However, this pattern was not exhibited in the middle-aged subjects. Age was clearly identified as a modifying factor on the risk projection of the combined states of Hp serology and sPG levels in gastric cancer screening, reflected by the augmented [tilde10.5 fold] risk of GC in the triple positive [Hp[positive]/sPGI[low]/sPGI/II[low]] 60 year-plus subjects, which was not evident in the middle-aged group