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
ABSTRACT
Stomach cancer is the most common cancer in Iran. A multi-ethnic population and wide variation in the environmental risk factors may lead to variations in cancer risk within this country. We have designed an ecological study and evaluated geographical variation regarding mortality from stomach cancer and its established risk factors in Iran. We used the Iranian National Causes of Death Registry and estimated the age-standardized mortality rates [ASMR] of stomach cancer in 29 Iranian provinces, stratified by sex and area of residence [rural/urban]. The average ASMR of stomach cancer among Iranian males was 15 per 100, 000 and females it was 8.1 per 100, 000. The highest and lowest mortality rates were observed in Kurdistan with an ASMR of 29.1 per 100, 000 in northwestern Iran and Hormozgan that had and ASMR of 5.0 per 100, 000 in southern Iran. Males had approximately a two-fold higher ASMR compared to females, as did rural residents when compared with urban residents. The prevalence of H.pylori infection was about 90% in the province of Ardabil [a high-risk area] and 27% in the province of Sistan-Baluchistan [a low-risk area]. The wide geographical variation and high mortality rate of stomach cancer in Iran is likely due to differences in the exposure to the environmental risk factors among people living in the high-and low-risk areas, particularly H. pylori infection, a well-established risk factor of stomach cancer