Evaluation of Role of Heavy Metals in Causation of Colorectal Cancer

ABSTRACT

Over last two decades, there is increasing incidence and high prevalence of colorectal cancer in young Indians, who are mostly from rural environment with a very low socio-economic condition, consuming a diet low in meat, fat, but rich in carbohydrate and fiber with a normal or less than normal body weight. These facts have clearly indicated a completely separate epidemiological profile of this cancer in our country and so may be caused by some different and unknown etiological factors. West Bengal and Bangladesh (the Gangetic belt) are quite developed in agriculture and to some extent in industry as well. This implies a significant contamination of drinking water for this large population with industrial wastes containing heavy metals. As many of the heavy metals (lead, chromium, cadmium) have proved to be associated with gall bladder cancer in our country and heavy metal poisoning (arsenic) is common in this geographical region, we searched for the effect of some heavy metals in causation of colorectal cancer here.METHODSOur case-control study compared the tissue levels of two heavy metals namely arsenic and lead. In a city government hospital of Kolkata (eastern India), 50 sporadic colorectal cancer patients were compared with 100 age and sex matched benign colorectal cases over a period of one and half years. Quantitative estimation of arsenic and lead in colonic tissues by atomic absorption spectrophotometry was done to detect any significant difference between these two groups.RESULTSOur study did not find any statistically significant difference in the tissue levels of arsenic and lead between the cases and controls (p value >0.05).CONCLUSIONSOur study does not show any association of heavy metals with colorectal cancer, although this remains a possibility. We do not have any population-based reference data on levels of heavy metals in tissues of normal population in this geographic region, which made the comparison difficult.