Environmental Risk Factors among Colorectal Cancer Patients in Alexandria, Egypt: A Case-Control Study

Background: Recognizing environmental risk factors that trigger Colorectal cancer (CRC) occurrence and progression is essential to apply more effective prevention and risk reduction measures. Objective(s): The main objectives of this study were to compare the plasma levels of lead and copper between CRC patients and healthy subjects and to estimate the relationship between exposure to some environmental risk factors and CRC. Methods: A case-control study was performed at the Alexandria Main University Hospital. The study sample consisted of 25 CRC patients and 25 healthy controls who matched the cases based on age and sex. An interview questionnaire collected data about possible environmental risk factors. Lead and copper Levels were measured by graphite furnace atomic absorption spectrometry. Results: Higher significant levels of lead and copper were detected in CRC patients compared to healthy subjects (p < 0.05). The multivariate stepwise logistic regression model revealed that four factors had a significant association with CRC: living near solid waste collection sites, environmental tobacco smoke (ETS) exposure, plasma lead level (>0.164 mg/L), and living in a house with old oily painting (OR=83.25, 95% CI=1.28-5419.13; OR=32.20, 95% CI=1.53-678.07; OR=31.06, 95% CI=1.55-622.59; OR=9.35, 95% CI=1.02-85.79, respectively). Conclusion: There were significant differences in lead and copper plasma levels between CRC patients and healthy subjects. Other notable risk factors included ETS exposure, old oily paint in homes, and living near solid waste sites. These findings suggested a link between chronic exposure to these pollutants and CRC, but further research is needed to solidify the connection between heavy metals and cancer.