Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 21 3 2026 09 02 387 397 Alireza Moayyedkazemi Department of Internal Medicine, School of Medicine, Shahid Rahimi Hospital, Lorestan University of Medical Sciences, Khorramabad, Iran Amal Khudair Khalaf Department of Microbiology, College of Medicine, University of Thi-Qar, Thi-Qar, Iraq Abdolreza Mirjani Universal Scientific Education and Research Network Office, Lorestan University of Medical Sciences, Khorramabad, Iran Maryam Sepahvand Universal Scientific Education and Research Network Office, Lorestan University of Medical Sciences, Khorramabad, Iran Parastoo Baharvand Social Determinants of Health Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran Hossein Mahmoudvand Social Determinants of Health Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran 2025 12 16 2026 09 02 Background: Helminths modulate host immune responses through immunoregulatory mechanisms that may influence carcinogenesis. We investigated the prevalence and risk factors of helminthic infections among colorectal cancer (CRC) patients in Lorestan Province, western Iran. Methods: This case-control study enrolled 87 CRC patients and 87 healthy controls from general hospitals between October 2022 and August 2024. Stool samples were examined via direct wet mount and formol-ether concentration, with agar plate culture used to detect Strongyloides stercoralis. Results: Helminthic infections were found in 15 of 87 CRC patients (17.2%) versus 6 of 87 controls (6.9%). Trichostrongylus spp. was most common (52.4%), followed by Enterobius vermicularis (19%) and S. stercoralis (14.3%). Among CRC patients, age under 40 years was associated with higher infection odds versus those ≥60 years (OR=12.33, 95% CI: 1.38–110.2, P=0.025), while animal contact was protective (OR=0.06, 95% CI: 0.01–0.30, P=0.008). Among controls, rural residence (OR=15.25, 95% CI: 1.70–136.5, P=0.015) and animal husbandry (OR=12.61, 95% CI: 1.32–120.5, P=0.024) increased odds, while frequent fast-food consumption was protective (OR=0.16, 95% CI: 0.03–0.94, P=0.045). Conclusion: Intestinal helminthic infections were significantly more prevalent among CRC patients than healthy controls, indicating potential clinical relevance in this population. Detection of S. stercoralis in CRC patients, along with links to environmental exposure factors, supports systematic parasitological screening in endemic regions, particularly before immunosuppressive treatment. Larger multicenter studies with molecular diagnostics are needed to clarify the association between helminthic infection and CRC. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/4851 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/4851/1514