A new international prospective study of fifty thousand individuals, published in the Lancet Global Health, provides robust evidence indicating that regular use of opium is associated with higher risk of developing cancers in different organs of the respiratory, digestive, urinary, and central nervous systems.

According to the Digestive Diseases Research Institute (DDRI) of Tehran University of Medical Sciences (TUMS) quoted by the International Agency for Research on Cancer (IARC) This report that is based on more than ten years of following up fifty thousand individuals of the Golestan Cohort Study (GCS), that was initiated in 2004 by the Digestive Disease Research Institute of the Tehran University of Medical Sciences, in collaboration with the International Agency for Research on Cancer (IARC), and the National Cancer Institute (NCI), documents the presence of dose-dependent associations between regular use of opium and a broad array of cancer types, including oesophageal, gastric, laryngeal, lung, pancreatic, liver, bladder, and brain.

“Opium is a highly addictive narcotic that is obtained from the latex of the unripe seedpod of the poppy plant and is widely used for recreational and pain relief purposes in some societies, particularly in Asia and North Africa. There is emerging evidence that indicate possible carcinogenic effects of opium and its derivatives which are categorized as opiates” says Professor Reza Malekzadeh, the principle investigator of the GCS, and the co-senior author of the study.

This recipient of the IARC medal of honour adds “Because of the challenges inherent in studying this exposure, there is a paucity of prospective studies of opium use with long-term follow-up. GCS is the only population-based prospective study that includes a large group of long-term opium users with validated opium use data, and therefore it provides a unique opportunity to assess different health hazards, including the risk of mortality and cancers among regular opium users”

“In societies where use of opium is prevalent, several factors can affect the use of this narcotic drug including gender, socioeconomic characteristics, and underlying diseases. In this study we found consistent associations between opium use and cancer among ever and never tobacco users, men and women, and individuals with lower and higher socioeconomic status. Furthermore, all routes and types of opium derivatives used by this population showed positive associations with cancer risk” says Dr Mahdi Sheikh, a postdoctoral scientist at the IARC and the first author of the study.

Based on the United Nations Office on Drugs and Crime, an estimated 29.2 million people used opiates in 2017, mainly as illicit drugs. The opiate crisis has resulted in thousands of deaths annually and billions in economic losses in many parts of the world.

“Given the huge increase in use of opiates in the past few years, further global initiatives to reduce opiate misuse and implement preventive strategies to mitigate their hazardous long-term effects are needed” says Dr Paul Brennan, Head of IARC’s Section of Genetics, and the co-senior author of the study.

Dr Brennan adds “this report is the only prospective analysis from human studies on associations between opium use and overall and site-specific cancer incidence. Therefore, this study has important implications for public health and could aid the translation of knowledge and implementation of evidence into practice and policy decision making”

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