ORIGINAL ARTICLE Retrospective study on melanosis coli as risk factor of colorectal neoplasm: a 3-year colonoscopic finding in Zhuhai Hospital, China Said Abasse Kassim 1 & Muhammad Abbas 2,3 & Weiyan Tang 3 & Shenzhen Wu 1 & Qingdao Meng 1 & Chengcheng Zhang 1 & Shagufta Naeem 4 & Xiaobo Li 1 & Rui Chen 1,5 Accepted: 17 October 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Background Melanosis coli (MC) is a colonoscopic finding in which the colonic mucosa appears darkly pigmented than usual and generally caused by extended anthranoid laxative use. Methods We performed a retrospective study at Zhuhai Hospital to investigate the risk of MC for CR neoplasm development. A total of 12,776 patients who underwent colonoscopy from 2013 to 2016 including 250 diagnosed with MC and 500 controls were included in this study. Odds ratios (OR) and 95% confidence intervals (95%CI) for associations of MC with CR neoplasm detection were estimated using univariate and multivariable multinomial logistic analyses for known risk factors. Results The presence of MC was associated with a significant increase in the CR neoplasm detection rate compared with controls (OR = 1.701, 95% CI = 1.252–2.31; P = 0.001). The effect was also observed in different tumor sites, age group, gender, and lifestyle. Using univariate multinomial analysis, patients with MC were significantly associated with both hyperplastic polyp (OR = 2.069, 95% CI = 1.253–3.415; P = 0.005) and low-grade (LG) adenoma (OR = 1.585, 95% CI = 1.115–2.254; P = 0.010). However, there was no significant difference with adenocarcinoma (OR = 1.701, 95% CI = 0.990–2.924; P = 0.055). Using multivariate multinomial analysis, MC patients remained associated with increased hyperplastic polyp (OR = 1.870, 95% CI = 1.119–3.125; P = 0.017) and LG adenoma (OR = 1.474, 95% CI = 1.027–2.114; P = 0.035), but not adenocarcinoma (OR = 1.620, 95% CI = 0.914–2.871; P = 0.098). A significant increase in CR neoplasm rate was observed with drinker, smoker, and elderly patients but not with gender. Conclusion Patients with MC were more likely to have both hyperplastic polyp and LG adenoma. If confirmed, such findings could suggest the discontinuation of anthranoid laxative use particularly in the elderly. Keywords Melanosis coli . Colorectal neoplasm . Colorectal adenoma . Colorectal carcinoma . Colonoscopy Introduction Colorectal cancer (CRC) is among the top causes of mortality and morbidity in both Western and Asian countries [1–4]. It is the third most common malignancy and the fourth leading cause of cancer-related deaths worldwide, accounting for ap- proximately 694,000 (8.5%) of total cancer deaths in 2012 [5]. In China, the incidence and mortality rates of CRC have in- creased markedly over the past decades [ 1, 3, 4] and accounted for approximately 376,300 new diagnosed cases and 191,000 deaths in 2015 [1]. This increase might be asso- ciated with changes in environmental factors including inter alia dietary patterns, sedentary habits, and increased aging population [6, 7]. For instance, Islami et al. [7] found that the approximately 718,000 and 283,100 cancer deaths in men and women respectively that occurred in China in 2012 Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00384-019-03435-7) contains supplementary material, which is available to authorized users. * Rui Chen 101011816@seu.edu.cn 1 Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, China 2 State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210023, China 3 Department of Medical Oncology, Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research & Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China 4 Department of Pathology, Ayub Medical College, Abbottabad, Pakistan 5 State Key Laboratory of Bioelectronics, Southeast University, Nanjing, China International Journal of Colorectal Disease https://doi.org/10.1007/s00384-019-03435-7