73 Colorectal cancer epidemiology Ann. Cancer Res. Ther. Vol. 29, No. 1, pp. 73-78, 2021 INTRODUCTION Colorectal Cancer (CRC) is the third cause of cancer deaths in the world and the third most commonly diag- nosed form of cancer globally. It is rising steadily, par- ticularly in developing nations 1) . CRC incidence shows up to eight-fold variations between countries, while incidence rates increase proportionally to the human development index, highlighting a possible causal rela- tionship 1, 2) . According to GLOBOCAN 2018 statistics, cancer of the colon and rectum are the fourth and eighth most incidents, respectively. In both sexes, the rates of age-standardized (world) mortality per 100,000 of CRC is 8.9 2) . In Morocco, according to the cancer registry of Greater Casablanca, colorectal cancer is ranking third after breast and lung cancers 3) . Even in the face of increased incidence, CRC mortal- ity has decreased with the improvements in treatments and early diagnosis. Treatment for colorectal cancer is based on surgery, radiotherapy, and chemotherapy, depending on the discovery stage of cancer. Thus, it is best treated with surgery when it is discovered at an early stage. However, additional radiation therapy might be required for rectal cancer to minimize the risk of recurrence. A combination of surgery, radiation, and chemotherapy, or surgery and chemotherapy, is used for advanced stages (stage III and stage IV) of colon cancer and rectal cancer respectively. The choice to use one regimen over the other relies on several conditions, including the clinicians’ decisions, the availability of chemotherapeutic agents, the tumor resistance, the toxic- ity occurrence, and the patients’ physical condition 4, 5) . Before each chemotherapeutic cycle or chemoradiation, Clinicopathological features of colorectal cancers in Morocco based on the registry of the National Institute of Oncology in Rabat Zineb Aoullay 1, 5) , Meriem Slaoui 2) , Rachid Razine 3, 4) , Bouchra Meddah 1) , Yahia Cherrah 1) 1) Laboratory of Pharmacology and Toxicology, Faculty of Medicine and Pharmacy of Rabat, Mohammed V University Rabat, Rabat, Morocco 2) Faculty of Medicine and Pharmacy of Rabat, Mohammed V University Rabat, Rabat, Morocco 3) Laboratory of Biostatistics, Epidemiology and Clinical Research, Mohammed V University-Souissi Faculty of Medicine and Pharmacy of Rabat, Rabat, Morocco 4) Department of Public Health, Mohammed V University-Souissi Faculty of Medicine and Pharmacy of Rabat, Rabat, Morocco 5) National Institute of Oncology, Rabat, Morocco Abstract Background and objectives: Colorectal cancer (CRC) is rising steadily, particularly in developing nations. In Morocco, colorectal cancer is ranking third most incident. Via this study, we present the epidemiological profile, clinical features of colorectal cancers, and chemotherapy outcome in a Moroccan population. Materials and methods: This study is a retrospective investigation, run between January and December 2013 of 290 patients with colorectal cancer. A descriptive and analytical study was carried out via statistical analysis to correlate clini- copathological data with overall chemotherapy-related toxicity occurrence, by the Chi2 test. The non-parametric Mann- Whitney test was used for comparison between the occurrence of diarrhea and bilirubin levels. Results: Most of the cases were between 40–59 years, and 50.5% (n = 147) were men. KRAS (12, 13 codon) was mutant in 10 patients (3.4%). Chemotherapy was administered to 146 patients (50.4%), and 85.6% had suffered from at least one toxic event during CMT treatment. The mean total bilirubin and mean conjugated bilirubin were found to be significantly high in patients who do not de- velop diarrhea, compared to those with diarrheal toxicity with a p-value of 0.02 and 0.03 respectively. Conclusion: Our study reveals a significant percentage of toxicity occurrence among patients who underwent chemothera- py. Keywords: Colorectal cancer, epidemiology, Moroccan population (Received April 8, 2021; Accepted April 20, 2021) Corresponding author : Dr. Zineb Aoullay, Laboratory of Pharmacology and Toxicology, Faculty of Medicine and Pharmacy of Rabat, Mohammed V University Rabat, Avenue Mohammed Belarbi El Alaoui – Souissi – BP, 6203 Rabat, Morocco. Tel: +212671193357, E-mail: zinebaoullay@gmail.com