ABSTRACT: Background and methods: Colorectal cancer (CRC) care has considerably improved considerably, particularly since the implementation of a quality of care program centered around national evidence-based guidelines. Formal quality assessmentevaluation of the quality of care is however still needed. The aim of this research was to identify factors associated with practice variation in CRC patient care. CRC patients identified from all cancer centers in South-West France were included. We investigated variations in practices (from diagnosis to surgery), and compliance with recommended guidelines for colon and rectal cancer. We identified factors associated with three colon cancer practice variations potentially linked to better survival: examination of [greater than or equal to]12 lymph nodes (LN), non-use and use of adjuvant chemotherapy for stage II and stage III patients, respectively. RESULTS: We included 1,206 patients, 825 (68%) with colon and 381 (32%) with rectal cancer, from 53 hospitals. For major practices cCompliance was high for (resection, pathology report, LN examination, and chemotherapy use for stage III patients. In). For colon cancer, patients, 26% of stage II patients received adjuvant chemotherapy and 71% of stage III patients. 84% of stage US T3T4 rectal cancer patients received pre-operative radiotherapy. In For colon cancer patients, factors associated with examination of <=12 LNs were: lower ECOG score, advanced stage and larger hospital volume; factors negatively associated were: left sided tumor location and one hospital district. Use of chemotherapy in stage II patients was associated with younger age, advanced stage, emergency setting and care structure (private and location); whereas under-use in stage III patients was associated with advanced age, presence of comorbidities and private hospitals. Limitations and conclusions: Although some changes in practices may have occurred since this observational study, these findings represent the most recent report on practices in CRC in this region, and offer a useful methodological approach for assessing quality of care. Guideline compliance was high, although several practice variations were highlighted in particular based on some organizational factors such as hospital size or location influence practice variation. These factors should be the focus of any future guideline implementation.