Predictive factors of positive circumferential resection margin after radiochemotherapy for rectal cancer: the French randomised trial ACCORD12/0405 PRODIGE 2.

Circumferential resection margin (CRM) appears as a new powerful prognostic factor of survival after surgery for rectal cancer. We aimed to evaluate predictive factors of positive CRM following preoperative radiochemotherapy in a French trial. Patients with rectal cancer were randomised in long course preoperative radiotherapy 45 Gy plus capecitabine versus 50 Gy plus capecitabine and oxaliplatin. Mesorectal excision was performed 6 weeks after treatment. Impact of clinical, pathological and surgical variables on positive CRM (≤1 mm) were analysed by multivariate analysis. Of 565 randomised patients, CRM was recorded in 390 cases and was positive in 8% (30/390). Patients with 50 Gy plus capecitabine and oxaliplatin had a 6% rate of positive CRM while those treated by 45 Gy plus capecitabine had a 10% rate (p=0.128). Three independent predictive factors of positive CRM were identified: abdominoperineal resection (APR) (odds ratio OR=3.24; p=0.004), vascular tumour invasion (OR=2.78; p=0.026) and poor histological response (modified Dworak 0-2) (OR=9.01; p=0.003). Significant predictive factors of positive CRM are related to type of surgery, especially APR, and poor histological prognostic factors. Intensification of neoadjuvant radiochemotherapy does not seem to have a major role in this study.

Diagnostic accuracy of community pathologists in the interpretation of colorectal polyps.

BACKGROUND AND AIMS: Management of patients with endoscopically removed colorectal polyps is generally dependent on pathological evaluation. The aim of this study was to assess the accuracy and clinical impact of pathologic interpretation of colorectal polyps by community pathologists. METHODS: Two expert gastrointestinal pathologists reviewed the slides of 300 colorectal polyps initially examined by 14 general pathologists. Polyps had been detected by a fecal occult blood test colorectal cancer screening program in Haut-Rhin, a French administrative district. RESULTS: Villous histology was overread in 24.8% of cases and high-grade dysplasia in 22.0%. The diagnosis of serrated adenoma was confirmed in 15.7% of cases. The diagnosis of T1 carcinoma was overestimated in seven cases (17.9%) and missed in four. In the screening program, the proportion of correct diagnoses of community pathologists was estimated at 45.3% of polyps, of misclassification without clinical impact at 27.5%, and of misclassification with a theoretical impact on management at 27.2%, leading to over-surveillance in 20.3% of polyps and to unnecessary surgical resection in three individuals. Overall, 37.5% of the pathology reports of malignant polyps were complete, presenting all criteria necessary for therapeutic decision-making. CONCLUSION: Community pathologists exhibited moderate accuracy for interpreting colorectal polyps, with an impact on patient management for around one out of five individuals. Our results confirm the intrinsic poor reliability of the pathologic interpretation of villous histology and high-grade dysplasia and suggest that these advanced pathologic features should be abandoned for clinical use. They illustrate the need for a clarification of the nomenclature of serrated polyps.