[Quality indicators of diagnosis and therapy in MRI-based neoadjuvant radiochemotherapy for rectal cancer - interim analysis of a Prospective Multicentre Observational Study (OCUM)].

Background: The interim analysis of a prospective multicentre observational study of selective neoadjuvant chemoradiotherapy (OCUM) in patients with rectal cancer should evaluate the quality of diagnosis and therapy as a prerequisite for continuation of the study.

Patients And Methods: 230 patients with the clinical stage cT2 - 4, each cN, M0 with radical tumour resection were enrolled until now. The values of 13 quality indicators were compared with the target values formulated by the workflow of the Working Group rectal cancer II and the German Cancer Society and were also compared with the results of the certified bowel centres of Germany 2010.

Results: The target values were fulfilled to a high degree regardless of caseload. 83 % of parameters have been fully achieved and 14 % nearly achieved. In primary surgery the proportion of patients with 12 or more histologically examined lymph nodes was 99.2 %, after neoadjuvant chemoradiotherapy 90 %. A R0 resection was performed in 98.3 % and a resection of TME in muscularis propria plane only in 2.2 %. The rate of positive circumferential resection margins (pCRM + ) was 5.7 % only.

Conclusions: The high quality of rectal surgery justifies the concept and the continuation of the study.