Patterns of local recurrence in locally advanced rectal cancer after intra-operative radiotherapy containing multimodality treatment.

BACKGROUND AND PURPOSE The purpose of this study is to analyze the patterns of local recurrence (LR) after intra-operative radiotherapy (IORT) containing multimodality treatment of locally advanced rectal carcinoma (LARC). METHODS AND MATERIALS Two hundred and ninety patients with LARC who underwent multimodality treatment between 1994 and 2006 were studied. For patients who developed LR, the subsite was classified into presacral, postero-lateral, lateral, anterior, anastomotic or perineal. Patient and treatment characteristics were related to subsite of LR. RESULTS After 5years, 34 patients (13.2%) developed LR. The most prominent subsite of LR was the presacral subsite. 47% of the local recurrences occurred outside the IORT field. Most recurrences developed when IORT was given dorsally, while least occurred when IORT was given ventrally. Especially after dorsal IORT a high amount of infield recurrences were observed (6 of 8; 75%). In multi-variate analysis tumor distance of more than 5cm from the anal verge and a positive circumferential margin were associated with presacral local recurrence. CONCLUSIONS Multimodality treatment is effective in the prevention of local recurrence in LARC. IORT application to the area most at risk is feasible and seems effective in the prevention of local recurrence. Dorsal tumor location results in unfavourable oncologic results.