(ChemotherapyAdvisor) – Adding intraoperative radiotherapy (IORT) to conventional treatment is associated with improved local tumor control and survival among patients with advanced or recurrent colorectal cancer (CRC), despite an increased risk of surgical wound complications, according to a meta-analysis published in the journal Surgical Oncology.

“Despite heterogeneity in methodology and reporting practice, IORT is principally applied for the treatment of close or positive (surgical) margins,” reported senior author Alexander H. Mirnezami, PhD, of the University of Southampton Cancer Sciences Division, Southampton University Hospital NHS Trust, in Southampton, United Kingdom, and coauthors. An analysis of comparative (IORT vs. no-IORT) studies found “a significant effect favoring improved local control (OR 0.22; 95% CI: 0.05-0.86; P=0.03), disease-free survival (HR 0.51; 95% CI: 0.31-0.85; P=0.009), and overall survival (HR 0.33; 95% CI: 0.2-0.54; P=0.001)” with no increase in total, urologic, or anastomotic complications.

The 29 studies published between 1965 and 2011, representing a total of 3,003 patients included in the analysis, 14 were prospective and 15 were retrospective studies. Overall, 1,792 patients had received IORT as a component of treatment for locally recurrent CRC and 1,211 patients underwent IORT as part of treatment for locally advanced CRC.

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Wound complications like delayed wound healing, wound infection, and dehiscence were, however, more common after IORT (OR 1.86; 95% CI: 1.03-3.38; I=0.049), they noted.

“Despite methodological weaknesses in the studies evaluated, our results suggest that IORT may improve oncological outcomes in advanced and recurrent CRC,” the authors concluded. “In patients with complex CRC, an aggressive loco-regional approach with addition of IORT to conventional multimodality treatment strategies can aid in local disease control and further broadens our array of therapeutic modalities with acceptable morbidity.”

Recurrent CRC and rectal tumors in particular represent “unique challenges” for achieving R0 resection because of “disrupted anatomical planes and the confines of the bony pelvis,” the authors noted. “Local control rates ranged between 56% and 79% after R0 resection and 18%-68% after R1/R2 resection. These figures compare favorably with previous reports in the literature where incidence of re-recurrence frequently exceeds 30% even after R0 resection.”

Future studies are needed that “more rigorously identify eligible patients by clearly defined primary indication” (primary vs. recurrent, R0 vs. R1 v.s R2, etc.), the authors advised. “In light of the small numbers of cases treated by most individual institutions, organized multicenter collaboration should be pursued.”