OBJECTIVETo compare the short-term efficacy and treatment-related adverse reaction between preoperative three dimensional conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT) concurrently combined with chemotherapy in the treatment of locally advanced rectal carcinoma (LARC).

METHODSClinical data of 334 patients with LARC undergoing preoperative 3D-CRT(172 cases) or VMAT(162 cases) with concurrent Xelox chemotherapy (main protocol: capecitabine plus oxaliplatin) and surgery in Sun Yat-sen University Cancer Center from May 2007 to April 2013 were retrospectively analyzed. The total radiation dose of VMAT group was: 50 Gy/2.0 Gy per fraction ×23 fractions for planning target volume 1(PTV1) and 46 Gy/1.84 Gy per fraction ×25 fractions for PTV2; the total radiation dose of 3D-CRT group was: 46 Gy/2.0 Gy per fraction ×23 fractions for PTV. The treatment-related adverse reaction of both groups during chemoradiotherapy was measured according to the criteria of Common Terminology Criteria for Adverse Events v3.0 (CTCAE 3.0). Rate of adverse reaction and short-term efficacy between 3D-CRT and VMAT group were compared, in terms of radiotherapy break, hematological and non-hematological toxicity, average duration of surgery and perioperative hospitalization, intraoperative blood loss, surgical procedures, R0 excision, sphincter preservation, postoperative complications, pathological complete response (pCR), and postoperative pathological staging.

RESULTSThere were no significant differences in baseline clinical parameters between 3D-CRT and VMAT group (all P>0.05), except for the distance from lower tumor margin to anal verge (P=0.009). The median radiation dose for all the patients was 46 (45 to 70) Gy. There was no significant difference in the rate of radiotherapy cessation between 3D-CRT and VMAT group [1.7%(3/172) vs. 1.2%(2/162), P=1.000]. During concurrent chemotherapy, incidences of grade 2 to 3 hematological toxicities, grade 2 diarrhea, and grade 3 non-hematological toxicities were not significantly different(all P>0.05), while in grade 2 non-hematological toxicities, ratio of radiodermatitis and hand-foot syndrome was higher in VMAT group as compared to 3D-CRT group [25.9%(42/162) vs. 10.5%(18/172), P=0.000; 3.7%(6/162) vs. 0, P=0.012]. There was no grade 4 adverse event in both groups. Surgical procedure, average duration of surgery, R0 excision, anus preservation, postoperative complications, pCR, and postoperative pathological staging were not significantly different(all P>0.05). As compared to 3D-CRT group, VMAT group had less intraoperative blood loss [(114.6±100) ml vs. (169±143.9) ml, P<0.001] and shorter perioperative hospitalization [16(8 to 84) d vs. 20(10 to 47) d, P<0.001]. There was no death case in two groups within 30 days after operation.

CONCLUSIONSCompared with 3D-CRT technique, preoperative VMAT technique can not significantly reduce the incidence of treatment-related adverse reaction and improve the short-term efficacy in the treatment of LARC.