[Short-term efficacy comparison between preoperative three dimensional conformal radiotherapy and volumetric modulated arc therapy concurrently combined with chemotherapy in the treatment of locally advanced rectal carcinoma].

OBJECTIVE: To 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).

METHODS: Clinical 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.

RESULTS: There 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.

CONCLUSIONS: Compared 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.