Intensity-modulated radiotherapy versus three-dimensional conformal radiotherapy in rectal cancer treated with neoadjuvant concurrent chemoradiation: a meta-analysis and pooled-analysis of acute toxicity

BACKGROUND: To compare the acute gastrointestinal (GI) and genitourinary (GU) toxicity profiles between intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT) in rectal cancer patients treated with neoadjuvant chemoradiation (NCRT) using meta-analysis and pooled-analysis from published articles. METHODS: Literature search was performed in PubMed and EMBASE from inception to March 2017. The odd ratios (ORs) were calculated and random effects model was used for meta-analysis. Chi-square or Fisher's exact test was performed for the pooled-analysis. RESULTS: Six studies including a total of 859 patients met the inclusion criteria. Most patients (98.7%) received NCRT. In the meta-analysis, IMRT reduced grade ≥ 2 acute overall GI toxicity, diarrhea and proctitis with ORs of 0.38, 0.32 and 0.60, respectively (all P < 0.05), compared to 3DCRT. IMRT also reduced acute grade ≥ 3 proctitis compared to 3D-CRT (OR, 0.24; P = 0.03). No significant heterogeneity or publication bias was detected. In the pooled-analysis, IMRT reduced the incidence of grade ≥ 2 acute overall GI toxicity, diarrhea, proctitis and GU toxicity (all P < 0.05). Moreover, lower incidence of grade ≥ 3 acute overall GI toxicity, diarrhea and proctitis were observed in the patients treated with IMRT (all P < 0.05). CONCLUSIONS: IMRT significantly reduced acute toxicity in locally advanced rectal cancer patients treated with NCRT compared to 3DCRT.