Intensity modulated radiation therapy (IMRT) is not superior to three-dimensional conformal radiation (3DCRT) for adjuvant gastric radiation: A matched pair analysis

Aims: To compare three-dimensional conformal radiation (3DCRT) and Intensity Modulated Radiation Therapy (IG-IMRT) for adjuvant gastric irradiation. Subjects and Methods: From Jan 2010-Aug 2013, all patients undergoing 3DCRT and IG-IMRT were included. Systemic chemotherapy included 1 cycle before and 2 cycles after chemoradiation. Planning Target Volume (PTV) received 45 Gy/25 fractions/5 weeks with concurrent capcetabine 825 mg/m2 bid. Matched pair analysis was performed to evaluate imbalance in two cohorts if any. Common Toxicity Criteria for Adverse Event (CTCAE) vs 3.0 was used to record gastrointestinal (GI), hematological (HL), and renal toxicity during treatment and follow-up. Patterns of recurrence were documented. Mann-Whitney U test was used for statistical comparison. Results: Of the 51 patients, 26 received 3DCRT and 25 IMRT. IMRT led to decrease in dose received by right and left kidney (12.4 Gy and 7.1 Gy and 29 Gy vs 8.2 Gy; P < 0.001). Overall, 17.6% and 19.6% patients had grade II GI and HL toxicity and 3.9% and 5.9% had grade III GI and HL toxicity. No difference was observed in acute grade II-V GI or HL toxicity (11.5% vs 24%, P = 0.07; 7.6% vs 20% P = 0.20) or late GI, HL, or renal toxicity between 3DCRT and IMRT. No difference was observed in patterns of local relapse (11.5% vs 12%, P = 0.14) or overall survival (39% and 38% (P = 0.97)) between 3DCRT and IMRT. Conclusions: 3DCRT and IMRT are equivalent in terms of toxicity and local control