IMRT Reduces Acute Toxicity in Patients Treated With Preoperative Chemoradiation for Gastric Cancer

Preoperative chemoradiation is being currently evaluated in 2 randomized international trials. However, chemoradiation for gastric cancer can be associated with relatively high rates of acute toxicity. We compared rates of toxicity, toxicity-related events, and oncologic outcomes in patients treated with intensity modulated radiation therapy (IMRT) and those treated with 3-dimensional conformal radiation therapy (3DCRT).

We retrospectively reviewed records of 202 patients with consecutive gastric cancer treated with preoperative intent radiation therapy at our institution from 1998 to 2018. Patients with gastroesophageal junction involvement and those with metastatic disease were excluded. Eighty-two patients received 3DCRT, and 120 patients received IMRT. The median radiation dose was 45 Gy, and 99% received concurrent chemotherapy.

There were no significant differences between the 3DCRT and IMRT groups regarding sex, race, histology, tumor location, histology, or nodal stage. The rate of grade 3 to 4 acute toxicity was significantly lower in patients treated with IMRT compared with 3DCRT (49% vs 70%, P = .004). The composite rate of toxicity-related events (hospitalization, feeding tube use, intravenous rehydration, or radiation therapy breaks) was also significantly lower in patients treated with IMRT compared with 3DCRT (56% vs 85%, P <.001). In addition, 68% of patients who received IMRT and 73% of patients who received 3DCRT underwent subsequent surgical resection (P = .245). Among patients who underwent surgery, the 3-year overall survival rates were not significantly different between those treated with IMRT and 3DCRT (71% vs 69%, P = .786). Patients receiving IMRT had a significantly higher absolute nadir lymphocyte count compared with patients receiving 3DCRT (median, 0.21 vs 0.16 K/UL; P = .047).

Our study suggests that IMRT might significantly reduce rates of grade 3 to 4 acute toxicity and toxicity-related events compared with 3DCRT, with no significant difference in oncologic outcomes. IMRT is an appropriate and possibly preferable radiation modality in patients treated with preoperative chemoradiation for gastric cancer.