The effect of IMRT on acute toxicity in patients with gastric cancer treated with preoperative chemoradiation.

Abstract

153 Background: Two trials are currently investigating preoperative chemoradiation (CRT) for localized gastric adenocarcinoma. However, radiation therapy (RT) can be associated with relatively high rates of acute toxicity. Newer techniques, such as intensity modulated RT (IMRT), could reduce toxicity by reducing radiation dose to normal structures. Our goal was to compare rates of toxicity and toxicity-related events in patients treated with IMRT compared to 3D conformal RT (3DCRT). Methods: The records of 202 gastric cancer patients treated with preoperative intent RT at our institution from 1998-2018 were retrospectively reviewed. Demographic data, treatment details, acute and late toxicities (CTCAE 4.0 criteria), progression and survival data were recorded. Patients who had stage IV disease were excluded. Statistical analysis included descriptive statistics, Cox regression analysis, and Kaplan-Meier survival. Results: 54% were male and the median age was 63. 82 patients received 3DCRT and 120 patients received IMRT (median 45Gy, IQR, 45-45Gy in each group). 78% of patients in the 3DCRT group and 91% of patients in the IMRT group received neoadjuvant chemotherapy prior to RT. 99% of patients received concurrent chemotherapy. The rate of grade 3-4 acute toxicity was significantly lower in patients treated with IMRT compared to 3DCRT (53% vs. 73%, p = 0.004). The composite rate of toxicity-related events (hospitalization, feeding tube, IV rehydration, or RT break) was also significantly lower in patients treated with IMRT compared to 3DCRT (80% vs. 91%, p = 0.031). 72% of patients who received 3DCRT and 68% of patients who received IMRT underwent subsequent surgical resection. The 3-year OS rate was 58.1% for patients receiving IMRT and 60.2% for patients receiving 3DCRT (p = 0.649). The 3-year PFS rate was 47.5% for patients receiving IMRT and 52.7% for patients receiving 3DCRT (p = 0.486). Conclusions: Our study indicates a marked reduction in the rates of grade 3-4 acute toxicity and toxicity-associated events in patients treated with IMRT compared to 3DCRT. These findings suggest that IMRT should be considered as the radiation modality in patients treated with preoperative CRT for gastric cancer.