Clinical outcomes for gastric cancer following adjuvant chemoradiation utilizing intensity modulated versus three-dimensional conformal radiotherapy

Abstract

Purpose/objectives: To determine if intensity modulated radiation therapy (IMRT) in the post-operative setting for gastric cancer was associated with reduced toxicity compared to 3D conformal radiation therapy (3DCRT).

Materials/methods: This retrospective study includes 24 patients with stage IB-IIIB gastric cancer consecutively treated from 2001-2010. All underwent surgery followed by adjuvant chemoradiation. Concurrent chemotherapy consisted of 5-FU/leucovorin (n = 21), epirubicin/cisplatin/5FU (n = 1), or none (n = 2). IMRT was utilized in 12 patients and 3DCRT in 12 patients. For both groups, the target volume included the tumor bed, anastomosis, gastric stump, and regional lymphatics.

Results: Median follow-up for the entire cohort was 19 months (range 0.4-8.5 years), and 49 months (0.5-8.5 years) in surviving patients. The 3DCRT group received a median dose of 45 Gy, and the IMRT group received a median dose of 50.4 Gy (p = 0.0004). For the entire cohort, 3-year overall survival (OS) was 40% and 3-year disease free survival (DFS) was 41%. OS and DFS did not differ significantly between the groups. Acute toxicity was similar. Between 3DCRT and IMRT groups, during radiotherapy, median weight lost (3.2 vs. 3.3 kg, respectively; p = 0.47) and median percent weight loss were similar (5.0% vs. 4.3%, respectively; p = 0.43). Acute grade 2 toxicity was experienced by 8 patients receiving 3DCRT and 11 receiving IMRT (p = 0.32); acute grade 3 toxicity occurred in 1 patient receiving 3DCRT and none receiving IMRT (p = 1.0). No patients in either cohort experienced late grade 3 toxicity, including renal or gastrointestinal toxicity. At last follow up, the median increase in creatinine was 0.1 mg/dL in the IMRT group and 0.1 mg/dL in the 3DCRT group (p = 0.78).

Conclusion: This study demonstrates that adjuvant chemoradiation for gastric cancer with IMRT to 50.4 Gy was well-tolerated and compared similarly in toxicity with 3DCRT to 45 Gy.

Figure 1. Disease-Free Survival.

Figure 2. Overall Survival.

Figure 3. A. 79 year-old gentleman with gastric adenocarcinoma, T1N1M0, who underwent subtotal gastrectomy with D2 nodal dissection and adjuvant chemoradiotherapy with 3DCRT to a dose of 45 Gy.

Figure 3B. 64 year-old woman with gastric adenocarcinoma, T2bN2M0, who underwent gastrectomy with D2 nodal dissection. Ten of 14 nodes were positive and she had positive proximal and distal surgical margins. She then received adjuvant chemoradiotherapy with IMRT to a dose of 45 Gy, with a 5.4 Gy boost to the anastomosis.