Intensity Modulated Radiotherapy for Gastric Cancers: Toxicity and Clinical Outcome

Abstract

To report the outcomes and toxicity of intensity-modulated radiotherapy (IMRT) for adenocarcinoma of the stomach. Nineteen patients with Stage IB-IV gastric cancers were treated with postoperative IMRT from August 2002 - August 2007 at Stanford University. Median dose was 45 Gy (range, 43.2-54 Gy). Respiratory gating was utilized in 68% of patients. All patients received concurrent chemotherapy with capecitabine (n = 13), 5-FU (n = 4), or carboplatin/capecitabine (n = 2). Eighteen patients received 1-3 cycles of chemotherapy prior to start of RT, and 17 patients received 1-2 cycles post-RT. The IMRT plans were generated to minimize dose received to the liver, kidneys, and spinal cord. Median mean dose to the kidney receiving higher radiation was 14.0 Gy (range, 7.0-19.7 Gy), and median mean dose to the kidney receiving less radiation was 11.2 Gy (range, 3.7-14.7 Gy). Median V20 for the higher dose kidney and lower dose kidney was 17.6% (range, 13.8-35.8%) and 9.6% (range, 0.9-23.2%), respectively. Median mean dose for both kidneys was 12.7 Gy (range, 5.4-15.5 Gy) and median V20 for both kidneys was 14.7% (range, 8.5-27.5%). Median mean liver dose was 16.1 Gy (10.1-23.8 Gy). Median age at diagnosis was 54.2 years (range, 43-76.4 years). Median follow-up time from diagnosis is 19.4 mo (range, 7-43.6 mo). Eighteen patients had adenocarcinoma and 1 had undifferentiated carcinoma. Seven patients had signet ring features. At last follow-up, 5 patients have died, 3 patients are alive with progressive disease, and 11 patients are alive with no evidence of disease. Median overall survival (OS) and progression-free survival (PFS) have not been reached. The 2-year OS and PFS from surgery was 88% and 78%, respectively. Two patients had a local recurrence at the anastomosis site. Seven patients had distant metastases. Overall, the radiation treatment was well tolerated. No feeding tube placement was required due to treatment toxicity, although 7 patients had feeding tubes placed at the time of surgery. No patient required treatment breaks due to toxicity, but 1 patient refused treatment for several days due to personal reasons. Mean weight loss was 5.9 lbs (range, 0-15lbs). A total of 14/18 (78%) of patients experienced Grade 2 or less acute GI toxicity. 4/18 (22%) had Grade 3 acute GI toxicity. Grade 3 late toxicity was experienced by 4 patients: small bowel obstruction (n = 2), strictures requiring surgery (n = 1), lysis of adhesions requiring surgery (n = 1). Grade 2 late toxicity was experienced by 2 patients (gastritis n = 1, ulcer n = 1). No late renal toxicity has been observed (median pre-RT and recent post-RT serum creatinine level were both 0.9 mg/dL). An IMRT for gastric cancers is a well-tolerated treatment technique that provides excellent local control, with less dose to normal organs. No evidence of late renal dysfunction has been observed.