Evaluation of acute intestinal toxicity in relation to the volume of irradiated small bowel in patients treated with concurrent weekly gemcitabine and radiotherapy for locally advanced pancreatic cancer.

BACKGROUND Treatment of concurrent gemcitabine and radiotherapy for pancreatic cancer was reported to have a higher rate of severe acute intestinal toxicity. This study evaluated the acute intestinal toxicity in relation to the volume of irradiated small bowel and other factors using dosimetric analyses in pancreatic cancer patients treated with gemcitabine-based chemoradiotherapy. MATERIALS AND METHODS The patient population was derived from a phase II trial of concurrent weekly gemcitabine and radiotherapy for locally advanced pancreatic cancer. Gemcitabine was administered weekly at a dose of 250 mg/m2. The total dose was 50.4 Gy in 28 fractions using a four-field conformal technique. A dose-volume histogram was generated for the small bowel, colon and planning target volume (PTV) and dosimetric parameters were recorded. Correlations between the acute intestinal toxicity and the volume of irradiated small bowel and other factors were evaluated. RESULTS Forty-two patients enrolled between July 2001 and July 2002 were analyzed. Grade 3+ acute intestinal toxicities were observed in twenty-four (62%) patients. There was no correlation between the acute intestinal toxicity and the volume of irradiated small bowel. However, the total volume of PTV was shown to be significantly correlated with the development of Grade 3+ acute intestinal toxicity (p = 0.021). CONCLUSION The volume of irradiated small bowel did not directly influence the acute intestinal toxicity, but only the volume of PTV significantly correlated with severe acute intestinal toxicity.