Gastrointestinal Cancer

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SU_17_2167 - Predictors of Acute and Late Toxicity in Patients Receiving Chemoradiation for Unresectable Pancreatic Cancer

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Predictors of Acute and Late Toxicity in Patients Receiving Chemoradiation for Unresectable Pancreatic Cancer
R. Das1, V. Sahai2, F. Bednar3, and K. C. Cuneo4; 1University of Michigan - Medical School, Ann Arbor, MI, 2Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 3Department of Surgery, University of Michigan, Ann Arbor, MI, 4Department of Radiation Oncology, University of Michigan, Ann Arbor, MI

Purpose/Objective(s): Patients with pancreatic cancer undergoing chemoradiation therapy may suffer from a variety of acute and chronic side effects. We conducted an exploratory analysis of locally advanced pancreatic cancer patients (LAPC) undergoing definitive chemoradiation to identify factors influencing the occurrence of acute and late toxicity.

Materials/Methods: Under an Institutional Review Board approved protocol, we retrospectively studied patients with LAPC treated with chemoradiation. Multivariate logistic regression and multiple linear regression models were used to test associations between patient and treatment related factors with gastrointestinal (GI) bleeding events. Secondary endpoints included weight loss, nausea, and abdominal pain during and after treatment.

Results: Between 1999-2012, 214 patients were treated with radiation for locally advanced pancreatic cancer. 212 patients received concurrent chemotherapy with gemcitabine (n=174) or 5-FU (n=40). 67 patients received intensity modulated radiation therapy (IMRT), and 50 received 3D conformal radiation. Overall, 18 patients experienced an upper GI bleed related to treatment with 70% of bleeds occurring in the stomach or duodenum. Out of the 18 patients who experienced a treatment related GI bleed, 11 patients had a pancreatic head tumor and 17 patients had a metallic biliary stent. For our primary outcome, the presence of a biliary stent was associated with an increased risk of an upper GI bleed with an odds ratio of 2.93 (p=0.005). In addition, patients requiring a biliary stent were at a higher risk of death from pancreatic cancer (hazard ratio 1.50, CI95 1.01-2.23, p=0.042). Prescribed biologically effective dose (BED) (p=0.73) was not a significant predictor of a GI bleed; however, the use of 3D conformal treatment technique was associated with greater risk of a GI bleed (OR = 2.36, p=0.151) compared to IMRT. In terms of short term toxicity, 21 patients required a radiation break during treatment and 101 patients experienced weight loss of more than 10% during treatment. The use of IMRT was associated with a trend for less weight loss relative to 3D conformal treatment (OR=3.66, p=0.165). Furthermore, IMRT was associated with reduced nausea (β=-0.52, p=0.032) at the end of treatment, as well as reduced abdominal pain 3 months after radiation (β=-0.34, p = 0.097).

Conclusion: Our analysis shows a potential association between the presence of a metallic biliary stent with an increased risk of an upper GI bleed post-radiation and overall mortality controlling for potential confounding factors. Furthermore, the use of IMRT was associated with a decreased risk of developing a GI bleed in addition to less weight loss during treatment and less nausea and abdominal pain after radiation.

Author Disclosure: R. Das: None. V. Sahai: Research Grant; Bristol-Myers Squibb, Celgene. Advisory Board; Celgene, Halozyme. F. Bednar: None. K.C. Cuneo: Service Chief; Ann Arbor Veterans Hospital.

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