Increased Bowel Toxicity in Patients Treated With a Vascular Endothelial Growth Factor Inhibitor (VEGFI) After Stereotactic Body Radiation Therapy (SBRT).

International Journal of Radiation Oncology, Biology, Physics

PubMedID: 23920388

Barney BM, Markovic SN, Laack NN, Miller RC, Sarkaria JN, Macdonald OK, Bauer HJ, Olivier KR. Increased Bowel Toxicity in Patients Treated With a Vascular Endothelial Growth Factor Inhibitor (VEGFI) After Stereotactic Body Radiation Therapy (SBRT). Int J Radiat Oncol Biol Phys. 2013;87(1):73-80.
PURPOSE
Gastrointestinal injury occurs rarely with agents that affect the vascular endothelial growth factor receptor and with abdominal stereotactic body radiation therapy (SBRT). We explored the incidence of serious bowel injury (SBI) in patients treated with SBRT with or without vascular endothelial growth factor inhibitor (VEGFI) therapy.

METHODS AND MATERIALS
Seventy-six patients with 84 primary or metastatic intra-abdominal lesions underwent SBRT (median dose, 50 Gy in 5 fractions). Of the patients, 20 (26%) received VEGFI within 2 years after SBRT (bevacizumab, n=14; sorafenib, n=4; pazopanib, n=1; sunitinib, n=1). The incidence of SBI (Common Terminology Criteria for Adverse Events, version 4.0, grade 3-5 ulceration or perforation) after SBRT was obtained, and the relationship between SBI and VEGFI was examined.

RESULTS
In the combined population, 7 patients (9%) had SBI at a median of 4.6 months (range, 3-17 months) from SBRT. All 7 had received VEGFI before SBI and within 13 months of completing SBRT, and 5 received VEGFI within 3 months of SBRT. The 6-month estimateĀ of SBI in the 26 patients receiving VEGFI within 3 months of SBRT was 38%. No SBIs were noted in the 63 patients not receiving VEGFI. The log-rank test showed a significant correlation between SBI and VEGFI within 3 months of SBRT (P=.0006) but not between SBI and radiation therapy bowel dose (P=.20).

CONCLUSIONS
The combination of SBRT and VEGFI results in a higher risk of SBI than would be expected with either treatment independently. Local therapies other than SBRT may be considered if a patient is likely to receive a VEGFI in the near future.