Regorafenib-induced transverse myelopathy after stereotactic body radiation therapy

The patient is a 51-year-old woman whose screening colonoscopy in March 2010 demonstrated cecal cancer at the appendiceal orifice. Right hemi-colectomy removed a 3.5 cm moderately differentiated mucinous adenocarcinoma, positive for Kras G12V mutation, invading the appendix with 6 of 30 positive lymph nodes (pT4aN2aM0, Stage IIIC adenocarcinoma of the colon). Postoperatively, she received 12 cycles of mFOLFOX6 and remained without evidence of disease at the completion of treatment. In July 2011, the patient was found to have three discrete liver nodules on routine imaging that were highly suspicious for metastatic disease on a follow-up positron emission tomography-computed tomography (PET-CT). A 1.1 cm (anterior) lesion was located in segment 2; a 2.1 cm (lateral) lesion was in segment 6, and an 8 mm [inferior vena cava (IVC)] lesion in segment 7. The proximity of the segment 7 lesions to the IVC precluded surgery, and she was referred for stereotactic body radiation therapy (SBRT). The patient was immobilized using a full body vacuum cushion with abdominal compression and a 4-dimensional computed tomography (4D-CT) was acquired. After the gross tumor volume was delineated on 4D-CT, an internal treatment volume was developed based on tumor motion; an additional margin was placed to form the planning treatment volume. She was treated to 20 Gy in a single fraction to each of the three lesions over 11 days. For each individual plan, the mean and maximum spinal cord doses were 429.8 cGy and 849.7 cGy for the IVC lesion, 203.7 cGy and 367 cGy for the anterior lesion, 13.3 and 19.6 cGy for the lateral lesion. For the summation of all three plans, the mean and maximum spinal cord doses were 646.8 and 1,205 cGy (Figure 1). The patient developed nausea and abdominal discomfort that resolved with ibuprofen after the first treatment, but otherwise tolerated the treatment well