Stereotactic body radiation therapy induced myonecrosis in a patient with prior gemcitabine administered for leiomyosarcoma.

We present the case of radiation myonecrosis of the iliopsoas muscle, identified five months after stereotactic body radiation therapy (SBRT, 21 Gy in three fractions) to a metastatic lesion in the right iliac bone of a patient with leiomyosarcoma. The patient had been treated with various chemotherapeutic agents, most notably docetaxel and gemcitabine for five cycles 10 months prior to SBRT. As skeletal muscle is a radio-resistant organ, myonecrosis is rare, but previous case reports suggest that the administration of gemcitabine may increase the likelihood of radiation toxicity, including radiation myonecrosis. Physicians may consider conventional fractionation, rather than a hypofractionated course, in patients who have received or will receive gemcitabine.