Secondary spindle cell sarcoma following external beam radiotherapy for prostate cancer: a rare but devastating complication.

We report a case of rapidly growing sarcoma that resulted in mortality only 6 years after radiotherapy for low-grade prostate cancer.At the age of 69 years and a prostate-specific antigen (PSA) that had risen to 9.0 µg/L, transrectal ultrasound-guided biopsy of the prostate found a single core of Gleason 3+3 disease involving 4 mm of a 10 mm core. The patient declined active surveillance and completed 78 Gy of external beam radiotherapy over 39 fractions to a prostate volume of 46 mL.His PSA nadir was 0.62 µg/L 1-year postradiation; however, in April 2017, his PSA began to rise satisfying the definition of biochemical recurrence. He underwent cystoscopy, biopsy favoured an undifferentiated pleomorphic sarcoma. Restaging scans (CT/bone scan) were completed showing no metastasis, and repeat MRI showed rapid growth of the lesion in 3 months.He underwent palliative pelvic exenteration, however, 1 month later presented with large volume tumour recurrence and was subsequently palliated and died. © BMJ Publishing Group Limited 2018. No commercial re-use. See rights and permissions. Published by BMJ.