Treatment of desmoplastic small round cell tumor with image-guided intensity modulated radiation therapy as a component of multimodality treatment

Aims and background: The authors report the case of a 31-year-old black male diagnosed with a pelvic desmoplastic small round-cell tumor who was treated with a unique radiotherapy approach incorporating intensity-modulated radiotherapy and daily ultrasound localization to ensure accurate tumor targeting. Desmoplastic small round-cell tumor is a very rare tumor, most commonly presenting in the abdominopelvic regions of adolescents and young adults. It has generally been associated with a very poor prognosis. Methods: The patient initially underwent biopsy of the mass and omentectomy for mesenteric implants followed by chemotherapy. Chemotherapy resulted in tumor shrinkage and was followed by a second-look laparotomy. Additional omental nodules were resected, but the primary tumor was adherent to the rectum and seminal vesicles. A radiation oncology consult was obtained, and a course of image-guided intensity-modulated radiotherapy ensued with daily ultrasound localization. This resulted in shrinkage of local disease, but a new lesion was identified. The patient was subsequently started on further chemotherapy, which has maintained the disease in a stable state for several months. Conclusions: Image-guided intensity-modulated radiotherapy is a feasible option in the treatment of pelvic desmoplastic small round-cell tumor. Such therapy may permit escalation of conventional radiotherapy doses and could have a favorable impact on local control of disease. Confirmation of this belief will require additional data in the form of case reports like this. Pending such confirmation, we continue to be of the impression that desmoplastic small round-cell tumor has an overall unfavorable prognosis, regardless of treatment modalities employed.