Reduced toxicity with intensity modulated radiation therapy (IMRT) for desmoplastic small round cell tumor (DSRCT): an update on the whole abdominopelvic radiation therapy (WAP-RT) experience.
OBJECTIVE
Desmoplastic small round cell tumor (DSRCT) is a rare malignancy typically involving the peritoneum in young men. Whole abdominopelvic radiation therapy (WAP-RT) using conventional 2-dimensional (2D) radiation therapy (RT) is used to address local recurrence but has been limited by toxicity. Our objectives were to assess the benefit of intensity modulated radiation therapy (IMRT) on toxicity and to update the largest series on radiation for DSRCT.


METHODS
The records of 31 patients with DSRCT treated with WAP-RT (22 with 2D-RT and 9 with IMRT) between 1992 and 2011 were retrospectively reviewed. All received multi-agent chemotherapy and maximal surgical debulking followed by 30 Gy of WAP-RT. A further focal boost of 12 to 24 Gy was used in 12 cases. Boost RT and autologous stem cell transplantation were nearly exclusive to patients treated with 2D-RT. Toxicities were assessed with the Common Terminology Criteria for Adverse Events. Dosimetric analysis compared IMRT and simulated 2D-RT dose distributions.


RESULTS
Of 31 patients, 30 completed WAP-RT, with a median follow-up after RT of 19 months. Acute toxicity was reduced with IMRT versus 2D-RT: P=.04 for gastrointestinal toxicity of grade 2 or higher (33% vs 77%); P=.02 for grade 4 hematologic toxicity (33% vs 86%); P=.01 for rates of granulocyte colony-stimulating factor; and P=.04 for rates of platelet transfusion. Post treatment red blood cell and platelet transfusion rates were also reduced (P=.01). IMRT improved target homogeneity ([D05-D95]/D05 of 21% vs 46%) and resulted in a 21% mean bone dose reduction. Small bowel obstruction was the most common late toxicity (23% overall). Updated 3-year overall survival and progression-free survival rates were 50% and 24%, respectively. Overall survival was associated with distant metastasis at diagnosis on multivariate analysis. Most failures remained intraperitoneal (88%).


CONCLUSIONS
IMRT for consolidative WAP-RT in DSRCT improves hematologic toxicity in particular. Although the long-term efficacy of current treatment options remains disappointing, the improved therapeutic index of IMRT may aid in generalizing its use and allowing the addition of novel approaches such as intraperitoneal immunotherapy.
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Neil B
NB
Desai
Nicholas F
NF
Stein
Michael P
MP
LaQuaglia
Kaled M
KM
Alektiar
Brian H
BH
Kushner
Shakeel
S
Modak
Heather M
HM
Magnan
Karyn
K
Goodman
Suzanne L
SL
Wolden
D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D016026:Bone Marrow Transplantation; D002648:Child; D003131:Combined Modality Therapy / Q000379:methods; D058405:Desmoplastic Small Round Cell Tumor / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000556:secondary / Q000601:surgery; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000008:administration & dosage; D006801:Humans; D007415:Intestinal Obstruction / Q000209:etiology; D007421:Intestine, Small / Q000528:radiation effects; D008297:Male; D010534:Peritoneal Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D017713:Platelet Transfusion / Q000706:statistics & numerical data; D011832:Radiation Injuries / Q000150:complications / Q000517:prevention & control; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D035583:Rare Diseases / Q000473:pathology / Q000532:radiotherapy*; D012186:Retroperitoneal Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D012189:Retrospective Studies; D055815:Young Adult
D016179:Granulocyte Colony-Stimulating Factor