Role of adjuvant radiotherapy after surgery in abdominal desmoplastic small round cell tumor: a retrospective analysis of 107 patients
Menée en France à partir de données portant sur 107 patients atteints, au niveau du péritoine, d'une tumeur primitive desmoplastique à petites cellules rondes et traités entre 1991et 2014, cette étude multicentrique évalue, du point de vue de la survie sans progression et de la survie globale à 3 ans, l'intérêt d'ajouter une radiothérapie adjuvante à une chirurgie cytoréductive complète ou incomplète
Purpose : Desmoplastic small round cell tumor (DSRCT) is a rare peritoneal tumor affecting predominantly children and young adult Caucasian males with a high rate of local failure after surgery. We performed a multicentric retrospective study to identify the prognostic impact of adjuvant abdominal radiotherapy. Methods and Materials : All patients treated for primary abdominal DSRCT in 8 French centers from 1991 to 2014 were included. Patients were retrospectively staged into 3 groups: group A treated with adjuvant radiotherapy (RT) after cytoreductive surgery, group B without RT after cytoreductive surgery and group C by exclusive chemotherapy. Peritoneal progression-free survival (PPFS), progression-free survival (PFS) and overall survival (OS) were evaluated. We also performed a direct comparison between group A and B to evaluate RT after cytoreductive surgery. RT was also evaluated according to completeness of surgery: complete cytoreductive surgery (CCS) or incomplete cytoreductive surgery (ICS). Results : Thirty-seven (35.9%), thirty-six (34.9%) and thirty (28.0%) patients were included in group A, B and C, respectively. Three-year OS was 61.2% (41.0-76.0), 37.6% (22.0-53.1), and 17.3% (6.3-32.8) for group A, B and C, respectively. OS, PPFS and PFS differed significantly between the 3 groups (p<0.001; p<0.001 and p<0.001, respectively). OS and PPFS were higher in group A (RT group) compared to group B (no RT group) (p=0.045 and p=0.006, respectively). Three-year PPFS was 23.8% (10.3-40.4) for group A and 12.51% (4.0-26.2) for group B. After CCS, RT improved PPFS (p=0.024) but differences in OS and PFS were not significant (p=0.40 and p=0.30, respectively). After ICS, RT improved OS (p=0.044). A trend of PPFS and PFS increase was observed but the difference was not statistically significant (p=0.073 and p=0.076). Conclusions : Adjuvant radiotherapy as part of multimodal treatment seems to confer oncological benefits for patients treated for abdominal DSRCT after cytoreductive surgery and perioperative chemotherapy.