title: Radiotherapy in desmoid tumors : Treatment response, local control, and analysis of local failures.
abstract: BACKGROUND
  Desmoid tumors (aggressive fibromatosis) are rare soft tissue tumors which frequently recur after surgery. Desmoid tumors arise from musculoaponeurotic tissue in the extremities, head and neck, abdominal wall, or intra-abdominally. Our aim was to examine the outcome of radiotherapy of desmoid tumors in a single institution series.
  
  
  METHODS
  We evaluated 41 patients with desmoid tumors treated with 49 radiotherapies between 1987 and 2012. Radiologic images for response evaluation were reassessed and responses to treatment registered according to RECIST criteria 1.1. For patients with local failures radiation dose distribution was determined in each local failure volume using image co-registration. Recurrences were classified as in-target, marginal, or out-of-target. Prognostic factors for radiotherapy treatment failure were evaluated.
  
  
  RESULTS
  Radiotherapy doses varied from 20-63 Gy (median 50 Gy) with a median fraction size of 2 Gy. The objective response rate to definitive radiotherapy was 55% (12/22 patients). Median time to response was 14 months. A statistically significant dose-response relation for definitive and postoperative radiotherapy was observed both in univariate (p-value 0.002) and in multivariate analysis (p-value 0.02) adjusted for potential confounding factors. Surgery before radiotherapy or surgical margin had no significant effect on time to progression. Nine of 11 (82%) local failures were classified as marginal and two of 11 (18%) in-target. None of the recurrences occurred totally out-of-target.
  
  
  CONCLUSIONS
  Radiotherapy is a valuable option for treating desmoid tumors. Radiotherapy dose appears to be significantly associated to local control.
authors.affiliation: Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, PO Box 180, 00029 HUS, Helsinki, Finland. kirsi.santti@hus.fi.
authors.forename: Kirsi
authors.initials: K
authors.lastname: Santti
authors.affiliation: Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, PO Box 180, 00029 HUS, Helsinki, Finland.
authors.forename: Annette
authors.initials: A
authors.lastname: Beule
authors.affiliation: Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, PO Box 180, 00029 HUS, Helsinki, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Tuomikoski
authors.affiliation: Department of Pathology, HUSLAB and University of Helsinki, Helsinki, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Rönty
authors.affiliation: Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, PO Box 180, 00029 HUS, Helsinki, Finland.
authors.forename: Anna-Stina
authors.initials: AS
authors.lastname: Jääskeläinen
authors.affiliation: Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, PO Box 180, 00029 HUS, Helsinki, Finland.
authors.forename: Kauko
authors.initials: K
authors.lastname: Saarilahti
authors.affiliation: Department of Plastic Surgery, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Ihalainen
authors.affiliation: Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, PO Box 180, 00029 HUS, Helsinki, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Tarkkanen
authors.affiliation: Comprehensive Cancer Center, Helsinki University Hospital and University of Helsinki, PO Box 180, 00029 HUS, Helsinki, Finland.
authors.forename: Carl
authors.initials: C
authors.lastname: Blomqvist
mesh_terms: D000293:Adolescent; D000368:Aged; D002648:Child; D002675:Child, Preschool; D018572:Disease-Free Survival; D005260:Female; D018222:Desmoid Tumors / Q000175:diagnosis* / Q000532:radiotherapy*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D017211:Treatment Failure; D016896:Treatment Outcome; D055815:Young Adult
keywords: Aggressive fibromatosis; Dose-response relationship, radiation; Local recurrence; Radiotherapy