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@ARTICLE{Bostel:157634,
      author       = {T. Bostel$^*$ and M. Mattke and N. H. Nicolay$^*$ and T.
                      Welzel and D. Wollschläger and S. Akbaba and A. Mayer and
                      T. Sprave and J. Debus$^*$ and M. Uhl},
      title        = {{H}igh-dose carbon-ion based radiotherapy of primary and
                      recurrent sacrococcygeal chordomas: long-term clinical
                      results of a single particle therapy center.},
      journal      = {Radiation oncology},
      volume       = {15},
      number       = {1},
      issn         = {1748-717X},
      address      = {London},
      publisher    = {BioMed Central},
      reportid     = {DKFZ-2020-01729},
      pages        = {206},
      year         = {2020},
      note         = {#EA:E050#},
      abstract     = {This study aimed to analyze the oncological long-term
                      results and late toxicity of carbon ion-based radiotherapy
                      (RT) of patients with sacral chordoma and to identify
                      potential prognostic factors for local control (LC) and
                      overall survival (OS).A total of 68 patients with sacral
                      chordoma treated at the Heidelberg Ion Beam Therapy Center
                      were included in this study. Of these 52 patients $(77\%)$
                      received a primary RT and 16 patients $(23\%)$ received a RT
                      in a recurrent situation. All patients were treated with
                      carbon ion RT (CIRT), either in combination with photons
                      (n = 22; $32\%)$ or as a monotherapy (n = 46; $68\%),$
                      with a median radiation dose of 66 Gy RBE (range
                      60-74 Gy). In 40 patients $(59\%),$ RT was performed in
                      the postoperative situation. Postoperative care included
                      regular MRI scans. Local progression was defined as an
                      enlargement of the maximum tumor diameter by $10\%$ or a new
                      tumor growth within the planning target volume (PTV). LC and
                      OS were determined using the Kaplan-Meier method.
                      Furthermore, the relevance of various prognostic factors for
                      LC and OS was assessed by univariate and multivariate
                      analysis.The median follow-up period was 60 months (range
                      1.3-97.4 months). The 5-year rates for LC,
                      progression-free survival, metastasis-free survival and OS
                      were 53, 53, 52 and $74\%,$ respectively. Local recurrence
                      was observed in 31 patients $(46\%),$ occurring after a
                      median follow-up time of 25 months (range
                      2.5-73.1 months). Only $10\%$ of local recurrences
                      occurred later than 5 years after RT. Statistical analysis
                      showed that RT in the relapse situation corresponded to
                      inferior LC rates compared to the primary situation, while
                      other factors such as the GTV, radiation dose (EQD2) and
                      treatment approach (CIRT alone vs. CIRT combined with
                      photons) were insignificant. For OS after RT, patient age
                      and PTV size proved to be significant predictors. The
                      incidence of late toxicity ≥ III° according to CTCAE v5.0
                      was $21\%.$ Sacral insufficiency fractures occurred in
                      $49\%$ of patients (maximum III°: $16\%)$ and were thus by
                      far the most frequent late side effect in our analysis.
                      Radiogenic damage to the peripheral nerves, intestinal tract
                      and skin was observed in only $9\%$ (≥ III°: $5\%),$
                      $3\%$ (all II°) and $9\%$ (all I°) of patients.Our
                      analysis showed only moderate long-term LC rates after
                      carbon ion-based RT, with sacral chordomas having a
                      particularly poor prognosis in the recurrent situation.
                      Therefore, future studies should evaluate the safety and
                      effectiveness of further dose escalation and
                      hypofractionation of RT in sacral chordoma and weight
                      potential benefits of dose escalation against side effects.},
      cin          = {E050 / E055},
      ddc          = {610},
      cid          = {I:(DE-He78)E050-20160331 / I:(DE-He78)E055-20160331},
      pnm          = {315 - Imaging and radiooncology (POF3-315)},
      pid          = {G:(DE-HGF)POF3-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:32831113},
      doi          = {10.1186/s13014-020-01647-8},
      url          = {https://inrepo02.dkfz.de/record/157634},
}