In an analysis of data from two clinical trials and a soft-tissue sarcoma registry reported in the Journal of Clinical Oncology, Koscielniak et al identified which patients aged ≤ 21 years with localized rhabdomyosarcoma appeared to derive benefit from radiation therapy.
Study Details
The study involved data from 1,470 patients aged ≤ 21 years with localized disease entered into two Cooperative Weichteilsarkom Studiengruppe (CWS) trials—CWS-96 and CWS-2002P—and the European SoTisSar Soft-Tissue Sarcoma Registry between July 1995 and December 2017.
Key Findings
Median follow-up was 6.5 years (interquartile range = 3.3–9.5 years). Overall, among 910 patients (62%) who received radiotherapy vs 560 who did not, 5-year event-free survival was 72% vs 69% (P = .29) and the 5-year local control survival was 78% vs 74% (P = .03).
Among 201 patients in Intergroup Rhabdomyosarcoma Studies (IRS) group I, 10 received radiotherapy and 191 did not; 90% of the latter patients had embryonal rhabdomyosarcoma. Event-free survival at 5 years was 87.5% in the radiotherapy group vs 85% in the no radiotherapy group (P = .72) and 5-year local control survival was 87.5% vs 88% (P = .9).
Among 209 patients in IRS group II, 5-year event-free survival was 77.5% among 109 who received radiotherapy vs 76% among 100 who did not receive radiotherapy (P = .55) and 5-year local control survival was 91% vs 80% (P = .01).
Among 1,060 patients in IRS group III, 5-year event-free survival was 71% among 791 receiving radiotherapy vs 56% among 269 who did not receive radiotherapy (P = 3.1e-06) and 5-year local control survival was 76% vs 61% (P = 4.1e-07).
A high proportion of patients with head and neck parameningeal tumors received radiotherapy (n = 339 vs 24 with no radiotherapy). Receipt of radiotherapy was associated with improved 5-year event-free survival (67% vs 35%, P = .0001), local control survival (73% vs 38%, P = 5.3e-06), and overall survival (71% vs 48.5%, P = .004). Irradiated head and neck parameningeal tumors were treated predominantly with photon radiotherapy (n = 196), with 5-year event-free survival (66% vs 70%), local control survival (73% v 78%), and overall survival (72% vs 73%) being comparable with the use of proton radiotherapy (n = 86).
Overall, the efficacy of low radiotherapy doses of 32 Gy (hyperfractionated, accelerated radiotherapy [HART]) and 36 and 41.4 Gy (conventional fractionated radiotherapy [CFRT]) produced similar outcomes in favorable-risk groups, and higher doses of 44.8 Gy (HART) and 50.4 and 55.8 Gy (CFRT) produced similar outcomes in unfavorable-risk groups.
The investigators concluded: “Radiotherapy can be omitted in patients with IRS group I embryonal rhabdomyosarcoma. Radiotherapy improves local control survival and event-free survival in IRS groups II and III. Radiotherapy improves overall survival in patients with head and neck parameningeal tumors, with proton radiotherapy comparable with photon radiotherapy. Doses of 32 Gy (HART) or 36 and 41.4 Gy (CFRT) had comparable efficacy in patients with favorable-risk profiles and 44.8 Gy (HART) or 50.4 and 55.8 Gy (CFRT) in the unfavorable groups.”
Ewa Koscielniak, MD, of Zentrum für Kinder-, Jugend- und Frauenmedizin, Klinikum Stuttgart, Germany, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the German Cancer Aid Foundation, German Children’s Cancer Foundation, and Förderkreis Krebskranke Kinder. For full disclosures of the study authors, visit ascopubs.org.
