Sarcoma and Cutaneous Tumors

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MO_21_2660 - Clinical Outcome After Multimodality Approach Including Radiation Therapy in Rhabdomyosarcoma: Single-Institution Experience

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Clinical Outcome After Multimodality Approach Including Radiation Therapy in Rhabdomyosarcoma: Single-Institution Experience
J. J. B. Lee1, S. Choi2, C. O. Suh2, and H. I. Yoon3; 1Yonsei cancer center, Seoul, Korea, Republic of (South), 2Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 3Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea, Republic of (South)

Purpose/Objective(s): To report the experience of treating rhabdomyosarcoma and evaluate treatment outcome and prognostic factors in subgroups based on primary sites.

Materials/Methods: Sixty-two rhabdomyosarcoma patients who received multimodal treatment involving radiotherapy from March, 2000 to November, 2015 were included in this retrospective study. Clinical and treatment characteristics, pathologic features, prognostic factor and pattern of failure were reviewed. Survival outcomes were calculated using Kaplan-Meier method and prognostic factors were evaluated by Cox regression analysis.

Results: Median follow-up was 33 months (mean 51, range, 2.5-179.2). Median age was 9.1 years (range, 0.4-74.1) and twenty patients were diagnosed with de novo stage IV disease. Fifteen patients had favorable primary site and embryonal type was the most common pathological type with 31 (50%) cases. Thirty eight patients underwent surgery and sixty patients received chemotherapy. The most commonly used chemotherapy regimen was vincristine, doxorubicin, and cyclophosphamide. Excluding stage IV patients, median radiation dose was 45.0 Gy (Mean 44.6, range, 14.0-60.0). While median overall survival (OS) was not reached, 1-year OS was 93.5 percent and 3-year OS was 63.6 percent. Median progression free survival (PFS) was 18.7 months with 1-year PFS of 65.2 percent and 3-year PFS of 41.8 percent. Univariate analysis revealed age (p=0.025), site (p=0.03), TNM stage (p<0.001), and Intergroup rhabdomyosarcoma study clinical group (IRSG) (p=0.001) as significant prognostic factors. In multivariate analysis, age (p=0.002) and TNM stage (p<0.001) were statistically significant. After excluding stage IV patients who had had worst outcome and categorizing patients into four groups according to age and primary site, patients who were younger than 10 with favorable primary site had significantly better survival outcome. For further investigation on primary site, we divided patients to five groups according to their primary sites as follows: non-parameningeal head and neck, parameningeal, genitourinary, extremity, and others, defined as the rest part of body such as retroperitoneum. 3-year OS was 90.0 percent in non-parameningeal head and neck patients, 57.1 percent in parameningeal patients, 87.1 percent in genitourinary subgroup, 30.0 percent in extremity and 45.5 percent in “others” subgroup. Respective 3-year PFS was 88.9 percent, 35.7 percent, 37.4 percent, 20.0 percent and 18.2 percent.

Conclusion: This study showed multimodality treatment including radiotherapy could result in acceptable survival outcomes especially in young patients whose primary sites are non-parameningeal head and neck or genitourinary. However, treatment strategies should be further improved to achieve better survival in unfavorable groups. Keywords: Rhabdomyosarcoma, radiotherapy, multimodality treatment, primary sites, prognostic factors

Author Disclosure: J. Lee: None. S. Choi: None.

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