Abstract
Purpose: This retrospective study was performed to evaluate the efficacy of radiation therapy (RT) and to investigate the prognostic factors for thymoma when treated with RT. Materials and Methods: We analyzed 21 patients with thymoma and also received RT from March 2002 to January 2008. The median follow-up time was 37 months (range, 3 to 89 months). The median patient age was 57 years (range, 24 to 77 years) and the gender ratio of males to females was 4：3. Of the 21 patients, complete resections (trans-sternal thymectomy) and R2 resections were performed in 14 and 1 patient, respectively. A biopsy was performed in 6 patients (28.7%). The WHO cell types in the 21 patients were as follows: 1 patient (4.8%) had type A, 10 patients (47.6%) had type B1-3, and 10 patients (47.6%) had type C. Based on Masaoka staging, 10 patients (47.6%) were stage II, 7 patients (33.3%) were stage III, and 4 patients (19.1%) were stage IVa. Three-dimensional RT was adminstered to the tumor volume (planned target volume), including the anterior mediastinum and the residual disease. The total RT dose ranged from 52.0 to 70.2 Gy (median dose, 54 Gy). Consistent with the WHO criteria, the response rate was only analyzed for the 6 patients who received a biopsy only. The prognostic factors analyzed for an estimate of survival included age, gender, tumor size, tumor pathology, Masaoka stage, the possibility of treatment by performing surgery, the presence of myasthenia gravis, and RT dose. Results: The 3-year overall survival rate (OS) and the progression free survival rate (PFS) were 80.7% and 78.2%, respectively. Among the 10 patients with WHO cell type C, 3 of 4 patients (75%) who underwent a complete resection and 3 of 6 patients (50%) who underwent a biopsy survived. Distant metastasis developed in 4 patients (19.1%). The overall response rate in the 6 patients who received biopsy only were as follows: partial remission in 4 patients (66.7%), stable disease in 1 patient (16.6%), and progressive disease in 1 patient (16.6%). Acute RTOG radiation pneumonitis occurred in 1 patient (4.8%), grade 2 occurred in 2 patients (9.5%), grade 3 occurred in 1 patient (4.8%), and grade 4 occurred in 1 patient (4.8%). A univariate analysis revealed that the significant prognostic factors for OS were age (${\geq}60$, 58.3%; <60, 100%; p=0.0194), pathology (WHO cell type A-B3, 100%; C, 58.3%; p=0.0194) and, whether the patient underwent surgery (yes, 93.3%; no, 50%; p=0.0096). Conclusion: For the 15 patients who received surgery, there was no local failure within the radiation field. In patients with WHO cell type C, surgical procedures could have resulted in a more favorable outcome than biopsy alone. We report here our clinical experience in 21 patients with thymoma who were treated by radiation therapy.
목 적: 흉선종환자에서 방사선치료 효과를 평가하고 생존율에 영향을 미치는 예후인자를 파악하기 위하여 후향적 분석을 시행하였다. 대상 및 방법: 2002년 3월부터 2008년 1월까지 본원에서 흉선종으로 진단 받고 방사선치료를 시행 받은 21명의 환자를 분석하였다. 대상환자의 추적관찰 기간은 3~89개월(중앙값, 37개월)이었다. 남녀 구성비는 4：3이었고 연령분포는 24~77세(중앙값, 57세)이었다. Masaoka병기는 II기 10명(47.6%), III기 7명(33.3%), IVa기 4명(19.1%)이었다. 전체 21명 중 15명(완전절제[흉선절제술], 14명; 불완전절제, 1명)에서 수술이 시행되었고, 시험적 개흉술(exploratory thoracotomy), 경부림프절 생검 등을 포함한 조직검사만 시행한 경우는 6명(28.6%)이었다. 병리학적으로 WHO 세포형 A 1명(4.8%), B1-3 10명(47.6%), C 10명(47.6%)이었다. 방사선치료는 3차원입체조형기법으로 시행하였고 총 방사선선량은 52~70.2 Gy (중앙값, 54 Gy)이었다. 성별, 연령, 종양의 크기, 병리학적 분류, Masaoka 병기, 수술시행 여부, 근무력증 유무 및 방사선량 등에 따른 전체 및 무진행생존율의 차이를 분석하였다. 결 과: 전체 환자에서 3년 생존율은 80.7%이었고 3년 무진행생존율은 78.2%이었다. WHO 세포형 C 10명에서 완전절제를 시행한 4명 중 3명(75%)이 생존하였고, 조직검사만 시행한 6명 중 3명(50%)이 생존하였다. 수술을 시행받은 15명 중 방사선조사 범위 내에서의 재발은 없었다. 4명(19.1%)에서 원격전이가 확인되었다. 조직검사만 시행받은 6명의 치료반응은 부분관해 4명(66.6%), 불변 1명(16.7%) 그리고 진행 1명(16.7%)이었다. 치료 후 방사선폐렴이 Radiation Therapy Oncology Group (RTOG) grade 1이 1명(4.8%), grade 2가 2명(9.5%), grade 3과 grade 4가 각각 1명(4.8%) 있었다. 단변량 분석상 생존율에 유의한 예후인자는 연령(60세 이상, 58.3%; 60세 미만, 100%; p=0.0194), 병리학적 분류(WHO 세포형 A-B3, 100%; C, 58.3%; p=0.0194), 수술시행여부(시행, 93.3%; 미시행, 50%; p=0.0096)이었다. 결 론: 수술 후 보조적으로 방사선치료를 시행 받은 15명 모두 방사선치료 조사야 내 재발이 없었고 WHO 세포형 C에서 방사선치료 전 수술이 시행된 경우 조직검사만 시행된 경우보다 좋은 성적을 보였다. 이에 저자들은 흉선종 환자들을 대상으로 한 방사선치료 경험을 보고하는 바이다.
