Postoperative radiotherapy in thymic carcinoma: treatment results and prognostic factors

Abstract

Short running head: Postoperative radiotherapy in thymic carcinomaABSTRACT Purpose: To analyze the treatment results and prognostic factors of patients with primary thymic carcinoma treated by total or subtotal tumor resection followed by radiotherapy alone. Materials and methods: From October 1987 to October 1997, twenty-six patients with thymic carcinoma were treated with complete or incomplete surgical resection and postoperative adjuvant irradiation without chemotherapy. The radiation was delivered with 10 MV X-ray given 5 days per week at 1.8~2 Gy per fraction. Total doses ranged from 40 to 70 Gy. All patients had at least 40 months of follow-up. Results: The 5-year overall survival rate, local control rate and distant metastasis-free rate were 77%, 91% and 57%, respectively. Several prognostic factors including sex, age, extent of resection (total resection vs subtotal resection), Masaoka staging (early stage?+?vs advanced stage?+?), pathology (low grade vs high grade) and postoperative radiation dose (?60 Gy vs?60 Gy) were evaluated in univariate analysis. The Masaoka staging system was the only statistically significant predictor in overall survival rate (p=0.0482) and distant metastasis-free rate (p=0.0193). Conclusions: The Masaoka staging system is the most important prognostic factor in primary thymic carcinoma patients receiving postoperative radiotherapy alone. For resectable tumor, surgery and postoperative radiotherapy can get a good local control but distant metastatic rate is still high. Further investigation of more effective chemotherapy is needed.

Radiotherapy in Thymic Neoplasms

“…Radiation dose was found to have a significant association for local control probability in a small series consisting of 27 patients with invasive thymoma and 6 patients with thymic carcinoma [49]. However, Hsu and colleagues also found that, while Masaoka staging was a statistically significant prognostic factor, radiation dose of <60 Gy, 60 Gy, or >60 Gy was not a significant predictor of overall survival rate [48]. Ogawa and colleagues showed 100% control rates in 40 patients with thymic carcinoma who underwent complete resection and adjuvant RT with prescription doses >50 Gy [50].…”

“…Most studies use a total dose ranging from 40 Gy to 70 Gy with daily fractions of 1.8 to 2.0 Gy. Hsu and colleagues analyzed 26 patients given adjuvant RT and show improved survival and local control with 77% 5-year survival rate, 91% 5-year local control rate, and 57% 5-year distant metastasis-free rate [48]. Radiation dose was found to have a significant association for local control probability in a small series consisting of 27 patients with invasive thymoma and 6 patients with thymic carcinoma [49].…”

“…Cord doses should remain <45 Gy. Although earlier reports found grade 3 and 4 toxicity ranging from 11% to 13% [48], newer reports suggest a decreased rate of 5% to 10%, potentially due to technical innovations in radiotherapy delivery [50]. Death secondary to complications from RT has been reported in 1% to 13% of cases [60].…”

Thymic epithelial tumours: from basic principles to individualised treatment strategies

“…In the Japanese series, 186 patients with thymic carcinoma were analysed with no survival difference based on post-operative treatment, regardless of the tumour stage [6]. In a more recent series of 26 patients with thymic carcinoma treated with surgery and radiotherapy, local control rate was 82% higher than that observed in a historical series [67].…”

Mediastinal Tumorlerde Radyoterapi

“…Timik karsinomların prognozlarının kötü olması nedeniyle hemen hemen tüm olgulara RT önerilmektedir (23). Sıklıkla 1.8-2.0 Gy fraksiyon dozlarında uygulanan 50-60 Gy RT ile olgularda %90-100 olasılıkla lokal kontrol sağlanabilmektedir (23,24). Sınırda rezektable ya da unrezektable olgular neoadjuvan KT ya da torasik RT'den fayda görebilir (25).…”