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MO23 - Radiotherapy II: Lung Toxicity, Target Definition and Quality Assurance (ID 107)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Radiation Oncology + Radiotherapy
- Presentations: 1
MO23.12 - DISCUSSANT (ID 3936)
10:30 - 12:00 | Author(s): A. Brade
Abstract not provided
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P1.15 - Poster Session 1 - Thymoma (ID 189)
- Event: WCLC 2013
- Type: Poster Session
- Track: Thymoma & Other Thoracic Malignancies
- Presentations: 1
- Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
P1.15-009 - Outcomes and Predictors of Recurrence in Patients Treated with Risk-adapted, Post-operative Radiotherapy (RT) for Thymoma - A Single Institution, 30 Year Retrospective Study (ID 3124)
09:30 - 16:30 | Author(s): A. Brade
Thymoma is a rare epithelial cell tumour of the thymus, with an incidence of 0.15 per 100 000 persons. Thymic carcinomas comprise a distinct subset and have a greater propensity for capsular invasion and distant metastases when compared to thymomas. Resection is the standard of care for localized disease but local recurrence is generally incurable, thus post-operative RT is often employed for high risk cases. The optimal dose of RT has not been established, nor whether lower doses can be utilized in a risk-adapted fashion for cases where RT is recommended but the aggressiveness of the disease/risk of recurrence is felt to be at the lower end of the spectrum. Use of lower dose RT may help reduce the chances of late RT toxicity. Our institution employs such a risk adapted strategy and we present here our long term results.
Princess Margaret Cancer Center radiation and surgical oncology databases were queried from 1983-2012. Retrospective analyses using electronic patient records and Mosaiq radiotherapy database were performed to assess demographic data, clinical presentation and treatment. Descriptive statistics were used to report demographic data. Time to event analyses and correlation of outcomes with demographic and treatment variables are planned.
Details on 104 patients treated with post-operative radiotherapy from 1983-2012 were available. The mean age was 52, range 29-73. Of patients assessed, 55/104 were male. Masaoka-Koga stage was assessed: 6% of patients were stage I, 31% IIA, 21% IIB, 27% III, 10% IV and 6% unknown. The most common WHO grade was B2 (37%) followed by B1 (16%). Complete surgical resection (R0) was obtained in 72% patients, R1 in 21%, R2 in 2% and 5% unknown. Radiotherapy doses ranged from 40 Gy – 66 Gy delivered in daily 2 Gy fractions; 57% patients were deemed low risk (typically R0 resection and WHO grade B2 or lower) and received 40Gy while 36% received between 45-66Gy. Neoadjuvant or adjuvant chemotherapy was delivered to 13% of all patients. The mean follow up period was 9.4 years, range 0.5-25.5 years, during which 22% patients experienced relapse. Of these, 43% experienced regional recurrence, defined as an intrathoracic relapse in an area not-contiguous with the thymic bed or original tumour; 39% local (intrathoracic relapse contiguous with original disease or thymic bed), and 17% distant recurrence defined as extrathoracic or intraparenchymal pulmonary nodules. For patients that experienced relapse, the median time to relapse was 8.7 years (range 1.3-18.3 years). Of the 59 patients who received 40 Gy/20 fractions, 8 developed local relapse (13.5%). Overall survival and multivariable analyses will be reported as will assessment of long term toxicities.
Risk-adapted RT prescription for patients with resected thymoma appears efficacious, and may result in an improved therapeutic ratio for these patients. Long-term, randomized controlled trials are required to further identify patients that are best suited to this approach.