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O14 - Radiotherapy - Toxicity and Clinical Trials (ID 105)
- Event: WCLC 2013
- Type: Oral Abstract Session
- Track: Radiation Oncology + Radiotherapy
- Presentations: 1
- Moderators:G. Pratt, S.K. Vinod
- Coordinates: 10/29/2013, 10:30 - 12:00, Parkside Ballroom A, Level 1
O14.02 - Vertebral fractures in NSCLC patients treated with IMRT and concurrent chemotherapy (ID 1880)
10:30 - 12:00 | Author(s): C. Chen
Purpose To report on the incidence of vertebral fractures in locally advanced NSCLC patients treated with intensity modulated radiation therapy (IMRT) and concurrent chemotherapy. The RT dose to the vertebra was analyzed for its association with fractures.
Methods A total of 524 patients were treated between 2007 and 2011, with hypofractionated IMRT (66Gy/24fx) and concurrent daily low dose cisplatin. Planning and follow-up CT or MRI scans were retrospectively utilized to identify vertebral collapse by an experienced radiologist and a technician. Clinical and dosimetric parameters were retrospectively collected. Patients were excluded if they had no follow-up CT/MRI scan; had prior irradiation for thoracic or head and neck cancer; showed a vertebral fracture in the planning CT; or had vertebral collapse due to other causes. First, we reported the incidence of vertebral fractures. Afterwards, we analyzed the RT dose effect relationship using the maximum (Dmax) and mean (Dmean) dose to each vertebra. Dose-response was modeled using Cox model with patient as random effect. Data were analyzed using R, package “coxme”.
Results Three hundred and thirty six patients were eligible for analysis. The median follow-up was 24 months The median age was 64 years (range 32-87); 40% of the patients female and 94% had a performance score (PS) 0-1. Twenty-eight (8%) patients developed ≥ 1 vertebral fracture; 22 had 1 vertebral fracture, 5 had 2 and 1 patient had 3 vertebral fractures. All fractures were located from the 6[th]-8[th] thoracic vertebra.The median onset time for the fracture was 7 months (range 2-26). The median age for the 28 fractured patients was 70 years (range 42-82); 61% were female, 89% had a PS of 0-1. The median Dmax was 40Gy (range 0-83) and 72Gy (range 42-83) for non-collapsed and fractured vertebrae, respectively. The median Dmean was 12Gy (range 0-65) and 51Gy (range 18-71) for non-collapsed and collapsed vertebras, respectively. Both Dmax and Dmean were significantly (p<0.001) associated with vertebral fractures.
Conclusion Vertebral fractures were retrospectively identified in 8% of NSCLC patients treated with IMRT and concurrent chemotherapy. The median onset time was 7 months. Both Dmax and Dmean of the vertebra were significantly associated with collapse in the collapsed population. A case-control study is in progress to analyze the dose-response relationship in the entire population and incorporate clinical variables, such as age, performance status and menopause status.
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