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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
O14.07 - IDEAL CRT: Isotoxic Dose Escalation and Acceleration in Lung Cancer ChemoRadiotherapy - a phase I/II trial of concurrent chemoradiation with dose-escalated radiotherapy in patients with stage II or stage III Non-Small Cell Lung Cancer. (ID 1368)
10:30 - 12:00 | Author(s): M. Illsley
The IDEAL-CRT trial uses an individual patient approach to radiotherapy (RT) dose escalation, escalating the dose within a fixed overall treatment time, 6 weeks, by increasing dose per fraction. Isotoxic RT is based on the calculated risk of RT-pneumonitis (RTPN), RT dose being escalated so that all patients are exposed to the same RTPN risk. We investigated the feasibility and safety of individualised, isotoxic dose escalation for once daily RT delivered in 30 once-daily fractions with concurrent chemotherapy.
Eligibility; NSCLC stage II/III, PS 0/1, FEV~1~ (≥40% predicted or ≥1L), DCLO (≥40% predicted). A radiobiological model was used to individualize RT dose-prescription – selecting a dose which, in 30# once daily for 6 weeks, is associated with a 10% risk of grade 3+ RTPN, but limiting prescribed doses to between 63Gy - 73Gy (2Gy dose equivalent α:β=10, 63.5Gy-86Gy). Dose constraints were fixed for spinal cord, heart, brachial plexus. In Arm 1, initially the maximum dose to 1cc oesophageal did not exceed 63Gy. Arm 2 comprised patients in whom oesophageal dose rather than lung dose limited the prescription dose: the oesophageal dose was raised from 65Gy to 68Gy, 71Gy and 73Gy in consecutive cohorts, the prescribed dose lying between 63Gy and 73Gy and being the highest consistent with the oesophageal limit. Dose escalation was determined using a 6+6 design. Dose limiting toxicity (DLT) was defined as Grade 3+ oesophagitis. MTD was determined if grade 3+ oesophagitis >42% (>5/12). Two cycles of Cisplatin-Vinorelbine chemotherapy given concurrently during RT. All contouring and dosimetry on planning CT scans was centrally reviewed. IMRT was introduced in November 2012. Primary endpoints: oesophagitis and RTPN. Serial pulmonary function tests and ECGs performed. Efficacy endpoints: overall survival (OS), progression free survival (PFS), and tumour response.
Between October 2010 and February 2013, 84 patients recruited (9 UK centres), 49 patients Arm 1, 35 patients Arm 2 (13 at 65Gy, 12 at 68Gy, 10 at 71Gy; none at 73Gy as the 73Gy upper prescription dose limit was only rarely associated with an oesophageal dose higher than 71Gy). Median follow up was 11 months (range 2,24); median age 66 years (range 43-84); 74% male; 39%/60% WHO 0/1; 30% adenocarcinoma, 54% squamous. Mean GTV 121cc (range 14-602cc). Mean prescribed dose for patients completing RT (n=80) 67.6Gy (range 63-73Gy) in Arm 1 and 70.1 Gy (63-73) in Arm 2. Mean 1cc-oesophageal-dose in Arm 1 55.5Gy (range 14.2-68.0Gy). In Arm 1 grade 3+ oesophagitis was 6% (3/49). In Arm 2, Grade 3+ oesophagitis was 17% (2/12) at 68Gy; no Grade 3+ oesophagitis in 65Gy (0/12) and 71Gy (0/10) cohorts. Grade 3+ RTPN 2% (1/49) in Arm 1 and 6% (2/35) in Arm 2. 1 year OS and PFS rates were 92% and 74% respectively.
Isotoxic RT dose escalation was safe and feasible. The MTD for oesophagus was not reached. Acceleration of the IDEAL-CRT schedule to five weeks is under investigation in a second study, currently recruiting.
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