Adaptive Radiotherapy in Lung Cancer – Is it Worthwhile??
JAI PRAKASH AGARWAL,
India
PO-1260
Abstract
Adaptive Radiotherapy in Lung Cancer – Is it Worthwhile??
Authors: JAI PRAKASH AGARWAL1, Anil Tibdewal2, Kumar Prabhas3, Naveen Mummudi1, Ritesh Mhatre4, Rajesh Kinhikar4
1Tata Memorial Centre, Homi Bhabha National Institute, Department of Radiation Oncology, Mumbai, India; 2Tata Memorial centre, Homi Bhabha National Institute, Department of Radiation Oncology, Mumbai, India; 3Tata Memorial Centre, Homi Bhabha National Institute, Department of Medical Oncology, Mumbai, India; 4Tata Memorial Centre, Homi Bhabha National Institute, Department of Medical Physics, Mumbai, India
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Purpose or Objective
Adaptive radiotherapy (ART) in lung cancer is required in approximately a quarter of patients, most common reason being resolution of atelectasis and rapid shrinkage of tutor during treatment. Adaptive radiotherapy requires timely detection, planning and execution with delineation uncertainties involved at the time of ART. In this study, we evaluated survival outcomes of patients who underwent ART in patients who on curative( chemo) radiotherapy.
Material and Methods
From Jan 2017 to Dec 2019, we treated 140 consecutive patients with definitive CTRT. All patients were treated with volumetric modulated arc therapy (VMAT)and image guidance was done using once weekly cone bean computed tomography. The need of ART was determined in our routine weekly audit. In patients deemed suitable for ART, replanning was done using four dimensional CT simulation and treated with VMAT. Overall survival (OS) and Progression free survival (PFS) was calculated from the date of diagnosis till the date of death/progression or last follow up, respectively. OS and PFS was calculated using Kaplan-Meier method.
Results
A total of 35 patients required ART after a median dose of 26 Gy (IQR 14-36 Gy). The median age was 61 years (range, 50 - 65), majority had non-small cell lung cancer. The need for ART was pre-emptively anticipated in approximately 30% patients initiation of treatment. The median pre-ART gross tumor volume (GTV) and planning target volume (PTV) were 153 cc (range, 3.2-1207 cc) and 544 cc (range,203-1659 cc). The median post-ART GTV was 80.8 (range,3.1-566 cc) and PTV was 419 (range, 144-1023 cc). After a median follow up of 27 months, the median OS and PFS was 29 months (95% CI, 22.6-35.8) and 15.1 months (95% CI, 12.3-18), respectively. The 2-year OS and PFS were 65.7% and 36%, respectively. Of 25 patients who progressed, local failure was seen in 15 patients (43%) after a median time of 6.3 months (range, 3.5-45.2 months).
Conclusion
Patients of lung cancer requiring ART during CTRT had comparable PFS and OS. However, local failures were comparably higher, which suggest careful delineation of target volume at the time of ART is of utmost importance to avoid missing the target.