79P - Volume changes with hypo-fractionated radiotherapy in early lung cancer: Time trends & outcomes

Date 17 April 2015
Event ELCC 2015
Session Poster lunch
Topics Non-Small-Cell Lung Cancer, Early Stage
Surgery and/or Radiotherapy of Cancer
Presenter Rima Pathak
Citation Annals of Oncology (2015) 26 (suppl_1): 18-23. 10.1093/annonc/mdv048
Authors R.S. Pathak1, A.R. Tibdewal1, S. Ghosh Laskar1, S. Chaudhari2, J.P. Agarwal1
  • 1Radiation Oncology, Tata Memorial Hospital Centre, 400012 - Mumbai/IN
  • 2Medical Physics, Tata Memorial Hospital Centre, 400012 - Mumbai/IN

Abstract

Aim/Background

Hypofractionated Radiotherapy (HFRT) is commonly used for medically inoperable early lung cancer/ oligometastasis in lung. Response to HFRT may be heterogeneous & the pattern of response may be used as an early predictor for outcome.

Methods

Twenty-six patients with early lung cancer/ oligometastasis in lung treated with HFRT from 2010 - 2014 were evaluated for their Gross Tumor Volume (GTV) change during the course of RT. Kilo-voltage CTs (KVCT) were acquired before every fraction & GTV volumes were contoured manually using standard ‘lung & mediastinal’ window & level. A total of 176 KVCTs were contoured. Patients were treated using 6/15 MV photons, with 3DCRT, to a dose of 48 - 60Gy in 6- 10#, on alternate days. The Overall survival (OS), Locoregional Recurrence Free Survival (LRFS) & Distant Metastasis Free Survival (DMFS) were computed using Kaplan Meier method.

Results

Of the 26 patients, 22 had primary lung cancer & 4 had lung metastasis. Median age was 65.5 yrs (range 23 - 82 yrs). Median GTV was 40.6 cc (range 7.2- 146.5 cc) on CT1 (KVCT for 1st fraction) & 33.3 cc (range 4 - 151.8 cc) on CTlast (KVCT of last fraction) suggesting 18% reduction for the whole group. Increase in tumor volume was noted in 20 (75%) patients at some time point during RT. In the mid treatment scan 13 (50%) patients had higher tumor volume than the CT1, however only 8 (30%) patients' GTV remained larger at the end of treatment compared to baseline. Median follow up was 12 months. The OS, LRFS & DMFS at 12 & 18 months were 63.4%, 85.1%, 59.1% and 57.1%, 73%, 35.5%, while for the patients with lung primaries were 75.2%, 86.3%, 67% & 67.7%, 73.9%, 40.2% respectively. In primary lung cancer patients, the median percentage reduction in GTV at CTlast compared to CT1 was 11%. Tumors that regressed in volume by >11% had significantly worse OS & LRFS compared to those that regressed by <11% (p = 0.003).

Conclusions

Significant changes of GTV are seen during HFRT. Early regression in tumor volume may help in deciding early adjuvant treatment interventions.

Disclosure

All authors have declared no conflicts of interest.