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MINI 33 - Radiotherapy and Complications (ID 164)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Treatment of Locoregional Disease – NSCLC
- Presentations: 1
MINI33.07 - A Restrospective Study of Shrinking Field Radiation Therapy in Chemoradiothrapy for Stage III Non-Small Cell Lung Cancer (ID 3195)
18:30 - 20:00 | Author(s): W. Mao
The study aimed at investigating the feasibility of shrinking field after complete or partial response during Chemoradiothrapy without surgery for stage III non-small cell lung cancer (NSCLC).
This retrospective study was carried on 97 consecutive patients with stage III non-small cell lung cancer (NSCLC), who were good responders to cheomoradiation without surgery between September 2009 and November 2014. Computed tomography scans were performed after 40-50 Gy to evaluate the curative effect. Fifty three-dimensional-conformal treatment or intensity-modulated radiation therapy were redelineated to shrink the radiation volume once or twice during conventionally fractionated radiotherapy, leading to a boost of 6-20Gy delieverd to the shrunk PTV. The gross tumor volume (GTV) and planned target volume (PTV) were messured. The acute symptomatic irradiation-induced pneumonia(ASIP) as well as first progression patterns and overall survival were investigated through follow-up.
Among 97 patients who obtained complete or partial response with median total dose of 60.0 Gy (range, 46.0-70.0 Gy), 50 patients received shrinking field radiation therapy with a median 184.24 cm[3 ](range, 28.1- 449.7cm) reduction of PTV between the first and last plan. The primary GTV and PTV in shrinking field group was greater than that in non-shrinking field group, as well as the 59Gy-greater radiation dose rate(GTV, 116.8 cm vs 102.9 cm[3 ]; PTV, 493.0 cm[3 ]vs 458.0 cm; 59Gy-greater dose rate, 70 % vs 61.7 %). The incidence of ASIP was 20.6%(20/97) for all the population, shrinking field group of 18%(9/50) and non-shrinking field group of 23.4%(11/47). Fifteen patients progressed locoregionlly, 12 distantly and 3 in both patterns in shrinking field group, while 22 locoregionlly, 16 distantly and 3 in both patterns in non-shrinking field group. Four regional-progression located out of PTV in both groups. The locoregion-progression rate and out-PTV rate were not significant difference(60% vs 61%, P=0.934; 63.3% vs 56.1%, p=0.54). As compared with non-shrinking field group, shrinking field had a similar overall survival(median OS, 29 mouths vs 30 mouths, P=0.546), an improved median progression free survival (median PFS, 19 mouths vs 14 mouths, P=0.945) and a lower incidence of acute irradiation-induced pneumonia, but they were all not statistically significant.
Shrinking field and dose escalation for good responders during chemoradiotherapy seem safe with acceptable toxicity and outPTV relapse, especially for the lung cancer with a bulky mass. More prospective trials are needed to validate these results.
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