344P - Loco-regional radiotherapy (RT) in M1a non-small cell lung cancer (NSCLC) downstaged with chemotherapy (CT)

Background

The role of loco-regional radiotherapy in M1a (pleural effusion) NSCLC is scanty. Ninety percent of patients present in advanced stage in our clinic. The standard of care is chemotherapy in advanced cases. CT leads to resolution of pleural fluid in some patients. Do such patients with good performance status benefit with radical RT? We present our experience of radical RT in M1a patients of NSCLC who responded to CT.

Methods

We conducted an audit of advanced NSCLC (locally advanced with /without pleural effusion) treated with CT followed by radical RT between January 2005 to December 2019. They were treated with either 4 cycles of cisplatin pemetrexed in adenocarcinoma or carboplatin/paclitaxel or cisplatin etoposide in squamous cell carcinoma [SCC]) followed by radical radiotherapy [RT] (50-66Gy by conventional RT) by 3D-CRT technique. Response to CT, overall survival (OS), factors affecting OS were analysed by univariate and multivariate analysis.

Results

Out of 154 patients, 36 were M1a. At a median follow-up of 14 months (IQR 10-22 months} the median OS was 14 months in the M1a subset vs 16 months in non-M1a (p=0.6). The mean planning target volume was larger in M1a patients as compared with M0 patients {767.1cc (SD 688.2) vs 596.03cc (SD 302.68). The factors which significantly impacted OS were gender[male vs female] (14 mo vs 17 mo in M0, 13 mo vs 22 mo in M1, p=0.012), Karnofsky Performance Status [>70 vs <70] ] (14 mo vs 11mo in M0, 18 mo vs 13 mo in M1, p=0.04), Diabetes mellitus [present vs absent] ] (12 mo vs 14 mo in M0, 10 mo vs 16 mo in M1, p=0.03)and biologically effective dose [BED <72 vs >72] ] (12 mo vs 15 mo in M0, 15 mo vs 18 mo in M1, p=0.012), presence of radiation esophagitis [yes vs none] ] (11 mo vs 14 mo in M0, 2 mo vs 18 mo in M1, p=0.001).

Conclusions

Radical RT is feasible and well tolerated in NSCLC M1a who respond to CT and yields equivalent outcomes as locally advanced disease (M0) inspite of higher PTV volume in M1a. This potential of RT must be further explored.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.