P30.06 Outcome Differences Amongst Histopathological Variants of Non Small Cell Lung Cancer Treated With Palliative Radiotherapy

Abstract

Squamous cell carcinoma and adenocarcinoma are the two major histopathological subtypes of non small cell lung cancer. Amongst these, Squamous Cell subtype is predominant in India. Thoracic palliative radiation therapy offers symptomatic relief to patients with distressing symptoms caused out of loco-regionally advanced disease. But the overall outcome of patients are often dependent upon intrinsic tumor biology and histopathological subtypes, apart from other relevant patient related characteristics. Between August 2018 and January 2020, newly diagnosed 48 patients of histopathologically proven non small cell lung carcinoma, presenting with thoracic distressing symptoms were included in this single armed, single institutional, prospective, observational study, after seeking informed consent from all, out of whom 36 patients had squamous cell carcinoma, while rest 12 had adenocarcinoma. Patients of stage IIIB to IVB, with ECOG performance status 2-3, requiring palliative radiation therapy for relief of local thoracic symptoms were included. All patients were treated with 30 Gy, divided in 10 fractions (3 Gy per fraction), over 2 weeks time (5 days in a week). Treatment response was assessed after 6 weeks of completion of radiation therapy by contrast enhanced CT scan of thorax in accordance with RECIST 1.1 criteria. Patients with partial response and stable disease were considered as treatment responders (having local control) while patients with progressive disease were taken as treatment non-responders. Patients were followed up via phone calls to the patients themselves or to their family members. Survival period was recorded as starting from the time of histopathological diagnosis to the date of death or termination of the study (June 2020). Tabled 1Distribution of patients with two major histopathological subtypes of non small cell lung cancer in accordance with treatment response at 6 weeks post palliative radiation therapyHistopathological subtypesPartial ResponseStable DiseaseProgressive DiseaseSquamous Cell Carcinoma (n=36)12 (33.33%)10 (27.78%)14 (38.89%)Adenocarcinoma (n=12)2 (16.67%)8 (66.67%)2 (16.67%) Open table in a new tab Adenocarcinoma variant responded more to radiation therapy as compared to squamous cell carcinoma in terms of local control (Treatment responders; adenocarcinoma vs squamous cell carcinoma : 83.33% vs 61.11%), though more percentage of patients with squamous cell carcinoma had partial response. Median overall survival (OS) of all 48 patients were 5.85 months. Patients with adenocarcinoma experienced better survival than that of squamous cell carcinoma (Median overall survival; adenocarcinoma vs squamous cell carcinoma : 11.35 vs 4.95 months) after palliative radiation therapy. Adenocarcinoma subtype of non small cell lung cancer tend to have better objective response after palliative thoracic radiotherapy in advanced stage diseases along with better overall survival as compared to squamous cell carcinoma.