This journal suppl. entitled: 20th Medical Research Conference; Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong KongINTRODUCTION: Squamous cell lung carcinoma (SCC) belongs to the second most common subtype in non–small-cell lung carcinoma. Recently, doublet chemotherapy regimens remain the cornerstone of first-line systemic treatment. Therefore, new therapeutic approach is urgently needed. Arsenic trioxide (ATO) is a traditional Chinese medicine which has multiple anti-cancer mechanisms including apoptosis. ATO has been used clinically in acute promyelocytic leukaemia. ATO has been shown to induce apoptosis in lung adenocarcinoma …published_or_final_versio