Aims ASCL2, a basic helix-loop-helix (bHLH) transcription factor, is putatively involved in tumour progression. This study aimed to evaluate ASCL2 expression level in non-small-cell carcinoma (NSCLC) and assess its prognostic value for patients.

Methods ASCL2 protein expression was detected by immunohistochemistry (IHC cohort) in 79 cases of squamous cell carcinoma (SCC) and 67 cases of adenocarcinoma (AC). Kaplan–Meier analysis and Cox regression analysis were performed to evaluate the prognostic significance of ASCL2. The same analyses were conducted in a cohort (n=790) from The Cancer Genome Atlas database (TCGA) to validate the expression pattern and prognostic value of ASCL2.

Results ASCL2 expression levels were significantly increased in SCC compared with normal lung tissue (p<0.001) and AC (p=0.008). High ASCL2 expression was associated with advanced tumour-node-metastasis (TNM) stage (p=0.023) and worse differentiation status (p=0.001) in SCC, but a positive correlation between ASCL2 expression level and advanced TNM stage (p=0.016) was observed in AC. Kaplan–Meier analysis showed that ASCL2 was prognostic in SCC (p=0.004) but not in AC (p=0.183). Multivariable Cox regression analysis indicated that elevated expression of ASCL2 was an independent prognostic factor (HR 2.764; p=0.030) in SCC patients. The expression pattern and prognostic significance of ASCL2 in SCC and AC were validated using the TCGA cohort.

Conclusions Elevated expression of ASCL2 may identify an aggressive subgroup in SCC and serve as an independent prognostic indicator in these patients.