Prognostic impact of tumour budding in squamous cell carcinoma of the lung: a systematic review and meta-analysis.

Abstract

Tumour budding is an established prognostic factor in various solid tumours, including colorectal cancers and oral squamous cell carcinomas. However, its role is unclear and needs to be defined for squamous cell carcinoma of the lung (LSCC). Hence, we conducted a systematic review and meta-analysis investigating the prognostic role of tumour budding in LSCC. PubMed, Embase and Scopus were searched for peer-reviewed literature investigating the association between tumour budding and survival outcomes or clinicopathological variables in LSCC. The primary outcomes were pooled estimates for overall and recurrence-free survival with hazard ratio (HR) as the effect measure. The association between tumour budding and clinicopathological parameters was also investigated. Of 243 studies, nine were included, comprising 2546 patients. An increased risk of death [HR=1.76, 95% confidence interval (CI)=1.50-2.05, P < 0.00001] and recurrence (HR=1.37, 95% CI=1.12-1.68, P=0.003) was evident in patients with high-grade tumour budding. Sensitivity and subgroup analyses revealed consistent results. Pathological stage II, lymph node metastasis, lymphovascular and pleural invasion were associated with high-grade tumour budding. Tumour budding is a new and promising prognostic factor in patients with LSCC. However, pervasive heterogeneity and publication bias reduces the credibility of these findings and the applicability of tumour budding in clinical practice. Future studies are required to standardise reporting on tumour budding in LSCC.