Prognostic implications of cellular senescence in resected non-small cell lung cancer

BACKGROUND: Cure and long-term survival for non-small cell lung cancer (NSCLC) remains hard to achieve. Cellular senescence, an emerging hallmark of cancer, is considered as an endogenous tumor suppressor mechanism. However, senescent cancer cells can paradoxically affect the surrounding tumor microenvironment (TME), ultimately leading to cancer relapse and metastasis. As such, the role of cellular senescence in cancer is highly controversial. METHODS: In 155 formalin-fixed paraffin-embedded (FFPE) samples from surgically resected NSCLC patients with pathological tumor-node-metastasis (pTNM) stages I–IV (8th edition), cellular senescence was assessed using a combination of four immunohistochemical senescence markers, i.e., lipofuscin, p16(INK4a), p21(WAF1/Cip1) and Ki67, and correlated to clinicopathological parameters and outcomes, including overall survival (OS) and disease-free survival (DFS). RESULTS: A tumoral senescence signature (SS) was present in 48 out of 155 NSCLC patients, but did not correlate to any clinicopathological parameter, except for p53 mutation status. In a histologically homogenous patient cohort of 100 patients who fulfilled the following criteria: (I) one type of histology, i.e., adenocarcinoma, (II) without known epidermal growth factor receptor (EGFR) mutation, (III) curative (R0) resection and (IV) no neoadjuvant systemic therapy or radiotherapy, the median OS and DFS for patients with a tumoral SS (n=30, 30.0%) compared to patients without a tumoral SS (n=70, 70.0%) was 53 versus 141 months (P=0.005) and 45 versus 55 months (P=0.25), respectively. In multiple Cox proportional hazards (Cox PH) model analysis correcting for age, pTNM stage I–III and adjuvant therapy, a tumoral SS remained a significant prognostic factor for OS (HR =2.03; P=0.014). CONCLUSIONS: The presence of a tumoral SS particularly based on high p16(INK4a) expression significantly affects OS in NSCLC adenocarcinoma. In this light, adjuvant senolytic therapy could be an interesting strategy for NSCLC patients harboring a tumoral SS, ultimately to improve survival of these patients.