IASLC grading system predicts distant metastases for resected lung adenocarcinoma.

Aims: The International Association for the Study of Lung Cancer (IASLC) has proposed a new histological grading system for invasive lung adenocarcinoma (LUAD). However, the efficacy of this grading system in predicting distant metastases in patients with LUAD remains unexplored. This study aims to assess the potential of the IASLC grading system in predicting the occurrence of brain and bone metastases in patients with resectable LUAD, thereby identifying individuals at high risk of post-surgery distant metastasis.

Methods: We retrospectively analysed clinical data and pathological reports of 174 patients with early-stage LUAD who underwent surgical resection between 2008 and 2015 at our cancer center. Patients were monitored for 5 years, and their bone and brain metastasis-free survival rates were determined.

Results: 28 out of 174 patients developed distant metastases in 5 years with a median overall survival of 60 months for metastasis-free patients and 38.3 months for patients with distant metastasis. Tumour grading of all samples was evaluated by both IASLC grading and predominant pattern-based grading systems. Receiver operating characteristic (ROC) curves were used to evaluate the predictive capabilities of the IASLC grading system and tumour stage for distant metastasis. Compared with the predominant pattern-based grading system, the IASLC grading system showed a better correlation with the incidence of distant metastasis and lymphovascular invasion. ROC analyses revealed that the IASLC grading system outperformed tumour stage in predicting distant metastasis.

Conclusions: Our study indicates that the IASLC grading system is capable of predicting the incidence of distant metastasis among patients with early-stage invasive LUAD.