The 8th lung cancer TNM classification and clinical staging system: review of the changes and clinical implications

Abstract

Lung cancer is the leading cause of cancer death in both men and women. Clinical staging plays a crucial role in predicting survivor as well as influencing management option in lung cancer patients. Guidelines are constantly being reviewed as more data becomes available to provide the most accurate prognostic markers, hence aiding in the clinical detection and staging of lung cancer. Since its introduction in the 1970s, the TNM staging has undergone significant revisions with the latest, 8 edition, being effective internationally from 2018. This edition re-categorizes the tumour size and other non-quantitative tumour descriptors (T), and further subclassifies extra-thoracic metastases (M). The clinical nodal (N) classifier is unchanged as the earlier version correlates well with prognosis. The downstream effects on staging to accommodate for the new T and M classifications are highlighted. The survival is inversely proportional to every centimeter increase in tumour size up till 7 cm, where the same prognosis as a T4 disease is reached. Hence, some of the T-classifiers based on size of the tumour is upstaged to reflect that. Invasion of the diaphragm is considered T4 instead of T3. On the other hand, involvement of the main bronchus regardless of tumour distance to carina as well as atelectasis is down-staged from a T3 to a T2 disease. Since the 7 edition, new entities of lung tumour known as adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) have been introduced. The T-defining features are also described in this manuscript. Extrathoracic metastases that were classified as M1b in the 7 edition is further subcategorized into M1b and M1c in the 8 edition, to better define oligometastasis which has a better prognosis, and may benefit from more aggressive local therapy. This overview aims to provide radiologists with a description of the changes in the latest edition including staging of subsolid and multiple nodules, outline potential limitations of this 8 edition, as well as discussion on the implications on treatment.

New perspective to evaluate N1 staging: The peripheral lymph node metastasis status of non‐small cell lung cancer

“…Previous studies have focused on N2 station LN metastasis due to its poor prognosis and complicated therapy pattern. Some studies have revealed that the subclassification of N1 LNs (single N1 involvement and multiple N1 involvement) were associated with the prognosis of patients with NSCLC . However, fewer studies have focused on the zone of N1 LN metastasis, and there is little knowledge about N1 station LN dissection, especially with regard to the dissection scope of N1 station LNs.…”

“…Some studies have revealed that the subclassification of N1 LNs (single N1 involvement and multiple N1 involvement) were associated with the prognosis of patients with NSCLC. 12,13 However, fewer studies have focused on the zone of N1 LN metastasis, and there is little knowledge about N1 station LN dissection, especially with regard to the dissection scope of N1 station LNs. At present, most surgeons do not proceed further than N1 station LN resection and classification at the levels 10, 11 and 12, and hardly any clinical attention is given to resection and sorting of intrapulmonary LNs, especially PLN.…”

“…According to the latest edition, lung cancer TNM stage classification, N1 station LNs are divided into two zones, including hilar/interlobar zone (regrouping levels 10 and 11) and peripheral zone (regrouping levels 12,13,14), which is proposed for future survival analysis. 5 Previously, many studies have focused on LN metastasis in N2 station, [6][7][8] but fewer studies have focused on LN metastasis in N1 station, especially on PLNs.…”

Microwave ablation combined with chemotherapy improved progression free survival of IV stage lung adenocarcinoma patients compared with chemotherapy alone

“…A total of 49 patients were enrolled into this retrospective study at the Department of Thoracic Surgery and Oncology, Jinan Central Hospital and the Department of Respiration and Oncology, Qilu Hospital of Shandong University between January 2013 and December 2015. The inclusion criteria were as follows: (i) Patients were confirmed to have lung adenocarcinoma following biopsy pathology; (ii) Only stage IV patients were included, and the clinical TNM staging system was summarized by the Union for International Cancer Control (UICC, 8th); (iii) Patients had not accepted any anticancer treatments such as surgery, chemotherapy, radiotherapy and targeted therapy before enrollment into the study. Patients had EGFR‐insensitive mutations or could not accept EGFR‐TKIs as the first‐line therapy; (iv) Patients scored 0–2 according to Eastern Cooperative Oncology Group (ECOG).…”

Influence of biological markers on overall survival in surgically treated patients with non-small cell lung cancer

“…Surgery represents a treatment of choice for patients with NSCLC stage I-IIIA according to tumor, node, metastasis (TNM) 8 th edition classification 7,8 . In addition to surgery, patients with resected NSCLC stage II-IIIA, who have a high risk of relapse, are treated with adjuvant chemotherapy and/or radiation therapy 6,9 .…”