TNM staging update for lung cancer: Why is this important?

Abstract

Cancer staging characterises the extent of disease facilitating selection of the most appropriate management and therapy and providing prediction of prognosis. As understanding of lung cancer evolves the opportunities arises to adjust disease staging. The adoption of the 7th edition tumour, node, metastasis staging system should result in improved treatment selection and more accurate prognostic information for the individual patient.

Key Words: Lung cancer, Tumour, Node, Metastasis, Staging

Lung cancer is responsible for around 1.3 million deaths word-wide with its incidence still rising, particularly in women. Outlook for lung cancer patients remains poor with an over-all five year survival of around 15%. Correct staging is essential to tailor optimal management and choose the appropriate therapy with lowest mortality and morbidity for the individual patient. Staging also allows more accurate prediction of prognosis. Because the use of staging systems allows continuity in data collection and temporal comparison such systems should not be altered without good cause. However novel technologies and the availability of computer aided data-sets on large surgical and non-surgical cohorts have enabled greater accuracy of outcome prediction, revealing potential areas for improvement in the lung cancer staging system, and as this new data on tumour biology and tumour response to therapy has become available honing of the system has become possible and the time has now been reached where an update of the staging system incorporating this knowledge is advisable. This update is more extensively discussed in the article by Mirsadraee et al[1] in this issue of the World Journal of Radiology.

The lung cancer reflect the appropriate therapy and particularly whether a malignancy may be amenable to potentially curative surgery. Many details of the 7th edition[2] are unchanged providing continuity with the 6th edition. The main changes are: a more precise characterisation of tumour size in T staging, differentiation of staging of satellite pulmonary nodules depending on their location and the differentiation of intrapulmonary from extrapulmonary metastatic disease. There has also been upstaging of some disease such as pleural and pericardial effusions where outcome data has shown involvement to result in poorer prognosis. Another development with version 7 is the recommendation for it’s use for staging of not just non-small cell lung cancer as with version 6 but also small cell lung cancer and carcinod tumours. The revision of the lung cancer staging system is being overseen by the International Association for the Study of Lung Cancer.

This is an on-going project and version 7 does not include information from newer developments such as positron emission tomography-computed tomography (PET-CT) scanning. Data collection is already underway as part of the 7 year cycle in preparation for the 8th edition of the lung cancer tumour, node, metastasis (TNM) staging, which will very likely incorporate the PET-CT data that are now part of routine management in many countries.

The 7th edition TNM staging system is now in widespread use and it is hoped that it’s introduction will result in better management of the individual patient and contribute to improved outcomes for patients who develop this common malignancy.