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Treatment implications of the new lung cancer staging system

May 1, 2012|Cleveland Clinic Journal of Medicine
Cristina P. Rodriguez, MD
Author and Disclosure Information

Cristina P. Rodriguez, MD
Division of Hematology & Medical Oncology, Oregon Health & Science University, Portland, OR

Correspondence: Cristina P. Rodriguez, MD, Assistant Professor, Division of Hematology & Medical Oncology, L586, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239; rodrigcr@ohsu.edu

Dr. Rodriguez reported that she has no relationships that pose a potential conflict of interest with this article.

This article was developed from an audio transcript of Dr. Rodriguez’s presentation at the “Advances in Lung Cancer Evaluation and Management” symposium held in Cleveland, Ohio, on April 30, 2011. The transcript was formatted and edited by Cleveland Clinic Journal of Medicine staff for clarity and conciseness and was then reviewed, revised, and approved by Dr. Rodriguez.

ABSTRACTThe American Joint Commission on Cancer along with the International Association for the Study of Lung Cancer (IASLC) has published new guidelines for lung cancer staging based on observations from 100,869 lung cancer patients. Revised tumor, node, metastasis (TNM) criteria were derived from IASLC patient survival curves, and were validated using data from the Surveillance, Epidemiology, and End Report program. The seventh edition TNM classification revised the T1, T2, T3, and M1 descriptors. It is estimated that 10% to 15% of newly diagnosed lung cancer patients will be assigned a different disease stage as a result of these changes.

N criteria unchanged

The N criteria subcommittee recommended that the existing N staging criteria should be retained without revision from the sixth edition.

M1 reclassified and subdivided

In the sixth edition, M1 disease was defined as any distant metastasis, including separate tumor nodules in a different lung lobe. In the seventh edition, pleural dissemination is reclassified from category T4 to M1 owing to significantly poorer survival among these subgroup of T4 patients.2 In addition, M1 disease is divided into two subcategories. M1a disease is defined as one or more tumor nodule(s) in a contralateral lobe, tumor with pleural nodules, or malignant pleural or pericardial effusion, whereas M1b disease is defined as any distant metastasis.

WHAT ARE THE IMPLICATIONS OF A NEW STAGING SYSTEM?

It is estimated that approximately 10% to 15% of newly diagnosed patients with lung cancer will be assigned to a different disease stage on the basis of this new classification system.6 Table 2 compares cancer staging using the sixth and seventh edition TNM classification criteria and includes the proportion of patients in the IASLC database who would be upstaged or downstaged.6 For example, 3.8% of patients in the IASLC database would be upstaged from the former stage 1B to the new stage 2A, and approximately 4.4% of patients would be downstaged from 2B to 2A.

These changes to lung cancer staging may have significant implications for clinical decision-making. In a recent survey, clinicians who treat lung cancer were presented with three patient scenarios in which the lung cancer stage differed between the sixth and seventh AJCC editions.6 The clinicians were first presented with the clinical vignettes accompanied by their sixth edition designations, and then with their seventh edition designations. At each presentation, clinicians were asked to choose from several possible management options. Approximately 77% of clinicians surveyed changed their management strategy based on the change in staging classification.

SUMMARY AND CONCLUSIONS

The AJCC seventh edition TNM classification is based on internally and externally validated survival curves derived from tens of thousands of patients with different disease characteristics enrolled at study sites around the world. Because the treatments received by the patients are not included in this analysis, it is essential to exercise caution when using staging information to make treatment decisions. Prospective patient data will be required to determine whether this classification system significantly improves long-term treatment outcomes. In addition, it will be important to consider the potential effects of different staging systems when comparing the results of clinical trials.

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