Journal of Thoracic Oncology:
Letters to the Editor
Raj, J Vimal MBBS, FRCR; Coulden, Richard FRCR, FRCP; Entwisle, James MBBS, MRCP, FRCR
University Hospitals of Leicester; Glenfield Hospital; Leicester, United Kingdom
Disclosure: The authors declare no conflicts of interest.
To the Editor:
We read recent articles from the International Association for the Study of Lung Cancer staging project (especially relating to T and N staging) with interest.1,2 We commend the tremendous work of the team and mostly support the proposed new staging system. There are at least three areas where we, as radiologists, feel that this system is suboptimal and find it difficult to stage patients in day-to-day practice.
First, relating to T descriptor, Lymphangitis carcinomatosis (LC), although uncommon, is a distressing form of metastatic lung cancer and has major impact in quality of life with an unfavorable prognosis.3 LC can occur from lymphatic invasion from the primary tumor or nodal spread.4 In other tumors, particularly, spread is thought to be hematogenous. Computed tomography (CT) is the imaging modality of choice and in most cases radiologists are the first to recognize it. In the tumor, node, metastasis (TNM) staging, there is no specific reference to LC, and we have always felt it difficult to give an accurate stage when present. In our practice, most patients with LC have advanced disease and are not candidates for radical treatment. LC may be seen in the same lobe as the primary lesion or may involve other ipsilateral lobes or both lungs. This is analogous to a satellite nodule but is likely to carry a poorer prognosis. The histologic diagnosis of lymphangitis is often not confirmed.
With regards to the N stage, we agree with your findings of prognostic difference between single N1/N2 nodes versus multiple N1/N2 nodes. There is substantial heterogeneity in clinical presentation, treatment, and prognosis relating to N2 disease.5 This has been recognized previously and subgroups of N2 disease have been proposed. At one end of this spectrum there is occult N2 disease, not found on conventional imaging workup with CT and CT/positron emission tomography (PET), but found at surgery after lymph node dissection. At the other end is N2 disease invading surrounding mediastinal structures, analogous to T4 stage. The revised TNM in such cases does not reflect the true picture of the disease. Nodal disease invading mediastinal structures is analogous to T4 for the primary tumor stage. It may often be difficult on CT where there is contiguous disease to differentiate where the primary lesion stops and nodal disease starts.
Historically, CT has been the primary investigation with its well-recognized limitations. The introduction of PET and then CT/PET gives more accurate information and is increasingly used in routine staging if patient is fit for radical therapy. The T stage may be expected to take account of metabolic activity in the tumor (Standard uptake value level). Equally intense uptake in N2 groups is likely to have a poorer prognosis than low-level single station uptake. A suspicious contralateral pulmonary nodule seen on CT is likely to be more significant if it shows increased uptake on CT/PET imaging.
If there is sufficient evidence, we would ask the authors to see if these unrepresented but well-recognized areas could be incorporated into the revised staging scheme. Future staging revisions may need to incorporate the developing prognostic information available from anatomic and particularly metabolic imaging techniques.
J. Vimal Raj, MBBS, FRCR
Richard Coulden, FRCR, FRCP
James Entwisle, MBBS, MRCP, FRCR
University Hospitals of Leicester
Leicester, United Kingdom
1. Rami-Porta R, Ball D, Crowley J, et al. The IASLC Lung Cancer Staging Project: proposals for the revision of the T descriptors in the forthcoming (seventh) edition of the TNM Classification for Lung Cancer. J Thorac Oncol 2007;2:593–602.
2. Rusch VW, Crowley J, Giroux DJ, et al. The IASLC Lung Cancer Staging Project: proposals for the revision of the N descriptors in the forthcoming seventh edition of the TNM Classification for Lung Cancer. J Thorac Oncol 2007;2:603–612.
3. Dettino AA, Negri EM, Pagano T. ASCO Annual Meeting Proceedings Part I. Pulmonary lymphangitis and cancer: prospective series of 37 patients in palliative care. J Clin Oncol 2006;24(18S):18600.
4. David SD. CT evaluation for pulmonary metastasis in patients with extrathoracic malignancy. Radiology 1991;180:1–12.
5. Robinson LA, Wagner H Jr, Ruckdeschel JC. Treatment of stage III a non-small cell lung cancer. Chest 2003;123:202S–220S.