Staging Of Lung Cancer

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[edit] Staging Of Lung Cancer

Once lung cancer has been confirmed by bronchoscopy the physician must assess how far the cancer has advanced at the time of diagnosis, before treatment can start. The reason for this are very different treatment protocols that are needed for the successful treatment of lung cancer. The lung cancer stage are: stage I, II, IIIA, IIIB and IV. Following the initial X-ray, the physician will then order a CT scan in order to further characterize the lung lesion.

The CT scan can show whether or not the lymph glands in the chest are involved or not. If there are lymph glands in the chest, a thoracic surgeon may be called in to do a mediastinoscopy, where the surgeon can look into the space between the lungs and the rib cage and assess the extent of the metastases in this otherwise difficult to assess space. The oncologist will want to continue to do the staging tests by doing CT scans of the liver, the adrenal glands and the brain to determine whether distant metastases are present. Blood tests and bone scans will rule out bone metastases. Finally, when all this information is gathered, the oncologist can do what is called an " extent of disease evaluation". The following would be found for the various stages:

Extent of disease evaluation
Stage:	Extent of lung cancer:
I	solitary lung tumor of less than 3 cm (=1 1/4") in diameter
II	tumor more than 3cm(= 1 1/4") in diameter, local lymph gland metastases on same side as tumor
IIIA	peripheral lung tumor: invaded chest wall; central lung tumor: invaded distal mediastinal nodes on the same side
IIIB	same as stage IIIA, but more extensive lymph gland invasion involving mediastinal organs and pleural cavity
IV	Any of the above stages, but in addition distal metastases

Why are oncologists "wasting time" to do the staging procedures? Studies over several decades have taught us that treatment of cancer without staging often gives everyone a false sense of security, where they learn later that the real extent of the cancer was much worse than originally thought.

While everyone was thinking no further therapy was necessary, the cancer quietly multiplied and spread until it was too late to do anything about it. With the progress in the treatment of childhood leukemia oncologists learnt that long-term survival and cure rates could be significantly improved with adequate staging in the beginning and by following appropriate treatment protocols. In the last few years this has paid off for lung cancer as well. The following is a survival map for the various stages of lung cancer (modified from Ref. 1 and 2):

Lung cancer (5-year survival rate)
Stage of lung cancer:	5-year survival rate:
Carcinoma in situ	› 90 %
I	60-80 %
II	25-50 %
IIIA	15-35 %
IIIB	› 5 %
IV	› 5 %

This table shows that the 5-year survival is fairly good when lung cancer is detected by bronchoscopy (cancer in situ). However, when there are symptoms of coughing up blood or having a chronic cough, the later stages are found and the survival rate is very poor.

Compared to other cancers the survival rate drops off already at stage two, which is likely due to the fact that lung tissue is full of blood vessels and that it spreads very fast when there is early invasion by the cancer.

This means that people at risk to develop lung cancer need to have regular bronchoscopies done to screen for lung cancer and hopefully diagnose it at the carcinoma at situ stage rather than a later stage with a much poorer 5-year survival.

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References:

1. Cancer: Principles &Practice of Oncology, 4^th edition, volume 1. Edited by V.T. De Vita,Jr., et. al J.B. Lippincott Co.,Philadelphia, 1993. Chapter on lung cancer.

2. Cancer: Principles&Practice of Oncology. 5th edition, volume 1. Edited by Vincent T. DeVita, Jr. et al. Lippincott-Raven Publ., Philadelphia,PA, 1997. Chapter on lung cancer.

3. The Merck Manual, 7^th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 81: Tumors of the lung.

4. GW Krystal et al. Clin Cancer Res 2000 Aug;6(8):3319-3326.

5. BJ Druker et al. N Engl J Med 2001 Apr 5;344(14):1031-1037.

6. MJ Mauro et al. Curr Oncol Rep 2001 May;3(3):223-227.

7. Conn's Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier

8. Ferri: Ferri's Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc