Lung cancer

Lung cancer.

Prognosis by stage and type – small vs. non-small cell.

Adenocarcinomas, squamous cell carcinomas and anaplastic large cell tumours are collectively known as non-small cell tumours, or large cell tumours to differentiate them prognostically and therapeutically from small cell tumours (‘oat cell’ tumours.) Bronchoalveolar carcinoma, another large cell type, spreads along bronchial walls, and may cross into the other lung. It may present as an unresolving lobar pneumonia.

Survival rates

A review¹ makes the point that after many years of research effort, overall survival rates at five years are still of the order of 14%. Figures are highly dependent on stage. Small cell disease confined to one hemithorax has a five year survival of 20%, but once outside the ipsilateral thorax, this drops to less than 5%. For non-small cell stage I (more than 2cm from the carina) it is 65%; once ipsilateral nodes are involved (stage II) it drops to 45%, and then to 15% with involvement of ipsilateral mediastinal nodes (IIIA.) Invasion of the mediastinum or the presence of a malignant pleural effusion (IIIB) drops it further to 7%, and with extrathoracic metastases (IV) it is 1%. It is important to note that these figures apply to individuals actually given appropriate oncotherapy.

Sputum cytology and FNAB versus bronchoscopy

Deciding which investigative route to pursue should be dictated by the probable stage of the disease and the presence of other intercurrent illnesses: an 80 year old man with a large upper lobe mass contiguous with the chest wall, with concurrent COPD and chronic renal failure warrants a much gentler workup than an otherwise completely well 40 year old with a 1 cm lesion in the parenchyma. In the former, the lesion is clearly inoperable and so diagnosis is for prognostication and to assist with arranging palliation. In the latter, more prompt work-up may improve outcome. The former can comfortably provide a few sputa for cytology, probably even as an outpatient, whereas the latter should be investigated promptly by either bronchoscopy or CT guided FNAB if sputum does not give an immediate answer.

Perspective – cytology versus bronchoscopy versus aspiration biopsy

One review² gave pooled sensitivities of 66% for sputum cytology, 74% for bronchoscopy, and 90% for transthoracic needle aspiration. However, if sputum is sent off on almost every older person who presents with chest pathology, the yield will be considerably lower, with one study quoting a sensitivity of only 5%. The yield of sputum cytology is related to the number of specimens. In one early study,³ sensitivity was 0.68 for one specimen, 0.78 for two specimens, and 0.86 for three or more specimens. It may be appropriate to take larger numbers of specimens (e.g. 6) in patients with a high index of suspicion for lung cancer and a technical impediment to proceeding on to either bronchoscopy or transthoracic needle aspiration.

Management of lung cancer

Surgery is only an appropriate consideration for large cell carcinomas Stage I, II and IIIa. This means that patients with contralateral lymph nodes or tumours involving the mediastinum or vertebrae, or causing a pleural effusion are not considered suitable candidates for surgery. Mean survival in such individuals is 8 months. Small cell carcinoma or higher stage large cell carcinomas do not benefit much if at all from surgery. If patients do get surgery (a small proportion), five-year survival is 25%. All the other large cell carcinoma patients, and all small cell tumour patients should be considered for radiotherapy if there is pain, haemoptysis or cough. Chemotherapy may be considered in some patients with small cell carcinomas.

1. Spira A, Ettinger DS. Multidisciplinary management of lung cancer. N Engl J Med. 2004;350:379-92 ↩

2. Schreiber G, McCrory D. Performance Characteristics of Different Modalities for Diagnosis of Suspected Lung Cancer. Chest. 2003;123:115S-128S ↩

3. Johnston W, Bossen E. Ten years of respiratory cytopathology at Duke University Medical Centre. I. The cytopathologic diagnosis of lung cancer during the years 1970 to 1974, noting the significance of specimen number and type. Acta Cytol. 1981;25:103-7 ↩