History
Presenting Complaint
Lung cancer of any type may present with symptoms related to:
- Local Disease (dyspnoea, cough, haemoptysis, pain, hoarse voice, upper body swelling due to SVC obstruction)
- Paraneoplastic disease (hypercalcaemia, syndrome of inappropriate ADH)
- Metastatic disease (bony pains, headache/confusion from cerebral metastases)
In small cell lung cancer, these complaints are often present for a shorter period of time due to the rapidity of disease growth. SCLC is commonly located within the central parts of the lung, leading to an increased likelihood of hoarse voice and SVC obstruction. Brain metastases are also more commonly seen at diagnosis when compared to non-small cell lung cancer. The paraneoplastic syndromes are also more commonly associated with small cell lung cancer. SIADH is seen in about 15% of SCLC patients. A lesser number of patients develop Cushing's disease from tumour production of adrenocorticotrophic hormone (ACTH). Finally, neurological paraneoplastic syndromes can be seen in SCLC. The hypothesis is that antibodies directed against the neuroendocrine small cell lung cancer cells may cross-react against neurons or other normal tissues. This is true of Lambert-Eaton myasthenic syndrome and a number of other neurological paraneoplastic syndromes. Neurological decline may be rapid and permanent, leading to death from this complication rather than the tumour bulk.
Past History
Patients may have a past history of smoking related diseases, such as cardiovascular disease or chronic obstructive pulmonary disease. Other diseases which may limit the applicability of radiotherapy or chemotherapy should be evaluated (eg. connective tissue or joint diseases, previous radiotherapy treatment for a different cancer).
Medications
It is important to document the use of radiosensitising agents (eg. methotrexate).
Allergies
No specific questions.
Family History
Specific familial mutations leading to lung cancer are difficult to identify. Those who smoke are likely to have relatives who smoke, and therefore higher rates of lung cancer are expected.
Social History
The patients ability to manage the intensive chemotherapy (and/or radiotherapy) schedule should be identified. Rural patients may need to spend a significant portion of time away from home.
Examination
Examination should be directed to:
- Identifying extent of local disease (full respiratory examination)
- Identifying lymphatic spread (supraclavicular fossa)
- Identifying metastatic disease (abdominal examination, neurological examination if indicated on history)
Bloods
Standard bloods should be ordered:
- Full blood examination (evidence of anaemia or bone marrow failure)
- Renal function and electrolytes (evaluation of SIADH or derangement of other electrolytes due to paraneoplastic processes)
- Liver function tests
Imaging
Plain X-Ray
Although lung cancer may be visible on plain x-ray of the chest, it provides insufficient information in the modern day to guide treatment decisions.
CT Chest/Upper Abdomen
The staple test of lung cancer imaging. The CT allows:
- Determination of the size and location of the primary tumour
- Presence of enlarged lymph nodes in the mediastinum and supraclavicular fossa
- Presence of pleural effusion or satellite lung nodules
- Detection of liver or adrenal metastases
MRI Brain
MRI of the brain is a useful investigation in patients with symptoms of neurological involvement; it is not routinely used in asymptomatic patients.
PET Scan
PET scan can provide useful information in patients with supposed limited-stage disease, but has no role in patients with extensive stage small cell lung cancer.
Whole Body Bone Scan
WBBS is useful for patients with symptoms of bony metastases, as it allows evaluation of the entire skeletal system at once
Histological Diagnosis
Most small cell lung cancers arise from the proximal bronchi, and as such bronchoscopy and biopsy or washings are usually successful means of detecting these tumours. More uncommonly, peripheral lesions may require CT guided biopsy for diagnosis.
Small cell lung cancer is a typical 'small round blue cell tumour'. The cells have a high nuclear-cytoplasm ratio, often with moulded nuclei and granular chromatin. Necrosis is usually present. There is a high mitotic rate. Cells stain positively for chromogranin, synaptophysin and other neuroendocrine markers. Small cell lung cancer is differentiated from other neuroendocrine tumours by the size of the cells, the presence of necrosis and the high mitotic index (often 70-80 per 10 high power fields compared with carcinoid tumorus which usually have < 10).
Staging
Staging for small cell lung cancer is usually done through the Veterans Administration Lung Study Group (VALSG), which classifies the cancer as either 'limited stage' or 'extensive stage' based on the ability of the tumour volume to be encompassed within a radiotherapy portal. With the development of more advanced radiotherapeutic techniques, the distinction of limited and extensive stage is more complex. There are no universally accepted guidelines for limited and extensive stage disease.
TNM staging can still be used.
T Stage
- T1: Tumour < 3 cm, not involving the main bronchi or visceral pleura
- T2: Tumour 3 - 7 cm, or involving the main bronchi but greater than 2 cm from the carina, or involving the visceral pleura
- T2a: Tumour 3 - 5 cm
- T2b: Tumour 5 - 7 cm
- T3: One of:
- > 7 cm
- Closer than 2 cm to the carina, without carinal involvement
- Involvement of parietal pleura, chest wall, mediastinum or pericardium
- Tumour causing collapse of a lung segment or lobe
- Multiple nodules within the same lung lobe
- T4: One of:
- Invasion of mediastinum, heart, trachea/carina, spine or great vessels
- Multiple nodules in different lobes of the same lung.
N Stage
- N1: Hilar nodes
- N2: Ipsilateral mediastinal nodes or subcarinal nodes
- N3: Contralateral mediastinal nodes or supraclavicular nodes
M Stage
- M1a: Pleural effusion, nodules in contralateral lung
- M1b: Other distant metastatic disease
Overall Stage
| Stage | T | N | M | VALSG |
|---|---|---|---|---|
| IA | T1 | N0 | M0 | Limited |
| IB | T2a | N0 | M0 | Limited |
| IIA | T1 T2a T2b |
N1 N1 N0 |
M0 | Limited |
| IIB | T2b T3 |
N1 N0 |
M0 | Limited |
| IIIA | T1-3 T3 T4 |
N2 N1 N0-1 |
M0 | Limited |
| IIIB | TAny T4 |
N3 N2 |
M0 | Limited |
| IV | TAny | NAny | M1a M1b |
Extensive |
