1. Metastasis Steps to metastases:
Theories explaining trends in metastases:
“Seed & soil” theory
Routes of blood supply theory
Both partially correct
“in broad terms, tumour spread through lymphatics will produce metastases in the anatomically related lymph nodes whilst spread through the blood is influenced more by ‘seed and soil’ considerations although anatomy is still of some importance”
Steps to metastases:
Tumour must grow to infiltrate surrounding connective tissue
Break through basement membrane
Overcome inhibitor substances to the enzymes it produces to break down the connective tissue proteins
Attach to endothelium and enter lymphatic/blood vascular channels
Evade immune cells in blood/lymph
Lodge in capillaries at destination
Attach to and travel through endothelium
Proliferate and produce tumour

2. Routes of metastasis spread

3. Staging for NSCLC

4. Treatment for NSCLC Surgery
Complete surgical removal of NSCLC offers the best possibility of a cure.
Appropriate for patients with stage I–II disease who are fit for surgery.
Chemotherapy
Systemic treatment improves symptoms from advanced disease, and has a modest survival benefit.
Appropriate for patients with stage III–IV disease particularly with good performance status.
Developing role prior to surgery and as adjuvant therapy for stage I–II.
Radiotherapy
Effective local treatment, giving prompt symptom relief from advanced disease especially involving large airways.
Can be curative in stage I–II and, infrequently, stage III.

5. Staging for SCLC SCLC accounts for 15–20% of all lung cancers.
Staging and management are quite distinct from NSCLC because:
almost all SCLC demonstrate rapid growth and early dissemination;
> 90% have systemic disease at presentation;
surgery is inappropriate in the vast majority—less than 10% are operable;
chemotherapy is the key primary treatment and has an important impact on survival.
A much simplified staging system is used for SCLC as the vast majority of patients are initially treated with chemotherapy irrespective of disease extent. A two-stage system was drawn up by the Veterans Administration Lung Group.
Limited-stage disease Tumour confined to one hemithorax and regional lymph nodes, and can be covered by tolerable radiotherapy fields.
Extensive-stage disease Disease beyond these bounds.