Lung cancer Flashcards
What are the major pathological classifications of lung cancers?
(list)
Split into small cell disease (20%) and non-small cell disease (80%)
- Non-small cell lung cancer (80%)
- Squamous cell carcinoma - 50%
- Adenocarcinoma - 20%
- Large cell anaplastic tumours - 10%
- Small cell anaplastic carcinoma (20%)
- AKA oat cell carcinoma
Describe the pathology of squamous cell carcinoma (SCC) of the lung
- SCCs arise from squamous metaplasia of the normally psuedostratified ciliated columnar epithelium, in response to cigarette smoke exposure
- They are usually central, and close to the carina, thus frequently present with collapse/infection secondary to obstruction
- They may secrete PTH, causing hypercalcaemia
- They are friable tumours so can often be diagnosed with sputum cytology
- They are relatively slow growing compared to other tumours, and may be resectable
Describe the pathology of adenocarcinoma of the lung
- Equal gender incidence unlike the other (3:1 male: female)
- Characteristically orginate in peripheral locations, potentially in areas of previous lung scarring
- Bronchoalveolar carcinoma is a special type of adenocarcinoma, accounting for less than 5% but associated with a better prognosis
Describe the pathology of large cell anaplastic carcinoma of the lung
- Features showing SCC or adenocarcinomatous origins may be seen, but they are not differentiated enough to be classified
- They have a poor prognosis, and are often widely disseminated at diagnosis
Describe the pathology of small cell anaplastic carcinoma of the lung
- Aka oat cell carcinoma, as the cell nuclei resemble oat grains
- Arises from neuroendocrine “Kulchitsky” cells, and expresses markers e.g. NCAM-1
- Usually centrally located, and rapidly growing
- The most highly malignant of lung cancers, often metastasied at diagnosis
- Originate from the bronchial epithelium, but differentiate into neuroendocrine cells to secrete active products:
- ADH: symptoms of SIADH - dillutionall hyponatraemia due to retention of water but not solute, leading to muscle weakness, cheyne-stokes respiration and neurological signs
- ATCH: Cushing’s syndrome
- They can also rarely cause Myasthenia Gravis like symptoms in ‘Eaton-Lambert syndrome’
- Reduced tendon reflexes
- Dry eyes, sexual inpotence and neuropathy
- Symptoms get better with usage unlike MG
Describe the risk factors for lung cancer
- Smoking
- Passive smoking (1.5x)
- living in an urban area
- Asbestos
- petroleum products
- radiation
- coal tar
- multiple other occupations exposures - Most occupational exposures related to adenocarcinoma, with less of a link with smoking.
- Family history (genetics) and fibrosis may also play a role in cancer development
Outline the epidemiology of lung cancer in developed countries
Lung cancer represents 13.6% of cancer load in the UK, but 22% of cancer-related deaths. The male:female ratio is 3:1
Describe the common clinical presentation of lung cancer
Symptoms and signs
Clinical features: (symptoms)
- Persistant cough: due to distal infection
- Haemoptysis: due to ulceration of the tumour
- Dyspnoea: due to ulceration of the tumour
- Chest pain: due to pleural/chest wall involvement
- B symptoms: e.g. fever, night sweats, weight loss
On examination: (signs)
- Clubbing
- Cachexia
- Signs of anaemia
- Hypertrophic pulmonary osteoarthropathy
- Paraneoplastic syndrome: clubbing and painful periosteitis of small joints of the hand
- Chest signs of collapse/consolidation/effusion
- Signs of metastases
What can local invasion of lung cancer cause?
i.e. what stuctures are affected?
- Recurrent laryngeal nerve palsy
- Change in voice, left cord paresis
- If present, indicates inoperability
- Phrenic nerve palsy
- asymptomatic if unilateral
- SVC obstruction
- Raised JVP
- raised arm BP/swelling
- facial swelling
- Often due to lymph nodes rather than the tumour itself
- Pancoast syndrome
- Malignant neoplasm of the lung apex, leading to destructive lesions of the thoracic inlet, often involving the brachial plexus
- Horner’s syndrome (miosis-pupil constrition, ptosis-drooping of upper eyelid, anhydrosis-inability to sweat in forehead)
- Shoulder pain, radiating along the ulnar forearm and hand
- Atrophy of hand/arm muscles
- Oedema (due to blood vessel compression)
- Pericarditis
- Atrial fibrilation
What paraneoplastic syndrome can local metastic manifetions of lung cancer cause?
- Hypertrophic pulmonary osteoarthropathy
- clubbing and periostitis of the small hand joints
- Distal expansion of the long bones as well as painful, swollen joints and synovial villous proliferation are often seen
- Lamert-eaton syndrome - resulting in muscle weakness
- SIADH
- Secondary Cushing’s
- HyperPTH
What investigation would you do for a patient with suspected lung cancer?
What might you find if they did have lung cancer?
- FBCs:
- anaemia/secondary polycthaemia (too many RBCs)
- LFTs:
- signs of liver metastases
- U&Es:
- hypercalcaemia, hyponatraemia
- CXR
- Sputum/pleural fluid cytology
- Staging CT: head to pelvis
- Biopsy: CT guided if peripheral, via bronchoscopy if central
- Pulmonary function tests: useful if planning surgery
- PET scan/radionucleotide bone scan if suspected metastatic diesease
Describe a bronchoscopy procedure to a patient
Fibre optic tube is passed through the nose, then the oropharynx and finally the pharynx, larynx, trachea and is able to visualise the carina and bronchioles. The patient may be offered a local anaesthetic spray, or, it may be done in the anaesthetic room pre-operatively.
