PBL 46 Flashcards
What are the 2 main sub-types of lung cancer?
- NSCLC
2. SCLC
What is the most common subtype of lung carcinoma?
Non-small cell lung carcinoma (87%) of which the majority are adenocarcinomas (40%)
What are the main causes of lung cancer?
- Smoking (90%)
- Occupational exposure to carcinogens such as radon, arsenic, asbestos, chromates, nickel (9-15%)
- Environmental radon (10%)
- Outdoor and indoor air pollution (1-2%)
- Underlying chronic lung disease
- FHx
Adenocarcinoma common driver mutations
- EGFR
- ALK
- KRAS
Which of the adenocarcinoma common driver mutations is most commonly seen in smokers and which is more common in non-smokers?
Smokers - KRAS mutation
Non-smokers - EGFR mutation
Non-small cell lung carcinomas are all associated with which lifestyle activity?
Smoking
What are the most common types of NSCLC?
- Adenocarcinoma (40%)
- Squamous cell carcinoma (20%)
- Large cell carcinoma (2%)
Squamous cell carcinoma has more mutations per megabase than other common cancers, true or false?
TRUE
What is the most frequent gene mutation in squamous cell carcinoma?
TP53 (encodes P53 protein)
Which of the subtypes of lung carcinoma is has the worst prognosis?
Small cell lung carcinoma (SCLC)
What are the common driver mutations for small cell carcinoma?
TP53 and RB1 - inactivated in 100% of tumours!
Mutation of which gene is said to be a hallmark of SCLC?
RB1
Explain the pathogenesis of squamous cell carcinoma?
- Normal respiratory epithelium - pseudostratified columnar ciliated epithelium
- Squamous metaplasia - adaptive process caused by irritation to bronchial epithelium (smoking etc), now you have squamous cell epithelium replacing the pseudostratified columnar ciliated (bronchial) epithelium because it is more resistant to these irritants
- Squamous dysplasia - since the squamous epithelium is not meant to be in this area, it goes through unregulated mutations and eventually dysplasia occurs. This is disordered cell growth which is seen by a loss of normal architecture and of uniformity of individual cells. PRECEDES BUT DOES NOT INVARIABLY LEAD TO CANCER
- Malignancy - Excessive growth of abnormal squamous cells. Locally invasive. Able to form metastases via lymphatics and blood vessels
Explain the pathogenesis of adenocarcinoma
- Pneumocytes lining epithelia begin changing from squamous cells to cuboidal cells, this is atypical alveolar cell hyperplasia = precursor lesion
- Eventually the tumour becomes invasive and infiltrates normal tissue
Common symptoms of lung carcinoma
- Cough (75%)
- Weight loss (40%) ADVANCED SIGN
- Chest pain (40%) ADVANCED SIGN
- Dyspnoea (20%)
Local effects of a lung carcinoma (in the lungs) - explain how for each one
- Pneumonia/abscess/lobar collapse - Tumour airway obstruction may cause tissue distal to the obstruction to become infected
- Lipid pneumonia - Secretions accumulate distal to the blockage (including lipid rich surfactant) can cause lipid pneumonia as airspaces are filled up with cells so no gas exchange
- Pleural effusion - Tumour spread to the pleura
- Hoarseness - Tumour invades the recurrent laryngeal nerve
Local effects of a lung carcinoma (extra to the lungs) - explain why for each
- Dysphagia - oesophageal invasion by tumour
- Diaphragm paralysis - phrenic nerve invasion by tumour
- Rib destruction - chest wall invasion by tumour
- SVC syndrome - SVC compression by tumour
- Horner syndrome - Sympathetic ganglia invasion by tumour at apex lung (Pancoast tumour)
- Pericarditis - pericardial involvement
- Pancoast tumour - brachial plexus invasion leads to hand muscle weakness and axillar & shoulder pain
What is Horner syndrome? S&S?
Combination of signs and symptoms caused by disruption of sympathetic ganglia which innervated the face and eye on one side of the body
S&S:
- Constricted pupil (miosis)
- Drooping of upper eyelid (ptosis)
- Absence of face sweating (anhidrosis)
SVC compression occurs particularly with tumours that spread to which lymph nodes?
Mediastinal lymph nodes
Systemic effects of lung carcinoma
- Metastatic spread: bone, brain, liver, skin, adrenal glands
- Paraneoplastic syndromes (S&S due to a tumour) secondary to ectopic production of hormones by the lung cancer cells
- Lambert-Eaton myaethnic syndrome - auto-antibodies against neuronal calcium channels
- Peripheral neuropathy
- Dermatological abnormalities
- Haematological abnormalities
- Hypertrophic pulmonary osteoarthropathy with clubbing
Examples of paraneoplastic syndromes secondary to ectopic production of hormones by the lung cancer cells
- ADH - hyponatraemia (commonly in SCLC)
- ACTH - Cushing syndrome
- Parahormone - hypercalcaemia (commonly in squamous cell carcinoma)
- Calcitonin - hypocalcaemia
- Gonadotrophins - gynaecomastia
- Serotonin and bradykinin - carcinoid syndrome
Treatment for lung cancer
- Surgery
- Radiation therapy
- Chemotherapy
- Targeted therapy
Main treatment for NSCLC that has not spread beyond the lung?
Surgery
When may surgery for NSCLC not be possible?
When it has spread beyond the lungs
When it is too close to the trachea
If the person has other serious conditions (severe heart or lung disease)