Cancer and Thoracic anatomy
Victoria’s X-ray shows diaphragmatic elevation — which nerve is most likely affected?
The phrenic nerve.
What function do Clara (club) cells have in detoxification of inhaled toxins?
Clara cells contain cytochrome P450 enzymes that detoxify inhaled toxins.
Clara cells: secretory cells in the bronchiolar epithelium that detoxify inhaled xenobiotics and pollutants.
Use: cytochrome P-450 enzymes and flavin monooxygenases in their smooth endoplasmic reticulum to metabolize toxins
also secrete Clara cell secretory protein (CCSP/CC16) to reduce inflammation and protect against oxidative damage.
Chronic smoke exposure overwhelms these systems, leading to accumulation of reactive metabolites that cause DNA adduct formation and mutation.
How does COPD increase lung cancer risk?
Chronic inflammation promotes carcinogenesis.
How does population ageing affect national lung cancer burden even when smoking rates decline?
Cancer incidence rises with age due to mutation accumulation. An ageing population increases total case numbers even if incidence per age group declines.
Why does cumulative pack-year exposure correlate more strongly with lung cancer risk than cigarettes per day alone?
Pack-years combine intensity and duration. Carcinogenesis depends on total mutagenic exposure over time, not just daily amount.
Why might involvement of the pleura contribute to chest pain in lung cancer?
The pleura has somatic sensory innervation. Tumour invasion stimulates pain fibres, causing sharp, localised pleuritic pain.
Why are smokers more vulnerable to respiratory infections? (2)
damages cilia
impairs macrophage function
reducing mucociliary clearance and immune defence.
Why might lung cancer cause dyspnoea without airway collapse?
Gas exchange impairment or pleural effusion.
Why does incidence rise after age 40?
Cancer develops after decades of mutation accumulation.
How does smoking affect neutrophil function in respiratory infections?
Smoking causes excessive neutrophil recruitment but impairs their killing efficiency. This increases tissue damage while reducing effective pathogen clearance.
How could a tumour at the lung hilum affect the recurrent laryngeal nerve, and what symptom would this cause?
The left recurrent laryngeal nerve loops under the aortic arch near the hilum. A tumour here can compress it, causing vocal cord paralysis
= hoarseness.
What features help distinguish pneumonia from malignancy?
Infection: Acute onset, Fever, Responds to antibiotics
Cancer: Persistent symptoms, Weight loss, Mass on imaging
Why might lung cancer present with weight loss before severe respiratory symptoms?
Systemic inflammation and tumour metabolism increase energy demand and cause cachexia.
What occupational exposures increase risk?
Radon, asbestos, arsenic.
Why is hypertrophic osteoarthropathy associated with lung adenocarcinoma?
hypertrophic osteoarthropathy: a rare syndrome characterized by digital clubbing, periostitis (inflammation/thickening of long bones), and joint pain (arthralgia).
Tumours may release growth factors that stimulate periosteal bone formation, causing clubbing and joint swelling.
Why does paralysis of the phrenic nerve result in an elevated diaphragm on imaging?
The phrenic nerve (C3–5) controls diaphragmatic contraction. If compressed by tumour, the diaphragm loses motor input and cannot contract downward during inspiration.
the affected diaphragm sits higher.
Why should recurrent infections in the same lung region raise suspicion of lung cancer?
A tumour may partially obstruct an airway, impairing clearance. This causes repeated infection distal to the blockage.
Why are hilar tumours more likely to be squamous cell carcinoma or small cell cancer?
Smoking-related carcinogens deposit in central airways → central tumours.
How might socioeconomic status influence lung cancer incidence beyond smoking behaviour?
Higher smoking prevalence, occupational exposure, delayed healthcare access, and environmental factors increase risk.
Why are neuroendocrine tumours like small cell lung cancer associated with paraneoplastic syndromes?
How could tumor growth/metastasis within the mediastinum lead to SVC syndrome?
SVC syndrome: a critical condition involving obstruction of the main vein carrying blood from the upper body to the heart
A tumour near the hilum can invade or compress the superior vena cava
obstructs venous return from the head, neck, and upper limbs, leading to venous congestion. This causes facial swelling, distended neck veins, and upper limb oedema.
How could chronic inflammation from infection contribute to carcinogenesis? (3)
Chronic inflammation leads to:
Repeated epithelial injury
Increased cell turnover
DNA damage via reactive oxygen species
Over time this promotes mutations and malignant transformation.
How could a Pancoast tumour cause shoulder pain and Horner’s syndrome?
Apical tumours invade:
Brachial plexus = shoulder pain
Cervical sympathetic chain = Horner’s syndrome
How does chronic epithelial injury from smoking lead to genetic mutations seen in NSCLC?
cigarette smoke= polycyclic aromatic hydrocarbons and nitrosamines which cause repeated epithelial injury.
increased cellular turnover and DNA replication.
Reactive oxygen species and direct mutagens induce DNA damage, promoting mutations in oncogenes (e.g. KRAS) and tumour suppressor genes (e.g. TP53).
drives malignant transformation.
How might lung cancer/COPD/chronic lung disease contribute to pulmonary hypertension and how does this cause eventual ___ (right or left?) heart strain?
Tumour burden, hypoxia, and destruction of pulmonary vasculature increase pulmonary vascular resistance. Chronic elevation of resistance leads to pulmonary hypertension, which increases workload on the right ventricle, potentially resulting in cor pulmonale
Cor pulmonale is right-sided heart failure caused by long-term high blood pressure in the lungs (pulmonary hypertension) resulting from chronic lung diseases, most commonly COPD.