Thoracic Oncology

🫁 Thoracic Oncology

Lung cancer histology, TNM staging, surgical resection, RLN anatomy, paraneoplastic syndromes, and the 4 T’s of anterior mediastinal masses.

Bronchogenic Carcinoma — Histology

Lung cancer is the leading cause of cancer death in the UK. It is divided into Non-Small Cell Lung Cancer (NSCLC — ~85%) and Small Cell Lung Cancer (SCLC — ~15%). The histological type determines prognosis, treatment, and the likelihood of specific complications.

Most common overall

Adenocarcinoma

Peripheral, non-smoker association, EGFR mutations

Most central

Squamous cell carcinoma

Hilar, smokers, PTHrP hypercalcaemia

Most aggressive

Small cell (SCLC)

Central, early mets, not surgical

Most paraneoplastic

Small cell (SCLC)

SIADH, Cushing’s, Lambert-Eaton

Pancoast tumour

Superior sulcus

Horner’s, brachial plexus, rib erosion

UK screening

Low-dose CT (LDCT)

High-risk smokers age 55–74. Targeted Lung Health Checks.

Histological Types — Detailed

Adenocarcinoma (~40%)

Most common NSCLC in non-smokers and women

LocationPeripheral (subpleural). Arises from Clara cells / type II pneumocytes. Lepidic growth pattern (spreads along alveolar walls).

AssociationsNon-smokers (but can occur in smokers), women, East Asian patients. Bronchoalveolar carcinoma (now called adenocarcinoma in situ — lepidic growth, ground-glass on CT).

MutationsEGFR mutations (~15% Western, ~50% East Asian) → EGFR TKIs (gefitinib, erlotinib, osimertinib). ALK rearrangement (~5%) → ALK inhibitors (crizotinib). KRAS, ROS1, BRAF.

ParaneoplasticHypertrophic pulmonary osteoarthropathy (HPOA — clubbing + periosteal new bone formation)

SurgeryMost amenable to curative resection if peripheral and early stage

Squamous Cell Carcinoma (~25%)

Central, hilar, Pancoast, keratin pearls

LocationCentral (hilar) — arises from bronchial epithelium. Proximity to major bronchi → obstructive pneumonia, haemoptysis, atelectasis.

AssociationsStrongly associated with smoking. Most common type in smokers overall (historically). Common in Pancoast tumour (superior sulcus).

HistologyKeratin pearls (intercellular bridges). Cavitates (central necrosis — “cavitating lung mass”).

ParaneoplasticHypercalcaemia via PTHrP (parathyroid hormone-related peptide) secretion — most common paraneoplastic metabolic complication of SCC. Not true hyperparathyroidism.

SurgeryAmenable if central — sleeve lobectomy to preserve lung function. Check bronchial margin.

Small Cell Lung Cancer (~15%)

Central, aggressive, chemo-sensitive, NOT surgical

LocationCentral. Rapidly growing. Derived from neuroendocrine cells (Kulchitsky cells) — hence extensive paraneoplastic phenomena.

AssociationsAlmost exclusively in smokers. Aggressive — widespread metastases at presentation in ~70%.

Histology“Oat cell” — small, scant cytoplasm, neuroendocrine markers (chromogranin A, synaptophysin, CD56). High Ki-67 (proliferation index).

StagingLimited disease (confined to one hemithorax ± ipsilateral nodes — can be included in one radiation field). Extensive disease (beyond one hemithorax).

TreatmentChemotherapy + radiotherapy (NOT surgery — systemic disease at presentation). Etoposide + cisplatin/carboplatin. Prophylactic cranial irradiation (PCI) to reduce brain metastasis risk. Very chemosensitive initially but rapid relapse.

ParaneoplasticSIADH (hyponatraemia), ectopic ACTH (Cushing’s), Lambert-Eaton myasthenic syndrome (anti-VGCC antibodies), encephalomyelitis. Most paraneoplastic syndromes of any lung cancer type.

Large Cell Carcinoma (~10%)

Peripheral, diagnosis of exclusion

DefinitionLarge undifferentiated NSCLC — does not have features of adeno-, squamous, or small cell. Diagnosis of exclusion on resection specimen.

LocationUsually peripheral. Large, bulky tumours.

BehaviourAggressive. Tends to metastasise early. Poor prognosis. Can produce β-hCG (gynaecomastia in males).

TreatmentSurgery if resectable. Platinum-based chemotherapy. Immunotherapy (pembrolizumab if PD-L1 positive).

You're reading the free preview.More detailed sections, comparisons, mnemonics and exam pearls continue below — for subscribers.

`;} document.getElementById('quiz-type-selection').addEventListener('click',e=>{if(e.target.tagName==='BUTTON'){startQuiz(allQuizData.all);}}); nextBtn.addEventListener('click',handleNext); prevBtn.addEventListener('click',()=>{if(!feedback&&idx>0){idx--;showQ();}}); subBtn.addEventListener('click',()=>{if(!feedback)handleNext();else showResults();});