lung cancer

see also:

• neoplasia / cancer / tumours
• palliative care
• lung lesions

• the vast majority of primary lung cancers are carcinomas which are divided into:
  • non small cell carcinoma (NSCLC) - accounts for 80%
  • small cell carcinoma (SMLC) “oat cell” - accounts for 17%
• other primary lung cancers include:
  • carcinoid - accounts for < 1%
  • sarcoma - accounts for 0.1%
  • mesothelioma
• > 85% of lung cancers occur in smokers
  • smokers have a 13% lifetime risk of lung cancer but this is doubled if they have a c.9976T BRCA2 gene mutation
• overall 5 year survival for lung cancer even with Rx is poor at ~14%
• lung cancer occurring in non-smokers is attributed to either:
  • passive smoking
  • genetic factors
  • viruses - perhaps human papilloma virus (HPV)
  • radon gas - 50% increased risk if levels exceed EPA recommended levels as they do in Cornwall, UK and in 1 of 15 homes in the US
  • air pollution - ultrafine particulate matter - an increase in air concentration of only 1% leads to 14% increase in cancer
  • mesothelioma (asbestos exposure) - 2-3% of all male deaths from lung cancer
  • perhaps ultra-processed food diets
    • a 2025 study showed those in the highest quarter of energy-adjusted UPF consumption were 41% more likely to be diagnosed with lung cancer than those in the lowest quarter ¹⁾
• LungVax lung cancer vaccine targeting neoantigens on lung cancer cells developed in 2024 and will be trialed

• accounts for 80%
• tends to be Rx surgically
• ~50% are squamous cell and the other 50% are adenocarcinomas
• some may metastasise to the brain in which case Ix workup of this possibility usually entails:
  • CT brain with iv contrast
  • plus MRI scan if either:
    • CT findings may represent other pathology such as infarcts instead of tumour
    • when surgical resection is being considered and thus there is need to exclude other metastases to brain or meninges

• accounts for 17%
• tends to respond better to chemoRx and radioRx
• most grow in the larger airways and grow rapidly and contain dense neurosecretory granules which may result in a variety of paraneoplastic neuroendocrine features including:
  • syndrome of inappropriate ADH secretion (SIADH) in 5-10% ⇒ hyponatraemia
  • ectopic secretion of ACTH in 5% ⇒ hypokalaemic nephropathy
  • atrial natriuretic factor
  • Eaton-Lambert reverse myasthenic syndrome 5-6%
  • Subacute cerebellar degeneration
  • Subacute sensory neuropathy - it seems to be related to the loss of the dorsal root ganglia with early involvement of major fibers responsible for detecting vibration and position.
  • Limbic encephalopathy via Anti-Hu, Anti-Yo antibodies and characterized by rapid onset of depression, seizures, irritability, and short-term memory loss
• see also emedicine

• an uncommon cancer (3% of all cancers) which is almost exclusively related to exposure to asbestos with a synergistic effect of smoking
• it has a latency period of 20-50 years following exposure to asbestos
• Australia has one of the highest incidences of mesothelioma in the world, largely due to its extensive use and mining of asbestos.
• currently ~500 Australians die each year with cases expected to peak this decade as cases hit 18,000 by 2020.
• mesothelioma may affect pleura (75%), peritoneum (20%), pericardium (5%) and rarely testicles.
• see mesothelioma

• unexplained haemoptysis, or,
• any of the following lasting more than 3 weeks in the adult (or < 3 weeks if risk factors)²⁾:
  • cough
  • chest pain and/or shoulder pain
  • SOB
  • abnormal chest signs
  • hoarseness
  • clubbing
  • cervical and/or supraclavicular lymphadenopathy
  • weight loss or anorexia
  • features suggestive of metastasis (eg. brain, bone, liver or skin)
  • signs of pleural effusion

• FH lung cancer
• smokers, ex-smokers, passive smokers
• Aboriginal or Torres Strait Islander people
• smoking-related COPD
• PH exposure to asbestos
• previous lung disease
• PH cancer, especially head and neck cancer

• NB. sputum cytology has a low sensistivity and is no longer recommended for the Ix of lung cancer
• massive haemoptysis or stridor then emergency admission for Ix
• urgent CT scan and referral to spscialist services if any of the following:
  • persistent haemoptysis in smokers or ex-smokers, aged > 40 years, or who have other risk factors, or,
  • signs of superior vena cava obstruction
• all other patients should have an urgent CXR and Mx according to findings:
  • CXR suspicious for lung cancer or normal but high risk ⇒ CT chest and urgent referral to specialist services
  • lower risk patients:
    • consolidation consistent with clinical picture:
      • Rx accordingly, repeat CXR in 6 weeks and if persistent consolidation ⇒ chest CT
    • pulmonary nodule
      • if no change from previous then monitor
      • if change then CT chest
    • those low risk patients having CT chest:
      • if scan suggests cancer or visible change in a nodule, then urgent referral to specialist services
      • otherwise, consider other diagnoses, and consider monitoring for 2 years.