User Tools

Site Tools


neo_lung

lung cancer

introduction

  • 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

non small cell carcinoma (NSCLC)

  • 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

small cell carcinoma (SMLC) "oat cell"

  • 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:
    • 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

mesothelioma

  • 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.

suggestive symptoms requiring urgent Ix

  • unexplained haemoptysis, or,
  • any of the following lasting more than 3 weeks in the adult (or < 3 weeks if risk factors)1):
    • 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

risk factors

  • 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

Ix for suspected lung 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.
neo_lung.txt · Last modified: 2014/06/01 22:21 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki