Describe the incidence of lung cancer amongst socio-economic groups
-Most affluent have least incidence -> education and access to healthcare
What age group is predominantly affected by lung cancer?
-People aged 60-80
List some risk factors for lung cancer
- Smoking
- Asbestos
- Radon
- Occupational carcinogens
- Genetic/familial factors
Where do lung cancers commonly metastasise?
- Draining LNs
- Brain
- Bone
- Adrenals
- Pericardium
What type of staging is used in lung ca.? Describe this system
- TNM staging
- Tumour size, lymph node involvement and metastases
What diagnostic imaging techniques are used in lung cancer?
- CXR
- CT and staging CT (includes abdo and pelvis)
- PET scan for distant metastases
What diagnostic techniques are used for tissue sampling in lung ca?
It is location dependant
- bronchoscopy bx
- ultrasound bx (neck/chest wall)
- CT Bx
- Surgical Bx
What are the clinical features of a primary lung tumour?
- Often asymptomatic
- Cough, wheeze, dyspnoea, haemoptysis, weight loss and malaise
What are the classical symptoms of regional metastases of lung cancer?
- Bloated face due to SVC obstruction
- Hoarseness due to left recurrent laryngeal nerve palsy
- Dysphagia due to oesophageal compression
What are the classical symptoms of distant metastases of lung cancer?
- Bone pain/fractures
- CNS symptoms including headache and visual distrubances
What are the metabolic presentations of lung cancer?
- Thirst and constipation due to hypercalcaemia
- seizures due to hyponatraemia
What signs of lung cancer may be present on examination?
- Clubbing
- Cachexia
- Pale conjunctiva
- Cervical lymphadenopathy
- Liver enlargement
- Bloated face
What paraneoplastic syndromes can occur with lung cancer?
- Endocrine ->Cushings, Hypercalcaemia
- Haematological -> anaemia
- Neurological -> encephalopathy
List the pathological types of lung cancer
- Non-small cell -> squamous, adenocarcinoma and large cell
- Small cell
- Carcinoid (rare)
What tumour markers are sometimes present in lung cancers?
-EGFR mutations
Which lung cancer can cause hypercalcaemia?
-Squamous cell carcinoma by secreting PTHrp
Which lung cancer can produce cushings or SIADH?
-Small cell carcinoma by secreting ACTH or ADH
How is small cell carcinoma primarily treated?
-Radiotherapy
List some important features of small cell carcinoma
- Shorter doubling time than other lung cancers
- Earlier development of metastases
- 18-24 month survival
List some important features of squamous cell carcinoma
- More common in men
- Highly associated with smoking
- Local mets occur with dissemination being late stage
- Histology shows keratin pearls
List some important features of adenocarcinoma of the lung
- Contains ducts and glands which secrete mucus
- Found peripherally in the lung
- Grows slower and is smaller
- Metastasise early
Which lung cancers are primarily treated by surgery?
- Squamous
- Adenocarcinoma
Describe the incidence of lung cancer
-Most common male cancer and exceeds breast cancer as a cause of death in women
How many people die of lung cancer each year in UK?
-40,000
Why is biopsy particularly important in cancer?
-Not only for a diagnosis but for guidance on prognosis and treatment too
Describe the 5 year survival rate in general for luncg cancer in UK
-10%
List the different catagories of possible toxins
-Chemical, bacterial, viruses, protozoa, helminth
What physical defences do with have to ingestion of toxins?
- Senses (Sight/smell/memory)
- Saliva
- Gastric acid
- Small intestine secretions
- Colonic mucus
- Anaerobic environment
- Peristalsis/segmentation
How is saliva a physical defence to toxins?
- Contains lysozyme and lactoperoxidase, complement, IgA and polymorphs
- Washes toxins down to stomach
What is xerostomia and its consequences regarding toxins?
- Reduced salivary flow
- Microbial over growth in mouth and dental caries can lead to hairy tongue and parotitis
What is the most common causative organism of parotitis?
-S.aureus
What is black hairy tongue?
-Infection of the mouth caused by aspergillus
How does the stomach act as a defence to toxins?
-Lots of gastric acid produced each day with a pH as low as 0.87 which kills the majority of bacteria and viruses
What is achlorhydria and its clinical relevance to toxins?
- Decreased acid production
- Patients are more susceptble to shigellosis, cholera, salmonella
Why are patients taking a PPI in hospital more prone to c.diff infections?
-Decreased gastric acid production increases susceptibility to infection
Why can gastric aspirates be used as a diagnostic tool for TB?
-Swallow sputum in the night and TB is resistant to gastric acid
List 2 bacteria which are resistant to gastric acid
- Helicobacter pylori
- Mycobacterium tuberculosis
Name 2 viruses which are resistant to gastric acid
- Hepatitis A
- Norovirus
What defences does the small intestine have which help to keep it sterile?
- Bile
- Proteolytic enzymes
- Lack of nutrients
- Anaerobic environment
- Shedding of epithelia
- Peristalsis
What is the main protective mechanism in the colon?
-Colonic mucus
Which conditions are associated with eosinophilia?
- Asthma
- Parasitic infections
- Allergy
Explain the mechanism of the guinae worm (dracunculiasis)
Worm egg is ingested and passes through duodenum to retroperitoneum -> emerges and makes its way to the feet -> when person stands in water will burrow out into water -> becomes an adult worm in the foot and needs to be pulled out bit by bit daily
What is the association between gut infections and mast cells? What is the consequence of this
- Gut infection which activate complement recruit mast cells which release histamine
- This causes vasodilation and increased capillary permeability
- Water moves into the gut and is passed in faeces (rice-water stool)
What is the main mechanism to remove toxins from the blood in the GI tract?
-Hepatic-portal system
List some causes of liver failure
- Alcohol
- Viral hepatitis
- Drugs
- Autoimmune
Why does hepatic encephalopathy occur in liver failure?
-Increased blood ammonia due to failure to clear ammonia via urea cycle
How does liver cirrhosis lead to portosystemic shunting? What are the clinical manifestations of this?
- Hepatic fibrosis leads to portal hypertension
- > Increased pressure causes backflow of venous blood and shunting into the systemic circulation
- Oesophageal varices, haemorrhoids and caput medusae
How come you can get anal bleeding with cirrhosis?
-Cirrhosis -> portal hypertension -> Submucosal veins have more blood in at anorectal junction due to portosystemic shunting -> during a rise in intrasbdominal pressure these veins normally swell -> Increased blood can lead to bursting and bleeding
Why can you get haemorrhoids in portosystemic shunting?
-Increased anorectal vein pressure causes veins to swell and appear as haemorrhoids
What is caput medusae?
-Dilation and filling of veins in anterior abdominal wall
What is the difference between the appearance of caput medusae and IVC obstruction?
-Caput medusae veins run in all direction whereas in IVC obstruction veins only run towards the heart
What adaptive defences are there against toxins?
-T and B lymphocytes
What innate defences is there against toxins?
-Macrophage, neutrophil, basophil, eosinophil, mast cell and complement
What is GALT?
-Gut associated lymphatic tissue eg tonsils, peyers patches, appendix
What is walders ring of fire?
-Palatine tonsil, lingual tonsil and nasopharengeal tonsil
Where do tonsils drain?
-Cervical lymph nodes
What are the most common causes of sore throat with cervical lymphadeopathy?
- Adenovirus
- Viridans strep
- Strep pyogenes
What is the relationship between ileoceal valve and peyers patches?
- Peyer’s patches are located in the terminal ileum beneath the mucosa
- Incompetent ileocecal valve results in reflux of bacteria when ther eis a rise in intraabdominal pressure
- Peyer’s patches prevent bacteria accessing the body
What is mesenteric adenitis? Why is its clinical presentation important?
- Inflammaiton of the mesenteric lymph nodes commonly caused by adenovirus
- Presents as right iliac fossa pain which is easily mistaken for appendicitis
What is the relationship between peyers patches and typhoid fever?
-Inflammation of peyer’s patches can perforate and kill patients
Name a few chemical toxins
-Lead, aluminium, mercury, arsenic
List some causes of gut ischaemia
- Arterial disease
- Systemic hypotension
- Intestinal venous thrombosis
How does the colon protect itself from toxins?
- Colonic mucus
- Epithelial shedding
Where are kuppfer cells? What role do they perform?
- Lining the hepatic sinusoids
- Phagocytosis and detoxifcation of blood which passes through from portal vein
In general, What is the prognosis like for lung cancers?
-Poor (highest ca related deaths)