NEOPLASMS OR TUMOURS (CANCER)

Question 1

NEOPLASMS OR TUMOURS

Answer 1

• a mass of tissues that grows faster than normal
• continuous growth after the initial stimulus has ceased
• tumours are classified as benign or malignant
• benign tumours only rarely change their characters and become malignant
• tumours may be classified according to their tissue of origin
• alignment tumours are further classified according to their origins
  difference between tumours:
  Benign:
  > slow growth
  > cells differentiated
  > No distant spread
  > recurrence is rare
  Malignant:
  > rapid growth
  > cells poorly differentiated
  > not encapsulated
  > spreads: via lymph, via blood

Question 2

INCIDENCE

Answer 2

• children and young people under 24 comprise 1% of cases
• adults between 25 & 49 = 9%
• 50 & 75 = 54%
• 75+ = 36%

Question 3

CAUSES

Answer 3

• some mutations are spontaneous
• exposure to mutagenic agent
• few are inherited
• cell division is regulated by genes. Some inhibit the cell cycle & others stimulate it
• proto-oncogene that becomes abnormally activated & allows uncontrolled cell division

Question 4

CARCINOGENES

Answer 4

• maligment changes the cell = irriversiable damage to DNA
• small dose may initate change but may not cause maligmency unless there are repeated dose over time that cumulative effect

Question 5

HOST FACTORS

Answer 5

• charactersitics can influence susceptibility to tumuors
• some are outwith indiviudal control
• others can be modified and are referred as lifesytle choices: smoking, diet, obesity, excersie levels
• these factors are implicated in the development of nearly half of maligment tumours

Question 6

CHEMCIAL CARCINOGENS

Answer 6

• many substances in ciggerette smoke = risk factor for lung (bronchi) lung cancer
• aniline dyes = bladder cancer
• absestos = pleural mesothelioma

Question 7

IONISING RADIATION

Answer 7

• exposure to radiation
• many cause mutations in some cells and kills others
• affected during mitosis

Question 8

ONCOGENIC VIRUSES

Answer 8

• some cause = neoplastic change
• virsues enter cells & incoperate DNA & RNA into the host cells genetic materials introduce mutations = neoplastic cells

Question 9

CHARACTERISTIC OF TUMOURS

Answer 9

• neuroplastic cells escape from normal controls & multiply in a uncontrollable manner = tumour
• Maligment cells = immortal when develop the ability to replicate

Question 10

CELL DIFFERENTITION

Answer 10

• differentition into specalised cells with particular structural and fucntional characteristics
• benign tumours the cells are very similar to parent cell
• tumours with well differentiated cells begin although some may be maligment
  > Mild Dysplasia: tumour cells retain most normal features and parent cells can be identifed
  > Anaplasia tumour cells have lost most of their normal features their parent cells cannot be idnetified adn the orignal structure identified

Question 11

BENIGN TUMOURS

Answer 11

• fibrous capsules
• partly from surrounding tissue
• partly from the tumour
  common sites of primary tumours and their metastases
  PRIMARY:
  > bronchi
  >alimentary tract
  > prostate gland
  > thyroid gland
  > breast
  METASTATIC TUMOURS
  > adrenal gland (brain)
  > abdominal and pelvic structure
  > pelvic bones

Question 12

MALIGNANT TUMOURS

Answer 12

• don’t have a capsule
• grow from a single mutated cell & enlarged with tissue of origin cancer in situ
• secret factors develop with new blood vessels with tumour (angiogenesis), providing a good supply of O2 & nutrients promoting growth
• growing into filtration nearby = invasion
• fragments break off travel to parts of the body in the blood or lymph
• phagocytosed & macrophages or destroyed by defence cells of the immune system
• others might escape detection & lodge into tissue away from primary sites, growing into secondary sites
• metastases are multiplited

Question 13

LOCAL SPREAD

Answer 13

• benign tumour is enlarged, they may have damaged local structures, impairing their functions
• both benign and malignant tumours compress local structures

Question 14

BODY CAVITY SPREAD

Answer 14

• malignant tumour penetrates the wall of a cavity
• where there is less scope for the movement of fragments within the cavity the tumour tends to bind layers of tissue together

Question 15

LYMPHATIC SPREAD

Answer 15

• malignant tumour invades lymph vessels
• cells break off and are carried to lymph nodes
• lodge and grow into secondary tumours
• spread through the lymphatic system and via the blood bevasue the lymph drains into subclavian veins

Question 16

BLOOD SPREADS

Answer 16

• malignant tumours erode blood vessel wall
• thrombus (blood clot) may form at the site, and emboli consisting of tumour fragments and blood clot through the bloodstream
• Emboli is a small blood vessel = infract
• development of metastatic tumours
• phagocytosis of tumour cells in emboli is unlikely to occur to protect the immune surveillance within the blood clot
• single cells can lodge into capillaries of other body organs
• divisions are subsequent growth of secondary tumours or metastases that may occur
• blood-spread metastases depend on the location of the original tumour and the anatomy of the circulatory system in the area
• common sites: bones, brain, lungs and liver

Question 17

EFFECTS OF TUMOURS

Answer 17

COMPRESSION OF LOCAL STRUCTURES
- benign and malignant tumours may compress and damage adjacent structures
- depends on the sites but not most marked in areas where there is little space for expansion
- comparison of adjacent structure may impair functions
- pressure on blood vessels = ischaemia (lack of oxygen)
- necrosis (death) of the tissue
- comparison of nerves = pain and loss of nerve control of the tissue and organs that they supply

Question 18

HORMONE SECRETION

Answer 18

• Benign and malignant tumours of endocrine glands
• producing the effects of hypersecretion
• cell dysplasia is an essential factor
• benign tumours are more likely to secrete hormones that markedly dysplastic malignant tumours
• high levels of hormones are found in the bloodstream, homeostatic control mechanisms

Question 19

CACHEXIA

Answer 19

• weight loss & weakness
• loss of appetite
  result of metastatic cancer

Question 20

CAUSE OF DEATH IN MALIGMENT DISEASE

Answer 20

• acute infection
• a common cause of death when advanced malignancy
• infection prolonged immobility and depresses the immune system by drugs and radiotherapy or radioactive isotopes used as treatment
• common infection: pneumonia, sepsis
• organ failure occurs when a tumour destroys so much healthy tissue that it becomes unstable to function
• haemorrhage may occur when a tumour grows into a rupture of the wall in the vein and arteries
• most common sites: GI tract, respiratory, brain, lungs
• Carcinomatosis is a widespread metastatic disease associated with cachexia. Increasingly severe psychological and biochemical disruption = causing death