The classification of tumours

Question 1

How do cancers develop?

Answer 1

• Accumulation of mutations which override the normal mechanisms which control cell proliferation

Question 2

What makes a normal cell divide?

Answer 2

• Normal cell needs to repopulate if cells die of old age or are damaged
• Each tissue has stem cells which respond to GFs, stop dividing once enough cells are made
• These signals are transmitted by protein molecules - stimulate cell receptors
• Signal transmitted via intermediate receptors to the nucleus, where replication and division is initiated

Question 3

Where do the oncogene products act?

Answer 3

• Oncogenes translate into proteins, which either drive cell proliferation or stop it from turning off
• GF binds to receptor, causing downstream effects - initiation of cell division by nuclear oncoproteins
• Gets protection from apoptotic destruction - can start the neoplastic process
• mRNA carries mutated transcript to ribosome
• > translated
• Mutated gene product then either secreted, incorporated in the cell surface or forms an IC molecule
• If secreted it can have paracrine or autocrine effects

Question 4

What are 4 typical features of benign tumours?

Answer 4

• Expansile growth
• Bland cut surface
• May be encapsulated
• No lymph node or vascular invasion

Question 5

What is a leiomyoma?

Answer 5

BEnign smooth muscle tumour

Question 6

What are 5 typical features of malignant tumours?

Answer 6

• Irregular infiltrating edge
• Satellite nodules
• Travels to distant sites via blood
• Travels to lymph nodes
• Affects adjacet organs

Question 7

Benign vs malignant macroscopic features

Answer 7

B - Circumscribed, pushing margin, homogeneous cut surface, little haemorrhage or necrosis, no spread to adjacent organs or nodes

M - ill-defined, infiltrating margin, looks different to rest of tissue, focal necrosis and haemorrhage, infiltration of adjacent organs and lymph nodes

Question 8

Benign vs malignant microscopic features

Answer 8

B - resembles tissue of origin, low tumour cellularity, low nuclear to cytoplasmic ratio, round nuclei with well-dispersed chromatin, normal mitosis, no dysplasia in adjacent tissue, no vascular innasion

M - little resemblance to tissue of origin, high cellularity, high nucleus to cytoplasm ratio, atypical nuclei, numerous atypical mitoses, dysplasia in adjacent tissue, vascular invasion

Question 9

What is squamous epithelium?

Answer 9

• Covers skin, oropharynx, oesophagus, anus, vagina and auditory canal
• Benign and malignant tumours can arise from viruses
• SCC may arise at inappropriate site following squamous metaplasia eg bronchus of smokers

Question 10

What is glandular epithelium?

Answer 10

• Covers GI tract from stomach to rectum
• Lines ducts and acini of glands
• Forms tubular structures such as renal tubules
• Glandular tumours may arise at innapropriate site following metaplasia - Barrett’s metaplasia in GORD

Question 11

What is uroepithelium?

Answer 11

• Covers urothelial tract - renal pelvis, ureter, bladder and urethra
• Benign tumours rarely if ever encountered

Question 12

What factors influence a patient’s prognosis?

Answer 12

• Grade
• Stage
• Site of tumour
• Production of ECM - enhances tumour spread
• Hormone secretion and cacheia
• Host response to tumour - immunosuppression