Lect 18 - Characteristics of Tumours

Question 1

what is the WHO definition of cancer?

Answer 1

“Cancer is the uncontrolled growth of cells, which can

invade and spread to distant sites of the body”

Question 2

tumour is synonymous with what term in modern medicine?

Answer 2

neoplasm

Question 3

what is HISTOGENESIS

Answer 3

The differentiation of cells into specialised tissues and organs during growth from undifferentiated cells (the 3 primary germ layers)

Question 4

what is the incidence of cancer (2011)

Answer 4

331,487 cases - 161,823 deaths

Question 5

describe the general trend in cancer incidence and mortality

Answer 5

incidence slowly going up. mortality very slowly going down

Question 6

which cancers are the most common?

Answer 6

most common:

breast 26% (of women)
lung ~ 15%
colon and rectum 10%
prostate 25% (of men)

note these cancers are also the most fatal ie kills the most people (lung is the worst). this is obviously skewed by how many of them there are.

Question 7

what 4 factors are used to categorise tumours?

Answer 7

Differentiation
Rate of Growth
Local Invasion
Metastasis

Question 8

do Malignant tumours tend to grow more rapidly than benign tumours?

Answer 8

Many exceptions to this rule

Not useful to discriminate

Different malignancies show varied growth rates

Question 9

what is the definition of Differentiation

Answer 9

The extent that neoplastic cells resemble the corresponding normal parenchymal cells, morphologically and functionally

WARNING - Well-differentiated malignant tumours and benign tumours can look very similar

Question 10

are benign or malignant tumours more likely to be poorly differentiated?

Answer 10

Benign tumours

usually well-differentiated
Mitoses are rare

Malignant neoplasms

wide-range of parenchymal differentiation
Most exhibit morphologic alterations showing malignant nature

Question 11

what is Anaplasia?

Answer 11

Neoplasms comprised of very poorly-differentiated cells are described as anaplastic - Cannot be identified by morphology alone

“Telltale sign of malignancy”

Question 12

what Morphological Changes can be seen with tumours which are not well differentiated?

Answer 12

Pleomorphism
Abnormal nuclear morphology
Mitoses
Loss of polarity
Other changes

Question 13

what is Pleomorphism?

Answer 13

Variation in:
Size
shape

of cells and or their nuclei

Question 14

how do you measure if cells are showing Pleomorphism?

Answer 14

Nuclear to cytoplasmic ratio 
Variability in nuclear shapes (faces)
Chromatin distribution
Hyperchromatism (dark)
Abnormally large nucleoli

Question 15

what variations in mitosis suggest malignancy?

Answer 15

atypical mitotic figures such as:

Tripolar
Quadripolar
Multipolar spindles

Question 16

what does loss of polarity mean?

Answer 16

The orientation of cells is disturbed. Therefore there is disorganised growth

Question 17

what measure is based on a cancer’s level of differentiation?

Answer 17

GRADE

Well differentiated = low grade / grade 1
Moderately differentiated = intermediate / grade 2
Poorly differentiated = high grade / grade 3

Question 18

why is it important to have well differentiated tumours?

Answer 18

Better differentiation = better retention of normal function

Benign and well-differentiated carcinomas frequently secrete hormones characteristic of origin (can help diagnosis)

Question 19

what is a Paraneoplastic Syndrome

Answer 19

a set of symptoms caused by a cancer - often because of hormones

Question 20

what types of cancer have the ability to invade tissues?

Answer 20

malignancies.

Question 21

what stops a benign tumour from invading tissues?

Answer 21

A rim of compressed fibrous tissue is formed. ENCAPSULATION.

extracellular matrix is deposited by stromal cells activated by hypoxia from pressure of tumour.

Question 22

what is Pseudoencapsulation?

Answer 22

the attempt by the body to encapsulate a malignant tumour. Microscopically seen as rows of cells penetrating margin.

Question 23

what is Metastasis?

Answer 23

“Spread of a tumour to sites physically discontinuous with the primary tumour”

Reduces life expectancy significantly
30% of non-skin malignancies at diagnosis have metastasised

Question 24

what pathways of Metastasis are there?

Answer 24

Direct seeding
Lymphatic spread
Haematogenous spread

Question 25

what is Direct Seeding?

Answer 25

Neoplasm penetrates a natural open field without physical barriers

Eg peritoneal cavity, pleural, pericardial, subarachnoid, joint spaces

Question 26

what is Lymphatic Spread?

Answer 26

spread via lymphatic system.

most common pathway - particularly important if there are lymphatic vessels at the tumour margins.

Question 27

what are sentinel nodes?

Answer 27

The first node in a regional lymphatic basin that receives lymph flow from the primary tumour

Identified by:
Injection of radiolabelled tracers/coloured dyes

Question 28

what is Haematogenous Spread

Answer 28

tumours spreading via bloodstream.

Typical of sarcomas
Also seen in carcinomas!
Veins more easily penetrated as they have Thinner walls

Question 29

where do cells moving via Haematogenous Spread tend to go?

Answer 29

Often come to rest in first encountered capillary bed

Liver (portal) and lungs (caval) most frequently involved

Question 30

what is stroma?

Answer 30

connective tissue framework that neoplastic cells are embedded in

Question 31

what is a Desmoplastic reaction?

Answer 31

fibrous stroma formation due to induction of connective tissue fibroblast proliferation by growth factors from the tumour cells

Question 32

what does the stroma contain?

Answer 32

Cancer-associated fibroblasts
Myofibroblasts
Blood vessels
Lymphocytic infiltrate

Question 33

give some local Clinical Complications of Tumours.

Answer 33

Compression/Destruction

Question 34

give some metabolic effects of tumours.

Answer 34

Warburg Effect
(Produces energy by high rate of glycolysis with fermentation of lactic acid)

Cachexia
(profound weight-loss despite apparently adequate nutrition)

Neuropathies
Myopathies
Venous thrombosis