Topic 1—Neoplasia

Question 1

Neoplasia

Answer 1

New growth of cells where it isn’t wanted (uncontrolled)

Question 2

Explain normal cell growth

Answer 2

Start as a single undifferentiated cell. Through mitosis our cells divide. They become more specialised. As they become more specialised they become less able to divide. (eg nerve cells are unable to divide) All cells contain complete DNA.

Question 3

Characteristics of Benign neoplasms

Answer 3

well differentiated
Slow growth
often encapsulated
often only 1 tumour

Question 4

Characteristics of Malignant neoplasm

Answer 4

Poorly differentiate

Rapid growth

radiating growth,

Metastic growth often resulting in secondary tumours elsewhere

Question 5

How can tumours interfere with normal function?

(4 main ways)

Answer 5

block ducts
replace tissue with poorly differentiated cells
compress tissue
secrete hormones

Question 6

The impact of tumors blocking ducts

Answer 6

When tumors block ducts and therefore interfere with the flow of substances such as bile, pancreatic
enzymes, air (in the lungs)

Question 7

The impact of tumors repacing tissue

Answer 7

Tumors can replace tissue with poorly differentiated cells that does not function in the same
way

Question 8

The impact of tumors compressing tissue

Answer 8

Tumors can compress tissue, cutting off circulation and causing ulceration and necrosis

Question 9

Why can both a benign and malignant neoplasm cause death?

Answer 9

because both tumour types can cause death, depending on where
the interference with normal function occurs. Nevertheless, a malignant neoplasm is more likely to kill simply
because it grows more rapidly and can spread throughout the body, thereby affecting more sites

Question 10

Tumors ending in -oma are usually

Answer 10

benign

eg. osteoma (tumor of the bone)

neuroma (tumor of nervous tissue)

Question 11

Tumors ending in ‘-sarcoma’ or ‘-carcinoma’ are usually

Answer 11

malignant

Question 12

What are the characteristics of neoplastic cells?

Answer 12

• usually less well differentiated than the tissue from which they originate.
• may have abnormalities of chromosome structure
• different proteins on their cell membranes
• secrete hormones
• contain unusual metabolic pathways
• Blood vessels and lymph vessels will develop to support a
  tumour (e.g. provide it with oxygen, remove wastes) just as they develop to support any developing organ.
• (a neoplastic cell is
  a cell that is part of tumor.)

Question 13

Dysplasia

Answer 13

Controlled cell division, that nevertheless results in cells which vary in shape, size and
appearance. An example is the cells that line the airways of smokers.

Question 14

Hyperplasia

Answer 14

A controlled increase in the number of cells in a tissue or organ. Examples include breast
and uterine enlargement during pregnancy.

Question 15

Metaplasia

Answer 15

The controlled and reversible replacement of one cell type with another. For example,
bronchial metaplasia is the reversible replacement of the ciliated cells lining the airway
with cells that lack cilia. This often occurs in the airways of smokers and can be reversed
by ceasing to smoke.

Question 16

Hypertrophy

Answer 16

A controlled increase in cell (or organ) size (remember that body builders often have
hypertrophied muscles).

Question 17

Atrophy

Answer 17

A controlled decrease in cell (or organ) size (remember that the muscles of bedridden or
inactive people often atrophy).

Question 18

What are the treatments of cancer?

Answer 18

_Surgery* _The most common treatment is removal or destruction of the tumour. Surgical removal can be extremely effective if the tumour hasn’t metastasised—obviously small, relatively recent tumours are more easily removed completely, but such tumours are also relatively difficult to detect. If the tumour is impossible to remove or thereis a likelihood of metastasis, radiotherapy and/or chemotherapy are often used, especially as a follow up after surgery.*

Radiotherapy -is the use of high energy radiation to kill living cells. It does not discriminate between normal **cells and cancer cells. There are techniques for directing radiation so that the area containing the tumour **receives the highest dose.

_Chemotherapy _is the administration of compounds that either kill living cells or stop them dividing. Fast growing tumours are often very susceptible to chemotherapy, but so are other rapidly dividing cells, suchas the tissues which produce red and white blood cells, cells which produce hair, and cells which line the gut. Chemotherapeutic compounds do not usually discriminate between normal cells and cancer cells, so chemotherapy often has unpleasant side effects.

Question 19

How does a cell become cancerous?

Answer 19

A normal cell can be transformed into a cancerous one by changes (mutations) to the DNA in its nucleus. It
usually takes several mutations within the same cell to make it cancerous. The carcinogens are
particularly good at changing and damaging DNA.

Proto-oncogenes are genes that help regulate (including preventing) cell division and cell growth. Damage to
these proto-oncogenes can transform them to oncogenes which no longer exert the same control, so the cell can
start dividing uncontrollably.

It appears that most cancers arise from changes to the DNA of only one reserve cell.

Question 20

What is haematologic cancers?

Answer 20

haematologic cancers involve circulating cells of the blood and lymph (e.g. leukaemia is an uncontrolled production of
lymphocytes).

Question 21

What is the role of the immune system in detecting cancerous cells?

Answer 21

The DNA in our cells is frequently damaged, but our immune system is very good at detecting and killing such
cells. Natural killer’ (NK) cells which patrol the body examining your
cells and destroying cancer cells or those which have been invaded by a virus.

T lymphocytes also kill cancer cells. Virtually every cell of your body except your red blood cells displays a set of proteins on its cell membrane that are specific to you—the ‘protein signature’.

Each cell in your body has the same signature, but if your cells also contain a bacterium, parasite, virus, or have become cancerous, the signature often changes because additional proteins are displayed on the cell membrane.

Natural killer cells and T lymphocytes constantly ‘examine’ your cells. A natural killer cell will usually kill a
cell of your body displaying extra proteins and this protects you against cells that contain foreign organisms or
have become cancerous. This (extreme) simplification can explain why cancer cells are eliminated and also why
foreign tissue is rejected (except between identical individuals who have identical protein signatures on their
cells) unless the immune system is suppressed.

It’s only when the immune system fails to detect and kill cancer cells that they are free to divide.

Question 22

What causes neoplasms

Answer 22

• Mendelian inheritance. (family tree)
• viruses
• Carcinogens - eg asbestos, soot, tar, oil, smoke, benzene, moulds, oestrogen, radiation, ultra violet ligh
• diet

Question 23

How do tumors spread?

Answer 23

Malignant tumours grow by extension of the primary tumour and seeding. (the latter where cells or clumps of cells break off and travel via the blood supply or lymph nodes to other parts of the body).

Question 24

Why are certain areas of the body such as lungs, liver and bones are likely to be sites of metastic spread?

Answer 24

Lymph nodes, and the
liver and lungs, are prime sites of metastatic (= secondary) growth from seeding.

Lymph nodes are associated with lymph vessels that often drain fluid from large areas of tissue, so the likelihood of a metastatic cell being trapped in a lymph node and subsequently growing is quite high.
All circulating blood flows through the capillaries in the lungs, so the chance of a metastatic cell being trapped in these capillaries is also high.
all blood from the stomach and intestines flows through the liver before being returned to the vena cava, sometastatic cells originating from primary growths in the abdominal area may often be trapped within the liver.
Once trapped, these cells will divide and form new tumours.