Introduction to Cancer

Question 1

Neoplasm

Answer 1

An abnormal mass of tissue
(1) the growth of which exceeds & is uncoordinated with that of the normal tissues
(2) persists in the same excessive manner after cessation of the stimuli which evoked the change.

Question 2

Basic Tumour Components (2)

Answer 2

1.Proliferating neoplastic cells that constitute the parenchymas(tissue of tumour)
2.Supportive stroma made up of connective tissue, blood vessels & possibly lymphatics

Question 3

Benign tumour nomenclature

Answer 3

ends with -oma

Question 4

Glandular tissue tumour

Answer 4

adenoma

Question 5

Polypoid shape

Answer 5

cauliflower-like appearances

Question 6

Cysts (Spherical)

Answer 6

Capsule with smooth surface/outline, not infiltrated/invasive

Question 7

Dermoid

Answer 7

Differentiated into various different tissues; ectodermal cells are proliferating into squamous epithelium, teeth, and hair.

Question 8

Malignant Tumours (Epithelial origin)

Answer 8

Carcinomas

→ arising from ectoderm, endoderm, mesoderm
Spread initially via lymphatics, evidence: spread near regional lymph nodes
e.g. breast - lymph nodes in axilla, prostate glands → obturator node in the pelvis.

Question 9

Malignant tumour (mesenchymal tissue)

Answer 9

Sarcomas - 10%
(Greek ‘sarca’ = flesh)

Invade into circulation via venules & small veins straight away, tumour emboli get into venous system and taken up though right side of heart into pulmonary capillary bed
Therefore, primarily spread into the lung

Question 10

Carcinoma in situ

Answer 10

confined by basement membrane
with no access to lymphatics in connective tissues

Question 11

Basal cell carcinoma

Answer 11

ulceration with pearlescent edge(raised), cell resembles basal cells

Question 12

Invasive squamous cell carcinoma

Answer 12

treatable with surgery or radiotherapy

Question 13

Gastric adenocarcinoma

Answer 13

Glandular tissue epithelial cell

Historically, most common cancer in 1900s

Droplets of mucins in the cytoplasm of cancer cells, nucleus are pushed off to one-side aka. “Signet ring cell carcinomas”

Question 14

Mechanism of Cancer Invasion (1-5)

Answer 14

1. Physical invasion
   presence & exertion of pressure by proliferating cells
2. Reduced adhesiveness & cohesiveness of tumour cells
3. Increased motility of tumour cells
4. Loss of “contact inhibition”
   stop growth when in touch of neighbouring cells
5. Release of destructive enzymes

Question 15

Differences between Benign & Malignant Neoplasms

Answer 15

1. Morphology
2. 2 Major criteria for diagnosis of cancer in its primary site of origin:
   (1) Anaplasia & (2) evidence of invasion of surrounding structures

Question 16

1. Differentiation & Anaplasia (Benign v.s. Malignant)

Answer 16

Apply to parenchymal cells of the neoplasm, not the supportive stromas
Differentiation → extent to which parenchymal cells resemble comparable normal cells (both morphological & functional resemblance)

Benign tumours ⇒ well-differentiated.

Malignant tumours ⇒ range from well-differentiated to undifferentiated.

Question 17

Anaplasia

Answer 17

undifferentiated or poorly-differentiated; “to form backward”

Question 18

2. Rate of growth (Benign v.s. Malignant)

Answer 18

Most benign tumours grow slowly over a period of years

Most malignant tumours grow rapidly, often at an erratic pace

Growth rate of tumours correlates with the level of differentiation, thus most malignant tumours grow more rapidly than benign tumours.

Question 19

3. Encapsulation - Invasion (Benign v.s. Malignant)

Answer 19

Benign tumours grow as localised expansile masses enclosed within a fibrous capsule.

Induced from benign tumour by GFs, and are influencing fibroblasts in local tissue

Some malignant tumour never spread, because their effect at the primary site is so devastating, it never progresses, e.g. brain tumours - glial cells - malignant gliomas

Cancers are never encapsulated & are characterised by infiltrative, erosive growth that extend crab-like feet into adjacent tissues.

Question 20

4. Metastasis (Benign v.s. Malignant)

Answer 20

Metastasis marks a tumour as malignant because benign tumours never metastasise

Question 21

Dissemination of Cancer

Answer 21

A. Direct seeding of body cavities or surfaces
B. Transplantation ⇒ surgeon should cut around tumour with shell of normal tissue all the way around
C. Lymphatic permeation ⇒ Carcinoma
first appear in subcapsular space when draining in
D. Embolisation through blood vessels ⇒ Sarcoma

Question 22

Essential steps for metastasis

Answer 22

Primary Neoplasm ⇒ Progressive growth ⇒ Vascularisation ⇒ Invasion ⇒ Detachment ⇒ Embolisation ⇒ Survival in the circulation(evade monocytes, natural killer cells) ⇒ Arrest (capillary, or lymph nodes) ⇒ Extravastation (out of circulation between endothelial cells) ⇒ Evasion of host defence (T-cells, macrophages) ⇒ Progressive growth ⇒ Metastasis