DDT.2

Question 1

What is cancer?

Answer 1

Cancer is a disease of unregulated growth of cells from genetic mutation. It is a generic term for a large group of diseases that can affect any part of the body.
–> Definition: Malignant, ill-regulated proliferation of cells causing either a solid tumour or other abnormal conditions.
Usually fatal if untreated!

!! Cancer causes death because the cells don’t die instead they populate continuously crowding out healthy cells !!

Question 2

How are cancer cells abnormal?

Answer 2

1) in the way they multiply indefinitely.
2) how they invade underlying tissue.
3) migrate to other sites of the body and multiply there.

Question 3

Most common cancer in 2020

Answer 3

Breast cancer

Question 4

Most deadliest cancer in 2020

Answer 4

Lung cancer

Question 5

What are the types of cancer?

Answer 5

Carcinomas (cells that cover internal and external body surfaces)

Sarcomas (cells in supportive tissues – bones & muscles)

Leukemia (Blood Cells)

Lymphomas
(Lymph nodes &tissues)

Question 6

Normal vs Neoplasm

Answer 6

Normal life processes are characterized by continuous growth and maturation of cells, and all cells are subject to control mechanisms that regulate their growth rate.

In contrast, Neoplasm is an overgrowth of cells that serve no useful purpose; for example a tumour.

Question 7

Classes of tumors: Benign vs Malignant

Answer 7

Growth rate:
slow vs rapid

Character of growth: expansion vs infiltration

Tumor spread:
remains localized vs metastasis in bloodstream and lymphatics

Cell differentiation:
well vs poorly

Question 8

How are tumors names and classified?

Answer 8

Tumours are named and classified according to the cells and tissues which they originate.

Question 9

Types of Malignant tumours

Answer 9

Carcinomas
“Malignant tumor from epithelial cells e.g. lung carcinoma, hepatic carcinoma, melanoma”
Sarcomas
“Malignant tumour from connective tissue (osteosarcoma, fibrosarcoma, myosarcoma)”
Lymphoma/Leukemia’s
“Neoplasm of blood cells leukemia, lymphomas, myeloma”

Question 10

Polyp, papilloma

Answer 10

Any benign tumour projecting from surface epithelium.

Question 11

Adenoma (adeno- gland )

Answer 11

Benigntumourofepithelial tissue withglandularorigin
-often from glandularorgans, including theadrenal glands,pituitary gland,thyroid,prostate.

Question 12

Carcinoma

Answer 12

Malignant tumor arising from surface, glandular or parenchymal epithelium (but not endothelium or mesothelium) approx. 90% of human cancers.

Question 13

Sarcoma

Answer 13

Malignant tumour of any primary tissue other than surface, glandular and parenchymal epithelium.

Question 14

Leukemia

Answer 14

Neoplasm of blood cells.

Question 15

What is a teratoma?

Answer 15

“A tumour of mixed cell components”

Often arise in the reproductive tract.

May consist of fat, muscle, bone, hair and oil.

E.g. Dermoid cyct: A common benign cystic teratoma that commonly arises in the ovary”

Question 16

Oncogenesis

Answer 16

AKA: Tumorigenesis/ carcinogenesis/oncogenesis

Transformation of normal cells into cancer cells entails concerted changes in the expression of many genes.

A single oncogene is insufficient to make normal cells cancerous, whereas cooperation between two distinct oncogenic mutations can BUT in many cases ‘normalizing’ the expression of even one of these genes is sufficient to attenuate tumor growth.

Question 17

Cancer cell division

Answer 17

Normally, cell divisions are controlled strictly. In cancer cells have lost the capacity to recognize signals from their surroundings. So, the cell number grows out of control;

• They may not detect neighbouring cells.
• They may produce there own growth hormones to stimulate cell division.
• They may not produce tumour suppressor proteins.
• They ignore normal apoptotic processes.

Question 18

Conventional Oncogenesis Model.

Answer 18

Aging primarily contributes to increased cancers by facilitating the accumulation of oncogenic mutations, including activating mutations in oncogenes or genetic/epigenetic inactivation of tumor suppressor genes.

More than 80% of human cancers being diagnosed after the age of 50, aging represents the single most important prognostic factor for many cancers, including lung, breast, colon, prostate, and certain leukemias.

Therefore, as we age the risk of cancer increases.

This model doesn’t account for all types of cancers so new models are emerging to describe the process….

Question 19

Adaptive Oncogenesis Model

Answer 19

The ability of an oncogene to induce cancer is context specific.
In a healthy population, the ability of cells to effectively compete for niche space is high due to optimal progenitor cell fitness. Thus, this competition is inherently tumor suppressive.
However, if cellular fitness decreases as a result of aging or environmental insults, the acquisition of an oncogenic mutation could beadaptivedue to its ability to correct or circumvent defective cellular function. In this context, these cells would be selected for leading to carcinogenesis.

Question 20

Growth of Cancer Cells

Answer 20

Cancer cells can reproduce every 2-6 weeks.

Size of cancer cells:
1M cancer cells = head of a pin
1B cancer cells = a small grape

2^30 = 1 billion cells

Question 21

Invasion vs Metastasis

Answer 21

Invasion: When cancer cells spread (no longer benign) from the primary site to another part of the body.

Metastasis: Tumor cells are transported through the circulatory system. Transport typically to the bone liver and lungs where they may form secondary/tertiary tumors. Most people who die of cancer die of metastatic disease.

Question 22

Angiogenesis vs Necrosis

Answer 22

Angiogenesis: as a tumor develops it requires oxygen and nutrients for survival. Cancers often secrete blood vessel stimulators (e.g. VEGF).
Blood vessels grow towards and into tumorgenic masses.

Necrosis: As a tumor enlarges the centre of the tumor may not receive enough nutrients forming a necrotic core.

Question 23

Skin cancer

Answer 23

To distinguish between a normal mole and a melanoma:
- Asymmetry: when half of the mole does not match the other half.
- Border: when the border of the mole is ragged or irregular.
- Color: when the color of the mole varies throughout.
- Diameter: if the mole’s diameter is larger than a pencil’s eraser.

Question 24

Nevus

Answer 24

A benign tumor of melanocytes.

Question 25

Melanoma

Answer 25

Malignant tumor of melanocytes.

Question 26

Skin cancer- Basal cell carcinoma

Answer 26

Accounts for approximately 75% of all skin cancers. This highly treatable cancer starts in the basal cell layer of the epidermis (the top layer of skin) and grows very slowly. Basal cell carcinoma usually appears as a small, shiny bump or nodule on the skin - mainly those areas exposed to the sun, such as the head, neck, arms, hands, and face. It commonly occurs among persons with light-colored eyes, hair, and complexion.

Question 27

Skin cancer- Squamous cell carcinoma

Answer 27

Accounts for about 20% of all skin cancer cases. Although more aggressive than basal cell carcinoma, this cancer is highly treatable. Squamous cell carcinoma, may appear as nodules or red, scaly patches of skin, and may be found on the face, ears, lips, and mouth. Squamous cell carcinoma can spread to other parts of the body. This type of skin cancer is usually found in fair-skinned people.

Question 28

Skin cancer- Malignant melanoma

Answer 28

Although less common, this type of skin cancer is the most deadly, accounting for approximately 79 percent of all skin cancer deaths. Malignant melanoma starts in the cells that produce pigment in the skin. Malignant melanoma usually begins as a mole that then turns cancerous. This cancer may spread quickly. Malignant melanoma most often appears on fair-skinned men and women, but persons with all skin types may be affected.

Question 29

Lung Cancer

Answer 29

Tobacco smoking is the leading risk factor. Lung cancers can arise in any part of the lung, but 90% to 95% of cancers of the lung are thought to arise from the epithelial cells, the cells lining the larger and smaller airways (bronchi and bronchioles);
for this reason, lung cancers are sometimes called “bronchogenic carcinomas”.

Cancers also can arise from the pleura (“mesotheliomas”) or rarely from supporting tissues within the lungs, for example, the blood vessels.

2 Types which grow and spread differently: the small cell lung cancers (SCLC) and non-small cell lung cancers (NSCLC).

Question 30

Blood cancer-Leukemia

Answer 30

A type of cancer found in your blood and bone marrow, is caused by the rapid production of abnormal white blood cells. The high number of abnormal white blood cells are not able to fight infection, and they impair the ability of the bone marrow to produce red blood cells and platelets.

Question 31

Blood cancer-Lymphoma

Answer 31

A type of blood cancer that affects the lymphatic system, which removes excess fluids from your body and produces immune cells. Lymphocytes are a type of white blood cell that fight infection. Abnormal lymphocytes become lymphoma cells, which multiply and collect in your lymph nodes and other tissues. Over time, these cancerous cells impair your immune system.

Question 32

Blood cancer- Myeloma

Answer 32

A type of blood cancer that specifically targets your plasma cells. Plasma cells are WBC that produce disease-and-infection-fighting antibodies in your body. Myeloma cells prevent the normal production of antibodies, leaving your body’s immune system weakened and susceptible to infection.

Question 33

Breast cancer

Answer 33

Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.
The most common type ofbreast canceris”ductal carcinoma”, which begins in thecellsof the ducts.

About 12% of women in the general population will develop breast cancer sometime during their lives.
Increased risk in females with tumor suppressor proteins BRCA1andBRCA2 mutations (25% of hereditarybreast cancers and about 5-10% of all breast cancers) mutation can be inherited from a person’s mother or father.

Question 34

Tests to diagnose breast cancer

Answer 34

• Physical examandhistory: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Clinical breast exam(CBE): An exam of the breast by a doctor or other health professional. The doctor will carefully feel the breasts and under the arms for lumps or anything else that seems unusual.
• Biopsy: The removal of cells or tissues so they can be viewed under amicroscopeby a pathologistto check for signs of cancer. If a lump in the breast is found, the doctor may need to remove a small piece of the lump.
• Ultrasound
• MRI(magnetic resonance imaging
• Blood chemistry studies
• Mammogram: an x-ray of the breast.

Question 35

Prostate cancer

Answer 35

Commonest malignant tumour in men over 65 years.
At age 50 to 65, 15-20% have histological evidence rising to 50% at age 80.
Most of these are tiny and may have remained latent for many years. Often metastasises to pelvic bone via lymphatic’s and blood supply.
Risk factors :
- Age: rare <40, 29% 6th decade, 67% 9th decade
- Hereditary: Risk doubled with 1st degree relative and x4 if 2 FDR
- Race: lower incidence of clinically evident disease in Japan and China
Black > white, Jamaica highest mortality rate
- Diet: High saturated fat increased risk.

Question 36

Risk factors for cancer development

Answer 36

Lifestyle…
-Smoking
-Diet high fat and low in fruits and vegetables
-Lack of exercise
-Unprotected exposure to the sun, (UV) rays
-Obesity

Family history…
- Increase risk with Heredity Breast or colon cancer

Environment…
-Viral
-Second hand smoke-Air pollution
-Industrial pollution
-Chemical exposures

Question 37

Causes of Cancer: Biological Mutagens

Answer 37

Biological mutagens may be viral or bacterial.
- Viral mutagens: may use a number of different complex mechanisms to cause a cell to become cancerous. Viruses that can be a risk factor for different cancers include the human papilloma virus (implicated in cervical cancer), the human T-cell lymphyocytic virus (implicated in lymphoma), and the hepatitis B virus (implicated in liver cancer).
- One known bacterial mutagen is helicobacter pylori (implicated in stomach cancer).

Question 38

Causes of Cancer: Chemical Mutagens

Answer 38

In the case of chemical mutagens, mutation is caused by foreign molecules binding to a cell’s DNA, causing it to be ‘misread’.
Examples of chemical mutagens:
Benzopyrene (found in cigarette smoke)
Vinyl chloride (found in the plastics industry)
Aflatoxin (found in certain moulds)
Hetrocyclic amines (found in over-cooked foods).

Question 39

Causes of Cancer: Physical Mutagens

Answer 39

Physical mutation of DNA can be caused by ionising radiation, ultraviolet radiation and by mineral fibres. These three mutagens act in very different ways.

–> Ionising radiationliterally punches holes in the DNA, breaking the correct genetic sequence. Ionising radiation can come from directly fromX-rays and solar radiation (cosmic rays) and indirectly from radon gas.

–> Ultraviolet radiation,which comes from the sun, causes mutations by causing certain portions of DNA to remain bound together (even when they shouldn’t). This causes mutations by causing misreading of the DNA.

–> Certain naturalmineral fibreslike asbestos, because of their size, can cause damage directly to DNA resulting in carcinogenic mutations.