The mass produced by the uncontrolled growth of abnormal cells
cancer cells do not differentiate into the normal tissue cells and so can be easily identified
Malignant Tumors are able to spread to other tissue, know as metastasis. This can result in secondary tumors
Tumors that are unable to spread are called benign. While they can be dengerous if they impact on vital organs, they are usually easily removed.
Three Types of Neoplasm
Benign
Potentially Malignant
Malignant
Benign Neoplasm
Can divide uncontrollably, but not rapidly
Grow inside a capsule, so do not destroy surrounding tissues
Cells do not penetrate to blood and lymph vessels
Potentially Malignant Neoplasm
Form localized masses which may invade other tissues and transform into cancer
cancer is typically defined as a disease characterized by the uncontrolled and abnormal growth of cells. These cells divide rapidly and can invade surrounding tissues or spread to other parts of the body through the blood or lymphatic system (a process called metastasis). Cancer can develop in almost any part of the body, and the abnormal cells may form a mass called a tumor (except in the case of blood cancers like leukemia). Cancer arises due to mutations in the DNA that affect the regulation of cell growth and division.
Malignant Neoplasm
Can divide uncontrollably and rapidly
Cell growth breaks outside of capsule, destroying surrounding tissues
Cells can spread to other tissues
Benign
don't invade other tissues or transform into cancer
Malignant
form masses that can grow uncontrolled, invading other tissues and transforming into cancer
Three categories of factors that can cause uncontrolled cell division:
Genetic
Environmental
Loss of Immunity
Genetic Factors:
proto-oncogenes
Tumor suppressor genes
Inherited genes
Proto-oncogetes
normally function to stimulate cell growth, but when mutated, they become oncogenes which cause uncontrolled cell division (a mutation in these genes wouldn't be inherited as the person wouldn't survive)
Tumor Suppressor Genes
normally function to slow cell division, inhibiting division of unhealthy cells, but when mutated, uncontrolled cell division can occur (A mutation in these genes wouldn’t be inherited as the person wouldn’t survive)
Inherited genes
in genes which have been passed down to you and are in all the cells of your body can increase the risk or cancer à e.g. breast cancer is associated with mutations in BRCA1/BRCA2 genes
Environmental factors
can cause damage to DNA and can lead to uncontrolled cell division, such as exposure to radiation or certain chemicals
Mutagens
Substances that can damage DNA
Three Types of Mutagens
Chemical Mutagens (e.g. X-rays and UV Light)
Physical Mutagens (e.g. tobacco or air pollution)
Biological Mutagens (e.g. viruses)
Loss of Immunity
Immune system is usually able to detect and destroy abnormal cells - if a person’s immune system is weakened, cells dividing in an uncontrolled manner may go undetected, which can lead to tumor formation.
Cancer Diagram
A) Abnormal Cells
B) Boundary
C) Normal Cella
D) Lymph Vessel
E) Blood Vessel
F) Normal Cells
G) Abnormal Cells
H) Abnormal Cells Multiply
I) Malignant or invasive cancer
Carcinogens
Environmental factors that can trigger malignant tumors e.g. UV light, X-rays
Untraviolet Light (sunlight)
Sunburn and overexposure to UV radiation is the main cause of skin cancer
X-Rays
Known to cause cancer, however, the amount produced by modern machines, along with control around use, poses little risk.
Ionizing Radiation
Produced by radium and ores of uranium (e.g., atomic bombs). Cause significant increase in incidence of cancer due to damage to DNA. Single exposure to high dose increases leukemia risk.
Viruses
Exposure to viruses found to causes some forms of cancer. E.g., HPV has been proven to cause cancer of the cervix.
Chemical Carcinogens
Although widespread in modern society, simple precaution usually taken to minimise effects of known chemical carcinogens such as excessive alcohol consumption, asbestos, soot/tar, tobacco, some solvents in glues/paints.
How to Reduce the Chance of Getting Cancer
Education, legislation, adopt a healthy lifestyle, get regular checks, early detection
Education
Makes public aware of the need to limit exposure to carcinogens. E.g., the ‘Slip, Slop, Slap!’ program introduced in 1981.
Legislation
Australian government has passed laws to control exposure to carcinogens. E.g., banning of smoking in public places, restrictions around selling of cigarettes, introduction of controlled procedures around X-ray machines and products containing asbestos have been banned.
Adopt a healthy lifestyle to reduce risk
Use protective clothing when handling carcinogens, don’t smoke (or vape!), slip/slop/slap/seek/slide, eat healthy diet, consume alcohol moderately.
Regularly check skin for changes, see doctor immediately if you notice changes such as lumps anywhere, unusual bleeding, changes to moles/warts or change in bladder/bowel habits.
How to reduce the risk of cancer in Women
Have cervical screening test every 5 years
HPV vaccination
Regular mammograms and bowel cancer tests over 50 years old
How to reduce the risk of cancer in Men
If over 50 years, talk to doctor about prostate check, and have regular bowel cancer tests.
Cervical Cancer
Human papilloma virus (HPV), a sexually transmitted infection, causes cervical cancer.
Changes in cervical cells occur before they become cancerous.
‘Pap’ (now cervical screening) test develop to detect these abnormal cells – cells collected and smeared on microscope slides to be examined.
Cervical Screening Tests every three to five years can prevent up to 90% of the most common form of cervical cancer.
Now one of the most preventable and curable of all cancers.
Breast Cancer
Screening for Breast Cancer, one of the most common types of cancer in Australian women, is done by mammogram – an x-ray of the breasts.
Digital mammography now uses a computer instead of x-ray film.
Can detect tumours as small as 1cm in diameter.
Free screening has been available to women 50+ years since 1991.
Bowel Cancer
Or colorectal cancer, is a malignant tumour in the large intestine (colon/rectum).
Treated successfully is detected in early stages, however, there are often no or very few symptoms present in early stages.
Bowel cancer screening program (eligible to 50-74 yr olds in Aus) is a test (faecal occult blood test) for blood in faeces which is taken at home and sent off for analysis.
Blood in faeces usually comes from polyps which can be/become cancerous, so if positive test, colonoscopy will occur.
Prostate Cancer
No screening available in Australia.
Prostate cancers usually grow very slow and don’t require treatment, but some forms are life-threatening and spread rapidly.
Diagnosed by digital rectal examination (DRE), prostate-specific antigen (PSA) blood test, and biopsy.
Cancer
a disease caused by the uncontrolled division of abnormal cells in a part of the body