Mutations of genes BRCA1 and BRCA2 (linked to an

increased risk of breast and ovarian cancers) can inhibit

the body's ability to safe-guard and repair DNA. Copies
of these mutated genes can be passed on genetically to
future generations, leading to an increased risk of
cancer.
Environmental Factors
Cancer can also result from the interaction between a
person's genetic factors and external agents including:
 Physical Carcinogens - ultraviolet rays, ionizing
radiation
 Chemical Carcinogens - asbestos, components of
tobacco smoke, aflatoxin (food contaminant), and
arsenic (drinking water contaminant).
 Biological Carcinogens - infections from certain
viruses, bacteria, or parasites.

Symptoms
A cancer can grow into or begin to push on nearby
organs, blood vessels, and nerves. This pressure causes
some of the signs and symptoms of cancer.
Cancer cells use up much of the body’s energy supply
and can also cause the immune system to react in ways
that produce these signs and symptoms.
Common signs and symptoms include:
 Fatigue
 Unexplained weight loss
 Appetite loss
 Unusual lumps or swelling
 Blood in stools
 Cough or hoarseness that does not go away
 Seizures, headaches or vision problems
 Sores that do not heal

Types of Cancer
 Carcinomas - Carcinomas are cancers that occur in
epithelial tissues in the body and comprise of 80-
90% of all cancers. This class includes the two most
common skin cancers, basal cell carcinoma and
squamous cell carcinoma and also includes
the glandular cancer adenocarcinoma.
 Ex. prostate, breast, lung, and colorectal

cancer.

 Sarcomas - Sarcomas occur in connective tissue like

the bones, cartilage, fat, blood vessels, and muscles.
 Ex. Bone cancers like osteosarcoma and Ewing
sarcoma
 Muscle cancers rhabdomyosarcoma and
leiomyosarcoma.

 Myelomas - Myelomas are cancers that occur in

plasma cells in the bone marrow.
 Ex. Kahler disease

 Lymphomas - Lymphomas are cancers of the

immune system cells.
 Ex. Hodgkin lymphoma
 A group of white blood cell cancers are known
as non-Hodgkin lymphoma
 Leukemias - Leukemias are a group of
different blood cancers of the bone marrow and
cause abnormal blood cells to enter the
bloodstream.

Metastatic Transformation of Cancer

Cells
A normal cell is transformed into a cancer cell through
alteration in differentiation of the genes that regulate
cell growth.
The affected genes consist of Oncogenes, which
promote cell growth and reproduction, and tumour
suppressor genes, which inhibit cell division and
survival. Malignant transformation can occur through
the formation of novel oncogenes, the over-expression
or under-expression of normal oncogenes, or disabling
of tumor suppressor genes.

 Oncogenes code for proteins that function to drive

the cell cycle forward, typically causing cells to
proceed from one of the G (gap) phases to
either chromosome replication (S phase) or
chromosome segregation (mitosis).
Genes that code for the normal proteins
controlling these processes are called proto-
oncogenes. However, once they are altered to
become oncogenes, their abnormal protein
products exhibit increased activity that contributes
to tumor growth.
 Therefore, instead of stopping within a G phase, a
tumor cell continues to progress through
subsequent phases of the cell cycle leading to
uncontrolled cell division.
 Proto-oncogenes turn into oncogene via
mutations which permanently activate proteins
that normally interchange between active or
inactive states.
 Proto-oncogene can also turn into an oncogene
through chromosomal translocation occurs
when the pieces of broken chromosomes
reattach haphazardly, leading either to the
formation of a fusion protein or the altered
regulation of protein expression.
 Tumor suppressor genes code for proteins that
normally operate to restrict cellular growth and
division or even promote programmed cell death.

 A type of this protein is known as

retinoblastoma protein (pRb) and its
corresponding gene, RB1, is a tumor
suppressor gene pRb activity stops the
expression of genes required for progression
into S phase of the cell cycle, and hence its
inactivation allows for uncontrolled cell
division.
Therefore, oncogenes and tumor suppressor genes,
link cell cycle control to tumor formation and
development.

Diagnosis
 Various tests may be performed in order to confirm a
cancer diagnosis. These include:
 Lab Tests – High or low levels of certain substances in
your body can be a sign of cancer while some tests
involve testing blood or tissue samples for tumour
markers. Tumour markers are substances secreted by
cancer cells in higher number than that of normal
cells.
 Ex. of tumour tissue markers - FGFR3 gene
mutation analysis to help determine treatment
for patients with bladder cancer
 Bone Scan - Bone scans are a type of nuclear scan that

check for abnormal areas or damage in the bones.

They may be used to diagnose bone cancer or cancer
that has spread to the bones. This is done by injecting
a small amount of radioactive material into the vein
which detects abnormal areas in the bone as it
travels through the blood. It is then picked up by the
scanner.
 Biopsy - A biopsy is a procedure in a sample of tissue
of the patient is taken and observed to identify
whether it is cancerous or not.
 PET-CT Scan - A small amount of radioactive glucose
is administered, which highlights areas of your body
where the cells are more active than normal (PET
Scan) and 3D images are generated. At the same
 time, x-rays are passed through your body and 3D
images of CT are generated.
After diagnosis, Doctors use the stages of cancer to
classify cancer according to its size, location, and extent
of spread. Staging helps doctors determine the
prognosis and treatment for cancer. The TNM staging
system classifies cancers according to:
 Tumour (T): Primary tumour size and/or extent
 Nodes (N): Spread of cancer to lymph nodes in the
regional area of the primary tumour
 Metastasis (M): Spread of cancer to distant sites
away from the primary tumour

The TNM classification is combined with other factors

to determine the stages of cancer:
 Stage 0: This refers to cancer that is "in situ,"
meaning that cancerous cells are confined to their
site of origin. This type of cancer has not spread
and is not invading other tissues.
 Stage I: This stage is usually a small cancer or
tumour that has not grown deeply into nearby
tissues. It also has not spread to the lymph nodes
 or other parts of the body. It is often called early-
stage cancer.
 Stage II and Stage III: These stages indicate larger
cancers or tumours that have grown more deeply
into nearby tissue r other lymph nodes but not to
other parts of the body.
 Stage IV: This stage indicates the cancer has
spread to distant lymph nodes, tissues, or organs
in the body far away from the site of origin.

Treatment
Numerous treatments for cancer which differ
depending on the type and stage of a cancer as well as
the overall health of the patient. These include:

Chemotherapy
It is the treatment of cancer with one or
more cytotoxic (cell toxic) anti-neoplastic (abnormal
growth) drugs. They consist of various drugs that act by
killing cells that divide rapidly.
Targeted therapy is a form of chemotherapy that
targets specific molecular differences between cancer
and normal cells. For ex. targeted therapies blocked
the estrogen receptor molecule, inhibiting the growth
of breast cancer.
Chemotherapy is curative for some cancers, such as
some leukemias and ineffective in some brain tumors
but its effectiveness is often limited by its toxicity to
other tissues in the body.

Radiation Therapy
Radiation therapy involves the use of ionizing
radiation in an attempt to either cure or improve
symptoms. It damages the DNA of cancerous tissue
and kills it while sparing normal tissues. This is done by
shaped radiation beams which are aimed from multiple
angles to intersect at the tumor, providing a larger
dose there than in the surrounding, healthy tissue.
Radiation can be delivered externally, where X-rays,
gamma rays, or other high-energy particles are
delivered to the affected area from outside the body,
or internally which involves the placement of
radioactive material inside the body near cancer cells
(brachytherapy).
 Ex. Radioactive iodine (I-131) for thyroid
cancer, strontium-89 for bone cancer

Surgery
Surgery is often performed to remove malignant
tumors and allows for the determination of the exact
size of the tumor as well as the extent of spread and
invasion into other nearby structures or lymph nodes.
Sometimes, cancer cannot be entirely surgically
removed it could damage critical organs or tissues.
Therefore, palliative surgery is performed to reduce
the effects of a cancerous tumor. Reconstructive
surgery can also be performed to restore the look or
function of a part of the body after cancer surgery.
Other treatments include:
 Hematopoietic Stem Cell Transplants - Involve the
infusion of stem cells into a cancer patient after
the bone marrow has been destroyed by high-dose
chemo and/or radiation.
 Photodynamic therapy (PDT) - Involves the
application of laser energy of a specific wavelength
to tissue that has been treated with a
photosensitizing agent, a medication that makes
cancerous tissue susceptible to destruction with
laser treatment.
 Angiogenesis inhibitors - Medications which inhibit
the growth of new blood vessels that cancerous
tumors need in order to grow.

Preventative Measures
More than a third of cancer could be prevented by
modifying or avoiding key risk factors which include:

Tobacco
Smoking causes approximately 30 percent of all
cancers and 90 percent of lung cancers. Globally,
tobacco causes just over five million deaths a year and
is projected to cause 1 billion deaths worldwide by the
end of the century. It also significantly increases the
risk of kidney, bladder, pancreas and cervical cancers.

Alcohol use
Alcohol use increases the risk for many cancer types
including cancer of the oral cavity, pharynx, larynx,
oesophagus, liver, colorectum and breast.

Physical activity
Regular physical activity and the maintenance of a
healthy body weight, along with a healthy diet, will
considerably reduce cancer risk. Exercise lowers the
risk of heart disease, stroke, diabetes, osteoporosis,
high blood pressure, and prevent cancer.
For ex. Exercise helps maintain healthy levels of
hormones like estrogen and progesterone in the blood
which prevent breast cancer while help control insulin
levels which can prevent colon cancer.

Diet
A healthy diet can help lower the risk of many
cancers. Evidence shows that a risk-reducing diet is:
largely plant based, low in animal products (red meat),
low in sodium, and for men, not too high in calcium
(less than 1500mg/day).
A daily multivitamin with folate, a B vitamin that has
been shown to lower the risk of colon cancer, as well
as breast cancer, may help reduce the overall risk of
cancer.
Glutathione plays a major role in the antioxidant
activities of the body. Glutathione metabolism is able
to play both protective and pathogenic roles and
hence, is crucial in the removal and detoxification of
carcinogens. Alterations in this pathway can greatly
affect cell survival.

Protection from the Sun

High sun exposure directly increases the risk of
melanoma (skin cancer). Tanning beds and indoor
tanning are carcinogenic to humans as it can increase
the risk of melanoma by around 20 percent.
To lower the risk of skin cancer, one must avoid the
sun during peak burning hours, wear long sleeve shirts,
long pants, and wide-brimmed hats, properly apply and
re-apply broad-spectrum sun screen.

Infectious diseases
Some infections cause chronic inflammation that can
change the behaviour of infected cells. Infections that
compromise the immune system (like HIV) also
increase cancer risk by making the body less able to
defend against infections that can cause cancer.
Viral hepatitis B and C cause cancer of the liver, HPV
infection causes cervical cancer, and the bacterium
Helicobacter pylori increases the risk of stomach
cancer. Preventive measures include vaccination and
prevention of infection and infestation.

Regular Screening Tests

Screening tests find cancers early when they’re most
treatable and are the best way to protect against
cancer. Breast (mammogram), cervical (Pap test), and
colon screening should be priorities for women. Colon
screening should be a priority for men.
For ex., the Pap test can find abnormal cells in the
cervix which may turn into cancer. The HPV test looks
for the virus (human papillomavirus) that can cause
these cell changes.

Bibliography
www.nature.com

www.euro.who.int

www.wikipedia.org

www.onhealth.com

www.cancer.org