Brief Overview of Cancer:
Cancer is a group of diseases characterized by uncontrolled cell growth and division.
The cells can invade surrounding tissues and spread to other parts of the body
through the blood and lymphatic systems. Cancer is a large group of diseases with
one thing in common: They happen when normal cells become cancerous cells that
multiply and spread. Your genes send instructions to your cells — like when to start
and stop growing, for example. Normal cells follow these instructions, but cancer
cells ignore them.
Cancer can affect almost any part of the body and is often named after the organ or
tissue where it originates (e.g., lung cancer, breast cancer). Early detection and
advancements in treatment have improved survival rates, but cancer remains one of
the leading causes of death worldwide.
Cancer is the second most common cause of death in the U.S. But fewer people are
dying of cancer now than 20 years ago. Early detection and innovative treatments
are curing cancer and helping people with cancer live longer.
Cancer is a disease where abnormal cells begin to grow uncontrollably. These cells
can form masses called tumors (except in blood cancers like leukemia). Cancer can
also spread to other parts of the body (metastasis) through the blood or lymphatic
system. This abnormal growth disrupts normal bodily functions, causing serious
health issues.
Causes of Cancer:
Cancer is a genetic disorder. But that doesn’t necessarily mean it’s inherited. It
happens when genes that manage cell activity mutate (change). They create
abnormal cells that divide and multiply, eventually disrupting how your body works.
These cells create cancer clusters, or tumors. Cancerous cells may break away from
tumors and travel to other areas of your body through your lymphatic
system or bloodstream.
For example, a tumor in your breast may spread to your lungs, making it hard for
you to breathe. In some types of blood cancer, your bone marrow makes abnormal
blood cells that multiply uncontrollably. Eventually, the abnormal cells crowd out
normal blood cells.
Risk factors
There isn’t one single cause for cancer. Rather, certain things can increase your
chance of developing it, like:
• Family history. If you have close biological family members (parents, siblings,
grandparents) who have cancer, you have a higher risk of developing it.
• Smoking. Smoking tobacco or using e-cigarettes increases your chance of
developing lung, esophageal, pancreatic and oral cancer.
• Environmental factors. Exposure to toxins in your environment, like
asbestos, pesticides and radon, can eventually lead to cancer.
• Malnutrition. High-fat or high-sugar foods can increase your risk for many
types of cancer. You’re also more vulnerable to disease if you don’t get enough
physical activity.
• Hormone therapy. Women and people assigned female at birth (AFAB) taking
hormone replacement therapy may have an increased risk for breast cancer
and uterine cancer.
• Radiation exposure. Ultraviolet (UV) radiation from the sun significantly
increases your risk of developing skin cancer. Over-exposure to radiation
therapy can also be a risk factor.
Types of Cancer:
There are more than 200 types of cancer and we can classify cancers according to
where they start in the body, such as breast cancer or lung cancer.
We can also group cancer according to the type of cell they start in. There are 5 main
groups. These are:
• carcinoma – this cancer begins in the skin or in tissues that line or cover
internal organs. There are different subtypes, including adenocarcinoma,
basal cell carcinoma, squamous cell carcinoma and transitional cell carcinoma
• sarcoma – this cancer begins in the connective or supportive tissues such
as bone, cartilage, fat, muscle or blood vessels
• leukaemia – this is cancer of the white blood cells. It starts in the tissues that
make blood cells such as the bone marrow.
• lymphoma and myeloma – these cancers begin in the cells of the immune
system
• brain and spinal cord cancers – these are known as central nervous system
cancers
Stages of Cancer:
The stage of cancer refers to how far it has spread in the body, which is crucial in
determining treatment.
There are 2 main types of staging systems for cancer. These are the TNM system and
the number system.
The systems mean that:
• doctors have a common language to describe the size and spread of cancers
• doctors can compare treatment results between research studies
• different hospitals and clinics have standard treatment guidelines
Some blood cancers or lymph system cancers have their own staging systems.
The TNM staging system
The TNM staging system stands for Tumour, Node, Metastasis.
• T describes the size of the tumour
• N describes whether there are any cancer cells in the lymph nodes
• M describes whether the cancer has spread to a different part of the body
The system uses letters and numbers to describe the cancer.
T refers to the size of the cancer and how far it has spread into nearby tissue. It can
be 1, 2, 3 or 4, with 1 being small and 4 large.
N refers to whether the cancer has spread to the lymph nodes. It can be between 0
and 3. 0 means that there are no lymph nodes containing cancer cells. And 3 means
that there are lots of lymph nodes containing cancer cells.
M refers to whether the cancer has spread to another part of the body. It can either
be 0 or 1. M0 means that the cancer hasn't spread and M1 that the cancer has spread.
So for example a small cancer that has spread to the lymph nodes but not to
anywhere else in the body may be T2 N1 M0. Or a more advanced cancer that has
spread may be T4 N3 M1.
Sometimes doctors use the letters a, b or c to further divide the categories. For
example, stage M1a lung cancer is a cancer that has spread to the other lung. Stage
M1b lung cancer has spread to one other part of the body. Stage M1c lung cancer
has spread to more than one part of the body.
The letter p is sometimes used before the letters TNM. For example, pT4. This stands
for pathological stage. It means that doctors based the staging on examining cancer
cells in the lab after surgery to remove a cancer.
The letter c is sometimes used before the letters TNM. For example, cT2. This stands
for clinical stage. It means that the stage is based on what the doctor knows about
the cancer before surgery. Doctors may look at your tests results and use the
information from examining you.
Number staging systems
Number staging systems use the TNM system to divide cancers into stages. Most
types of cancer have 4 stages, numbered from 1 to 4. Doctors often write the stage
down in Roman numerals. So they may write stage 4 as stage IV.
Here is a brief summary of what the stages mean for most types of cancer:
Stage 1 usually means that a cancer is small and contained within the organ it started
in
Stage 2 usually means that the tumour is larger than in stage 1 but the cancer hasn't
started to spread into the surrounding tissues. Sometimes stage 2 means that cancer
cells have spread into lymph nodes close to the tumour. This depends on the
particular type of cancer
Stage 3 usually means the cancer is larger. It may have started to spread into
surrounding tissues and there are cancer cells in the lymph nodes nearby.
Stage 4 means the cancer has spread from where it started to another body organ.
For example to the liver or lung. This is also called secondary or metastatic cancer
Sometimes doctors use the letters A, B or C to further divide the number categories.
For example, stage 3B cervical cancer.
Symptoms of Cancer:
Signs and symptoms caused by cancer will vary depending on what part of the body
is affected.
Some general signs and symptoms associated with, but not specific to, cancer,
include:
• Fatigue
• Lump or area of thickening that can be felt under the skin
• Weight changes, including unintended loss or gain
• Skin changes, such as yellowing, darkening or redness of the skin, sores that
won't heal, or changes to existing moles
• Changes in bowel or bladder habits
• Persistent cough or trouble breathing
• Difficulty swallowing
• Hoarseness
• Persistent indigestion or discomfort after eating
• Persistent, unexplained muscle or joint pain
• Persistent, unexplained fevers or night sweats
• Unexplained bleeding or bruising
Diagnosis of Cancer:
Diagnosing cancer at its earliest stages often provides the best chance for a cure.
With this in mind, talk with your doctor about what types of cancer screening may be
appropriate for you.
• Physical exam. Your doctor may feel areas of your body for lumps that may
indicate cancer. During a physical exam, your doctor may look for
abnormalities, such as changes in skin color or enlargement of an organ, that
may indicate the presence of cancer.
• Laboratory tests. Laboratory tests, such as urine and blood tests, may help
your doctor identify abnormalities that can be caused by cancer. For instance,
in people with leukemia, a common blood test called complete blood count
may reveal an unusual number or type of white blood cells.
• Imaging tests. Imaging tests allow your doctor to examine your bones and
internal organs in a noninvasive way. Imaging tests used in diagnosing cancer
may include a computerized tomography (CT) scan, bone scan, magnetic
resonance imaging (MRI), positron emission tomography (PET) scan,
ultrasound and X-ray, among others.
• Biopsy. During a biopsy, your doctor collects a sample of cells for testing in
the laboratory. There are several ways of collecting a sample. Which biopsy
procedure is right for you depends on your type of cancer and its location. In
most situations, a biopsy is the only way to definitively diagnose cancer.
In the laboratory, doctors look at cell samples under the microscope. Normal cells
look uniform, with similar sizes and orderly organization. Cancer cells look less
orderly, with varying sizes and without apparent organization.
Treatment of Cancer:
Cancer treatment varies based on the type and stage of cancer. The main options
include:
1. Surgery: Removal of tumors or affected organs.
2. Chemotherapy: Drugs that kill or slow the growth of cancer cells.
3. Radiation Therapy: High-energy radiation to target and destroy cancer cells.
4. Immunotherapy: Boosts the immune system to fight cancer.
5. Targeted Therapy: Targets specific molecules involved in cancer cell growth.
6. Hormone Therapy: Blocks or alters hormones that fuel certain cancers.
7. Stem Cell Transplant: Replaces damaged bone marrow or blood cells.
8. Precision Medicine: Tailors treatment based on genetic testing of the cancer.
9. Clinical Trials: Tests new treatments or drugs.
10. Palliative Care: Focuses on symptom relief and quality of life.
Treatments are often combined, and the best plan depends on the individual’s
cancer type and health.
Prevention of Cancer:
While not all cancers can be prevented, certain lifestyle changes and preventive
measures can lower the risk:
Cancer prevention involves key lifestyle changes:
1. Avoid tobacco: Quit smoking and avoid secondhand smoke.
2. Healthy diet: Eat fruits, vegetables, and whole grains; limit alcohol and
processed foods.
3. Exercise: Aim for 150 minutes of moderate exercise weekly.
4. Maintain a healthy weight: Prevent obesity, which is linked to several cancers.
5. Limit alcohol: Drink moderately (1 drink/day for women, 2 for men).
6. Sun protection: Use sunscreen and avoid tanning beds.
7. Get vaccinated: Protect against HPV and hepatitis B.
8. Screenings: Regular cancer screenings (e.g., mammograms, colonoscopies).
9. Avoid toxins: Limit exposure to chemicals like asbestos.
10. Genetic testing: If at risk, consider testing for inherited mutations.
By adopting healthy habits and seeking medical advice regularly, individuals can
reduce their cancer risk and enhance early detection, which is key to successful
treatment.
Reference:
[1] https://www.who.int/news-room/fact-sheets/detail/cancer
[2] https://www.cancer.gov/about-cancer/understanding/what-is-cancer
[3] https://www.ncbi.nlm.nih.gov/books/NBK9963/
[4] https://byjus.com/biology/cancer/
[5] https://cancer.ca/en/cancer-information/what-is-cancer/what-causes-cancer
[6] https://www.healthline.com/health/cancer
[7] https://www.medicalnewstoday.com/articles/323648
[8]https://stanfordhealthcare.org/medical-conditions/cancer/cancer/cancer-
causes.html
