Cancer results when cellular changes cause the uncontrolled growth and division of cells.

Certain forms of cancer result in visible growths called tumours, while others, such as leukaemia, do not. Cancerous cells can form tumours, impair the immune system and cause other changes that prevent the body from functioning regularly.

Causes

There are many causes of cancer, and some are preventable. In addition to Smoking, risk factors for cancer include:

• heavy alcohol consumption

• excess body weight

• physical inactivity

• poor nutrition

Other causes of cancer are not preventable. Currently, the most significant unpreventable risk factor is age.

Genetic Factors

Genetic factors can contribute to the development of cancer. Changes in the genes can lead to faulty instructions, and cancer can result. Finally, a person can inherit a predisposition for a type of cancer.

Types of Cancer

The most common type of cancer is breast cancer, followed by lung and prostate cancers. Each year, around the world thousands of people  receive a diagnosis of one of the following types of cancer:

• Bladder
• Colon and Rectal
• Endometrial
• Kidney
• Leukaemia
• Melanoma
• Non-Hodgkin's lymphoma
• Breast Cancer
• Liver & Bile Duct Cancer
• Lung Cancer
• Lymphoma  
• Pancreatic Cancer
• Prostate Cancer
• Skin Cancer
• Thyroid Cancer
• Uterine Cancer
• Brain & Spinal Tumours

Other forms are less common. Research reveals that  there are over 100 types of cancer.

Signs and symptoms

Fatigue; Lumps; Weight fluctuation, Skin changes including sores that won't heal, or changes to existing moles ; changes in bowel or bladder habits; persistent cough; difficulty swallowing; hoarseness; unexplained muscle or joint pain, fevers or night sweat, etc

Treatments

Doctors usually prescribe treatments based on the type of cancer, its stage at diagnosis, and the person's overall health. Innovative research has fueled the development of new medications and treatment technologies.

Few of the  approaches to cancer treatment are as follows:

• Chemotherapy aims to kill cancerous cells with medications that target rapidly dividing cells. The drugs can also help shrink tumours, but the side effects can be severe. The side effects of chemotherapy include hair loss. However, advances in treatment are improving the outlook for people with cancer.
• Hormone therapy involves taking medications that change how certain hormones work or interfere with the body's ability to produce them. When hormones play a significant role, as with prostate and breast cancers, this is a common approach.
• Immunotherapy uses medications and other treatments to boost the immune system and encourage it to fight cancerous cells. Two examples of these treatments are checkpoint inhibitors and adoptive cell transfer.
• Precision or personalised medicine, is a newer, developing approach. It involves using genetic testing to determine the best treatments for a person's particular presentation of cancer. Researchers have yet to show that it can effectively treat all types of cancer, however.
• Radiation therapy uses high-dose radiation to kill cancerous cells. Also, a doctor may recommend using radiation to shrink a tumour before surgery or reduce tumour-related symptoms.
• Stem cell transplant can be especially beneficial for people with blood-related cancers, such as leukaemia or lymphoma. It involves removing cells, such as red or white blood cells, that chemotherapy or radiation has destroyed. Lab technicians then strengthen the cells and put them back into the body.
• Surgery is often a part of a treatment plan when a person has a cancerous tumour. Also, a surgeon may remove lymph nodes to reduce or prevent the disease's widespread.
• Targeted therapies perform functions within cancerous cells to prevent them from multiplying. They can also boost the immune system. Two examples of these therapies are small-molecule drugs and monoclonal antibodies.

Doctors will often employ more than one type of treatment to maximise effectiveness and customise the treatment options per need of the hour.