What causes cancer? Known causes, risk factors and warning signs.

When a disease with a silent threat is mentioned, most people automatically think of cancer. The nature of all the various forms of cancer is to slowly cause abnormalities in the body. But by the time people find out that they have cancer, their organs have already been damaged. Therefore, the best approach is to maintain a look-out for early warning signs.

Getting to know cancer

Cancer is a disease caused by DNA abnormalities in cells. The abnormalities cause uncontrollable rapid cell proliferation, often resulting in an abnormal lump. The lump can spread, or metastasize, to nearby areas and other organs. Certain cancers such as leukemia and others don’t cause lumps. The abnormalities can occur in cells in organs throughout the body. Generally, cancers are named after the organ in which they occur, i.e. lung cancer, brain cancer, breast cancer, cervical cancer, leukemia, lymphoma, and skin cancer. Treatments vary depending on the organ affected, the stage and the condition of the patient.

Risk factors for cancer

As mentioned, cancer is caused by DNA abnormalities. Factors behind DNA abnormalities come in three categories:

  1. Error in the cells’ genetic material formation process. The body has a system that normally detects and corrects these errors. However, as we get older, this ability is impaired. That's why we tend to find cancer in older people rather than younger people.
  1. Environmental factors that damage genetic material, causing cancer. Environmental factors include ultraviolet rays from sunlight, smoking, drinking, and foods containing alpha toxin such as peanuts and cashews that are not kept properly.
  1. Affliction with certain diseases such as hepatitis B, hepatitis C, HPV, HIV, liver fluke, and others. These diseases increase the chance of cancer in some organs. Obesity is another risk factor for many types of cancer. Some cancers can also be hereditary.

Cancer warning signs

Even though cancer is a silent threat, you can watch out for even slight abnormalities in your body that may be warning signs such as:

• Enlargement of warts or moles

• Rapidly growing lumps or blisters

• Wounds taking longer to heal

• Abnormal bleeding from passages of the body such as eyes, ears, nose, mouth, sexual organ and anus (a warning sign not only for cancer but possibly for other diseases, depending on diagnosis)

• Hoarseness of voice or persistent coughing

• Difficulty swallowing or prolonged heartburn

• Changes in the excretory system, feces, and urine

• Black stool or bloody urine

• Weight loss, loss of appetite

The above symptoms are only suspected symptoms of cancer. A biopsy of the abnormal portion is required to clearly confirm the presence of cancer cells or not. In many cases, patients have worrying symptoms for a significant time before doing anything about them. They have trouble eating and sleeping, resulting in physical and mental deterioration. Then when they actually get a diagnosis, they find they have some other condition completely unrelated to cancer. So if in doubt, see a doctor and get a diagnosis. Don’t worry beforehand.

Cancer can be successfully treated if you find out fast

Before we find a cure for cancer, the most important thing is to avoid avoidable risks. Be mindful of your physical condition and get an annual health check-up and, depending on your age, a cancer screening. These checks will alert you to any initial risk that might call for a thorough examination of the area or organ in question. If cancer is diagnosed, the treatment can start immediately. These days, cutting-edge medical science and technology can give patients a certain measure of confidence that they can be healed. Keep in mind that even if the number of people being diagnosed with cancer is increasing every year, the number of survivors is rising faster.

This article has been verified for accuracy by Dr. Patawee Boontanon, Infectious Disease Pathologist, Queen Sirikit Hospital.


• National Cancer Institute, Department of Medicine, Ministry of Public Health

• Ministry of Public Health

• Bumrungrad Hospital

• Corporate Communications, Faculty of Medicine Ramathibodi Hospital