about cancer

Cancer Information

  • What is cancer?
  • General Cancer Statistics
  • cancer types:
  • Breast Cancer
  • Colorectal Cancer
  • Lung Cancer
  • Nasopharyngeal Cancer
  • Stomach Cancer
  • Cancer Prevention
About Cancer > Cancer Information > What is cancer?

What is cancer?

Cancer is the term for a group of diseases caused by the uncontrolled growth of mutated cells. Cancers are typically named for either the organ where they originated from, or from the type of cells that they mutated from.

According to Center for Health Protection statistics, cancer is the leading single cause of death in Hong Kong. In 2013, an estimated 13,538 individuals died of cancer.

Cancers begin when a cell undergoes a mutation that affects its normal growth and reproduction. While a healthy cell has built in mechanisms that cause it to commit suicide upon cell damage, these mutated cells persist. The result is a buildup of cells where the body does not need, which can create a tumor.

There are two types of tumors, benign and malignant:
· Benign tumors lack the ability to invade adjacent tissues or to spread to distant regions of the body. These are relatively low-risk to one's health, although they still can cause health problems from being a physical mass in the body where one is not supposed to belong.
· Malignant tumors are cancers. These cells can invade other nearby tissues, and if they manage to enter the lymphatic system or the circulatory system (blood vessels) they can spread to distant parts of the body to do more damage. This process is called metastasis. Even when they are removed, malignant tumors can return.

Cancer Staging

Cancer staging describes the severity and extent of a patient's cancer and whether or not it has spread throughout the body. While the process of cancer staging is complicated, it involves the size of the original tumor and whether or not it has penetrated the surrounding tumors, as well as whether or not the cancer has spread to the nearby lymph nodes and to distant parts of the body.

Cancers are typically divided into Stages 0 through 4. A cancer's stage is determined at diagnosis and never changes, even if the disease continues to grow. Stage 0 is the least severe and the easiest, also known as carcinoma in situ, or a small tumor of dysfunctional cells that have not yet become a cancer. On the other hand, a Stage 4 cancer has metastasized and spread to distant parts of the body.

Staging is used by physicians to plan a patient's treatment as well as to determine his or her prognosis, or the likely outcome of the patient's disease. Cancers can typically be cured or managed if they are found at early stages. However, the likelihood of cancer survival falls drastically at higher stages. Most Stage 4 cancers cannot be completely cured by existing treatments.