Cancer does not grow in the body until promotion occurs. Promoters are agents such as mutations, immune disorders, hormone disorders, or carcinogens that allow the cancer to grow. Promoters can create further cellular damage, allowing malignant cells to spread; they can inhibit the removal of the cancerous cells by damaging the immune system's function; or they can alter body tissues to make them more favorable for cancer growth.
The other process necessary for the
development of cancer is initiation. Initiation is the process in which genetic material within a cell changes, making possible for the cell to become cancerous by the change brought about by carcinogens. Often initiation cannot happen without the help promotion, and promotion is ineffective on cells that have not been initiated.