Cancer is a group of diseases that involve abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans.
Cancer cells can spread through the bloodstream and lymphatic system to other organs in the body. Metastasis is a common feature of cancer cells and it occurs when cancer cells break away from the original tumor site and establish new tumors in other tissues. The process by which cancer cells metastasize is complex and not fully understood but it involves the ability of cancer cells to migrate from one location to another and to survive in different microenvironments. Cancer cell metastasis is responsible for most deaths from cancer since it is often difficult to effectively treat once it has occurred.
There are many risk factors for developing cancer including genetics, lifestyle choices (such as smoking), certain infections (such as HPV), radiation exposure and environmental factors (such as air pollution). However, it should be noted that having one or more risk factors does not necessarily mean that an individual will develop cancer; many people with multiple risk factors never develop the disease while some people who develop cancer have no known risk factors. Early detection of cancers usually leads to better outcomes so it is important for individuals to be familiar with possible signs and symptoms and to see their doctor if they have any concerns. There are many effective treatments forcancer available including surgery, radiation therapy, chemotherapyand targeted therapy; treatment selection depends on the typeand stageofcancer as well as the patient’s overall health status