Cancer is a disease in which abnormal cells grow uncontrollably and can spread from their original site in the body to adjoining parts of the organism. It is also known as a malignant tumour or neoplasm. Cancer is the second leading cause of death worldwide, causing an estimated 9.6 million deaths in 2018, with lung, colorectal and breast cancer among the most common forms in men and lung, prostate and cervical cancer in women.
The earliest stage of cancer is a long run of cell division without normal controls, which leads to the accumulation of genetic changes called mutations. Mutations can happen by chance when a cell is dividing or through exposure to outside factors, such as tobacco smoke or radiation. Once a cell has accumulated enough mutations to become cancerous, it will no longer respond to the normal growth and reproduction cues of its environment and can start growing out of control.
This is when the cell begins to divide without control and begin to accumulate genetic mutations and evade cellular growth controls, such as those that prevent inappropriate cell proliferation or kill cells with faulty DNA. It can also start to spread from one area of the body to other areas through the bloodstream, a process called metastasis.
A growing population of cancer cells will be subject to selection pressures from the environment, which can be stabilizing or directional. Like other populations, the cancer cells will compete with each other and with healthy cells for resources such as nutrients and space. Selection pressures will favor those cells with advantageous traits that promote their survival, such as resistance to apoptosis and ability to evade the immune system.
Despite the fact that we now know much more about how cancers develop, our understanding of the causes of cancer remain somewhat incomplete. This is largely due to the fact that cancer is constantly changing and evolving.
Improvements in early diagnosis, a reduction in tobacco use, and advances in treatment are all helping to reduce the number of people who die from cancer. However, cancer is still a major health challenge, and there are many different types of the disease, each with its own unique set of symptoms. Some cancers are more serious than others and will have a different impact on each individual. Cancer is a disease that destroys the body and the mind, destroying families and friendships along the way. It is also a terrible economic burden, imposing huge costs on society. The economic costs include the cost of medical treatments and lost productivity. The emotional and psychological impacts are just as devastating, leaving individuals and their families with permanent scars. Ultimately, it is better to prevent cancer from occurring in the first place. To learn more about how you can help kick cancer to the curb, click here.