Dr. Nitin Singhal

Anyone can. Risk rises with age, and individual risk depends on factors such as smoking, diet and exercise, family history, and exposures at work or in the environment.

Cells normally grow, divide, age and die, and are replaced. Sometimes cells mutate, grow out of control and form a mass, or tumour, instead of dying. Tumours can be benign or malignant. Malignant tumours can invade and destroy tissue, and can spread to other parts of the body — a process called metastasis, which represents late-stage disease.

Cancer is a genetic disease in the sense that it is caused by changes to the genes controlling how cells behave. Those changes are inherited in roughly 5–10 percent of cases; far more often they occur during a person's lifetime for reasons other than inheritance. Where there is a known family history of hereditary cancer, genetic testing is often recommended.

No. Cancer is not like a cold or the flu. You cannot catch it from someone who has it.

There is no vaccine against cancer itself, but there are vaccines against viruses known to cause cancer. HPV vaccination protects against strains linked to cervical, anal, throat and penile cancers. Hepatitis B vaccination reduces liver cancer risk. In both cases the vaccine protects against the virus, not the cancer directly.

Yes. When treatment appears to be working, a doctor may describe the cancer as being in remission — partial, where the cancer shrinks but does not disappear, or complete, where there is no longer any sign of it. The longer a complete remission holds, the less likely the cancer is to return, and at some point a doctor may call it cured.

Stage 0: the cancer is still where it started and has not spread to nearby tissue; often curable. Stage I: usually a small tumour that has not grown deeply into nearby tissue. Stages II and III: larger tumours or deeper growth into nearby tissue, possibly involving lymph nodes, but not other organs. Stage IV: the cancer has spread to other organs or parts of the body, sometimes called metastatic or advanced cancer.

Not always. Signs depend on where the cancer is and how large it is. Some cancers grow where they cause no symptoms until advanced — pancreatic cancer, for example, often causes nothing until it presses on other structures. General signs can include unexplained weight loss, fever, fatigue, pain, skin changes, changes in bowel or bladder habits, sores that do not heal, unusual bleeding or discharge, a lump or thickening, indigestion or trouble swallowing, a change in a mole or wart, and a persistent cough or hoarseness. These can all have other causes; if they persist, get them checked.

Chemotherapy uses drugs to destroy cancer cells, and can harm healthy cells too, which is where side effects come from. Targeted drugs block specific genes or proteins found in cancer cells and usually cause less harm to healthy cells, though side effects remain. Immunotherapy works with the immune system to treat the cancer.

Which screening tests you need, and from what age, varies by cancer type. Discuss with your doctor what applies to you and when.