What are the critical ways to tell that you have cancer?

Several ways to tell: Patients who have Cancer may be asymptomatic for variable period of time but soon begin to have symptoms of pain, swelling, fever(persistent) loss of appetite and loss of weight which will draw your attention enough to go seek medical advice. Next step is doctor's examination which may reveal tumor/s(swelling) and make him/her to order blood tests or X-rays which will show abnormalities.