There are seven common ones. They are often called the Seven Danger Signals of Cancer:
- Change in bowel or bladder habits
- Sores that do not heal
- Unusual bleeding or discharge
- Thickening or lump in breast or elsewhere
- Indigestion or difficulty in swallowing
- Obvious change in wart or mole
- Nagging cough or hoarseness
You should at once consult a doctor upon the appearance of any sign