Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumours,which do not spread
to other parts of the body.Possible signs and symptoms include a
lump,abnormal bleeding,prolonged cough, unexplained weight loss,and a change in bowel
movements.Whiles these symptoms may indicate cancer ,the may have other causes.over 100
types of cancer effects humans.
Tabocco use is the cause of about 22% of
cancer deaths.Another 10% are due to
obesity,poor diet, lack of physical activity,
and exposure to radiation and
environmental pollutants.In the
developing world nearly 20% of cancers are
due to infections such as hepatitis B,
hepetitis C and human papillomarvirus
infections.These factors act,atleast
partly,by changing the genes of a cell.
Typically many genetic changes are
are required before cancer gevelops.
Approximately 5-10% of cancers are due to
inherited genetic defects from person's
parents.Cancer can be detected by
certain signs and symptoms or screening
tests.It is then typically further
investigated by medical imaging and
confirmed by biopsy.