Chapter 12: Cancer
What is Cancer
•Cancer is the abnormal, uncontrolled growth of cells, which left
untreated, can ultimately cause death.
•Most cancers take the form of tumours, although not al tumours
are cancerous.
•A tumour is simply a mass of tissue that serves no physiological
purpose. It can be benign, like a wart or malignant, like most
lung cancers.
•Benign Tumours are made up of cells similar to the surrounding
normal cells and are enclosed in a membrane that prevents them
from penetrating neighbouring tissues. They are dangerous only
if their physical presence interferes with body functions.
•Malignant tumour (neoplasm) is synonymous with cancer. A
malignant tumour/ cancer is capable of invading surrounding
structures, including blood vessels, the lymphatic system and
nerves. It can also spread to distant sites via blood and lymphatic
system. Cancers like leukemia (cancer of the blood) do not
produce a mass but still have the fundamental property of rapid,
uncontrolled growth of cells.
•A tumour that is cancerous and capable of spreading.
•Every case of cancer begins as a change in a cell that allows it to
grow and divide when it should not.
•A malignant cell divides without regard for normal control
mechanism and gradually produces a mass of abnormal cells, or
a tumour.
•It takes about a million cells to make a mass the size of a pea, so
a single tumour cell must go through many divisions, often
taking years before the tumours grows to a noticeable size.
•Eventually a tumour produces a sign or symptom that is
detected. In an accessible location, a tumour may be felt as a
lump. In less accessible location a tumour may be noticed only
after considerable growth has taken place and may then be
detected only by an indirect symptom – for instance a persistent
cough or unexplained bleeding or pain.
