Uncontrolled growth of cells can be caused by several factors. A hereditary predisposition gives a higher chance than average of tumor formation. This genetic inheritance leads to an easier activation of oncogenes. Many environmental factors can induce neoplastic growth. Specific substances, called carcinogens or mutagens, can damage DNA and by breaking DNA strands they can cause mutations in the DNA.
Examples of those environmental factors are chemicals, plant poison, and all sorts of radiation. Certain viruses (e.g. papilloma virus) can cause cancer as well. Also lifestyle factors like smoking and an unhealthy diet give a higher chance for cancer. And the last group mentioned here are chemotherapeutic drugs. Although these drugs are indeed used to treat tumors, they can also cause new tumors because of their actions on DNA.
Which of the following definitions is NOT correct:
Extra info: Metaplasia: differentiation of a mature tissue into a different mature tissue
I Viral infections are a potential cause of cancer.
II Each mutation in DNA will result in a tumor cell.
Extra info: Certain viruses can cause cancer. Not each mutation in the genetic material will cause cancer. Only mutations that induce translation of a different amino acid in a specific protein can result in cancer.