In which stage of cancer does metastasis occur?

Which genes are inactivated in cancer cells?

Select the true statements.
$I.$ Cancer can be detected by the use of antibodies against cancer-specific antigens for certain types of cancer.
$II.$ The tumor cells are surgically removed to reduce the load of cancerous cells.
$III.$ Certain chemotherapeutic drugs are used to kill the cancerous cells,but the majority of the drugs have side effects like hair loss,anaemia,etc.

Oral cancer may be caused by

Assertion $A$: Interferons are used in the treatment of cancer.
Reason $R$: Interferons protect cells from viral infection.
Which option is correct for Assertion $A$ and Reason $R$?

Which of the following statements is $NOT$ associated with cancer?