Spread of cancerous cells to distant sites is termed as

What are the agents that cause cancer called?

Cigarette smoking causes

Which of the following can be included in non-ionizing radiations that act as carcinogens?

Assertion $:-$ Metastasis is the most feared property of malignant tumors.
Reason $:-$ Cells sloughed from such tumors reach distant sites through blood and interfere in functions of other tissue.

Explain in detail the treatment of cancer.