Ais a substance which alone or in combination with other chemicals stimulate the growth of cancer.

Combination therapy, a treatment modality that combines two or more therapeutic anti-cancer benefits, such as reducing tumour growth and metastatic potential, agents initially used for the treatment of different diseases other than cancer. Newer approaches that do not rely solely on a single agent's

Explanation:

exposure to hazardous carcinogens and toxic substances can cause breathing problems, such as copd and various types of cancer. it also increases the risk of heart attacks and strokes and has serious (but no less unattractive) side effects, such as aging, yellow teeth, a terrible smell and damage to the vocal cords.