Cancer is caused by mutations to the DNA within cells.A disease in which abnormal cells divide uncontrollably and destroy body tissue. Chemotherapy is an aggressive form of chemical drug therapy meant to destroy rapidly growing cells in the body. It’s usually used to treat cancer, as cancer cells grow and divide faster than other cells. Chemotherapy is most often used to treat cancer, since cancer cells grow and multiply much more quickly than most cells in the body. Various cancer treatment options such as Surgery, Chemotherapy, Radiation therapy, Bone marrow transplant, Immunotherapy, Hormone therapy, Targeted drug therapy, Cryoablation etc. Chemotherapy is often used in combination with other therapies, such as surgery, radiation, or hormone therapy. Adjuvant chemotherapy given after surgery or irradiation to destroy micrometastasis and prevent development of secondary neoplasm. and Neo-adjuvant chemotherapy given before surgery or radiotherapy in order to diminish the volume of large primary neoplasm. By primary site of origin, cancers may be of specific types like breast cancer, lung cancer, prostate cancer, liver cancer renal cell carcinoma (kidney cancer), oral cancer, brain cancer etc. Leukemia is a cancer of white blood cells. There are four common types of leukemia namely Acute lymphoblastic leukemia (ALL), Acute myeloblastic leukemia (AML), Chronic lymphocytic leukemia (CLL), and Chronic myeloid/myclocytic leukemia (CML). Result-Chemotherapy destroys cells with the aim of killing cancer cells and preventing their growth. It can be very stressful for the body and cause various side effects. some alternatives to chemotherapy, including surgery, immunotherapy, targeted therapies, active surveillance, supportive measures such as massage therapy, or psychotherapy to manage stress and pain generated in patients. Keywords- Chemotherapy, Cancer, Leukemia, Adjuvant chemotherapy, Neoadjuvant chemotherapy, carcinogenesis, AML, CML, CLL,ALL.