Cancers arise due to mutations in genes involved in the regulation of cell division, which leads to unrestricted cell proliferation. Modern science and medicine have made great strides in the understanding and treatment of cancer, including eradicating cancer in some patients. However, there is still no cure for cancer. This is largely due to the fact that cancer is a large group of many diseases.

Tumors may result in a case where two people have the same mutations in an oncogene or tumor suppressor gene. Initially, the tumors may be very similar. However, the uncontrolled cell division results in new random mutations. As the tumor cells continue to divide, they become more varied. As a result, the two tumors will grow at different rates and undergo angiogenesis and metastasis at different times. The two cancers become so distinct from one another that they will not respond in the same way to the same therapy. This demonstrates why even a particular type of cancer, breast cancer, for example, can be a myriad of different cancers, each disease case with its unique properties, potentially requiring unique treatment approaches.

As such, new cancer research and clinical trials focus on tailoring therapeutic approaches specifically for each patient’s genomic and molecular landscape. This is called personalized medicine. On the other hand, chemotherapy and other general treatments are also still needed and used successfully to treat many cancers. These approaches rely on the characteristic feature of all cancers: abnormal cell proliferation. Chemotherapy targets cell division processes, slowing down proliferation or killing fast-growing cells throughout the body. A different combination of cytotoxic drugs, chemicals that are toxic to cells, are used depending on the type and stage of the cancer.