What's the difference between chemotherapy, radiation, and immunotherapy?

Depending on the type, grade, and site of a cancer, a variety of treatment modalities may be used to target it. Chemotherapy is the use of a chemical (e.g., drug compound, drug cocktail) to kill cancer cells. In many cases, due to the toxic nature of the chemical used and the nonspecific distribution of the chemical throughout the body, chemotherapy side effects will include symptoms like oral mucositis and hair loss (both are indicative of cell death impacting rapidly dividing cells).

Radiation is similar to chemotherapy in that the goal is to kill rapidly dividing cancer cells while sparing the more slowly dividing cells. Both modalities rely on the body's normal cell repair processes to ameliorate damaged DNA in non-cancer cells, while cancer cells with abnormal repair mechanisms continue to divide, leading to their checkpoint-mediated death. Radiation is different from chemotherapy in that the active agent is DNA-damaging radioactivity.

The outlier of the bunch is immunotherapy, where the goal is to spur the immune system to selectively identify and attack cancer cells. To many, this seems like a gentler approach, but overstimulating or excessively dampening the immune system can have wildly differing impacts across a patient population. As such, there is no single perfect solution, and the approach to each patient must be an individualized one. For more information on immunotherapy please visit our expanded section here.