Systemic Treatment of Cancer

Cancer is a systemic disease. This implies that although the manifestation of a tumor may be local, i.e., a breast lump or a rectal mass, if treated only with local therapy such as surgical removal, then there is a reasonable chance of metastasis developing in the future. The likely explanation for the development of metastasis is the presence of residual microscopic disease, which grows over time to present as widespread metastatic disease. The treatment that addresses this microscopic disease and delays or prevents a relapse is referred to as “systemic treatment” for cancer. It is often referred to as adjuvant cancer treatment, as it follows the initial treatment of a tumor, which could be in the form of a surgery or local radiation therapy. The goal of this treatment is cure. Systemic treatment can also be administered to cancers that are already advanced or metastatic. In this setting, it is called palliative therapy, and the major goals are symptom control and prolongation of life.