Systemic Treatment of Cancer

In medicine systemic treatment refers to drugs or therapies that potentially affect the entire body.  Local treatment addresses the disease or injury at a specific point. Cancer can be treated both ways.

Local (or regional) treatment is done where the doctor knows or strongly suspects the presence of cancer in one part of the body.  It is ideally done early in the cancer’s progression, before metastasis. Surgery and radiation are local treatments, as are the less used topical therapy and cryotherapy.

Cancer is potentially a systemic disease – just like the flu.  Many cancers stay local. Either the body’s immune system or medical intervention prevents them from spreading broadly.  Experts estimate 50% of discovered (diagnosed) cancers spread so far they are considered metastatic. Surgery and radiation are impractical for addressing distributed cancer.  Systemic therapy, which includes most methods of administering chemotherapy, works throughout the body, and is thus more appropriate for treating widespread cancer. The chemotherapy agent travels through the bloodstream (or perhaps the lymphatic system) to all areas of the body.  Even when a cancer is not known to be widespread through the body, oncologists often administer systemic drug therapy.  Aside from conventional chemotherapy, hormone therapy and targeted chemo treatment (including immunotherapy) are usually (but not always) delivered as systemic therapy.

The downsides are that more medicine is required than is used for regional therapy and that side effects are consequently more severe.  A big advantage of surgery and radiation for cancer treatment are their localization.  The parts of the body that are not known to have cancer are not treated.  Systemic therapy treats the whole body, and thereby causes side effects in healthy tissue.

body's circulatory system

Systemic Treatment of Cancer

Doctors give systemic therapy for a variety of goals, including

 

Sources:

https://moffitt.org/treatments/systemic-therapy/

https://www.foxchase.org/clinical-care/conditions/lung-cancer/treatment-lung-cancer/systemic-therapy

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3646247/

https://www.msdmanuals.com/professional/hematology-and-oncology/principles-of-cancer-therapy/systemic-cancer-therapy