External beam radiation therapy (XRT) is a treatment modality employed to treat a wide variety of cancers. The general principles of XRT are as follows. A beam of radiation is targeted to a region of the body affected by cancer. Radiation consists of a variety of sub-atomic particles that bombard the tissues at which they are directed. These subatomic particles are energetic and they impart this energy on everything within the radiation beam. On a cellular level, energy is imparted to DNA inside the cancer cells (and other normal cells) damaging it. This DNA damage causes the process of cell division to stop and the cell to undergo a form of programmed cell death know as apoptosis (also known as cell suicide).
Because cancer cells divide rapidly, the effects of radiation affect them more intensely than other normal cells that do not undergo rapid proliferation. Based on the principle, the dose of radiation is calibrated as carefully as possible to be just enough to damage cancer cells, while being mild enough to minimize effects on healthy tissue. However, some degree of damage to healthy tissue is unavoidable with radiation therapy and these risks must be weighed against the cancer fighting benefits of XRT. The healthy tissues most at risk are those that divide most rapidly, such as cells in the GI tract, mucous membranes, and the bone marrow. The bone marrow is a rapidly dividing tissue that produces all of the blood cells that circulate in our body. Depending on where the XRT beam is focused, the risk for suppression of bone marrow, and thus reduction of circulating red and white blood cells, varies. The other complicating factor is that people with cancer are often on chemotherapy which also has the potential to suppress white blood cell production and immune function. The risks and benefits of XRT in any individual patient is an very complex and important matter that can only be discussed in person with a doctor
who is familiar with such issues. It would be most appropriate to set up an appointment with a hematologist/oncologist
or a radiation oncologist
, so that they may fully evaluate you and discuss the risks and benefits of XRT in your specific case.