Soft Tissue Radionecrosis
Soft tissue radionecrosis (STRN) refers to the death (necrosi) of soft tissues as a result of exposure to ionizing radiation. It is a counterpart of osteoradionecrosis, which is the death of bone tissue due to radiation.
Exposure to radiation is the cause of soft tissue radionecrosis. Upon exposure, tissue starts to become damaged and results in the proliferation of cells lining the small arteries and capillaries (proliferative endarteritis). When this happens, blood flow to the tissues decreases, because the blood cannot travel effectively through these arteries. This leads to progressive ischemia (lack of oxygen and nutrients) of the affected tissues. These tissues, though damaged, can still survive. However, the appearance of an inciting agent, such as trauma or infection, causes the tissues to die. The surrounding area (not exposed to radiation) may also exhibit some form of damage.
Soft tissue radionecrosis can cause extensive tissue death, resulting in ulceration of the affected area. More often than not, the wounds caused by soft tissue radionecrosis are of the nonhealing type. There is no spontaneous normalization of the blood vessels even if the radiotherapy sessions have been completed.
Patients who are receiving radiotherapy for the treatment of cancers, such as head and neck or breast cancer, are at increased risk for soft tissue radionecrosis. Exposure to radiation is measured in units called Gray (Gy), and studies have shown that those receiving an accumulated dose of more than 60 Gy may be prone to develop soft tissue radionecrosis and/or osteoradionecrosis.