Radiotherapy for benign disease; assessing the risk of radiation-induced cancer following exposure to intermediate dose radiation

Abstract

Most radiotherapy (RT) involves the use of high doses (.50 Gy) to treat malignant disease. However, low to intermediate doses (approximately 3-50 Gy) can provide effective control of a number of benign conditions, ranging from inflammatory/proliferative disorders (e.g. Dupuytren's disease, heterotopic ossification, keloid scarring, pigmented villonodular synovitis) to benign tumours (e.g. glomus tumours or juvenile nasopharyngeal angiofibromas). Current use in UK RT departments is very variable. This review identifies those benign diseases for which RT provides good control of symptoms with, for the most part, minimal side effects. However, exposure to radiation has the potential to cause a radiation-induced cancer (RIC) many years after treatment. The evidence for the magnitude of this risk comes from many disparate sources and is constrained by the small number of long-term studies in relevant clinical cohorts. This review considers the types of evidence available, i.e. theoretical models, phantom studies, epidemiological studies, longterm follow-up of cancer patients and those treated for benign disease, although many of the latter data pertain to treatments that are no longer used. Informative studies are summarized and considered in relation to the potential for development of a RIC in a range of key tissues (skin, brain etc.). Overall, the evidence suggests that the risks of cancer following RT for benign disease for currently advised protocols are small, especially in older patients. However, the balance of risk vs benefit needs to be considered in younger adults and especially if RT is being considered in adolescents or children.

Primary cutaneous CD4+ small‐ to medium‐sized pleomorphic T‐cell lymphoproliferative disorder in a pediatric patient successfully treated with low‐dose radiation

“…Studies have shown that intermediate‐dose (> 20 Gy) to high‐dose (> 50 Gy) radiotherapy in pediatric patients can increase secondary cancer risk, such as basal cell carcinoma, since children have enhanced radiosensitivity and expected longevity . However, low‐dose radiation has relatively low risk of both acute and long‐term toxicities and can still provide a complete remission even when aggressive markers are shown on pathology .…”

Radiation-Induced Sarcoma Originating in Recurrent Juvenile Nasopharyngeal Angiofibroma

“…There are studies that claim radiation-induced sarcomas to be more sinister in their course and having shorter latency than other RIM [19, 20]. Studies evaluating risk of RIM in intermediate dose radiation given to benign diseases indicate a very small risk but have advised caution in pediatric population in view of long latency of these tumours [21]. …”

“…Due to the small number of affected individuals and long latency period associated with RIM, there is currently no level 1 evidence analyzing risk factors predicting the development of RIM. However, McKeown et al [21] have reviewed the existing literature and have found a trend towards increased risk of RIM with increasing dose, estimated to be 10%/Sv for high-dose rate exposure. The effect was more pronounced in children.…”

Low-Dose Radiotherapy of Painful Heel Spur/Plantar Fasciitis as an Example of Treatment Effects in Benign Diseases

“…Therefore, other groups argue that a significantly lower risk of radiogenic cancer inductionapprox. ten times less-should be adopted [49,61]. Furthermore, taken the new standard scheme with 6 × 0.5 Gy into account, these risks are additionally halved.…”