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Low Risk Of Intracranial Malignancy After Stereotactic Radiosurgery

Incidence of radiation-associated intracranial malignancy following stereotactic radiosurgery is comparable to that of primary intracranial tumours in the general population
30 Nov 2018
Central Nervous System Malignancies;  Complications/Toxicities of Treatment;  Radiation Oncology

Author:  By Shreeya Nanda, Senior medwireNews Reporter
medwireNews: Individuals who undergo stereotactic radiosurgery have a low risk of radiation-associated intracranial malignancy in the long term, indicates research published in The Lancet Oncology.

The risk of malignant transformation or development of a secondary intracranial cancer in these patients was similar to the risk of developing a primary central nervous system (CNS) tumour that is found in the general population, say Douglas Kondziolka, from New York University in the USA, and fellow investigators.

They continue: “Although prospective cohort studies with longer follow-up are warranted to support the results of this study, the available evidence suggests the long-term safety of stereotactic radiosurgery and could support physicians counselling patients on Gamma Knife stereotactic radiosurgery.”

The study included 4905 patients who received stereotactic radiosurgery with a Gamma Knife (Elekta AB, Stockholm, Sweden) for a variety of conditions, including benign intracranial tumours and functional disorders, between 1987 and 2011 at five international centres.

Over a median follow-up of 8.1 years, one patient developed a new intracranial malignancy that was considered related to radiosurgery as it was within the irradiated field (defined as within the 2 Gy isodose line) and two of the 3251 patients with benign tumours had a malignant transformation, giving an incidence of 2.26 and 6.87 per 100,000 person–years, respectively.

The overall incidence of radiosurgery-associated malignancy was 6.80 per 100,000 person–years and the cumulative incidence over 10 years was 0.00045%.

The researchers note that this estimated incidence was similar to the age-adjusted annual incidence of primary CNS tumours in the US and European general populations, as calculated using data from the Central Brain Tumor Registry of the United States and the International Agency for Research on Cancer, respectively. Specifically, the incidence was 7.15 per 100,000 patient–years in USA and ranged from 3.6–9.1 per 100,000 men and 3.1–7.9 per 100,000 women across European countries.

The authors of an accompanying commentary agree that “the overall risk of secondary cancers appears reassuringly low at 10 years, and this concern alone should not preclude stereotactic radiosurgery when warranted.”

But they highlight certain study limitations, including the lack of information regarding the surveillance methods and “the absence of a formal statistical estimate of the standardised incidence ratio or absolute excess risk compared with the general population.”

Alejandro Berlin and co-authors, from the University of Toronto in Ontario, Canada, therefore conclude: “With an expected long survival of patients with benign conditions, it is prudent to advocate for properly quantified longer-term outcomes (>15–20 years) to guide judicious decision making and surveillance strategies.”

medwireNews (www.medwireNews.com) is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group


Wolf A, Naylor K, Tam M, et al. Risk of radiation-associated intracranial malignancy after stereotactic radiosurgery: a retrospective, multicentre, cohort study. Lancet Oncol; Advance online publication 22 November 2018. doi: http://dx.doi.org/10.1016/S1470-2045(18)30659-4

Berlin A, Hodgson D, Dawson LA. Radiosurgery and risk of intracranial malignancies: more research needed. Lancet Oncol; Advance online publication 22 November 2018. doi: http://dx.doi.org/10.1016/S1470-2045(18)30711-3

Last update: 30 Nov 2018

medwireNews (www.medwireNews.com) is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group

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