Incidental irradiation of the spleen - RCR guidance

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The spleen is seldom irradiated intentionally and is rarely considered an organ at risk (OAR) in other treatments. While computed tomography (CT)-planned radiotherapy enables treatment to be much more accurate, it can also highlight unforseen risks to normal tissues. As the authors of this guideline explain, irradiating tumours in the lower lung or upper abdomen can result in clinically significant doses of unwanted splenic radiation.

Radiotherapy teams need to contour the spleen as an OAR and to develop protocols for vaccination and antibiotic prophylaxis if the mean dose exceeds 10 Gray (Gy).

The purpose of this guidance is to raise awareness of the spleen as an organ at risk (OAR) structure and to ensure that, for all patients receiving radiotherapy to the spleen, the risk of resultant functional hyposplenism is assessed and decisions on appropriate management are made if required.

The guidance applies to all patients who may receive radiotherapy to the spleen as a defined OAR as a result of being referred for radiotherapy to the upper abdomen or an adjacent anatomical site where the upper abdomen might also be irradiated. Treatment may be delivered using photon or proton external-beam radiotherapy to a range of tumour sites.