{"entity":{"id":"idea-pu-pregnancy-test-or-ask-before-radiotherapy","kind":"idea","name":"Routine pregnancy testing compared with asking, before radiotherapy","aka":[],"tldr":"Before radiotherapy, people who could be pregnant are asked whether they might be; some departments also do a pregnancy test for everyone in an age range. Which approach misses fewer pregnancies, and at what cost in delays and false alarms, has never been compared. Some cancers make the pregnancy hormone themselves and can give a false positive test.","summary":"The rules. In the UK, the Royal College of Radiologists' IR(ME)R guidance for radiotherapy (second edition, 2026) leaves the age range for enquiries and any routine testing to each employer's procedure: it allows routine testing for people with irregular cycles after a risk assessment, says a test should be done if pregnancy cannot be excluded, and, for molecular radiotherapy, that menstrual history alone is not adequate to exclude pregnancy.\n\nWhat practice looks like. In an international survey of 434 radiation oncologists (69.1 per cent in the United States), 84.8 per cent agreed one should screen for pregnancy before radiotherapy, yet 29.7 per cent said their department had no screening policy and 7.1 per cent did not screen. Of 93 who had treated a known pregnant patient, 17 had done so accidentally, and not screening at simulation was associated with treating a pregnant patient (p = 0.0459).\n\nThe catch with testing. Some tumours secrete human chorionic gonadotropin and give a positive pregnancy test in people who are not pregnant; one report describes a gastrointestinal stromal tumour found this way before radiotherapy (Andruska 2020).\n\nWhat is unknown. No study compares asking alone with routine testing for missed pregnancies, delays or false positives in radiotherapy.","asOf":"2026-11-11","links":[{"label":"The Royal College of Radiologists, IR(ME)R: Implications for clinical practice in radiotherapy, second edition, chapter 13 (2026)","url":"https://www.rcr.ac.uk/our-services/all-our-publications/clinical-oncology-publications/ionising-radiation-medical-exposure-regulations-implications-for-clinical-practice-in-radiotherapy/"},{"label":"Zaki et al., Pregnancy screening practices and treatment of pregnant patients among radiation oncologists: results of an international survey (ecancermedicalscience 2021)","url":"https://doi.org/10.3332/ecancer.2021.1169"},{"label":"Andruska et al., False-positive pregnancy test secondary to ectopic expression of human chorionic gonadotropin by a gastrointestinal stromal tumor (Journal of Surgical Oncology 2020)","url":"https://doi.org/10.1002/jso.26067"}],"tags":["protocol-upgrade","upgrade:untested","evidence:insufficient"],"related":[],"cancers":[],"sections":["radiation"],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["cancer-in-pregnancy"],"trials":[],"people":[],"bottlenecks":["b-knowledge-diffusion"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"hypothesis":"Routine urine pregnancy testing at the planning scan for everyone of reproductive potential, on top of a structured enquiry, finds pregnancies that enquiry misses at an acceptable rate of false positives and delays.","rationale":"A missed pregnancy in radiotherapy is rare but grave, policies vary widely, the only practice survey links not screening at simulation with accidental treatment, and the cost of a urine test is small; but tumour-made hormone can mislead, so testing has its own harms.","test":"A multicentre audit linking enquiry and test results at planning to later-recognised pregnancies, followed if justified by a cluster comparison of structured enquiry alone against enquiry plus routine testing.","maturity":"speculative","actor":"clinic","cost":"small","horizonYears":3},"route":"/ideas/idea-pu-pregnancy-test-or-ask-before-radiotherapy/","neighbours":{"section":[{"id":"radiation","kind":"section","name":"Radiation Therapy","route":"/fronts/radiation/"}],"term":[{"id":"cancer-in-pregnancy","kind":"term","name":"Cancer during pregnancy","route":"/terms/cancer-in-pregnancy/"}],"bottleneck":[{"id":"b-knowledge-diffusion","kind":"bottleneck","name":"Knowledge reaches practice too slowly","route":"/bottlenecks/b-knowledge-diffusion/"}],"protocol":[{"id":"radiotherapy-pregnancy-and-breastfeeding-enquiry","kind":"protocol","name":"Pregnancy and breastfeeding checks before radiotherapy","route":"/protocols/radiotherapy-pregnancy-and-breastfeeding-enquiry/"}]}}