{"entity":{"id":"alopecia-radiotherapy-persistent","kind":"term","name":"Persistent radiation-induced alopecia","aka":["persistent radiation-induced alopecia","permanent radiation alopecia","radiotherapy hair loss"],"tldr":"Radiotherapy takes hair only where the beam passes through the scalp, and whether it returns depends on the dose the follicles received. Below a threshold it regrows in months; above it, the patch can stay thin for good.","summary":"Radiation alopecia is local, not systemic: hair falls from the area the beam enters and leaves, beginning two to three weeks into treatment. The National Cancer Institute's guidance says hair often grows back three to six months after radiotherapy ends, and that after a very high dose it may grow back thinner or not at all in the treated area.\n\nThe dose relationship has been measured twice. Lawenda and colleagues (2004) scored 61 scalp regions in 26 patients after cranial irradiation and found that permanent alopecia correlated with the calculated follicle dose and with nothing else they tested, not age, sex, family history of baldness, smoking, diabetes or beam energy. In a later cohort of 71 children and adults treated for central nervous system tumours or head and neck sarcoma (Phillips et al., JAMA Dermatology 2020), the median estimated scalp dose was 39.6 Gy and the dose at which half of patients were estimated to have moderate (grade 2) alopecia was 36.1 Gy (95 per cent confidence interval 33.7 to 39.6 Gy); higher dose and proton irradiation were each associated with greater severity. Of 34 patients treated with topical minoxidil 5 per cent, 28 (82 per cent) responded, and a small number were helped by hair transplantation or surgical reconstruction.\n\nThe practical consequence is a question for the radiotherapy planning team rather than a treatment: what dose does this plan deliver to the scalp, and can the beam arrangement reduce it without compromising the tumour. Scalp-sparing intensity-modulated planning is used where tumour position allows.","asOf":"2026-10-02","links":[{"label":"Phillips et al., assessment and treatment outcomes of persistent radiation-induced alopecia in patients with cancer (JAMA Dermatology 2020)","url":"https://doi.org/10.1001/jamadermatol.2020.2127"},{"label":"Lawenda et al., permanent alopecia after cranial irradiation: dose-response relationship (International Journal of Radiation Oncology, Biology, Physics 2004)","url":"https://doi.org/10.1016/j.ijrobp.2004.04.031"},{"label":"National Cancer Institute: hair loss (alopecia) and cancer treatment","url":"https://www.cancer.gov/about-cancer/treatment/side-effects/hair-loss"}],"tags":[],"related":["alopecia-persistent-chemotherapy","late-effects"],"cancers":[],"sections":["rejuvenation","supportive-care","radiation"],"technologies":["imrt-igrt","proton-therapy","minoxidil-chemotherapy-alopecia"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Side effects"},"route":"/terms/alopecia-radiotherapy-persistent/","neighbours":{"term":[{"id":"hair-anagen-effluvium","kind":"term","name":"Anagen effluvium (chemotherapy hair loss)","route":"/terms/hair-anagen-effluvium/"},{"id":"late-effects","kind":"term","name":"Late effects and survivorship toxicity","route":"/terms/late-effects/"},{"id":"alopecia-persistent-chemotherapy","kind":"term","name":"Persistent chemotherapy-induced alopecia","route":"/terms/alopecia-persistent-chemotherapy/"}],"section":[{"id":"radiation","kind":"section","name":"Radiation Therapy","route":"/fronts/radiation/"},{"id":"rejuvenation","kind":"section","name":"Recovery & Rejuvenation","route":"/fronts/rejuvenation/"},{"id":"supportive-care","kind":"section","name":"Supportive Care & Survivorship","route":"/fronts/supportive-care/"}],"technology":[{"id":"hair-camouflage-and-restoration","kind":"technology","name":"Camouflage and restoration: fibres, micropigmentation, transplantation","route":"/technologies/hair-camouflage-and-restoration/"},{"id":"imrt-igrt","kind":"technology","name":"IMRT / IGRT (modern external beam)","route":"/technologies/imrt-igrt/"},{"id":"minoxidil-chemotherapy-alopecia","kind":"technology","name":"Minoxidil for persistent chemotherapy- and endocrine-therapy hair loss","route":"/technologies/minoxidil-chemotherapy-alopecia/"},{"id":"proton-therapy","kind":"technology","name":"Proton therapy","route":"/technologies/proton-therapy/"},{"id":"scalp-care-cancer-treatment","kind":"technology","name":"Scalp care during and after cancer treatment","route":"/technologies/scalp-care-cancer-treatment/"}]}}