ArticleBritish journal of cancer2026
Contralateral breast cancer after radiotherapy and hormone therapy in two cohorts of US breast cancer survivors.
Article in British journal of cancer, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.
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Who cites it
5 citing papers in PubMed.
- Feasibility and trade-offs of incorporating cardiac substructure dose constraints in left-sided breast volumetric modulated arc therapy planning.Radiation oncology journal · 2026Article
- Risk Factors for Estrogen Receptor Subtype-Specific Contralateral Breast Cancer in Women Under Age 55 Years.International journal of cancer · 2026Article
- Continuous positive airway pressure in breast cancer radiotherapy: Protocol of a prospective clinical trial.Clinical and translational radiation oncology · 2026Article
- In their own words: A qualitative study of patient narratives on daily life after breast cancer radiotherapy.PEC innovation · 2026Article
- Exposure and impact: highlights from the second scientific conference and recent activities of the International Society of Radiation Epidemiology and Dosimetry (ISoRED).Journal of radiological protection : official journal of the Society for Radiological Protection · 2026Article
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16 authors.
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Abstract
backgroundRadiotherapy increases contralateral breast cancer risk, while hormone therapy reduces it; their combined effects are unclear.
methodsData from two US retrospective cohort studies of 5-year breast cancer survivors (stage I-III, ages 20-84), Kaiser Permanente (KP, 1990-2012) and SEER (1990-2013), were analysed. Contralateral breast radiation doses were estimated for the KP cohort. Multivariable Poisson regression estimated relative risks (RRs) and excess relative risks per Gray (ERR/Gy), stratified by hormone therapy use.
resultsKP cohort (n = 9053) included 353 contralateral breast cancer cases (73% ER+); SEER cohort (n = 244,834) included 10,470 cases (72% ER+). Among women with ER+ first breast cancer, radiotherapy increased the risk of ER+ contralateral breast cancer in non-users of hormone therapy (KP RR = 2.2, 95%CI:1.20-4.14; SEER RR = 1.12, 1.04-1.21), but not in users (KP RR = 0.88, 0.61-1.26; SEER RR = 1.03, 0.94-1.12). In KP, higher radiation dose increased risk of ER+ contralateral breast cancer among non-users (ERR/Gy=1.39, 95%CI:0.33,3.66), but not among users (ERR/Gy= -0.13, -0.36,0.23). Radiotherapy also increased risk of ER- contralateral breast cancer (KP RR = 1.85, 95%CI: 0.95-3.59; SEER RR = 1.12, 1.01-1.23), especially in younger exposed women (SEER RR = 1.31, 1.02-1.69 for age <40 vs 40+ years). Additionally, the risk increased linearly with radiation dose to the contralateral breast (ERR/Gy=0.87, 0.04,2.72).
conclusionsRadiotherapy increased contralateral breast cancer risk, but hormone therapy appeared to mitigate this risk for ER+ cases. These findings have important implications for individuals exposed to chest radiation.
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