In multivariable analyses for OS on the whole population, donor age >36 years (HR 1.74 95% CI 1.11–2.71; p = 0.02), BC at HSCT (HR 1.85 95% CI 1.13–3.04; p = 0.01) and lower CD34+ cell dose (HR 1.12 95% CI 1.04–1.20; p = 0.003 and HR 2.14 95% CI 1.33–3.45 using categorical variables) were independently associated with shorter OS (Table 4). This evidence concerns the gene CD34 and breast cancer.