Sustained application of triamcinolone for 5 years in patients with estrogen receptor-positive breast cancer reduces 15-year mortality by 1/3, which is the current standard of care. The results of this clinical study were presented at the 2013 ASCO Annual Meeting. 6,953 patients with early invasive breast cancer were selected from 176 UK treatment centers between 1991 and 2005 and randomized to 2 groups, one with 5 years of triamcinolone and then discontinued and one with 10 years of continued use. The recurrence rate and mortality rate were compared between the two groups. The results showed that the 10-year triamcinolone group further reduced the recurrence rate of breast cancer compared with the 5-year group (580/3468 vs. 672/3485, p=0.003), and this reduction was time-dependent, with a risk ratio of 0.99 [95% CI=0.86-1.15] for 5-6 years, 0.84 [95% CI=0.73- The 10-year triamcinolone group further reduced breast cancer mortality compared to the 5-year group [392 vs. 443 (deaths after recurrence), p=0.05].The risk ratios were 1.03 [95% CI=0.84-1.27] for 5-9 years and 0.77 [95% CI=0.64-1.27] for more than 10 years. % CI=0.64-0.92]. The risk ratio was 2.20 (95% CI=1.31-2.34, p<0.0001). 37 (1.1%) deaths in the 10-year triamcinolone group and 20 (0.6%) in the 5-year group (0.5 absolute risk increase in the 10-year group, p=0.02). The combined treatment benefit and risk results showed that the 10-year triamcinolone group further reduced overall mortality compared to the 5-year group (849 vs. 910 deaths, p=0.1), with risk ratios of 1.05 [95% CI=0.90-1.22] for 5-9 years and 0.86 [95% CI=0.75-0.97] for more than 10 years. CONCLUSION: ATTOM results show that in estrogen receptor positive breast cancer patients, treatment with triamcinolone acetonide for 10 years reduces the recurrence rate after 7 years and breast cancer mortality after 10 years compared to 5 years. Combining ATTOM with the ATLAS clinical study published last year, it can be found that 10 years of triamcinolone acetonide further reduces the risk of recurrence and breast cancer mortality compared with 5 years of triamcinolone acetonide, thus improving overall survival. The publication of these 2 results is expected to change the current gold standard of 5 years of adjuvant endocrine in early breast cancer.