Table 1
A summary of research studies on adjuvant tamoxifen

Study	Design	Subject	Treatment	Results
NSABP, 2001 [14]	Randomized	1,172 patients	Tamoxifen × 5 yr	For tamoxifen × more than 5 yr:
		ER (+)	→placebo vs.	No additional benefit
		Node (–)	Tamoxifen ×5 yr
		7-yr follow-up	→Tamoxifen
EBCTCG, 2005 [12]	Meta-analysis, 71 trials	ER (+)	Tamoxifen × 5 yr vs.	For tamoxifen × 5 yr:
		15-yr follow-up	Tamoxifen × 1–2 yr	Improvement in survival
				Breast cancer mortality 31%↓/yr
				regardless of age, menopause,
				chemotherapy and node metastasis
ATLAS, 2013 [15]	Randomized	6,846 patients	Tamoxifen × 5 yr vs.	For tamoxifen × 10 yr:
		Early breast cancer	Tamoxifen × 10 yr	Recurrence↓
		ER (+)		Breast cancer mortality↓
				Overall mortality↓
				Pulmonary embolism ↑(HR, 1.87)
				Endometrial cancer ↑(HR, 1.74)
				Ischemic heart disease ↓(HR, 0.76)
aTTom (ongoing)		6,934 patients	Tamoxifen × 5 yr vs.
		ER (+)	Tamoxifen × 10 yr
		ER unknown
		4.2-yr follow-up

NSABP, National Surgical Adjuvant Breast and Bowel Project; ER, estrogen receptor; EBCTCG, Early Breast Cancer Trialists’ Collaborative Group; ATLAS, Adjuvant Tamoxifen Longer Against Shorter; aTTom, adjuvant Tamoxifen Treatment offers more.