Table 1.

Breast cancer tumor characteristics by age.

	Age <45 (n=529)		Age ≥45 (n=1,534)
	n	%	n	%
ER status
Positive	219	59.2%	804	67.6%
Negative	151	40.8%	385	32.4%
SEER stage
Localized	225	49.7%	832	64.6%
Regional	211	46.6%	401	31.1%
Distant	17	3.8%	55	4.3%
Grade
Well-differentiated	36	8.5%	187	15.2%
Moderately differentiated	146	34.4%	473	38.4%
Poorly or undifferentiated	243	57.2%	571	46.4%
Tumor size
≤ 1.0 cm	81	19.8%	339	27.7%
>1–2.0 cm	135	32.9%	474	38.7%
>2 cm	194	47.3%	411	33.6%

ER status was unknown or missing for 159 cases <45 years and 345 cases ≥45 years; SEER stage was unknown or missing for 76 cases <45 years and 246 cases ≥45 years; grade was unknown or missing for 104 cases <45 years and 303 cases ≥45 years; tumor size was missing for 119 cases <45 years and 310 cases ≥45 years.