Table 1.

Characteristics of invasive breast cancers at diagnosis by ER status among participants with known tumor ER status^*

	ER-positive disease			ER-negative disease
Characteristic	Placebo, No. (%)	Tamoxifen, No. (%)	P value†	Placebo, No. (%)	Tamoxifen, No. (%)	P value†
Lymph node status
Negative	90 (68.2)	32 (76.2)		18 (58.1)	22 (57.9)
Positive	33 (25.0)	10 (23.8)		13 (41.9)	15 (39.5)
Unknown‡	9 (6.8)	0 (0)	.839	0 (0)	1 (2.6)	.999
Tumor size
≤1.0 cm	53 (40.2)	18 (42.9)		5 (16.1)	15 (39.5)
1.1–2.0 cm	50 (37.9)	12 (28.6)		14 (45.2)	13 (34.2)
2.1–3.0 cm	13 (9.8)	6 (14.3)		6 (19.4)	7 (18.4)
≥3.1 cm	15 (11.4)	6 (14.3)		5 (16.1)	3 (7.9)
Unknown‡	1 (0.8)	0 (0)	.823	1 (3.2)	0 (0)	.069
TNM stage
I	79 (59.8)	27 (64.3)		16 (51.6)	17 (44.7)
II	42 (31.8)	13 (31.0)		11 (35.5)	18 (47.4)
III/IV	7 (5.2)	2 (4.7)		3 (9.7)	2 (5.3)
Unknown‡	4 (3.0)	0 (0)	.953	1 (3.2)	1 (2.6)	.607
Detection method
Clinical breast exam only	21 (15.9)	6 (14.3)		7 (22.6)	2 (5.3)
Mammography only	54 (40.9)	19 (45.2)		10 (32.3)	12 (31.6)
Both	57 (43.2)	17 (40.5)	.999§	14 (45.2)	24 (63.2)	.068§
Total	132 (100)	42 (100)		31 (100)	38 (100)

^*ER = estrogen receptor; TNM = tumor–node–metastasis.

^†The comparison was of the distributions by treatment group, excluding participants with unknown values. The Wilcoxon–Mann–Whitney exact test was used for comparing tumor sizes between the two arms, and the Fisher exact test was used for all other comparisons. All statistical tests were two-sided.

^‡Excluded numbers of patients in the statistical tests are listed as unknown.

^§The comparison was of the combined categories of mammography only and both mammography and clinical breast examination to those of clinical breast examination only.