Table 1 Clinicopathologic characteristics and distribution of CD8⁺ intratumoral lymphocytes in the study population

Age at diagnosis, years

< 0.001

< 40

294 (7.4)

38.9 (98/252)

40-49

844 (21.1)

37.5 (273/728)

50-65

1,425 (35.7)

31.3 (377/1,203)

> 65

1,429 (35.8)

29.2 (356/1,220)

Grade

< 0.001

1: well differentiated

209 (5.2)

24.4 (40/164)

2: moderately well or partially differentiated

1,563 (39.2)

26.9 (361/1,342)

3: poorly differentiated

2,040 (51.1)

37.2 (652/1,754)

Unknown

180 (4.5)

Tumor size, centimeters

0.076

≤ 2

2,078 (52.1)

30.5 (540/1,768)

> 2-5

1,667 (41.8)

34.1 (494/1,449)

> 5

221 (5.5)

34.9 (59/169)

Unknown

26 (0.6)

Nodal status

0.051

Negative

2,265 (56.7)

31.0 (593/1,911)

Positive

1,719 (43.1)

34.3 (509/1,484)

Unknown

8 (0.2)

Lymphovascular invasion

0.638

Negative

2,106 (52.8)

32.5 (576/1,770)

Positive

1,710 (42.8)

31.8 (474/1,492)

Unknown

176 (4.4)

Histology

< 0.001

Medullary

66 (1.7)

78.4 (40/51)

Not medullary

3926 (98.3)

31.7 (1,064/3,352)

AJCC stage

0.004

I

1,393 (34.9)

28.8 (337/1,172)

II

2,255 (56.5)

34.6 (677/1,959)

III

317 (7.9)

32.9 (83/252)

Unknown/missing

27 (0.7)

Adjuvant systemic therapy

0.012

No adjuvant systemic therapy

1,676 (42.0)

21.2 (302/1,427)

Tamoxifen only

1,276 (32.0)

18.6 (206/1,105)

Chemotherapy only

727 (18.2)

27.2 (169/622)

Tamoxifen + chemotherapy

297 (7.4)

29.4 (73/148)

Other

16 (0.4)

21.4 (3/14)

ER

< 0.001

Negative

1,200 (30.1)

39.9 (370/927)

Positive (≥ 1% nuclei stained)

2,761 (69.1)

29.6 (728/2,456)

Uninterpretable/missing

31 (0.8)

HER2

< 0.001

Negative

3,316 (83.1)

31.3 (907/2,902)

Positive

498 (12.5)

39.6 (176/444)

Uninterpretable/missing

178 (4.4)

Subtype

< 0.001

Luminal A

1,518 (38.0)

25.4 (353/1,392)

Luminal B

829 (20.8)

36.9 (285/773)

Luminal/HER2

224 (5.6)

39.8 (82/206)

Luminal not further assigned

244 (6.1)

21.5 (37/172)

HER2⁺/ER^-

250 (6.3)

39.6 (90/227)

TNP

630 (15.8)

42.2 (226/535)

Core basal

330 (8.3)

49.2 (151/307)

5NP

162 (4.1)

35.2 (50/142)

TNP not assignable

138 (3.4)

29.1 (25/86)

Unassignable

297 (7.4)

31.6 (31/98)

Total

3,992 (100)

32.4 (1,104/3,403)