Standardized assessment of tumor-infiltrating lymphocytes in breast cancer: an evaluation of inter-observer agreement between pathologists

Figures & data

Table 1. Histopathological tumor characteristics.

	N	%
Histology type
Invasive ductal carcinoma	104	84
Invasive lobular carcinoma	16	13
Other types	4	3
Estrogen receptor status^a
Positive	110	89
Negative	13	10
Missing	1	1
HER2 status
Positive	35	28
Negative	83	67
Missing	6	5
Malignancy grade
I	30	24
II	66	53
II	24	19
Missing	4	3

^a 1% cut off.

Figure 1. (A) Heat map showing graphically the individual recordings of TILs sorted in columns from left to right according to ascending mean stromal TILs values shown in the top row. The rows underneath represents the nine observers recordings arranged from top to bottom according to increasing individual mean values. Single outliers are represented by, e.g., red pixels among otherwise green or yellow pixels or vice versa. (B) A carcinoma with very low mean TILs level (0.03), (C) a carcinoma with a mean TILs level around the 50–60% cut off (0.56) and (D) a carcinoma with a high mean TILs level (0.83). The black bars in (B–D) measures 200 µm (HE, original magnification 100×).

Table 2. Interobserver agreement in assessment of tumor-infiltrating lymphocytes (TILs).

Intraclass coefficient (ICC)	0.71 (95% CI: 0.65–0.77)
Fleiss’ kappa values
TILs 0–10%, 11–39%, ≥40%	0.41
TILs 0–20%, 21–49%, ≥50%	0.36
TILs <50% vs. ≥50%	0.48
TILs <60% vs. ≥60%	0.44
Concordance rates
TILs 0–10%, 11–39%, ≥40%	0.79 (range: 0.60–0.94)
TILs 0–20%, 21–49%, ≥50%	0.82 (range: 0.54–0.92)
TILs <50% vs. ≥50%	0.93 (range: 0.81–0.99)
TILs <60% vs. ≥60%	0.95 (range: 0.77–0.99)