Development and external validation of a radiomics model for assessment of HER2 positivity in men and women presenting with gastric cancer

Insights into Imaging

Table 1 Baseline data for three gastric cancer (GC) study cohorts

Characteristics		Training cohort	Internal validation cohort	External validation cohort	p value
Line of care		Tertiary	Tertiary	Tertiary	–
Participants (n)		388	325	237	–
Age	> 60 y	200 (51.5)^a	181 (55.7)^a	112 (47.3)^a	0.140
Age	≤ 60 y	188 (48.5)^a	144 (44.3)^a	125 (52.7)^a	0.140
Gender	Male	241 (62.1)^a	227 (69.8)^a	169 (71.3)^a	0.025*
Gender	Female	147 (37.9)^a	98 (30.2)^a	68 (28.7)^a	0.025*
Type of tissue for confirmation	Biopsy tissue	164 (42.3)^a	174 (53.5)^b	100 (42.2)^a	0.004*
Type of tissue for confirmation	Surgical specimen	224 (57.7)^a	151 (46.5)^b	137 (57.8)^a	0.004*
HER2 status	HER2-p	194 (50.0)^a	46 (14.2)^b	48 (20.3)^b	< 0.001*
HER2 status	HER2-n	194 (50.0)^a	279 (85.8)^b	189 (79.7)^b	< 0.001*

Values are the number (percentage) unless otherwise indicated. HER2-p = HER2-positive, HER2-n = HER2-negative; * p < 0.05;
^a,bpairwise comparison results. There was no difference between cohorts given consistent letters, while there was a statistically significant difference between cohorts given inconsistent letters