Beyond the tumor region: Peritumoral radiomics enhances prognostic accuracy in locally advanced rectal cancer

Table 3 C-indices of prognostic models for progression free survival prediction in locally advanced rectal cancer

Model	Training set			Validation set
	C-index (95%CI)	1P value	2P value	C-index (95%CI)	1P value	2P value
Clinicoradiological model
YpTN	0.670 (0.593-0.748)	Ref.	0.003	0.670 (0.558-0.781)	Ref.	0.009
Clin	0.718 (0.639-0.797)	0.003	Ref.	0.733 (0.634-0.833)	0.009	Ref.
Radiomics model
Intra	0.670 (0.603-0.736)	Ref.	0.297	0.669 (0.574-0.764)	Ref.	0.310
Peri	0.754 (0.680-0.827)	0.015	0.194	0.703 (0.597-0.809)	0.316	0.839
Omics	0.797 (0.741-0.853)	< 0.001	< 0.001	0.758 (0.670-0.847)	< 0.001	0.101
Clinicoradiological-omics model
Clin + intra	0.764 (0.697-0.832)	Ref.	< 0.001	0.765 (0.677-0.853)	Ref.	0.030
Clin + peri	0.804 (0.740-0.868)	0.044	< 0.001	0.778 (0.685-0.871)	0.432	0.010
ICRO	0.836 (0.787-0.886)	< 0.001	< 0.001	0.801 (0.722-0.879)	0.001	< 0.001

¹P represents the comparison between models within the same group.

²P represents the comparison across all models.

P value of C-indices between models calculated using the DeLong test. Eight prognostic models were constructed, integrating different types of features as follows: (1) Model pathological T and N stages after neoadjuvant chemoradiotherapy (NCRT) based on pathological T stage after NCRT and pathological N (ypN) stages; (2) Model based on clinicoradiological features, including body mass index, mesorectal fascia status, ypN stage, and tumor regression grade; (3) Model based on intratumoral radiomic features; (4) Model based on peritumoral radiomic features; (5) Model based on intratumoral-peritumoral radiomic features; (6) Model based on clinicoradiological-intratumoral features; (7) Model based on clinicoradiological-peritumoral features; and (8) Model based on clinicoradiological-intratumoral–peritumoral features. CI: Confidence interval; C-index: Concordance index; Clin: Clinicoradiological; Intra: Intratumoral; Peri: Peritumoral; ypT stage: Pathological T stage after neoadjuvant chemoradiotherapy; ypN stage: Pathological N stage after neoadjuvant chemoradiotherapy; YpTN: Pathological T and N stages after neoadjuvant chemoradiotherapy; ICRO: Integrated clinical-radiological-omics.