External validation of a rectal cancer outcome prediction model with a cohort of patients treated with preoperative radiochemotherapy and deep regional hyperthermia

Figures & data

Table 1. Patient and treatment characteristics in the training and validation cohort.

	Training cohort		Validation cohort
	n	%	n	%
Age (years)
≤49	378	13.5%	10	11.6%	p = 0.39
50–59	746	26.7%	22	25.6%
60-69	1131	40.5%	31	36.0%
≥70	540	19.3%	23	26.7%
Tumour height
Low	953	34.2%	46	53.5%	p < 0.001
Mid	1461	52.5%	38	44.2%
High	369	13.3%	2	2.3%
cT category
2	18	0.7%	2	2.3%	p = 0.24
3	2228	88.4%	75	87.2%
4	275	10.9%	9	10.5%
cN category
cN0	309	36.2%	15	17.4%	p < 0.001
cN+	544	63.8%	71	82.6%
RT dose
<45	50	1.8%	1	1.2%	p < 0.001
45	2205	78.7%	0	0.0%
>45	547	19.5%	85	98.8%
Concurrent chemotherapy
No	868	31.0%	0	0.0%	p < 0.001
Yes	1933	69.0%	86	100.0%
Surgery
LAR	1600	59.9%	55	64.0%	p = 0.45
APR	1071	40.1%	31	36.0%
Postoperative chemotherapy
No	1209	43.5%	24	27.9%	p < 0.001
Yes	1572	56.5%	62	72.1%
Postoperative T category
0	299	11.0%	17	19.8%	p = 0.08
1–2	1008	37.2%	32	37.2%
3	1329	49.0%	35	40.7%
4	74	2.7%	2	2.3%
Postoperative N category
0	1879	69.3%	66	76.7%	p = 0.17
1–2	833	30.7%	20	23.3%

RT: radiotherapy; LAR: low anterior resection; APR: abdominoperineal resection.

Counts between groups were compared by the chi-square test.

Figure 1. Kaplan–Meier estimates for overall survival (a), distant-metastases-free survival (b) and local control after nomogram-based division of patients into a low-, medium- and high-risk groups. Survival-curves were compared using the log-rank test.

Figure 2. Calibration plots of predicted and observed rates with 95% confidence intervals for (a) overall survival (OS), (b) distant-metastases-free survival (DMFS) and (c) local control (LC).