Table 1. Characteristics of the patients included in the study.

Patient and prognostic information	No. of patients	%
Age, years	4859	66*
Missing values	9	0.2
Comorbidity count
No comorbidities	2735	56.2
One comorbidity	1309	26.9
Two comorbidities	566	11.6
Three or more comorbidities	258	5.3
Gender
Male	3610	74.2
ECOG (WHO) performance status
Carries out all normal activity	2515	51.7
Restricted but walks/does light work	1550	31.8
Walks, full self-care but no work	526	10.8
Limited self-care—fully disabled	120	2.5
Missing values	157	3.2
Size and/or extent of the primary tumour (T)
No evidence of primary tumour T(0)	202	4.1
Tumour invades lamina propria or submucosa T(1)	927	19.0
Tumour invades muscularis propria T(2)	790	16.2
Tumour invades adventitia T(3)	2318	47.6
Tumour invades adjacent structures T(4)	489	10.0
Missing values	142	2.9
Regional lymph nodes (N)
No regional lymph node metastasis N(0)	2137	43.9
Metastasis in 1 to 2 regional lymph nodes N(1)	1496	30.7
Metastasis in 3 to 6 N(2)	614	12.6
Metastasis in 7 or more N(3)	507	10.4
Missing values	114	2.3
ASA Scale
Normal healthy patient	811	16.7
Mild systemic disease	2498	51.3
Severe systemic disease	1246	25.6
Life-threatening disease/ Moribund patient	60	1.2
Missing values	253	5.2
Cancer location
Squamous cell carcinomas of the oesophagus	491	10.1
Adenocarcinomas of the upper and middle oesophagus	183	3.8
Adenocarcinomas of the lower third of the oesophagus and Siewert type 1 tumours	1904	39.1
Siewert type II and type III tumours	840	17.3
Tumours of the stomach	1450	29.8
Deprivation
1 Least deprived	838	17.2
2	859	17.6
3	844	17.3
4	799	16.4
5 Most deprived	745	15.3
Missing values	783	16.1

*Mean