3. Additional results reported from included studies.

	Tumour stage (TNM)	Clinical vs pathologic staging	Median overall survival (95% CI)	Median progression‐free survival	Median time to tumour progression	5‐Year survival	Follow‐up time	Statistical test used (uni‐ vs. multivariable)
Christopherson 2008	All T, N0, M0	Pathological	6.14 (5.22 to 7.99)	Not reported	Not reported	Not reported	Up to 9 years	Data extracted from Kaplan‐Meier curve; HR and SEHR calculated according to Tierney (Tierney 2007)
Myles 2011	All T, all N, no distant metastasis (M0) 'complete surgical excision'	Not reported	Epidural group: 3.3 (95% CI 2.1 to 4.5) Control group: 3.7 (95% 2.0 to 5.4)	Epidural group: 2.6 (IQR 0.7 to 8.7) Control group: 2.8 (IQR 0.7 to 8.7)	Epidural group: 1.1 (95% CI 0.7 to 1.6) Control group: 1.4 (95% CI 0.6 to 2.3)	Epidural group: 42% Control group: 44%	Up to 12 years	Univariable testing, log‐rank statistics, intention‐to‐treat analysis
Tsui 2010	All T, all N, M not reported	Pathological	Not reported	Not reported	1644 days	Not reported	Up to 3403 days (˜9.3 years)	Unadjusted Cox model, no intention‐to‐treat analysis
Binczak 2013	Primary tumour resection (all stages) with or without residual disease postoperatively	Not reported	Not reported	Not reported	Not reported	Not reported	Up to 17 years	Unadjusted HR (reported by the contact author through personal communication)

IQR = interquartile range.

TNM classification of malignant tumours: T = tumour size, N = lymph node involvement, M = distant metastasis.

HR = hazard ratio.

SEHR = standard error of hazard ratio.

CI = confidence interval.