Table 1. Published meta-analyses in multiple tumour types.

Tumour type	Studies included	Reference	Relationship analysed	Number of studies	Slope coefficient	R 2
Breast: metastatic	All randomised studies reporting progression and survival times by treatment	Current analysis	Ratio of median progression and ratio of median survival times (centred at zero)	67	0.32	0.30
Breast: metastatic	Studies of anthracyclines and taxanes with individual patient data	Burzykowski et al (2008)	Log hazard ratio for progression and log hazard ratio for survival	11	Not provided	0.23
Breast: metastatic	Studies of epirubicin regimens with individual patient data	Bruzzi et al (2005)	Log hazard ratio for response and log odds ratio for survival	10	Not provided	0.10
Breast: advanced	Studies of first-line treatments using FAC or FEC	Hackshaw et al (2005)	Log hazard ratio for time-to-progression and log hazard ratio for survival	17 before 1990	0.58 before 1990	0.67 before 1990
				9 after 1990	0.40 after 1990	0.41 after 1990
Breast: adjuvant	Studies reporting 2- to 3-year disease-free survival and 5-year overall survival (N⩾100)	Ng et al (2008)	Difference in proportion with disease-free survival at 2 years and difference in proportion surviving >5 years	126	Not provided	0.38
Colorectal: advanced	Studies of FU+leucovorin with individual patient data	Buyse et al (2007)	Log hazard ratio for progression- free survival and log hazard ratio for survival	10	0.81	0.98
Colorectal: metastatic	Studies with ‘mature data’ (N⩾100)	Tang et al (2007)	Hazard ratio for progression and hazard ratio for survival	39	Not provided	0.55 (PFS) 0.27 (TTP)
Colorectal: metastatic	Studies of first-line treatments	Johnson et al (2006)	Difference in months-to-progression and difference in survival months	146	0.096	0.33
Colorectal: metastatic	Studies of first-line treatments (N⩾100 per arm)	Louvet et al (2001)	Median months progression-free survival and median months survival by treatment group	29	0.68	0.23
Colon: adjuvant	Studies selected based on ‘relevance, maturity and data availability’ (individual patient data)	Sargent et al (2005)	Hazard ratio for disease-free survival and hazard ratio for survival	18	0.89	0.90
Lung (non-small-cell)	Studies reporting hazard ratios since 1977	Johnson et al (2004)	Log hazard ratio for time-to-progression and log hazard ratio for survival	48	Not provided	0.42
Lung: metastatic	Studies of first-line treatments	Johnson et al (2006)	Difference in months-to-progression and difference in survival months	191	0.62	0.19

R²=coefficient of determination for multivariate analysis or derived as squared correlation coefficient.