Table 2.

Effect of ‘earlier or shorter’ radiotherapy versus ‘later or longer’ radiotherapy on overall survival according to different trial subsets

Trials characteristics	HR [95% CI]a	Heterogeneityb
		Between-subset	Residual (or within-subset)
CT compliance between arms
Similar	0.79 [0.69–0.91]	19.5***	1.9
Different	1.19 [1.05–1.34]
RT dose per fraction
<1.8 Gy	0.82 [0.71–0.96]	7.5* (Ptrend = 0.02)c	14.1*
1.8–2.4 Gy	1.11 [0.90–1.35]
>2.4 Gy	1.06 [0.94–1.20]
Type of RT
Hyperfractionated	0.82 [0.71–0.96]	7.4**	14.2*
Standard	1.07 [0.96–1.19]
RT overall treatment time
≤30 days in both arms	0.89 [0.78–1.02]	5.6 (Ptrend = 0.02)c	16.0*
One arm ≤30 days, one >30 days	0.99 [0.85–1.15]
>30 days in both arms	1.16 [0.98–1.38]
Platin-based CT during RT in both arms
Yes	0.89 [0.79–1.01]	5.5**	16.1*
No	1.09 [0.97–1.24]
Concurrent CT in both arms
Yes	0.95 [0.85–1.06]	1.5	20.1**
No	1.06 [0.92–1.22]
Same RT in the two arms
Yes	0.96 [0.85–1.08]	0.5	21.1**
No	1.02 [0.90–1.16]

CI, confidence interval; CT, chemotherapy; HR, hazard ratio; RT, radiotherapy.

^aHazard ratio of death following ‘earlier or shorter’ versus ‘later or longer’ radiotherapy.

^bTotal heterogeneity is the sum of between-subset and residual (within-subset) heterogeneity and is equal to 21.6 (analysis based on nine trials) except for CT compliance 21.4 (eight trials). The test associated with between-subset heterogeneity corresponds to the interaction test. The lower the residual heterogeneity, the greater was the overall heterogeneity of the treatment effect between trials explained by the trial characteristic.

^cTest for trend.

*P < 0.05; **P < 0.01; ***P < 0.001.