A time-dependent receiver-operating characteristic ( ROC ) curve analysis was subsequently utilised to evaluate the best cut-off for TTC , identifying 7 weeks as the best threshold for longer OS ( p = 0.043 ) : 8-year OS 88 % ( 95 % CI 85-90 ) for patients with a TTC < 7 weeks and 78 % ( 95 % CI 68-87 ) for the other group .