Subgroup analyses showed a 5-year disease-specific survival benefit for patients with pathological tumour ( pT ) 1 disease in the D1 group ( 98 per cent versus 83 per cent for the D2 group ; P = 0.015 ) , and for patients with pT2-4 status and positive lymph nodes in the D2 group ( 59 per cent versus 38 per cent for the D1 group ; P = 0.055 ) .