A revised stratification using pT classification , margin status , and the number of lymph nodes identified produced @ subgroups with significantly different LF risk in both cohorts : low risk ( pT@ ) , intermediate risk ( pT@ with negative margins AND @ lymph nodes identified ) , and high risk ( pT@ with positive margins OR < @ lymph nodes identified ) with @-year LF rates of @ % , @ % , and @ % , respectively , in the SWOG cohort and @ % , @ % , and @ % , respectively , in the development cohort .