Compared with screen-detected cancers , interval cancers were diagnosed at more advanced stages ( 29 [ 83 % ] of 35 interval cancers vs 44 [ 22 % ] of 196 screen-detected cancers diagnosed in stage III or IV ; p < 00001 ) , were more often small-cell carcinomas ( seven [ 20 % ] vs eight [ 4 % ] ; p = 0003 ) and less often adenocarcinomas ( nine [ 26 % ] vs 102 [ 52 % ] ; p = 0005 ) .