Figure 8. Smoothed plots of frequency distributions of node-negative percentage for 5051 invasive cancers of known nodal status that were identified at diagnostic mammography (among radiologists finding five or more invasive cancers of known nodal status), as a function of indication for examination. An overlaid solid line indicates the 50th percentile (median), paired dashed lines indicate the 25th and 75th percentiles, and paired dotted lines indicate the 10th and 90th percentiles. A, Work-up of abnormal results detected at screening examination; B, short-interval follow-up; C, evaluation of breast problem, no lump or lump unknown; D, evaluation of breast problem, palpable lump; E, all diagnostic examinations. Corresponding arithmetic mean values for all 6324 invasive cancers of known nodal status are listed in Table 4.