Table 2. The histopathological findings and classification of whether a delay in diagnosis had occurred of 29 patients who were diagnosed with breast cancer having been previously discharged from the breast clinic.

						Histopathology of ‘interval’ cancer
Classification of interval cancer	No. of patients	Mean age years (range)	Mean time from initial discharge to diagnosis of breast cancer (months)	Mammographic density (BI-RADS 1–4)	Imaging review classificationa	Mean size mm (range)	Grade	Nodal statusb	ER status	% of patients with NPI >3.4 (moderate/ poor/very poor prognostic groups)c	Interval cancer rate per 1000 patients seen in a symptomatic clinic
No delay	10	50 (41–56)	19.4	1: 0 2: 0 3: 6 4: 4	10 Normal/benign	20 (8–33)	Gd 1: 1 Gd 2: 3 Gd 3: 6	1: 5 2: 3 3: 2	+ve 5 −ve 5	70	1.4
Probably no delay	7	58 (39–87)	23.6	1: 1 2: 0 3: 4 4: 2	7 Unclassifiable	29 (17–50)	Gd 1: 0 Gd 2: 0 Gd 3: 7	1: 4 2: 3 3: 0	+ve 5 −ve 2	100	1.0
Possible delay	3	59 (53–69)	17.3	1: 0 2: 1 3: 1 4: 1	3 Uncertain	33 (16–52)	Gd 1: 1 Gd 2: 1 Gd 3: 1	1: 1 2: 1 3: 1	+ve 3 −ve 0	66	0.4
Delayd	9	57 (36–96)	21.8	1: 1 2: 0 3: 5 4: 3	7 Unclassifiable 1 Uncertain 1 Suspicious	33 (20–60)	Gd 1: 0 Gd 2: 4 Gd 3: 4	1: 1 2: 3 3: 4	+ve 5 −ve 3	100	1.3
Totald	29	55 (38–96)	20.9	1: 2 2: 1 3: 16 4: 10		27 (8–60)	Gd 1: 2 Gd 2: 8 Gd 3: 18	1: 11 2: 9 3: 8	+ve 18 −ve 10	86	4.1

^aImaging Review Classification: Unclassifiable (imaging unavailable for review), normal/benign (no suspicious features), uncertain (neither clearly benign or malignant imaging changes), suspicious (‘missed’ cancer).

^bAccording to the Nottingham Prognostic Index (Blamey et al, 2007a, 2007b).

^cNPI indicates Nottingham Prognostic Index (Blamey et al, 2007a, 2007b).

^dFinal histology unknown in one patient who emigrated and underwent treatment abroad.