Second reading of screening mammograms increases cancer detection and recall rates. Results in the Florence screening programme.
OBJECTIVE
To assess double reading effectiveness in mammography screening.


METHODS
Retrospective study of 177,631 consecutive mammograms double read during 1998-2003.


METHODS
The Florence screening programme, involving 11 trained radiologists. Abnormalities reported by at least one reader prompted assessment.


RESULTS
The referral rate was 2.89% for the first reader, 3.15% for the second reader, and 3.59% for either reader. Of 713 total cancers detected, 43 were suspected only by the second reader (6.4% relative, 0.024% increase in absolute detection rate) and had a lower stage compared to the first reader (pTis-pT1b = 65.7 versus 52.0%): 41 were reviewed and classified (error type) as "minimal sign" in six, and "screening error" in 35 cases, or as BI-RADS 3 in one, 4a in 20, 4b in 13, and 4c in three cases. The second reading cost was 2.70 per woman examined, or 11,168 per additional cancer detected (versus 11,585 at a single reading).


CONCLUSIONS
Second reading is effective in detecting a limited number of additional cancer cases. Tumour stage (one-third over 1 cm in diameter) and review findings (high rate of "screening errors" and BI-RADS R4b-c categories) suggest that second reading detects small "difficult cases" as well as larger cancers missed due to fatigue or loss of attention. Second reading reduces screening specificity to a minor extent, and since cancer detection at second reading seems cost-effective the procedure is recommendable in routine practice.
Ciatto
S
S
Department of Diagnostic Imaging, Centro per lo Studio e la Prevenzione Oncologica, viale A. Volta 171, 50131 Florence, Italy. s.ciatto@cspo.it
Ambrogetti
D
D
Bonardi
R
R
Catarzi
S
S
Risso
G
G
Rosselli Del Turco
M
M
Mantellini
P
P
D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis*; D003362:Cost-Benefit Analysis; D003365:Costs and Cost Analysis; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D007558:Italy; D008327:Mammography / Q000379:methods*; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014962:X-Ray Film