Analysis of interval cancers observed in an Italian mammography screening programme (2000-2006).
OBJECTIVE
The purpose of this study was to assess the interval cancer (IC) proportional incidence and review IC cases observed in an Italian mammography screening programme during 2000-2006.


METHODS
ICs were identified through linkage of a screening database with the local cancer registry and hospital discharge records to calculate proportional (observed/expected) incidence. Negatively reported mammograms preceding ICs underwent blind review (randomly mixed with negative controls in a 2:1 ratio) by three expert radiologists and classified according to European guidelines criteria (OC=occult, MS=minimal sign, SE=screening error) according to majority report. Proportional IC incidence and rate of reviewed IC classified as SE were compared with European guideline standards.


RESULTS
Proportional IC incidence was 10.8% in the first and 40.0% in the second year of the interval (European standard=30% or 50%, respectively). Sensitivity estimate for the 2-year interval was 74.6%. ICs were reviewed as SE, MS or OC in 15.0%, 14.0% or 71.0% of cases, respectively. Corresponding review results for negative controls were 7.0%, 25.0% or 68.0%, respectively. Positive predictive value for IC was 51.7% for SE and 21.8% for MS reporting category, respectively (p=0.008). European standard (<20% reviewed as SE) was reached.


CONCLUSIONS
The study shows that the sensitivity of the mammography programme was good, complying with European guideline recommendations. Assessment of IC-based early indicators of screening efficacy is feasible in a current screening programme and should become a routine procedure.
Caumo
F
F
Centro di Prevenzione Senologica (CPS), PO Marzana, ULSS 20, Verona, Italy.
Vecchiato
F
F
Pellegrini
M
M
Vettorazzi
M
M
Ciatto
S
S
Montemezzi
S
S
D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D016022:Case-Control Studies; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008327:Mammography / Q000592:standards*; D008403:Mass Screening / Q000592:standards; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D015397:Program Evaluation; D011786:Quality Control; D011787:Quality of Health Care; D012042:Registries; D012680:Sensitivity and Specificity