Early diagnosis, not differential treatment, explains better survival in service screening.
Italian population-based breast cancer screening programmes with 2-year, high-quality mammography started in the cities of Florence and Turin in the early 1990s. Breast cancer cases from the local Tumour Registry were classified by method of detection and tumour characteristics (size, nodal-status and grade). Follow-up was at December 2001. In total, 4444 breast cancer cases were analysed. The Hazard Ratio comparing before and after-invitation breast cancer cases indicated a 27% reduction (HR=0.73; 95%CI: 0.61-0.87) in the risk of dying for the disease. After adjustment for tumour characteristics, survival rate was comparable by invitation status, whereas the proportion of early cancer was 33.7% and 46.6% in the before and after-invitation group. Survival rates by tumour characteristic subgroups was comparable by invitation status. Late stage and grade 3 were indicators of poor prognosis. Adjustment for tumour characteristics confirmed screening and not differential treatment as the most important reason for the observed survival benefit. The survival analysis by specific subgroups did not support the hypothesis that the difference in prognosis was attributable to differential treatment.
Paci
Eugenio
E
Unit of Clinical and Descriptive Epidemiology, Centre for Study and Prevention of Cancer, Research Institute of Tuscany Region, Via di San Salvi 12, 50125 Firenze, Florence, Italy. e.paci@cspo.it
Ponti
Antonio
A
Zappa
Marco
M
Patriarca
Silvia
S
Falini
Patrizia
P
Delmastro
Gabriella
G
Bianchi
Simonetta
S
Sapino
Anna
A
Vezzosi
Vania
V
Senore
Carlo
C
Crocetti
Emanuele
E
Frigerio
Alfonso
A
Zanetti
Roberto
R
Del Turco
Marco Rosselli
MR
Segnan
Nereo
N
D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D002278:Carcinoma in Situ / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D016019:Survival Analysis