Early diagnosis, place of diagnosis and persistent differences at 10 years in breast cancer survival. Hospitals and breast clinic cases prognosis.

In the Province of Florence (central Italy), the Center for Cancer Prevention (CSPO) runs a breast clinic for early diagnosis of breast cancer at which women can present as self-referrals or be referred by a general practitioner. About 55% of breast cancers incident in the area were diagnosed at CSPO. This paper evaluates the differences observed in 10-year observed and relative survival between hospitals and breast clinic cases. A population-based data set of 1182 invasive cases diagnosed in the years 1985 and 1986 (Tuscany Cancer Registry) was analyzed. Cox models were used to evaluate the effects of place of diagnosis on observed survival. In comparison to hospital cases, breast clinic cases showed a significantly higher frequency of localized cancer (55% vs 37%) and a better relative survival, persistent at 10 years of follow-up (69% vs 58%). The better survival of breast clinic cases persisted after age adjustment (hospitals cases; RR = 0.71, 95% CI: 0.60-0.84) and after age + diffusion of disease adjustment (RR = 0.79, 95% CI: 0.66-0.93). For regionally diffused cancers, breast clinic cases showed a 10-year survival significantly better than hospital cases. In conclusion, even if some bias (i.e. lead-time and length bias) could affect the comparison, breast clinic cases showed a better survival persistent until 10 years after diagnosis. An earlier stage distribution explained, at least partly, the different prognosis.