Screen-detected breast cancer and prognosis
Year: 2013
Type: dissertation
Study design: Observational Study
Abstract: The incidence of breast cancer has increased world-wide over recent decades. The survival rate of breast cancer patients has improved mainly due to innovative therapies and mammography screening programs. Despite improvements in survival, breast cancer is still the leading cause of cancer death among women. Breast cancers detected at screening mammography are, in general, smaller at the time of the diagnosis and less aggressive than cancers found by other methods, and are reported to be associated with generally favorable survival. It is, however, unclear whether this survival advantage can be explained by early detection and favorable tumor biology only, or whether other unknown factors might account for the survival advantage. The purpose of this study was to study the long-term prognosis and biological profiles of screen-detected breast cancers as compared to non-screen-detected cancers (FinProg database www.finprog.org). The generalizability and geographic transportability of breast cancer survival estimates were investigated by comparing the current study series, the FinProg database, with a large dataset from the United States, the SEER. Despite differences in demographic variables, use of adjuvant therapies and screening mammography between series, the prognostic factors produced close to overlapping survival curves. When commonly used prognostic factors, such as tumor size, nodal status and histological grade are evaluated, survival estimates were similar in these large unselected cohorts of breast cancer patients. The molecular subtypes associated with favorable survival rates were more frequent in screen-detected breast cancers than in non-screen-detected cancers. The differences in molecular subtypes between mammography screen-detected cancers and cancers found otherwise could not, however, explain all of the survival advantage associated with breast cancer detection at screening. Breast cancers detected by the mammography screening program had a significantly lower 10-year risk for distant recurrence than cancers of similar size diagnosed by other methods. Patients with screen-detected breast cancer had also significantly better breast cancer-specific survival compared with patients with non-screen-detected cancer. This advantage persisted over a 15-year follow-up period. There was no significant difference in the risk for contralateral breast cancer between these two groups. The biological factors investigated in the current study could not explain entirely the survival advantage associated with cancer detection at mammography screening, suggesting that there are other biological factors that may also explain the difference, which is in line with some previous studies. The risk for recurrence may be overestimated for women diagnosed by mammography screening unless the method of detection is taken into account in risk estimations, which may lead to overtreatment of patients with screen-detected breast cancer.
Source: Työväentutkimus Vuosikirja
Author: Terho Lehtimäki
Institution: Institute for Molecular Medicine Finland
Language: English
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2106195264