Abstract
BackgroundThe aim of this study was to measure the biological characteristics involved in tumorigenesis and the progression of breast cancer in symptomatic and screen-detected carcinomas to identify possible differences.MethodsFor this purpose, we evaluated clinical-pathological parameters and proliferative and apoptotic activities in a series of 130 symptomatic and 161 screen-detected tumors.ResultsAfter adjustment for the smaller size of the screen-detected carcinomas compared with symptomatic cancers, those detected in the screening program presented longer disease-free survival (RR = 0.43, CI = 0.19-0.96) and had high estrogen and progesterone receptor concentrations more often than did symptomatic cancers (OR = 3.38, CI = 1.72-6.63 and OR = 3.44, CI = 1.94-6.10, respectively). Furthermore, the expression of bcl-2, a marker of good prognosis in breast cancer, was higher and HER2/neu expression was lower in screen-detected cancers than in symptomatic cancers (OR = 1.77, CI = 1.01-3.23 and OR = 0.64, CI = 0.40-0.98, respectively). However, when comparing prevalent vs incident screen-detected carcinomas, prevalent tumors were larger (OR = 2.84, CI = 1.05-7.69), were less likely to be HER2/neu positive (OR = 0.22, CI = 0.08-0.61) and presented lower Ki67 expression (OR = 0.36, CI = 0.17-0.77). In addition, incident tumors presented a shorter survival time than did prevalent ones (RR = 4.88, CI = 1.12-21.19).ConclusionsIncident carcinomas include a variety of screen-detected carcinomas that exhibit differences in biology and prognosis relative to prevalent carcinomas. The detection method is important and should be taken into account when making therapy decisions.
Highlights
The aim of this study was to measure the biological characteristics involved in tumorigenesis and the progression of breast cancer in symptomatic and screen-detected carcinomas to identify possible differences
After adjustment for the smaller size of the screendetected primary tumors compared with control cancers, the differences between the two groups were maintained and related to axillary nodal metastases (OR = 0.25; CI = 0.13-0.47), percentage of in situ carcinomas (OR = 6.19, CI = 1.35-28.37) and estrogen and progesterone receptor expression (OR = 3.38, CI = 1.72-6.63; Odds Ratio (OR) = 3.44, CI = 1.94-6.10, respectively)
We found the method of detection to be an important prognostic factor for breast cancer survival, even after adjusting for tumor characteristics
Summary
The aim of this study was to measure the biological characteristics involved in tumorigenesis and the progression of breast cancer in symptomatic and screen-detected carcinomas to identify possible differences. Tumors detected by mammographic screening are generally considered to have good prognoses because of several biases, such as selection bias, lead-time bias, length bias, and, possibly, overdiagnosis (some tumors might never have surfaced) [2]. In support of these observations autopsy studies have revealed occult breast cancer in 1.3% and in situ. The presence of lymph node metastases is generally considered to be the most important prognostic factor. In screen-detected cancers, the incidence of tumors with lymph node involvement is low because of earlier diagnosis and the smaller size of the tumor and is, of limited prognostic value. It is theoretically possible to eliminate length bias by adjusting for the aggressiveness of tumors on the basis of a full biological description [5,7,8]
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