Impact of adjuvant chemotherapy on the survival of patients with breast cancer diagnosed by screening.

Irene Zarcos‐Pedrinaci,María Sala,Francisco Medina Cano,Francisco Rivas‐Ruiz,Xavier Castells,Maximino Redondo,Diego Pérez,Antonio Rueda,Javier Louro,Laia Domingo,Kenza Machan,Maria Mar Vernet,Teresa Téllez,Maria Padilla‐Ruiz

doi:10.1002/cam4.2488

Abstract

The aim of this study is to determine the survival of patients with breast cancer treated with adjuvant chemotherapy (ACh) after the diagnosis by screening, taking comorbidity into account. This multicenter cohort study examined a population of patients taking part in four national screening programs for the early detection of breast cancer (localized or locally advanced), during the period 2000‐2008. Of the 1248 cancers detected, 266 were prevalent (21.3%), 633 were incident (50.7%), and 349 were interval (27.9%). No significant differences were detected between the three groups in terms of the distribution of comorbidity according to the CCI. After a median follow‐up of 102 months, 22.1% of the patients with interval cancer had died. The corresponding figures for the incident and prevalent cancers were 10.4% and 7.9%, respectively (P < .001). The adjusted Cox regression analysis by the stage, CCI and group revealed no differences in the risk of recurrence between the different groups according to the ACh performed. However, there were significant differences in the overall survival; for the interval cancer group without ACh, the risk of death was higher (Hazard ratio: 2.5 [1.0‐6.2]) than for the other two groups. However, for the prevalent and incident groups that did not receive ACh, there was no greater risk of death. This study shows that adjuvant chemotherapy seems to benefit patients with interval breast cancer, who have a poorer prognosis than those with prevalent or incident cancer. However, the role of ACh is unclear with respect to prevalent and incident cancers when comorbidity is taken into account.

Highlights

Breast cancer is the malignant tumor most commonly diagnosed in women in North America and Europe, with approximately 1 151 000 new cases per year (22.7% of all cancer cases among the female population)[1] and the most prevalent tumor worldwide for 5 years, among both sexes (19.2%)
The breast cancer tumors detected by the screening generally have a good prognosis, due to the existence of biological differences associated with reduced aggressiveness and better survival compared to symptomatic tumors, such as positivity for the expression of hormonal receptors and a lower rate of cellular proliferation.[5,6]
It is well established that breast cancers detected by screening have a better prognosis, even after adjusting for the stage of the disease.[5,9,13]

Summary

Introduction

Breast cancer is the malignant tumor most commonly diagnosed in women in North America and Europe, with approximately 1 151 000 new cases per year (22.7% of all cancer cases among the female population)[1] and the most prevalent tumor worldwide for 5 years, among both sexes (19.2%). The breast cancer tumors detected by the screening generally have a good prognosis, due to the existence of biological differences associated with reduced aggressiveness and better survival compared to symptomatic tumors, such as positivity for the expression of hormonal receptors and a lower rate of cellular proliferation.[5,6]. This better prognosis is due to associated biases such as selection bias, lead‐time bias, duration bias, and possibly overdiagnosis bias.[7,8]

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Conclusion