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Journal of Clinical Oncology, Vol 23, No 9 (March 20), 2005: pp. 2116 © 2005 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.05.254
Trends in Survival of Patients With Metastatic Breast Cancer
Department of Epidemiology, Maastricht University, Maastricht, the Netherlands To the Editor: Considering the results of three French cancer centers described in the study of Andre et al,1 remarkable progress has been made in the treatment of breast cancer patients with synchronous metastases between 1987 and 2000. The 3-year overall survival rates of the patients improved from 27% to 44%, and the median survival increased from 23 to 29 months. In the Discussion of their article, the authors attribute part of the improvement to the increased use of taxanes and aromatase inhibitors. Although they recognize the limitations of their study design to make such a causal connection, some other potential confounders remain underexposed. From the Tables and the information in the Patients and Methods section, it is not clear whether all patients with metastatic disease have been included and if all patients have been seen by medical oncologists and have received systemic treatment. Data from the Eindhoven Cancer Registry in the Netherlands and clinical experience suggest that there will always be some patients with metastatic breast cancer who refuse systemic treatment or who are not referred to a medical oncologist because of serious comorbid conditions or an extremely short life expectancy. According to the data of the Eindhoven Cancer Registry, at least 6% of the patients with primary metastatic breast cancer diagnosed in the period from 1995 to 1997, did not receive systemic treatment; some of them received no treatment at all or only locoregional treatment, and others underwent nonsystemic palliative treatment such as radiotherapy for painful bone metastases or pleurodesis for malignant pleural effusions.2 What proportion of the patients in the study of Andre et al received no systemic treatment, and did it change over time? Exclusion of such patients from the analyses would overestimate the median and overall survival rates. Another possible source of bias that was not discussed is lead-time bias. The authors state that staging procedures for primary breast cancer were similar from 1987 to 2000, including physical examination, blood tests, chest x-ray, liver ultrasound, and bone scan. However, in many countries, the growing use of mammography during the 1980s and the introduction of breast cancer screening programs in the 1990s have led to the diagnosis of breast cancer tumors in an earlier stage. An earlier detection of the primary tumor may have led to earlier detection of metastatic disease and a better overall survival. To confirm this hypothesis, one would expect a decrease in the proportion of patients with metastatic disease in the presence of a large primary tumor and/or locally advanced breast cancer. To rule out the effect of lead-time bias, it might be necessary to adjust for changes in the local and regional tumor stage. Authors' Disclosures of Potential Conflicts of Interest The authors indicated no potential conflicts of interest. REFERENCES
1. Andre F, Slimane K, Bachelot T, et al: Breast cancer with synchronous metastases: Trends in survival during a 14-year period. J Clin Oncol 22:3302-3308, 2004 2. Coebergh JWW, Janssen-Heijnen MLG, Louwman WJ, et al (eds): Cancer incidence, care and survival in the South of the Netherlands, 1955-1999: A report of the Eindhoven Cancer Registry with cross-border implications. Eindhoven, the Netherlands: Comprehensive Cancer Centre South (IKZ), 2001
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Copyright © 2005 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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