Short- and Long-term Cause-specific Survival of Patients with Inflammatory Breast Cancer

Patricia Tai, University of Saskatchewan
Edward Yu, University of Western Ontario
Ross Shiels, University of Saskatchewan
Juan Pacella, University of Saskatchewan
Kurian Jones, University of Saskatchewan
Evgeny Sadikov, University of Saskatchewan
Shazia Mahmood, University of Saskatchewan

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Published in: BMC Cancer, 2005, 5:137. doi: 10.1186/1471-2407-5-137

Abstract

Background: Inflammatory breast cancer (IBC) had been perceived to have a poor prognosis. Oncologists were not enthusiastic in the past to give aggressive treatment. Single institution studies tend to have small patient numbers and limited years of follow-up. Most studies do not report 10-, 15- or 20-year results.

Methods: Data was obtained from the population-based database of the Surveillance, Epidemiology, and End Results program of the National Cancer Institute from 1975-1995 using SEER*Stat5.0 software. This period of 21 years was divided into 7 periods of 3 years each. The years were chosen so that there was adequate follow-up information to 2000. ICD-O-2 histology 8530/3 was used to define IBC. The lognormal model was used for statistical analysis.

Results: A total of 1684 patients were analyzed, of which 84% were white, 11% were African Americans, and 5% belonged to other races. Age distribution was < 30 years in 1%, 30-40 in 11%, 40-50 in 22%, 50-60 in 24%, 60-70 in 21%, and > 70 in 21%. The lognormal model was validated for 1975-77 and for 1978-80, since the 10-, 15- and 20-year cause-specific survival (CSS) rates, could be calculated using the Kaplan-Meier method with data available in 2000. The data were then used to estimate the 10-, 15- and 20-year CSS rates for the more recent years, and to study the trend of improvement in survival. There were increasing incidences of IBC: 134 patients in the 1975-77 period to 416 patients in the 1993-95 period. The corresponding 20-year CSS increased from 9% to 20% respectively with standard errors of less than 4%.

Conclusion: The improvement of survival during the study period may be due to introduction of more aggressive treatments. However, there seem to be no further increase of long-term CSS, which should encourage oncologists to find even more effective treatments. Because of small numbers of patients, randomized studies will be difficult to conduct. The SEER population-based database will yield the best possible estimate of the trend in improvement of survival for patients with IBC.