What drove changes in the use of breast conserving surgery since the early 1980s? The role of the clinical trial, celebrity action and an NIH consensus statement

Abstract

Background: Three important events in the history of breast cancer treatment occurred between 1983 and 1995: a large clinical trial, first lady Nancy Reagan's choice of mastectomy and the publishing of an NIH consensus statement.

Objective: To assess the effects of these events on use of breast conserving surgery (BCS).

Research design: Data from the cohort study of the surveillance, epidemiology and end results (SEER) Program from 1983 to 1995 were divided into four periods: Baseline, Trial, Celebrity, and Consensus.

Subjects: Of the women, 169,466 diagnosed with early stage breast cancer in nine SEER areas.

Measures: Monthly percentages of BCS.

Results: A linear regression model generated a separate intercept and slope term for four time periods, adjusting for demographic characteristics of breast cancer patients. For the Baseline, Celebrity and Consensus Periods, slopes indicated an increasing use of BCS which varied between 0.24% and 0.28% per month. Slopes for these three periods were not statistically different (p = 0.120). In contrast, there was no change in use of BCS during the trial period (p = 0.247). We tested the magnitude of discontinuity between periods. At the beginning of the trial, celebrity and consensus periods, there were increases in BCS of 5.54% (p < 0.001), -3.55% (p < 0.001), and 2.37% (p < 0.001), respectively.

Conclusions: The use of BCS was substantially affected by the reports of a clinical trial of BCS and by celebrity action. These effects were abrupt but transient. The NIH consensus statement stimulated a small change in use of BCS and may be an important intervention for maintaining the increasing trend in use of BCS since the 1990s.