Clinical Investigation
One Decade Later: Trends and Disparities in the Application of Post-Mastectomy Radiotherapy Since the Release of the American Society of Clinical Oncology Clinical Practice Guidelines

This work was presented at the 53rd Annual Meeting of the American Society of Radiation Oncology, Miami, FL, October 3, 2011.
https://doi.org/10.1016/j.ijrobp.2012.02.002Get rights and content

Purpose

In 2001 ASCO published practice guidelines for post mastectomy radiotherapy (PMRT). We analyzed factors that influence the receipt of radiotherapy therapy and trends over time.

Methods and Materials

We analyzed 8889 women who underwent mastectomy as primary surgical treatment for stage II or III breast cancer between 1995 and 2008 using data from the Kentucky Cancer Registry. We categorized patients according to ASCO group: group 1, PMRT not routinely recommended (T2, N0); group 2, PMRT controversial/evidence insufficient (T1-2, N1); group 3, PMRT recommended or suggested (T3-4 or N2-3). Probability of receiving PMRT was assessed using logistic regression.

Results

Overall, 24.0% of women received PMRT over the study period. The rates of PMRT for group 1, 2, and 3 were 7.5%, 19.5%, and 47.3%, respectively. Since 2001, there was an increase in the use of PMRT (from 21.1%-26.5%, P<.0001), which occurred mainly among group 3 members (from 40.8%-51.2%, P<.0001). The average rate remained constant in group 1 (from 7.1%-7.4%, P=.266) and decreased in group 2 (from 20.0%-18.1%, P<.0001). On multivariate analysis, the rate of PMRT was significantly lower for women aged >70 years (vs. younger), rural Appalachia (vs. non-Appalachia) populations, and Medicaid (vs. privately insured) patients.

Conclusions

ASCO guidelines have influenced practice in an underserved state; however PMRT remains underused, even for highest-risk patients. Barriers exist for elderly, rural and poor patients, which independently predict for lack of adequate care. Updated guidelines are needed to clarify the use of PMRT for patients with T1-2, N1 disease.

Introduction

Over a decade has passed since the publication of the major randomized studies that demonstrated a survival benefit for selected patients who received post-mastectomy radiotherapy (PMRT) as adjuvant treatment for locally advanced breast cancer 1, 2. In 2001, the American Society of Clinical Oncology (ASCO) issued clinical practice guidelines, outlining a “best practice” policy for the selection of patients most likely to benefit from the administration of PMRT, based on the preponderance of the medical evidence (3). As a result of these and other similar guideline publications 4, 5, 6, the use of PMRT became the standard of care for a significant portion of patients with American Joint Committee on Cancer (AJCC) stage II breast cancer and the overwhelming majority of patients with stage III disease.

Despite these recommendations, large national studies that have attempted to quantify adherence to treatment PMRT guidelines have shown mixed and even disappointing results 7, 8, 9, 10. Other studies have identified disparities in the receipt of PMRT among patients according to age, race, socioeconomic status, and geography, with access to breast cancer services in the Southeastern United States significantly lower than the national average 11, 12, 13. The Commonwealth of Kentucky does not encompass a city listed among the top 25 incorporated entities (according to the US Census Bureau) nor a top 40 metropolitan statistical area (as defined by the US Office of Management and Budget) in the United States. Additionally, Kentucky does not contain a National Cancer Institute (NCI) designated cancer center. The purpose of this study is to analyze trends of PMRT for locally advanced breast cancer in this underserved southern state prior to and since the release of the ASCO guidelines, and to identify disparities and barriers to recommended care.

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Methods and Materials

This study concept, design, and completion represents a collaborative effort of investigators at the University of Louisville's James Graham Brown Cancer Center (Louisville, KY) and the Kentucky Cancer Registry at the University of Kentucky's Markey Cancer Center (Lexington, KY). Institutional review board approval was obtained for extraction of data for female only breast cancer cases diagnosed between 1995 and 2008 from the Kentucky Cancer Registry, a population-based registry which is part

Results

Patient demographics, disease characteristics, and rates of PMRT receipt for the 8889 subjects are shown in Table 1. The analysis includes a median of 673 patients included per year (range, 505-723). Most patients were white and between the ages of 50 and 69 years old. Most patients carried medical insurance and resided in urban and non-Appalachian locations. Cancers were most commonly AJCC stage II, moderately or poorly differentiated, ductal histology, and hormone receptor positive. The

Discussion

Published in 2001, the ASCO guidelines for the use of PMRT are widely recognized to have had a strong and lasting influence on the field of radiation oncology and breast cancer medicine as a whole. These and other similar guidelines for PMRT have set in place standards that have broad-ranging implications from cancer center accreditation to medical-legal considerations. However, the effect of these guidelines on the shaping of clinical practice, beyond that which was accomplished by the

Conclusions

The 2001 ASCO guidelines have influenced practice in an underserved state; however, PMRT remains largely underused, even for the highest-risk patients. Barriers exist for elderly, rural, and poor patients, which independently predict for lack of adequate care. Updated guidelines are needed to clarify the use of PMRT for patients with T1-2, N1 disease. We advocate for techniques that will improve the ability of population-based databases to more accurately measure the use of adjuvant therapies

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