Published Ahead of Print on April 13, 2017 as 10.1634/theoncologist.2016-0397.

Breast Cancer

Endocrine Therapy Initiation and Medical Oncologist Utilization Among Women Diagnosed with Ductal Carcinoma in Situ CHELSEA ANDERSON,a ANNE MARIE MEYER,a STEPHANIE B. WHEELER,b LEI ZHOU,c KATHERINE E. REEDER-HAYES,c,d HAZEL B. NICHOLSa a

Department of Epidemiology, Gillings School of Global Public Health, bDepartment of Health Policy and Management, Gillings School of Global Public Health, cLineberger Comprehensive Cancer Center, and dDivision of Hematology/Oncology, UNC School of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA Key Words. Endocrine therapy



Ductal carcinoma in situ



Medical oncologist



Breast cancer

Background. Though randomized clinical trials have demonstrated a reduction in second breast events with endocrine therapy among women with ductal carcinoma in situ (DCIS), use of these therapies remains highly variable. The purpose of this study was to evaluate patient and treatment-related factors associated with endocrine therapy initiation and medical oncology specialty utilization after DCIS. Materials and Methods. We identified women with a DCIS diagnosis during 2006–2010 in the North Carolina Central Cancer Registry with linked public and private insurance claims in the University of North Carolina Integrated Cancer Information Surveillance System data resource. Multivariable generalized linear regression models were used to estimate risk ratios (RR) and 95% confidence intervals (CI) for endocrine therapy initiation in the year following DCIS diagnosis.

Results. Among 2,090 women with a DCIS diagnosis, 37% initiated endocrine therapy. Initiation was less common among women aged 751 at diagnosis (RR 5 0.79; 95% CI: 0.64–0.97 vs. age 45–54) and women treated with breast-conserving surgery (BCS) who did not receive radiation (RR 5 0.63; 95% CI: 0.50–0.78 vs. BCS plus radiation). Consultation with a medical oncologist was strongly associated with endocrine therapy initiation (RR 5 1.40; 95% CI: 1.23–1.61). Women who saw a medical oncologist more often had private insurance, higher census tract-level income, hormone receptor positive disease, and treatment with BCS and radiation. Conclusion. Treatment strategies for DCIS remain controversial. Our data suggest that endocrine therapy is more often used in addition to standard therapies such as BCS plus radiation, rather than as an alternative to radiation. The Oncologist 2017;22:1–7

Implications for Practice: Randomized trials have demonstrated a reduction in second breast cancer events with use of endocrine therapy for ductal carcinoma in situ (DCIS). However, notable variation exists in the uptake of these therapies among DCIS patients. In this study, factors associated with endocrine therapy initiation in the year following a DCIS diagnosis included consultation with a medical oncologist and treatment with breast-conserving surgery with radiation. Our findings help to explain the wide variation in endocrine therapy initiation and suggest the need for clear guidelines in the treatment of DCIS.

INTRODUCTION The incidence of ductal carcinoma in situ (DCIS), a stage 0 breast cancer confined to the lumen of mammary ducts, has increased dramatically since the 1970s, in large part due to parallel increases in screening mammography [1]. DCIS currently accounts for over 20% of all breast cancer diagnoses, with more than 60,000 new cases annually in the United States [2]. Recommended therapies for DCIS include breast-conserving surgery (BCS) with radiation or mastectomy, the goals of which are to reduce risk of local recurrence and progression to invasive cancer. With current therapies, less than 3% of women will die of invasive breast cancer within 8–10 years of a DCIS diagnosis [3]. However, given the heterogeneous nature of DCIS and the lack of reliable prognostic indicators for recurrence and

evolution into invasive cancer, treatment strategies remain controversial [4]. Randomized trials, including the National Surgical Adjuvant Breast and Bowel Project B-24 trial [5] and the U.K., Australia, and New Zealand DCIS trial [6], have shown a long-term reduction in second breast events with the use of tamoxifen as adjuvant endocrine therapy for DCIS. Tamoxifen has been approved by the Food and Drug Administration for treatment of DCIS since 2000, and current guidelines from the National Comprehensive Cancer Network recommend consideration of tamoxifen for DCIS patients with estrogen receptor (ER) positive disease [7]. Recent trials have also demonstrated the efficacy of anastrozole, an aromatase inhibitor, in the reduction of breast

Correspondence: Chelsea Anderson, MPH, Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, 135 Dauer Drive, Chapel Hill, North Carolina 27599, USA. Telephone: (919) 966-7430; e-mail: [email protected]. c AlphaMed Press 1083-7159/2017/$20.00/0 http://dx.doi.org/ edu Received October 12, 2016; accepted for publication December 6, 2016. O 10.1634/theoncologist.2016-0397

The Oncologist 2017;22:1–7 www.TheOncologist.com

c AlphaMed Press 2017 O

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ABSTRACT

Published Ahead of Print on April 13, 2017 as 10.1634/theoncologist.2016-0397.

Endocrine Therapy After Ductal Carcinoma in Situ

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MATERIALS AND METHODS Data Source and Study Sample Data for this study were analyzed from the University of North Carolina Integrated Cancer Information and Surveillance System, a data resource which links cancer case data from the North Carolina Central Cancer Registry to administrative and claims data from Medicare, Medicaid, and private health insurance plans [21]. North Carolina Central Cancer Registry records were used to identify women diagnosed with breast carcinoma in situ from 2006 to 2010 (N 5 7,922). We excluded those with an in situ diagnosis other than DCIS (n 5 821) and those with a prior cancer diagnosis (n 5 1,369). To capture only endocrine therapy initiation resulting from a DCIS diagnosis, rather than an invasive cancer diagnosis, we also excluded women who experienced a second cancer diagnosis within 1 year of the index DCIS diagnosis (n 5 63). We excluded those who were not continuously enrolled in their health plan for the 12 months prior to diagnosis (n 5 3,290) and the 12 months after diagnosis with pharmacy benefit (n 5 144), and those who had no surgery within 180 days post-diagnosis (n 5 70). The 1 year window of continuous enrollment prior to diagnosis was required for measuring claims attributable to comorbidity, used in the calculation of the Charlson comorbidity score [22]. Women who were simultaneously enrolled in all three health insurance types (private insurance, Medicare fee for service, and Medicaid; n 5 75) were excluded, as this was considered to be an implausible coverage pattern. Thus the final analytic sample included 2,090 women.

Outcome Definitions Endocrine therapy initiation was determined from pharmacy claims that identify specific National Drug Codes for Tamoxifen c AlphaMed Press 2017 O

Figure 1. Women with a DCIS diagnosis. Criteria for inclusion in final analyses.

and aromatase inhibitors. Women were defined as having initiated endocrine therapy if they had at least one claim within the year after diagnosis. Consultation with a medical oncologist was determined using provider codes on claims that identify the specific specialty of the provider billed for that visit. A window of 12 months from diagnosis was used to define consultation with a medical oncologist from claims.

Statistical Analysis To estimate adjusted risk ratios (RR) and 95% confidence intervals for endocrine therapy initiation, we used generalized linear models with log links, Poisson distributions, and robust standard errors. Exposures of interest were evaluated in both ageadjusted and multivariable models. Due to collinearity between age at diagnosis and insurance type, RRs associated with insurance type were not adjusted for age. Multivariable Poisson regression models were also used to evaluate factors associated with seeing a medical oncologist in the year following DCIS diagnosis.

RESULTS We identified 2,090 eligible women with a DCIS diagnosis (Fig. 1). The average age at diagnosis was 61.6 years (SD 5 12.1). The majority of women were non-Hispanic white (79%), privately insured (61%), and had no comorbidities in the 12 months prior to diagnosis (71%) (Table 1).

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cancer events among women with hormone2receptor-positive DCIS [8, 9]. Despite their potential benefit, adjuvant endocrine agents are not without the possibility of adverse side effects [10, 11], suggesting that women and their providers must weigh the risks and benefits when choosing a course of therapy. Notable variation in the uptake of endocrine therapy after DCIS has been reported, with estimates across studies ranging from less than 20% to greater than 70% [12–oˆ20]. In addition to having ER positive (ER1) disease, other factors most consistently associated with initiation in recent studies include age and receipt of surgery and/or radiation [13–oˆ15, 17, 20]. While older women, particularly those over age 70, appear to be less likely to initiate endocrine therapy [13–oˆ15, 17, 20], women who receive BCS and radiation may be more likely to initiate than women who receive either mastectomy or BCS alone [13, 14, 16, 20]. Associations with other patient characteristics, such race, education, income, insurance type, and comorbidity index, have been either infrequently evaluated or less consistently demonstrated across studies. Furthermore, few studies have assessed whether seeing a medical oncologist following a DCIS diagnosis influences the likelihood of initiating endocrine therapy. Therefore, the purpose of this study was to evaluate characteristics associated with endocrine therapy initiation in the year following a DCIS diagnosis. We also investigated factors associated with receiving medical oncology consultation among women with DCIS.

Published Ahead of Print on April 13, 2017 as 10.1634/theoncologist.2016-0397.

Anderson, Meyer, Wheeler et al.

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Table 1. Factors associated with endocrine therapy initiation in the year after DCIS diagnosis

Total

No endocrine therapy, n (%)

Endocrine therapy, n (%)

1311

779

RR (95% CI)a

RR (95% CI)b

0.98 (0.78, 1.22)

0.96 (0.79, 1.17)

Age category

Endocrine Therapy Initiation and Medical Oncologist Utilization Among Women Diagnosed with Ductal Carcinoma in Situ.

Though randomized clinical trials have demonstrated a reduction in second breast events with endocrine therapy among women with ductal carcinoma in si...
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