Impact of Radiation Therapy on Breast Conservation in DCIS

Study Overview
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Brief Summary
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Large regional variation exists in the use of radiotherapy after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS). Although patients who do not receive initial radiotherapy for DCIS are candidates for subsequent BCS if they experience a second breast event, many undergo mastectomy instead.

Detailed Description
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Patients and their physicians are often confronted with a decision between more intensive versus less intensive treatment for a particular diagnosis. Quality decision-making between these options requires careful balancing of the risks and side-effects, as well as weighing the expected outcomes and their associated value as assessed by the patient. Although the incidence of DCIS has risen dramatically (1), there exists considerable debate about optimal treatment. In general, people with DCIS have high rates of recurrence-free survival. Intensive therapies for DCIS such as mastectomy (removal of the breast) or radiation therapy following BCS reduce the likelihood of a second breast diagnosis,(2-5) but have not been shown to improve survival.(6) In addition, radiation usually necessitates mastectomy should a new cancer or DCIS develop in the same breast at any point during the patient's lifetime. Patients also have a small chance of experiencing long-term toxicity. Previous radiation can also complicate reconstructive options following mastectomy. The tradeoff between risk of second breast diagnosis and side-effects and potential consequences of radiation therapy underscores the need for patient preference-driven decision making. Patients who receive BCS alone without radiation therapy may be candidates for repeat BCS if they have a second breast event in the same breast. One study suggests that some women choose not to have radiation after DCIS because they want to preserve a breast-preservation option should a second breast diagnosis occur.(7) However, the likelihood of mastectomy versus BCS at time of new diagnosis in a previously un-irradiated breast is variable.(8-10) Whether a woman receives repeat breast-conserving surgery for a new diagnosis may not only be a function of the stage of diagnosis, but may be also determined by the regional treatment patterns used for management of DCIS. We sought to study whether regional intensity of radiation use for DCIS treatment increases the likelihood of mastectomy at time of second breast event, among women who have not received radiation therapy at initial DCIS diagnosis. (Punglia RS, Cronin AM, Uno H, et al. Association of Regional Intensity of Ductal Carcinoma In Situ Treatment With Likelihood of Breast Preservation. JAMA Oncol. Published online July 21, 2016.)

Official Title
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Impact of Radiation Therapy on Breast Conservation in DCIS

Conditions
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DCIS

Participation Criteria
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Eligibility Criteria
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This study used data from SEER and SEER-Medicare.

Ages Eligible for Study
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Minimum Age: 21 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Surveillance, Epidemiology, and End Results (SEER) Database<br>Data were obtained for women in Surveillance, Epidemiology, and End Results (SEER) with a diagnosis of ductal carcinoma in situ (DCIS) between 1990 and 2011 who had not undergone radiotherapy for DCIS and experienced a subsequent breast cancer or DCIS diagnosis. | |
| Surveillance, Epidemiology, and End Results (SEER)-Medicare<br>Data were obtained for women in Surveillance, Epidemiology, and End Results (SEER)-Medicare with a ductal carcinoma in situ (DCIS) diagnosis between 1991 and 2009 who had not undergone radiotherapy for DCIS and experienced a subsequent breast cancer or DCIS diagnosis. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Association Between Patient Characteristics and Three-Level Cluster of Treatment Intensity for Primary DCIS | The investigators defined treatment intensity in a health services area to be the proportion of patients undergoing breast conserving surgery for DCIS who receive radiation therapy. Because a proportion is challenging to analyze statistically given that the precision of the estimate depends on the size of the denominator which varies across service areas, we used hierarchical modeling to categorize the health service areas into three categories (low, medium, high), using a latent variable to determine which health service area belongs to each of the three categories. The cutoffs separating the groups were based on the hierarchical model, taking the precision of the estimated proportion of patients receiving radiation into account. Health service areas with the highest proportions of patients receiving radiation were assigned to the high cluster; those with the lowest proportions to the low cluster; and those in the between to the medium cluster. | 20 Years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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DCIS, PCORI, ductal carcinoma in situ, radiation, oncology, patient-centered, decision aid, decision-making