Local Therapy of Breast Cancer in Community Populations

描述（由申请人提供）：早期乳腺癌治疗的指南和共识声明指出：(a)保乳术提供与乳房切除术相当的生存率，(b)接受保乳手术（BCS）的患者也应接受放射治疗。这些陈述基于临床试验数据；然而，只有2.5%的癌症患者参加了临床试验，因此，试验结果并不总是为所有患者的治疗提供明确的指导。那些参加临床试验的患者往往比其他患者更年轻、更健康，他们通常由在癌症中心执业或与癌症中心有关联的医生照顾。此外，临床试验可能不足以评估具有特定人口统计学或临床特征的患者亚组的结果。通过仔细的设计和分析，观察性数据可以解决在随机试验中无法回答的有关治疗有效性的问题。在这项研究中，我们将使用倾向评分技术来检查生活在美国不同地区的社区妇女群体在局部治疗乳腺癌后长达10年的生存率。我们将评估所有妇女和妇女亚组的结果，如老年妇女、患有更多合并症的妇女和晚期肿瘤妇女，对这些妇女很少有临床试验数据可用于指导治疗决策。这些队列包括63750名生活在SEER地区的妇女，1991-2002年被诊断为I期或II期乳腺癌，并被纳入SEER- medicare数据库，以及3828名1993-1995年在明尼苏达州或马萨诸塞州被诊断为I期或II期乳腺癌的妇女。具体而言，我们将：

DESCRIPTION (provided by applicant): Guidelines and consensus statements for the treatment of early-stage breast cancer state that: (a) breast conservation offers survival rates equivalent to mastectomy and (b) patients undergoing breast-conserving surgery (BCS) should also receive radiation. These statements are based on clinical trial data; however, only 2.5% of cancer patients enroll in clinical trials, and therefore, findings from trials do not always provide definitive guidance for the treatment of all patients. Those who enroll in clinical trials tend to be younger and healthier than other patients and they are typically cared for by providers who practice at or are affiliated with cancer centers. Moreover, clinical trials may be underpowered to assess outcomes among subgroups of patients with certain demographic or clinical characteristics. Through careful design and analysis, observational data may address questions regarding treatment effectiveness that are not feasible to answer within the context of randomized trials. In this study, we will use propensity score techniques to examine survival for up to 10 years after local treatment of breast cancer among community-based cohorts of women living in various regions of the U.S. We will assess outcomes among all women and among subgroups of women, such as older women, women with more comorbid illness, and women with advanced tumors, for whom few clinical trial data are available to guide treatment decisions. The cohorts include 63,750 women living in a SEER region and diagnosed with stage I or II breast cancer during 1991-2002 and included in the SEER-Medicare database and 3,828 women in Minnesota or Massachusetts and diagnosed with stage I or II breast cancer during 1993-1995. Specifically, we will: 1. Assess whether long-term survival for mastectomy versus BCS with radiation is equivalent across clinically distinct groups of women with early-stage breast cancer in community populations. 2. Assess whether long-term survival is equivalent among women with early-stage breast cancer who do and do not undergo radiation therapy following BCS in community populations. 3. Assess the robustness of our estimates of treatment effectiveness obtained for Aim 1 and Aim 2 using instrumental variable techniques. By providing reliable estimates of treatment effectiveness, the proposed work will help clinicians guide treatment choices for women with early-stage breast cancer, including women for whom few clinical trial data are available, such as older women, women with more comorbid illness, or women with more advanced tumors. Moreover, the work will provide insight into different techniques for the analysis of observational data.