SAN DIEGO (EGMN) – Magnetic resonance imaging identified additional breast cancer in 11% of women with newly diagnosed disease who were otherwise eligible for partial breast irradiation, preliminary results from an ongoing study demonstrated.

Treatment of these patients with limited radiation fields would result in undertreatment of the tumor and could potentially compromise disease control, Dr. Paige L. Dorn said at the annual meeting of the American Society for Radiation Oncology.

Treatment for early-stage breast cancer with partial breast irradiation is currently under investigation in a multi-institutional, randomized controlled trial, NSABP B-39. Retrospective data from the University of Chicago Hospitals and Clinics and other institutions “have shown that MRI is able to find additional disease in 5%-10% of otherwise partial breast irradiation–eligible candidates, based on mammogram and ultrasound alone,” said Dr. Dorn of the university’s department of radiation oncology. “The purpose of this study is to evaluate the utility of MRI in detecting clinically occult foci of disease in a prospectively identified cohort of partial breast irradiation candidates uniformly undergoing MRI in addition to mammogram and ultrasound.”

Since June of 2009, all imaging and surgical pathology have been reviewed in a multidisciplinary setting by radiologists, surgeons, pathologists, and radiation oncologists at the university to determine candidacy for partial breast irradiation. In patients eligible for partial breast irradiation, Dr. Dorn and her associates prospectively documented whether MRI identified additional lesions in the same quadrant (multifocal), a different quadrant (multicentric), or the contralateral breast. They biopsied suspicious MRI findings to confirm pathology and then prospectively recorded whether MRI findings prompted a change in the eligibility for partial breast irradiation according to the entry criteria outlined in NSABP B-39. Prospectively collected data was verified by retrospective evaluation of all patient records.

Of 486 patients screened by the researchers between June 2009 and October 2010, Dr. Dorn reported that 91 (18.7%) were deemed eligible for partial breast irradiation based on mammogram, ultrasound, and pathology alone. Their median age was 56 years.

Of the 91 patients, 66 had invasive ductal or lobular carcinoma, 18 patients had ductal carcinoma in situ, and 7 had invasive lobular disease. MRI identified additional disease in 10 patients. Multifocal disease was seen in 9 of these patients, while contralateral disease was confirmed in 1.

The researchers also found that MRI was more likely to identify occult disease in patients younger than age 50, in those who were premenopausal, and in those who had tumor sizes of 2 cm or greater.

Dr. Dorn said the study had certain limitations, including the fact that the potential impact of MRI on disease outcomes after partial breast irradiation remains unknown. “Whether these multifocal lesions would have been surgically excised is unknown,” she added.

Based on the results of this and other studies, she concluded that MRI “should be increasingly considered as part of the work-up for partial breast irradiation candidates. MRI may help refine criteria for patient selection, especially in those with higher-risk features. We plan to continue this prospective study to further define the role of MRI in this population.”

Dr. Dorn said she had no relevant financial conflicts.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

圣地亚哥(EGMN)——根据一项正在进行的研究初步结果，核磁共振成像(MRI)能为11%新诊断出乳腺癌、适合进行部分乳腺照射治疗的患者提供额外帮助。研究者表示，如果这些患者接受的辐射治疗不充分的话，将使这些肿瘤患者疏于治疗，从而影响疾病治疗。

 

目前多中心开展合作的NSABP(美国国家乳腺和肠道外科辅助治疗项目)B-39试验正在通过随机对照方法调查乳腺癌早期患者经过部分乳腺照射治疗后的效果，旨在评估前瞻性队列研究中，除了乳房X线照射和超声外，接受MRI检测的乳腺癌患者被检测出隐秘病灶的情况。相关的回顾性数据“已经表明MRI能够仅通过乳房X线照射和超声结果来找到5%~10%通过部分乳腺照射患者的其他疾病情况”。

 

自2009年6月以来，芝加哥大学由放射学、外科、病理学和放射肿瘤学专家组成的多中心研究小组对患者所有影像和手术病理资料进行了审查，并通过MRI结果来证实病理学结论，从而前瞻性地证实MRI的结果是否能引起NSABP B-39规定的部分乳腺照射治疗患者治疗策略策略的改变。

 

研究者对2009年6月～2010年10月间招募到的486例患者进行的筛选，发现通过乳房X线照射、超声检查以及病理学检验，能确定91例(18.7%)适合进行部分乳腺照射。他们平均年龄56岁。91例患者中，66例有浸润性导管癌或小叶癌，18例患有原位导管癌，7例患有浸润性小叶疾病。MRI可以帮助鉴定出10例患者的其他疾病。其中，9例患者确定了多病灶性疾病，而1例确定了对侧疾病。研究者同时还发现，MRI似乎更容易鉴定出年龄在50岁以下、绝经前患者的隐蔽疾病，其肿瘤通常在2 cm以上。

 

该研究受到一定因素的制约，包括MRI对部分乳腺照射的潜在影响和这些多发性病灶切除是否可以进行手术切除仍然未知。

 

基于此研究和其他研究结果，研究者作出以下结论：MRI应该被人们越来越多地考虑用来确定出适合部分乳腺照射治疗的候选人；MRI同时还可以帮助改进乳腺癌患者的确定标准，特别是存在高风险的乳腺癌患者。

 

研究者表示无经济利益冲突。

 

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