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Special populations: Patients with DCIS
Breast-conserving therapy (which includes lumpectomy and radiation treatment) increases survival rates for patients who have DCIS. But what amount of extra tissue outside the tumor should be removed to minimize breast cancer recurrence? (10/4/16)
Determining the extra amount of breast tissue surgeons should remove during breast-conserving therapy (lumpectomy and radiation) for patients with ductal carcinoma in situ (DCIS, also known as stage 0 breast cancer) to minimize cancer recurrence in the same breast.
If surgeons don’t remove enough breast tissue during surgery, breast cancer may return, requiring another surgery. Additional surgery may result in more discomfort for the patient, surgical complications, additional stress, and increased healthcare costs.
The results of this study were used by professional societies to develop margin width guidelines for breast-conserving surgery. The 2-millimeter margin width recommendation was approved by the Society of Surgical Oncology (SSO) Executive Council, the American Society for Radiation Oncology (ASTRO) Board of Directors, and the American Society of Clinical Oncology (ASCO) Board of Directors, and endorsed by the Board of Directors of the American Society of Breast Surgeons. This guideline was developed to assist patients, along with their healthcare providers, in determining the best treatment for them. While the study has some limitations, because no clinical trials are planned to address this question, this is currently “the best available evidence for clinical decision making” regarding margin width and breast cancer recurrence.
Oncology Nursing News
During breast-conserving therapy, a surgeon removes a patient’s breast tumor and an area of surrounding tissue (called a margin) that does not include the breast tumor. Studies have found that breast-conserving therapy (lumpectomy followed by radiation therapy) improves long-term survival rates for women with DCIS (ductal carcinoma in situ, also known as stage 0 breast cancer). However, the optimal margin width to minimize the risk of breast cancer recurrence is unknown.
Monica Morrow and her colleagues from Memorial Sloan Kettering Cancer Center and other institutions published work in the June 2016 issue of Practical Radiation Oncology that examined the optimal margin width to minimize breast cancer recurrence for patients with DCIS.
What surgical margin width minimizes the risk of cancer recurrence in the same breast in DCIS patients who have breast-conserving surgery?
This research study was a meta-analysis, meaning the researchers pooled data from a number of previously published studies. The researchers only used studies with at least 50 patients with DCIS. The studies in this meta-analysis were all retrospective, meaning the researchers used patient data that other researchers collected in past studies. In total, 20 studies with a total of 7,883 patients (865 with breast cancer recurrence in the same breast) were used.
Removal of an additional 2 millimeters of breast tissue beyond the DCIS tumor (2-mm margin width) during lumpectomy and followed by radiation (breast conserving therapy) is associated with lower rates of breast cancer recurrence in the same breast.
No evidence suggests that removing more than 2 millimeters of breast tissue reduces breast cancer recurrence more for DCIS patients who receive breast-conserving therapy.
When no additional tissue beyond the tumor is removed during breast-conserving therapy, DCIS patients have a significantly increased risk of breast cancer recurrence in the same breast.
Surgical tumor removal without whole breast radiation is associated with higher rates of recurrence in the same breast, compared to DCIS patients who undergo both treatments, regardless of margin width. The researchers say that although there is not enough evidence to determine the optimal margin width for treatment with surgery alone, it should be at least 2 millimeters.
A randomized clinical trial (researchers design the study and randomize patients into groups that receive different treatments) would provide the strongest evidence. Because this study is a meta-analysis consisting of many retrospective studies (meaning the researchers used data that other researchers collected in past studies) and does not include any randomized clinical trials, the evidence isn’t as strong. Additionally, it only applies to patients with DCIS, and should not be applied to patients who have invasive cancer. Finally, the study did not consider whether or not the women had mutations in BRCA or other genes associated with increased cancer risk.
The results of this study suggest that a 2-millimeter margin width for DCIS patients undergoing breast-conserving therapy (lumpectomy and whole breast irradiation) reduces risk of breast cancer recurrence in the same breast. While the study has some limitations, it still provides good evidence that has been approved and endorsed by many organizations. A new margin width guideline for breast-conserving therapy has been developed on the basis of this finding. Patients should discuss margin widths with their healthcare providers to determine what the best treatment options are for them.
It is important to note that women with mutations in BRCA or other genes that increase breast cancer risk have a greater chance of developing a second cancer in the same or opposite breast. Women who are diagnosed with DCIS before age 50 meet national guidelines for genetic counseling and testing, and may want to discuss this with their healthcare providers before making decisions about surgery.
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Morrow M, Van Zee KJ, Solin LJ, et al. “Society of Surgical Oncology—American Society for Radiation Oncology—American Society of Clinical Oncology Consensus Guideline on Margins for Breast-Conserving Surgery With Whole-Breast Irradiation in Ductal Carcinoma in Situ.” Practical Radiation Oncology. 2016, 6(5): 287-295.
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