AT THE ACS CLINICAL CONGRESS

SAN FRANCISCO (FRONTLINE MEDICAL NEWS)Recent research and guidelines have changed how surgeons should be thinking about some aspects of treating breast cancer, a panel of experts said in a press briefing at the annual clinical congress of the American College of Surgeons.

New guidelines on surgical margins, data supporting radiation rather than complete lymphadenectomy for patients with positive sentinel nodes, and other studies supporting targeted radiation therapy instead of whole-breast irradiation after lumpectomy should be on a surgeons’s radar, the speakers said.

The first U.S. guidelines on surgical margins for lumpectomy in women with breast cancer who are planning to undergo whole-breast radiation therapy adopted a standard of “no ink on tumor,” meaning no cancer at the edge of the tissue that was removed, Dr. Richard J. Gray said. The 2014 joint guidelines from the Society of Surgical Oncology and the American Society of Radiation Oncology based the recommendations on a meta-analysis of studies that found no advantage to wider excision margins for preventing in-breast recurrence ( Ann. Surg. Oncol. 2014;21:717-730 ).

Previously, many surgeons sought to take 1, 2, or 3 mm of normal tissue around the cancer removed to reduce the risk of recurrence, he said.

“This guideline will become the standard throughout the United States. The evidence on which this is based is reasonable, but it will be important for individual institutions and national databases to track the rates of local recurrence over time as these guidelines are implemented,” said Dr. Gray of the Mayo Clinic, Scottsdale, Ariz. He confessed to being “a recovering addict” to margins of 2 mm or greater.

The guidelines apply only to patients with invasive cancer undergoing breast-conserving treatment, he noted. There are no guidelines yet specifically for surgical margins in women undergoing mastectomy for breast cancer, nor for women with ductal carcinoma in situ (DCIS).

While there is no evidence that a margin width wider than “no ink on tumor” is better for women undergoing mastectomy, Dr. Gray cautioned against extrapolating the guidelines to women having mastectomies “because they will generally not undergo adjuvant radiation therapy,” he said.

For women with DCIS, the available evidence suggests that a minimum 2-mm margin of excision is reasonable for those undergoing lumpectomy or at least negative margins (no ink on tumor) for those undergoing mastectomy, Dr. Gray said. Wider margins may help select patients with DCIS who undergo lumpectomy to avoid adjuvant radiation therapy, he added.

A separate recent study should change the way surgeons approach decisions about axillary surgery in patients with breast cancer, Dr. Roshni Rao said. She reported on a study that randomized women who had cancer in sentinel lymph nodes after mastectomy to further treatment by removing the rest of the lymph nodes under the arm, as is common practice, or to radiation of the lymph nodes area.

Rates of cancer recurrence did not differ between groups but the radiation approach significantly reduced the risk of lymphedema and other morbidity, said Dr. Rao of the University of Texas Southwestern Medical Center, Dallas.

“Going forward, we’re going to be performing less and less axillary lymph node dissections,” she said.

Also on the topic of radiation therapy, two recent studies of targeted breast irradiation rather than whole-breast radiotherapy suggest that the targeted approach may be beneficial, Dr. Courtney A. Vito said. Whole-breast radiation after lumpectomy reduces the risk of local recurrence by 50%, previous studies have shown, but it comes with potential side effects including burns, lymphedema, and damage to underlying structures like the heart and lungs. Patients who don’t live near specialized radiation centers may not be able to access the daily month-long treatments.

A randomized Italian trial of 1,305 patients found similar rates of overall survival or breast cancer–specific survival in patients treated with whole-breast radiation therapy or with intraoperative radiation therapy, in which a single, more intense dose of radiation is directed just at the site of lumpectomy during surgery. Survival rates were similar between groups but the rate of local recurrence after 5 years was 10 times higher in the intraoperative radiation group (4.4%), compared with the whole-breast radiation group (0.4%) ( Lancet Oncol. 2013;14:1269-77 ).

Subset analyses showed, however, that most of the recurrences were in women who would not be considered ideal candidates for intraoperative radiotherapy in the United States because they had tumors larger than 2 cm, four or more positive lymph nodes, estrogen receptor–negative tumors, or other aggressive tumor biology, said Dr. Vito of the City of Hope National Medical Center, Duarte, Calif. Recurrence rates were more favorable in patients with lower-risk tumors.

“When you take out the high-risk group, the data actually look a lot better,” she said.

A separate randomized British trial of intraoperative radiation therapy produced similar overall results in 1,721 patients, but two-thirds of patients would be considered unsuitable or cautionary in the United States, Dr. Vito said ( Lancet 2014;383:603-613 ).

Overall survival and breast cancer survival were similar in the intraoperative and whole-breast radiation groups except for worse outcomes in patients who had intraoperative radiation done as a second surgery after the operation to perform lumpectomy.

The rate of deaths from causes other than breast cancer was higher in the whole-breast radiation group, in many cases due to cardiac events, Dr. Vito noted. Whole-breast radiation on the left side of the chest has been shown to accelerate atherosclerosis of the vessels in the heart, and it may be that avoiding this through intraoperative targeted radiotherapy may provide a cardiovascular benefit, though this is yet to be proven, she added.

A separate presentation at the meeting explored the increasing rate of women with cancer in one breast who choose prophylactic mastectomy of the healthy contralateral breast. The rate of prophylactic contralateral mastectomy increased 150% between 1998 and 2003 in the United States, from 1.8% to 4.5%, Dr. Swati Kulkarni said.

She and her associates surveyed a diverse cohort of 150 women before surgery for cancer in one breast and again 6 months after surgery. Only 14% said that medical staff had provided information about removing the healthy breast along with the cancerous breast; 63% said they did not get that information, and 23% were unsure, reported Dr. Kulkarni of the University of Chicago.

Thirty-nine percent of patients had thought about their surgical choices before they were diagnosed with breast cancer, and 58% of the cohort wanted or considered contralateral prophylactic mastectomy.

Patients with a family history of breast cancer who had undergone genetic testing were significantly more likely to want or consider prophylactic contralateral mastectomy. Factors that were not significantly associated with prophylactic contralateral mastectomy were family history by itself, age, race, insurance status, cancer stage, use of breast MRI, or having one or more biopsies.

The findings suggest that education about prophylactic mastectomy is needed “inside and outside of the doctor’s office,” Dr. Kulkarni said.

The speakers reported having no financial disclosures.

sboschert@frontlinemedcom.com

On Twitter @sherryboschert

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