Postsurgical Local Breast Cancer Therapies Compared in Two Large Studies


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A study presented at the 13th Annual Meeting of the American Society of Breast Surgeons suggested that accelerated partial-breast irradiation (APBI) using brachytherapy might control the tumor bed better than whole-breast irradiation (WBI), while another study suggested that radiofrequency ablation might effectively substitute for radiation therapy in some patients with breast cancer. The studies were highlighted at a press briefing during the meeting, which was held May 2–6 in Phoenix.

In a study of 1,444 patients with early breast cancer in the MammoSite Registry Trial,1 rates of local recurrence 60 months after lumpectomy were 3.5%, and only 1.1% were considered tumor-bed failures, reported Peter D. Beitsch, MD, a surgical oncologist who directs the Dallas Breast Center. Specifically, 50 patients treated who underwent accelerated partial-breast irradiation (3.5%) developed an ipsilateral tumor recurrence, 14 (1.1%) at the initial tumor site and 36 (2.6%) elsewhere in the breast. Of these recurrences, 28% were in the tumor bed and 72% occurred elsewhere.

This was not a controlled study, but Dr. Beitsch noted that in historical controls, whole-breast irradiation has been associated with recurrence rates in the tumor bed of 2% to 7.1%—about double the rates of recurrences elsewhere in the breast (1.9% to 3.8%). Proportionally, 69% of these are tumor bed recurrences and 31% recur elsewhere. This is essentially the reverse of what investigators found in the current MammoSite Registry study, Dr. Beitsch pointed out.

“These data suggest that although tumor control in the breast appears to be similar for APBI and WBI, disease control at the initial tumor site may be better with APBI,” he commented, adding, “I believe APBI improves care. My feeling is that there is something unique in its ability to control the tumor bed.”

Conflicting Results

The findings of the MammoSite Registry Trial contrast with those recently reported from investigators at The University of Texas MD Anderson Cancer Center,2 which was a larger retrospective analysis of nearly 93,000 women in a Medicare billing claims database, 7% of whom had accelerated partial-breast irradiation and 93%, mastectomy. It found accelerated partial-breast irradiation to be associated with a higher risk for complications and double the rate of subsequent mastectomy, compared with whole-breast irradiation.

Dr. Beitsch commented on the discrepant findings, noting that it is unclear why women subsequently underwent mastectomies in the MD Anderson study, and that it was not necessarily because of local recurrences.

“We radiate the breast to control undetectable cancer cells left behind around the lumpectomy cavity. Common sense would say internally targeted radiation would be the best method to kill these cells,” he suggested. “We now have strong data to support that, and we showed the complication rate is very low from this form of therapy.”

Radiofrequency Ablation Prevents Local Recurrence

In another study presented at the meeting, investigators suggested that radiofrequency ablation of the lumpectomy site may be an effective alternative to external-beam radiation therapy as a way to rid the cavity of residual disease.3 The study, one of the first published long-term studies to examine postlumpectomy outcomes, was reported by Misti H. Wilson, MD, of the University of Arkansas for Medical Sciences, Little Rock.

Radiofrequency ablation can create an additional disease-free zone around the cavity, and can extend this zone sufficiently to eliminate the need for repeat surgery to achieve clear tumor margins. Some 20% to 75% of patients required second or even third surgeries to accomplish this.

“We hypothesized that excision followed by [radiofrequency ablation] to extend the margin by 1 cm may decrease the reexcision rate and provide therapeutic benefit similar to [that of external-beam radiotherapy] at the time of the initial operation,” Dr. Wilson said.

Because of the ablation-extended margins, only patients with grossly positive margins on pathology or residual calcifications on postoperative mammography would require additional excision of the tumor bed, she explained.

The study included 73 patients with tumors ≤ 3.0 cm and clinically negative lymph nodes who underwent lumpectomy and excision followed by radiofrequency ablation without external-beam radiotherapy. Pathology reports indicated that 19 patients had close or focally positive margins, and 16 (84%) were spared reexcision after undergoing initial excision and radiofrequency ablation. Only 3 patients of 73 (4%) required a second surgery, she reported.

At a median follow-up of 55 months, there was one local recurrence in the tumor bed (1.7%) and three recurrences elsewhere. The recurrence rate for lumpectomy with radiation is 1% per year for the first 5 years, then about 0.5% thereafter, which suggests that the excision followed by radiofrequency ablation technique is as protective as radiotherapy, Dr. Wilson said.

“Without the side effects of radiation, [radiofrequency ablation] is an extremely appealing choice. The ablated tissue remains in the breast, so less breast mass is lost and post-treatment tissue shrinkage is not a problem,” she said. “The cosmetic results are excellent. Often, you can barely tell the patient has had surgery.” The study found good to excellent cosmesis in 90% of patients.

Principal investigator V. Suzanne Klimberg, MD, the Muriel Balsom Chair in Surgical Oncology at the University of Arkansas for Medical Sciences, and President of the American Society of Breast Surgeons, noted, “for patients in rural areas, radiotherapy—the standard of care following lumpectomy surgery—simply isn’t an option if a therapy center is not located nearby. Today, these patients have no choice but mastectomy.” Another advantage of excision followed by radiofrequency ablation is that patients receive complete treatment before discharge.

Based on these results, excision followed by radiofrequency ablation is being examined in the multicenter ABLATE (Radiofrequency Ablation after Breast Lumpectomy Added to Extend Intraoperative Margins) trial.  ■

Disclosure: Drs. Beitsch, Wilson, and Klimberg reported no potential conflicts of interest. The study by Wilson et al was funded by grants from angioDynamics, the Fashion Footwear Association of New York, and ZVC.

References

1. Beitsch P, Vicini F, Whitworth P, et al: Improved tumor bed control with MammoSite® accelerated partial breast irradiation. American Society of Breast Surgeons Annual Meeting. Abstract 58. Presented May 4, 2012.

2. Smith GL, Xu Y, Buchholz TA, et al: Association between treatment with brachytherapy vs whole-breast irradiation and subsequent mastectomy, complications, and survival among older women with invasive breast cancer. JAMA 307:1827-1837, 2012.

3. Wilson M, Korourian S, Boneti C, et al: Long-term results of excision followed by radiofrequency ablation as the sole local therapy for breast cancer. American Society of Breast Surgeons Annual Meeting. Abstract 136. Presented May 4, 2012.



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