Similar invasive breast cancer survival after sentinel-node or axillary dissection

By Will Boggs MD

NEW YORK (Reuters Health) - Overall survival at 10 years among women with invasive breast cancer and sentinel-node metastasis is similar regardless of whether or not they undergo more-extensive axillary dissection, according to findings from the ACOSOG Z0011 randomized trial.

“Perhaps the most surprising result was the low event rate in either arm after 5 years,” Dr. Armando E. Giuliano from Cedars-Sinai Medical Center, Los Angeles, told Reuters Health by email. “Axillary recurrence in the past was felt to be an early event. However, we anticipated that for this group of largely hormone-receptor positive tumors treated with adjuvant systemic therapy that perhaps axillary recurrences would be seen later and impact overall survival.”

Sentinel lymph node dissection (SLND) supplanted axillary lymph node dissection (ALND) as a breast cancer-staging method by the early 2000s, and initial results from ACOSOG Z0011, after a median follow-up of 6.3 years, showed that overall survival was noninferior in women randomized to SLND alone rather than ALND.

Dr. Giuliano and colleagues now report the 10-year overall survival of 856 women (446 assigned to SLND alone, 445 assigned to SLND followed by ALND) with breast cancer and 1 or 2 positive sentinel nodes. Median follow-up was 9.3 years.

More than 95% of both groups underwent adjuvant systemic therapy and radiation therapy, according to the September 12 JAMA report.

The 10-year overall survival rate was 86.3% with SLND alone and 83.6% with ALND. In multivariable analysis, group assignment was not significantly associated with overall survival. Disease-free survival at 10 years was also statistically similar for SLND alone (80.2%) versus ALND (78.2%).

“This study shows that even with long-term follow-up, the sentinel-node-positive woman can be managed successfully with sentinel-node biopsy and adjuvant breast radiation and systemic therapy,” Dr. Giuliano concluded. “Hopefully, physicians will realize that management of the axilla has changed dramatically and that axillary dissection is not necessary to improve survival for the sentinel-node-positive patient with early disease.”

Dr. Edward H. Livingston from University of Texas Southwestern Medical Center, in Dallas, and deputy editor of JAMA, who coauthored an accompanying editorial, told Reuters Health by email, “It is now clear that for women fulfilling the Z0011 criteria, axillary-node dissection should not be performed. One could even question the need for performing sentinel-node dissection - an ongoing study is asking this research question.”

“Less can be more in clinical medicine, meaning that providing fewer diagnostic tests or treatments may be just as good for patients as when very aggressive interventions are pursued,” the editorial concludes. “The same can be true for clinical research when sometimes less than perfect clinical trials can be interpreted with common sense instead of statistical purity, resulting in changed clinical practice that improves patient care.”

Dr. Melissa L. Pilewskie from Memorial Sloan-Kettering Cancer Center, New York City, told Reuters Health by email, “These findings should solidify use of (SLND) alone for women meeting ACOSOG Z0011 criteria in clinical practice. We now have robust, long-term data supporting the safety of this approach, which significantly minimizes surgical morbidity for our patients.”

“Initial critiques of the ACOSOG Z0011 study are disproved by the current report,” she said. “Here we see that the survival equivalence and low axillary recurrence rates are maintained at 10 years. In addition, we see once again that tumor biology trumps extent of surgical resection. The authors break down overall survival by hormone-receptor subtype and extent of axillary surgery - and show similar overall survival by hormone-receptor subtype regardless of axillary management, again reiterating that (SLND) alone is appropriate regardless of tumor subtype in patients meeting appropriate selection criteria.”

“As breast surgeons, we are tasked with maximizing oncologic safety while minimizing surgical risk,” Dr. Pilewskie concluded. “By continuing to perform ALND in patients with a low nodal-disease burden meeting ACOSOG Z0011 criteria, patients are being exposed to unnecessary harm. Surgeons should continue to explore avenues to safely avoid ALND to minimize the potentially life-altering side effect of lymphedema.”

Dr. Chrissy Harris from Anne Arundel Medical Center, Annapolis, Maryland, who recently investigated whether ALND is necessary after a positive ultrasound-guided lymph node biopsy, told Reuters Health by email, “It is not very often in this era of medicine that a randomized control trial (can) be performed, let alone to the scale of this trial with 10-year follow-up data. While the results of this trial have already changed the landscape of surgical breast cancer management, the consistency of the findings after 10 years of follow-up should solidify sentinel node biopsy alone as the standard of care for patients fitting within the aforementioned criteria.”

“However,” she cautioned, “it is equally important that these practices are not extrapolated to patients that do not fall within the study criteria outside of enrollment in an ongoing study.”

SOURCES: http://bit.ly/2h3FJf1 and http://bit.ly/2h2KYbg

JAMA 2017.

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