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Utilization of SLNB alone increased in early-stage breast cancer
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A greater proportion of women with early-stage breast cancer underwent sentinel lymph node biopsy without axillary node dissection since the 2010 publication of the American College of Surgeons Oncology Group Z0011 study, according to study results.
However, the utilization of sentinel lymph node biopsy (SLNB) alone has also increased among women who did not meet eligibility criteria for the study, results showed.
Katherine Yao
“The [American College of Surgeons Oncology Group Z0011] trial results have changed clinical practice for breast cancer patients nationwide,” Katharine Yao, MD, FACS, of the department of surgery at NorthShore University HealthSystem, said in a press release. “The [Z0011] trial has had a huge impact because of the lower risks for patients who undergo SLNB alone.”
The Z0011 trial showed that the addition of axillary lymph node dissection to SLNB did not improve outcomes for women with early-stage breast cancer who underwent lumpectomy. However, few studies have examined the impact of these results on patient practice, according to study background.
Yao and colleagues used the National Cancer Data Base to identify patients who did and did not meet Z0011 trial inclusion criteria who underwent SLNB alone between 1998 and 2011. Women were considered to have undergone SLNB alone with the removal of four or fewer nodes, whereas women who had 10 or more nodes removed were considered to have undergone axillary lymph node dissection. Cases that fell in between were considered indeterminate.
Of the 74,309 patients who met Z0011 eligibility criteria, 23.7% (n = 17,630) had four or fewer nodes removed, 21% (n = 15,619) had five to nine nodes removed, and 55.3% (n = 41,060) had 10 or more nodes removed.
Researchers noted utilization of SLNB alone increased from 6.1% of women who underwent a lumpectomy in 1998 to 56% in 2011, the first year after the study’s publication (P < .001).
Factors for receiving axillary lymph node dissection in addition to SLNB among women who underwent lumpectomy from 2001 to 2011 included triple-negative tumors (OR = 1.4; 95% CI, 1.16-1.66), having two or more positive sentinel nodes (OR = 1.97; 95% CI, 1.77-2.19), having macrometastases (OR = 3.25; 95% CI, 2.89-3.65) and age younger than 50 years (OR = 1.17; 95% CI, 1.04-1.3).
Researchers also observed SLNB alone was common among patients who did not meet Z0011 inclusion criteria. The use of SLNB alone increased from 1998 to 2011 among patients with tumors larger than 5 cm (14.7% to 54%; P < .001), who received accelerated partial breast irradiation or no radiation therapy (8.7% to 52.5%; P < .001), who had clinically node-positive disease (12.7% to 35.9%; P <.001), who had three positive nodes (2.3% to 12.9%; P < .001) and who underwent mastectomy (5.2% to 22.3%; P < .001).
“It is a little concerning that patients who fall outside the [Z0011] eligibility criteria are getting SLNB alone,” Yao said. “It’s controversial to perform SLNB alone in mastectomy patients because we don’t know if it affects overall outcome.”
Although the researchers observed that the results of the Z0011 have changed clinical practice, they also noted a trend toward increased usage of SLNB before the study period.
“From 1998-2002, there was an increase of the use of SLNB alone, perhaps related to the rapid adoption of SLNB to stage the axilla versus upfront [axillary lymph node dissection] over that time period,” Yao and colleagues concluded. “The Z0011 trial findings have stimulated other clinical trial concepts with SLNB alone being examined for patients with tumor-positive sentinel nodes in the neoadjuvant setting. Over time, the management of the axilla will continue to evolve and future studies may even render SLNB obsolete.” – by Cameron Kelsall
Disclosure: The researchers report no relevant financial disclosures.
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