Axillary Ultrasound versus Sentinel Lymph Node Biopsy in Invasive Breast Cancer
Vancouver, BC—In the aftermath of the Z0011 study from the American College of Surgeons Oncology Group, oncology centers across the United States are reexamining their approach to axillary management in breast cancer.
The Z0011 researchers determined that axillary lymph node dissection (ALND) is not beneficial in patients with T1 or T2 invasive breast cancer, 1 or 2 positive sentinel nodes, and breast-conserving therapy followed by whole-breast irradiation (Giuliano AE, et al. JAMA. 2011;305:569-575).
At the US & Canadian Academy of Pathology’s 2012 annual meeting, researchers from the University of Chicago Medical Center explained why, in some patients, axillary ultrasound may be useful in lieu of sentinel lymph node biopsy (SLNB) to assess the need for ALND. Axillary ultrasound with biopsy is much faster, less invasive, and less costly than SLNB.
“Based on the Z0011 results, SLNB has to be done in women with T1 or T2 invasive breast cancer to see if they have 1 or 2 positive sentinel nodes, and hence whether they require ALND,” lead investigator Rebecca Wolsky, MD, a pathology resident in the Department of Pathology, University of Chicago Medical Center, told Value-Based Cancer Care. “But we feel that for patients who don’t fall under Z0011’s inclusion criteria—for example, patients who are at stage T3 disease or those who will get a mastectomy—axillary ultrasound can be used before SLNB to check whether any nodes are positive.”
To determine the accuracy of axillary ultrasound and what tumor characteristics affect the accuracy, Dr Wolsky and colleagues reviewed the surgical pathology reports and slides from 461 consecutive cases of breast cancer in the University of Chicago patient archives.
They found 67 cases in which there was a negative axillary ultrasound, and yet SLNB revealed metastatic carcinoma. An average of 3 sentinel nodes were removed during an SLNB in these cases. The team also found that a lower number of positive SLNBs after negative axillary ultrasound corresponds to a lower axillary-tumor burden.
The predictive rates for axillary ultrasound were 60% true-negative (ie, the SLNB was also negative), 14% false-negative, 14% false-positive, and 12% true-positive. The team found that false-negative axillary ultrasounds are more likely with larger primary tumors and multifocal cancer.
“This makes sense, because these features are classically predictive of nodal involvement and, when present, should increase concern for nodal disease, despite a negative ultrasound,” said Dr Wolsky. She added that an increasing number of positive nodes are linked to true-positive axillary ultrasound.
“The feedback that I got from speaking to folks from other institutions is that some are already implementing the recommendations based on Z0011, but many are not. So, many hospitals do not need to fit ultrasound into the new Z0011 paradigm, and they continue to use ultrasound on the majority of patients,” noted Dr Wolsky.
She hopes to continue the work by teaming up with radiologists to determine how to increase the accuracy of axillary ultrasound, and hence perhaps to allow SLNB to be skipped in more cases.