Past:
Sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) in clinically node-positive patients is a newer approach to axillary management endorsed by the National Comprehensive Cancer Network (NCCN).1 Among patients with a negative axillary clinical exam after NAC, there is no consensus on the most accurate, cost-effective approach to select those who are eligible for SLNB. MRI and ultrasound (US) are the imaging modalities most frequently used after NAC. US assessment of the axilla shows an accuracy of 62–65%2,3 in determining the pathologic status of axillary nodes after NAC, with 28% of patients potentially undergoing an unnecessary procedure if suspicious US findings are used to assign them to axillary dissection.4 The accuracy of MRI in predicting the status of the sentinel lymph nodes in clinically node-positive patients with a negative axillary clinical exam after NAC has not been studied.
Present:
This study examined the accuracy of axillary clinical exam alone vs clinical exam combined with MRI in predicting the presence of residual axillary disease in cN1 patients after NAC. We found that the addition of MRI to a negative clinical exam did not significantly improve prediction of the pathologic status of sentinel nodes after NAC, with an accuracy of 58%. In patients with a negative clinical exam, there was no difference in the frequency of positive sentinel nodes on final pathology based on whether patients had clinical exam alone (52%), a positive MRI finding (58%), or a negative MRI finding (42%)(p = 0.09). The use of abnormal findings on MRI to assign patients to axillary dissection would have resulted in 42% of patients undergoing an unnecessary procedure.
Future:
The adoption of SLNB in patients with clinically positive lymph nodes who downstage after NAC, has spared many the morbidity of an axillary dissection. However, consensus on how to best select patients who are candidates for SLNB after NAC is needed. Our findings indicate that in patients with a negative axillary clinical exam, MRI after NAC does not provide useful information for axillary management. This study taken together with those on US use in the post-NAC setting highlights the limited accuracy of both imaging modalities. If patients are assigned to axillary dissection based on suspicious imaging findings, then a large number would potentially undergo an unnecessary procedure. Perhaps a negative axillary clinical exam after NAC should be used as the gold standard to select patients who downstage for SLNB.
Footnotes
ASO Author Reflections is a brief invited commentary on the article, “Is Clinical Exam of the Axilla Sufficient to Select Node-Positive Patients Who Downstage After NAC for SLNB? A Comparison of the Accuracy of Clinical Exam vs MRI,” Ann Surg Oncol. (2019)
Disclosures: Dr. Monica Morrow has received speaking honoraria from Genomic Health and Roche.
References
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