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Completion axillary dissection may not be required after positive sentinel node biopsy

Tuesday, December 18 2007 | Comments
Evidence Grade 0 What's This?
Although completion axillary dissection following a positive sentinel biopsy is helpful in prognosis and treatment planning, it may not be required in patients with small tumors and in the absence of lymphovascular invasion, according to data from the NSABP B-32 study.

The researchers explained that a positive sentinel node biopsy is generally followed by a completion axillary dissection but added that most clinically node negative patients have a low risk for positive nonsentinel axillary nodes. In this study, they evaluated factors affecting the positive nonsentinel node rate and the need for an axillary dissection following a positive sentinel node biopsy.

A total of 5,611 patients entered into the protocol and were assigned to sentinel node resection with immediate conventional axillary dissection (group 1) or to sentinel node resection without an axillary dissection (group 2). Patients in group 2 who had positive sentinel nodes underwent axillary dissection.

A total of 1,361 patients with positive sentinel nodes underwent axillary dissection, but only data from 1,166 patients (595 from group 1 and 571 from group 2) were available for multivariate analysis.

According to multivariate analysis, a significantly higher percentage of group 2 patients had positive nonsentinel nodes as compared with group 1 (41.5% vs 35.5%; P=.032).

One of the significant predictors for positive nonsentinel nodes was clinical tumor size (P=.0010). The percentages of patients who had positive nonsentinel nodes were significantly increased by the number of positive sentinel nodes they had (P<.0001).

Another significant predictor for positive nonsentinel nodes was lymphovascular invasion (P<.0001).

Further, as the number of "hot spots" identified increased, the proportions of patients with positive nonsentinel nodes significantly decreased (P<.0047). The proportions of patients with positive nonsentinel nodes also decreased as the number of sentinel nodes removed increased (P<.0001).

Among the variables that were not significant multivariate predictors of having positive nonsentinel nodes were age at study entry, type of biopsy performed, histologic stage, HER-2 status, location of tumor, and estrogen receptor/progesterone receptor status.

Using multivariate analysis, the researchers created a predictive model. For patients in group 1, the number of positive sentinel nodes was a predictor of positive nonsentinel axillary nodes (OR, 2.01; 95% CI, 1.33-3.05). In group 2, the number of positive sentinel nodes was also a predictor of positive nonsentinel axillary nodes (OR, 2.12; 95% CI, 1.40-3.21).

Dr. Thomas Julian, the lead investigator, told VerusMed that the findings have the potential to change clinical practice.

"It helps, first of all, to potentially identify a subgroup of patients who might not require a completion axillary dissection even with a positive sentinel node, and, therefore, could decrease the morbidity that is associated with an axillary dissection," Dr. Julian told VerusMed.

He explained that completion axillary dissection may be avoided in patients in whom combinations of low probability variables exist. "That would include patients who had a small tumor, who had no lymphovascular invasion, and where you identified a number of sentinel nodes (≥5) but only one was positive," Dr. Julian told VerusMed. (Abstract 51.)

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