What terms are used to describe axillary lymph node metastases in breast cancer?

Updated: Mar 20, 2019
  • Author: Oudai Hassan, MD; Chief Editor: Chandandeep Nagi, MD  more...
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Answer

Answer

See Table 3 below. [2]

Table 3. Definitions of Terms Used to Describe Axillary Lymph Node Metastases (Open Table in a new window)

Feature

Definition

Pathologic N Stage

Isolated tumor cells (ITCs) only

Tumor cell deposit ≤0.2 mm

pN0(i+)

Positive molecular findings Positive molecular findings by reverse-transcriptase polymerase chain reaction (RT-PCR); no ITCs detected pN0 (mol+)

Micrometastasis

Tumor cell deposit >0.2 mm and ≤2 mm

pN1mi

Macrometastasis

Tumor cell deposit >2 mm

pN1

Number of positive axillary lymph nodes (LNs)

If there is one tumor cell deposit >2 mm, then all LNs with micrometastases or macrometastases are counted as positive LNs. Cancerous nodules in the axillary fat without histologic evidence of residual LN tissue are classified as regional LN metastasis.

pN1a (1-3 positive axillary LNs)

pN2a (4-9 positive axillary LNs)

pN3a (≥10 positive axillary LNs)


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