For Information OnlyBreast
Tumor size is a major predictor of tumor behavior.18 The tumor should be measured in at least 2 dimensions, and the single greatest dimension of the invasive component used for determining tumor stage.6 The size of the tumor, as measured by gross examination, must be verified by microscopic examination. If there is a discrepancy between gross and microscopic tumor measurement, the microscopic measurement of the invasive component takes precedence and should be used for tumor staging. For pT1 lesions or those with an extensive in situ component, measurement of tumor size on the histologic slide is more accurate than gross measurement. For tumors with both invasive and in situ components, only the invasive component is included in the tumor measurement for pT classification and stage assignment (see Note M). When 2 or more distinct invasive tumors are present, each is separately measured and reported; they are not combined into a single larger size. Determination of tumor size may not be possible with a core or incisional biopsy.
Grossly uninvolved nodes should be submitted in their entirety for histologic examination, while representative sections of grossly positive nodes may be submitted. Small nodes may be submitted intact, but larger nodes should be sectioned for proper fixation and examination.
The pathology report should clearly state the total number of lymph nodes examined, the total number of involved nodes, and the greatest dimension of the largest metastatic focus. A single microscopic section from each lymph node block is considered sufficient for routine evaluation. The presence of extranodal tumor extension should be included in the pathology report since it may be associated with a higher frequency of axillary recurrence.
Isolated tumor cells (ITCs) are defined as single cells or small clusters of cells not larger than 0.2 mm, usually with no histologic evidence of malignant activity (eg, proliferation or stromal reaction). If morphologic techniques (any morphologic technique, including hematoxylin-eosin and immunohistochemistry) are used to detect ITCs, the regional lymph nodes should be designated as pN0(i+) or pN0(i-), as appropriate.19 If nonmorphologic (molecular) methods (eg, reverse transcriptase polymerase chain reaction [RT-PCR]) are used, the nodes are designated as pN0(mol-) or pN0(mol+), as appropriate.20
Micrometastases are defined as tumor deposits larger than 0.2 mm but not larger than 2.0 mm. Cases in which only micrometastases are detected are classified as pN1mi. While the prognosis for patients with a solitary micrometastasis has been reported to be better than those with larger metastatic deposits, the significance of multiple micrometastases in 1 node or multiple lymph nodes with metastases of that size is unknown. These are still classified as pN1mi. The number of nodes that contain micrometastases should be clearly specified in the pathology report since this may affect treatment.
The number of sections submitted varies with the size and character of the specimen, the nature of the underlying neoplastic process, and whether the surgical margins need to be assessed. If the biopsy is performed because of a mammographic abnormality, the entire mammographic lesion (not necessarily the entire specimen) should be submitted,