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4.4 Pathology Reporting for Breast Cancer

Updated October 2015

4.4.1 Hormone Receptor Levels and HER2 Testing

The estrogen receptor status of breast carcinoma can be determined by immunocytochemical staining of tissue specimens or of aspirates. When possible it is preferable to submit the specimens unfixed immediately to the pathologist who can select the most appropriate technique for handling each individual specimen. Progesterone receptors are also indicated as they may provide evidence of a potentially hormone sensitive tumour.

Immunocytochemical staining is the standard technique to test for estrogen receptors. It can be performed on fresh tissue, frozen tissue, core biopsies scrapings obtained from the surface of small lesions or frozen sections, and on aspirates with reliable results. Staining may also be performed on fixed tissue blocks, but the results may not be as accurate depending upon the fixative used and on delay in fixation of the specimen. In addition, estrogen receptor staining may be a useful technique in evaluating metastases in patients with unknown primaries in whom the possibility of metastatic breast carcinoma is in the differential diagnosis. For further information consult your hospital pathologist or regional pathologist as several hospitals, including BC Cancer, provide estrogen receptor staining.

HER2/neu (cerbB2) (human epidermal growth factor receptor 2) is an oncogene which is over-expressed in approximately 20% of breast cancers. Testing is done on the primary tumour and/or the recurrent tumour. HER2 overexpression is associated with a poor prognosis, possibly differences in response to different cytotoxics and is a predictor for responsiveness to Herceptin® (trastuzumab).

Accurate and reliable identification of HER2 overexpression is necessary. The DAKO 04B5 is the choice initial IHC screen. For 2+ tests, FISH testing is of value to identify true HER2 positive over-expression which may benefit from Herceptin® therapy and may be of greater predictive value than the IHC testing.

4.4.2 Pathologic Handling of Surgical Specimens

All specimens should be measured and margins inked. Ideally, all wire-guided biopsies and wide excisions short of complete mastectomy should be processed in entirety.

Where the specimen is very large, acceptable alternative methods of sampling and blocking can be found in guidelines from the Royal College of Pathologists.

The pathologist should mark the margins of the specimen with silver nitrate or India ink and, if this has not already been done, send a portion of tumour for receptor studies. Label all blocks separately and designate each block as to site in the gross description (e.g. Block A = Nipple; B-E = Tumour; F = deep margin etc.). Blocks from wire-guided biopsies and wide excisions should be taken sequentially so the size of the tumour can be assessed by calculating the number of blocks involved multiplied by the block thickness.

Margin status: State how the block is taken in relation to the margin. Usually blocks are taken perpendicular to the margin but if taken "en face" this must be recorded in the dictation or on a specimen diagram.

Submit all lymph nodes and state the number included in each cassette. In general the entire node should be processed.

Sentinel nodes should be handled as in the separate SLN biopsy protocol

Frozen sections should be avoided if possible as it results in distortion of the tissue and may complicate definitive diagnosis - especially on lesions, which measure <1cm. in diameter.  Frozen section may be considered if the Surgeon is proceeding directly to further definitive surgery after excisional biopsy.

4.4.3 Breast Cancer Surgical Pathology Reporting

In order to assist with optimal management of patients with breast cancer, the oncologists in British Columbia have requested the following information to be included in pathology reports. For the convenience of the reporting pathologist, the required information is presented in the form of a checklist. This information may be incorporated in the standard report format or may be listed in the form of a synoptic report.

SOURCE: 4.4 Pathology Reporting for Breast Cancer ( )
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