Why do we need to send pathology reports after surgery? How to read breast pathology reports? 6 exclusive interpretation secrets, recommended to save

Why do we need to send the surgery to pathology?

In simple terms: sending the tumor for pathology examination is to determine whether it is benign or malignant, and to guide subsequent treatment.

1 Pathological diagnosis can be used for accurate diagnosis and is the gold standard for diagnosis

Taking breast patients as an example, some friends who suffer from breast nodules can use a variety of examination methods in clinical practice, such as breast ultrasound and mammography, to basically preliminarily infer the benign or malignant nature from a clinical perspective. Clinicians can use these examinations to determine whether you can be followed up or should undergo surgery.

However, in some cases, it is difficult to distinguish. For example, some breast malignant lesions, such as solid papillary carcinoma in situ and encapsulated papillary carcinoma, cannot be judged as benign or malignant by preoperative imaging examinations because of their clear boundaries. Some benign lesions, such as sclerosing adenosis of the breast and fibromatosis of the breast, are likely to be suspected of malignant lesions during preoperative examinations because of their unclear boundaries. In addition, intraductal papillary tumors may also be accompanied by atypical hyperplasia and carcinoma in situ. In this case, imaging is even more helpless. Therefore, in the face of these situations, postoperative pathology is required to provide accurate answers [2].

2 Pathological diagnosis can guide the next treatment plan, especially for breast cancer

Accurate pathological diagnosis is the basis for accurate treatment. If the postoperative pathological report shows a benign lesion , the patient can breathe a sigh of relief and just need to maintain healthy living habits and have annual physical examinations in the future. If it is a malignant lesion , the clinician will determine the patient's specific treatment plan based on the pathological type and immunohistochemistry results, such as hormone therapy, targeted therapy, immunotherapy, chemotherapy, or radiotherapy.

If necessary, the patient will be asked to undergo further genetic testing (which is also part of the pathology department's testing) to check for familial genetic mutations, new targetable gene mutations, drug-resistant gene changes, or to predict the risk of recurrence, so as to further adjust the treatment plan [3].

What should we look for in breast pathology?

Taking invasive breast cancer as an example, the contents of the pathology report include the pathological tissue type of the disease, the degree of tissue differentiation, the size of the lesion, the presence of vascular tumor thrombus and nerve invasion; whether the lesion involves the nipple and skin tissue, the resection margin, and lymph node metastasis.

This is a tissue morphology report. In addition, the report also includes the tumor's hormone expression, HER2 expression, and tumor proliferation. If the HER2 expression is judged to be 2+, the patient needs to undergo further FISH testing[4]. For patients with familial clustering, clinicians generally recommend BRCA gene testing.

How to read a breast pathology report?

The breast pathology report is densely written. I can recognize each word individually, but when they are put together, I have no idea what they are talking about? o(╥﹏╥)o

Don’t worry, save these 6 “ exclusive interpretation secrets ” and you can also easily interpret them!

1 Invasive breast cancer (unifocal)

Experts’ key points

First of all, it can be determined that this is a cancer . "Differentiation" refers to the degree of similarity to normal tissue. The higher the differentiation, the better, and the lower the differentiation, the worse.

Lymph node metastasis, 1/14, means that 1 out of 14 lymph nodes has metastatic cancer. Macrometastasis is metastatic cancer larger than 2mm.

In the immunohistochemistry results, ER and PR represent the expression of estrogen and progesterone receptors, respectively. (Strong positive, 90%) means that 90 cells out of every 100 cells have strong expression.

HER2 is human epidermal growth factor receptor-2, which is closely related to the occurrence and development of breast cancer. At present, the interpretation is divided into several levels, including 0, 1+, 2+, and 3+. HER2 expression (0, 1+) ​​is a negative result and is usually regarded as a good prognostic indicator. HER2 (2+) requires FISH to further verify whether targeted drugs are used.

FISH testing uses fluorescent groups to label DNA probes, then hybridizes the labeled DNA probes with sample DNA in situ, and finally counts the fluorescent signals under a fluorescence microscope as a basis for diagnosis.

Here we need to remind everyone that patients with 0, 1+ and 2+ but FISH-negative are not suitable for anti-HER2 treatment represented by trastuzumab and pertuzumab, while patients with 2+ but FISH-positive and 3+ can be treated with anti-HER2 treatment represented by trastuzumab and pertuzumab. Now with the emergence of drugs for low HER2 expression, some people who could not be treated with trastuzumab and pertuzumab before can be treated with new targeted drugs [5].

Ki-67 (index 15%) represents a proliferation index of 15%, which means that about 15 cells out of every 100 cells are in a proliferative state. **The higher the proliferation index, the faster the tumor grows, which is an indicator of a poor prognosis. **However, since chemotherapy drugs generally target cancer cells in a proliferative state, a higher Ki-67 index means a higher sensitivity to chemotherapy drugs. Other immunohistochemical indicators are markers for differential diagnosis and will not be described here.

2 Invasive breast carcinoma (multifocal)

Experts’ key points

This patient had two foci of invasive cancer, one was a mixed carcinoma of invasive micropapillary carcinoma and mucinous carcinoma, and the other was pure invasive micropapillary carcinoma. The sizes of the two foci were reported separately.

Intermediate-grade nuclear grade ductal carcinoma, also known as ductal carcinoma in situ, can be seen around invasive carcinoma. Ductal carcinoma in situ is a precursor lesion of invasive carcinoma.

When invasive cancer is multifocal, the hormone level, HER2 and proliferation index Ki-67 expression of each cancer foci need to be tested separately. Sometimes the expression of different cancer foci is different, and a comprehensive evaluation is needed to formulate a treatment plan.

In this case, the ER and PR expressions of both lesions were negative, and the HER2 expression was 3+, so targeted therapy drugs can be used directly.

When invasive cancer and carcinoma in situ coexist, if the hormone expression of the invasive cancer is all negative, it is also necessary to evaluate the hormone expression of the surrounding carcinoma in situ, because if the hormone expression of the carcinoma in situ is positive, hormone replacement therapy can still be used.

3 Microinvasive breast cancer

Experts’ key points

This is a case of carcinoma in situ, accompanied by small foci of invasive carcinoma. When the breast tumor is mainly carcinoma in situ and there is no clear invasive carcinoma, the pathologist needs to take samples of all the carcinoma in situ and carefully look for the possibility of invasive carcinoma. **Invasive carcinoma ≤1 mm is called microinvasive carcinoma. **If you are lucky enough and the invasive carcinoma has not been completely removed in immunohistochemistry, the hormone expression, HER2 and Ki-67 expression of the carcinoma in situ and invasive carcinoma will be reported separately, so that clinical physicians can formulate precise treatment plans. But 1 mm is very small and is often completely removed in immunohistochemistry testing. At this time, the report will state that "the tissue is too small and cannot be evaluated by immunohistochemistry."

4 Intraductal papilloma, ductal epithelial hyperplasia, metaplasia

Experts’ key points

These are all benign breast lesions. ER/PR is expressed in varying degrees under normal circumstances. Fibroadenoma and adenosis are the most common breast lesions. It is worth mentioning that adenosis, which is usually considered to be very common, sometimes forms lumps and is removed as a tumor.

5 Atypical hyperplasia

Experts’ key points

Atypical hyperplasia is a precancerous lesion of the breast. If atypical hyperplasia is found, regular follow-up is required. This is a special case of atypical hyperplasia, which requires further examination of the PTEN gene mutation. If this kind of supplementary report is found, it is mostly when the test is sent, and no malignant or precancerous lesions are expected, and no prepayment is made. At this time, the pathologist will issue you a report recommending immunohistochemistry and prescribe immunohistochemistry instructions. After payment, immunohistochemistry will be automatically performed, and you can wait for the results on your mobile phone at home without having to go back to the hospital for inquiries.

6 Malignant phyllodes tumor

Experts’ key points

This is a case of malignant phyllodes tumor. Breast tumors are divided into epithelial tumors (most commonly hyperplasia, tumors or cancers, etc.), fibroepithelial tumors, mesenchymal tumors and lymphohematopoietic system tumors. Among them, fibroepithelial tumors are the most common type of tumor besides epithelial tumors, including benign phyllodes tumors, borderline phyllodes tumors and malignant phyllodes tumors. Borderline phyllodes tumors have a higher risk of recurrence, while malignant phyllodes tumors can metastasize to distant sites and endanger life.

Mesenchymal malignant tumors of the breast are relatively rare, and are usually named with "malignant" or "sarcoma" at the end. If it is a lymphohematopoietic tumor, it is usually named "XX lymphoma". If it is a lymphohematopoietic system tumor, your first choice is not surgery, but to go to the hematology department for further diagnosis and treatment.

The above are some common interpretations of breast pathology reports. I hope they will help you understand.

Finally, I wish everyone to maintain good living habits and a positive and optimistic attitude, have regular physical examinations, face up to the disease status, strive for early diagnosis and treatment, and cooperate with regular treatment, which is the best way to deal with malignant tumors.

【References】

1.Xia C, Dong X, Li H,et al.Cancer statistics in China and United States, 2022: profiles, trends, and determinants[J]. Chin Med J (Engl). 2022 Feb 9;135(5):584-590.

2.Breast Cancer WHO Classification of Tumors[M].5th Edition, Volume 2, 2019.

3. NCCN Clinical Practice Guidelines (Fourth Edition). www.nccn.org/patients

4. Yang Wentao, Bu Hong. Guidelines for HER-2 detection in breast cancer (2019 edition)[J]. Chinese Journal of Pathology, 2019, 48(3):169-175.

5. Modi S, Jacot W, Yamashita T, et al. Trastuzumab Deruxtecan in Previously Treated HER2-Low Advanced Breast Cancer[J]. N Engl J Med. 2022,387(1):9-20.

▌The popular science theme of this article comes from the article "Correlation between CD117 and DOG1 expression levels and clinical pathological characteristics and prognosis in patients with triple-negative breast cancer" in the 3rd issue of "Journal of Peking Union Medical College" in 2024

Original author: Wang Yajuan, Wang Yuan, Ren Xinyu

Editor: Liu Yang and Zhao Na

Proofread by Li Na and Li Yule

Producer: Peng Bin

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