How to Understand Your Breast Cancer Pathology Report

Author: Wang Siyuan, Peking University People's Hospital. Understanding the breast cancer pathology report is key for treatment planning, providing clarity for patients and families. The pathology report is the "gold standard" for diagnosing breast cancer, and it is directly related to the selection of treatment plans and patient prognosis. This seemingly complex report encapsulates the comprehensive assessment of the patient's condition by a multidisciplinary team and serves as the foundation for formulating personalized treatment plans. Upon receiving a breast cancer pathology report, the abundance of English abbreviations and specialized terminology often leaves patients and their families confused, and they may even feel anxious due to their inability to understand it. In fact, the pathology report acts as a "compass" for breast cancer treatment; by grasping the key indicators, one can gain a clear understanding of the condition. Today, let's take a step-by-step approach to decipher this critical report.

Firstly, the core of the pathology report is the fundamental information about the tumor, which includes its size, type, degree of differentiation, and lymph node metastasis. The size of the tumor is directly related to the staging; generally speaking, a tumor with a diameter of less than 2 centimeters is classified as early stage, and the larger it is, the later the stage. Among the pathological types, invasive ductal carcinoma is the most common, accounting for over 80%, while lobular carcinoma, mucinous carcinoma, and others are relatively rare, with slight differences in their degree of malignancy. The degree of differentiation is categorized into high, moderate, and low. Well-differentiated cancer cells are closer to normal cells, have a low degree of malignancy, and a good prognosis, while poorly differentiated cells are the opposite, with faster growth and greater invasiveness. Lymph node metastasis is an important indicator for assessing the risk of recurrence. The report stating "axillary lymph nodes 0/12" indicates that 12 lymph nodes were examined with no metastasis; the more numerous the metastases, the higher the risk of recurrence.

Secondly, there are immunohistochemical markers, which are crucial for determining treatment plans and are the most concerning part for everyone. ER stands for estrogen receptor and PR stands for progesterone receptor. If either one is positive, it is categorized as hormone receptor-positive breast cancer. Patients with this type can manage their condition post-surgery through endocrine therapy, leading to a better prognosis; the higher the positivity rate, the better the effectiveness of the endocrine treatment. HER2 refers to the human epidermal growth factor receptor 2, with results classified as negative or positive. Positive breast cancer is more aggressive and prone to recurrence and metastasis, but there are now targeted drugs available that significantly improve treatment outcomes, so it is no longer considered a "bad signal." Ki-67 is a cell proliferation index; the higher the value, the faster the cancer cells divide and the more active their growth. Generally, a rate below 14% is considered low proliferation, while above 30% requires more aggressive treatment.

Additionally, the pathology report will indicate the status of surgical margins. Negative margins signify that the surgery successfully removed all cancerous cells without any remaining, which is a sign of a successful operation. Conversely, positive margins indicate that further surgery or radiotherapy is necessary to reduce the risk of local recurrence. Many patients struggle with the diagnosis of "triple-negative breast cancer," which means that the cancer is negative for estrogen receptors (ER), progesterone receptors (PR), and HER2. While this type does not have options for targeted or endocrine therapies, it is not untreatable. Early treatment through a combination of surgery, chemotherapy, and radiotherapy can lead to a good prognosis, and for advanced stages, there are also new chemotherapy and immunotherapy options available.

Finally, I would like to remind everyone that the interpretation of pathology reports needs to be assessed in conjunction with the patient's age, overall health, and tumor staging; one should not draw conclusions based solely on a single indicator. Do not overreact with anxiety if one indicator is positive, nor should you let your guard down if the indicators appear favorable. It is crucial to communicate adequately with your attending physician and develop a personalized treatment plan based on the report, as this is the correct approach to dealing with breast cancer. Understanding these indicators is not intended for self-diagnosis, but rather to alleviate the fear of the unknown so that we can approach treatment with a more composed mindset and win this battle against cancer.