Cómo entender un informe de patología del cáncer de mama: guía paso a paso

Author: Wang Siyuan, Renmin University of Beijing Hospital

Title: How to Understand a Breast Cancer Pathology Report: A Step-by-Step Guide

The pathology report is the "gold standard" for diagnosing breast cancer and is directly related to the choice of treatment plan and patient prognosis. This report, which may seem complex at first glance, represents the comprehensive assessment of the patient's condition performed by a multidisciplinary team and forms the basis for developing a personalized treatment plan. Upon receiving a breast cancer pathology report, the abundance of abbreviations in English and technical terms often leaves patients and their families confused and even fearful due to misunderstandings. However, the pathology report serves as a "compass" in the treatment of breast cancer; by focusing on key indicators, one can clearly understand the state of the disease. Today, I invite you to learn how to interpret this crucial report step by step.

First, the most fundamental aspect of the pathology report is the basic situation of the tumor, which includes tumor size, type, grade of differentiation, and the status of lymph node metastasis. Tumor size is directly related to staging; generally, a diameter of less than 2 centimeters is considered early stage, and the larger the size, the more advanced the stage. In terms of pathological types, infiltrating ductal carcinoma is the most common type, representing over 80%, while lobular carcinoma and mucinous carcinoma are relatively less common, and different types exhibit slight variations in their malignancy grade. Differentiation is classified as high, medium, and low. Well-differentiated cancer cells resemble normal cells more, presenting lower malignancy and better prognosis, whereas poorly differentiated cells are the opposite: they grow rapidly and exhibit high aggressiveness. Metastasis in lymph nodes is an important indicator for assessing the risk of recurrence; in the report, "axillary lymph nodes 0/12" means that a total of 12 lymph nodes were examined and no metastasis was found; the more metastasis present, the greater the risk of recurrence.

Second, there are immunohistochemical indicators, which are key in determining the treatment plan and also the aspect that concerns everyone the most. ER represents estrogen receptor and PR represents progesterone receptor; if one of them is positive, it is classified as hormone receptor-positive breast cancer. Patients of this type can manage the disease postoperatively with endocrine therapies, which leads to better prognosis; the higher the positivity rate, the better the effect of endocrine treatment. HER2 is the human epidermal growth factor receptor 2, and results are divided into negative and positive; positive breast cancer is more aggressive and prone to relapse and metastasis, but today, targeted drugs have significantly improved treatment outcomes, no longer representing a "negative signal". Ki-67 is the cellular proliferation index; a higher value indicates that cancer cells are dividing faster and more actively; generally, an index below 14% is considered low proliferation, while above 30% requires more aggressive treatment.

Additionally, the pathology report will also indicate the status of surgical margins. A negative margin means that the surgery has completely removed the tissue without residual cancer cells, which is a sign of a successful operation. If the margin is positive, additional surgery or radiotherapy is required to reduce the risk of local recurrence. Many patients are concerned about "triple-negative breast cancer," which actually refers to both ER, PR, and HER2 being negative, implying that there are no opportunities for targeted or endocrine treatments. However, this does not mean that treatment options are unavailable. With a comprehensive approach that includes surgery, chemotherapy, and radiotherapy, good prognoses can be achieved, and even in advanced stages, new options for chemotherapy and immunotherapy are available.

Finally, it is important to remember that the interpretation of pathology reports must be done in conjunction with the patient's age, health status, and tumor stage to arrive at a comprehensive judgment; conclusions should not be based solely on a single indicator. We should not fall into excessive anxiety over a positive result in any indicator, nor should we relax simply because the results are favorable. It is essential to communicate in a timely manner with the treating physician and design a personalized treatment plan based on the report, as this is the proper way to approach breast cancer. Understanding these indicators does not mean we should self-diagnose, but it helps us eliminate the fear of the unknown and adopt a calmer attitude to collaborate with treatment, aiming to win this battle against cancer.