Differentiation, grading, staging, and typing of tumors in pathology reports

　　It is difficult for many patients to accept the pathology report and see tumor or cancer. In fact, the prognosis of early and late tumors is related to the differentiation, grade, stage, and type of the tumor. These four dimensions are the most important indicators for evaluating tumor biological behavior and diagnosis, and are also the basis for prognosis evaluation. For cancer patients, understanding the differentiation, grading, staging and typing of their own tumors will also help them communicate with doctors more conveniently and cooperate with doctors for treatment. Then, how are the differentiation, grading, staging and typing of tumors specifically divided?
　　Tumor differentiation
　　Tumor is a progressive disease. Cancer cells originate from individual normal cells, some are similar to normal cells, and some are very different, which involves the differentiation of tumors. Pathology reports use the word “differentiation” to describe the difference between cancer cells and normal cells, usually using five levels of well-differentiated, moderately differentiated, poorly differentiated, undifferentiated, and dedifferentiated to describe. Among them, highly differentiated cancer cells are very similar to the surrounding normal cells or tissues, with little difference; poorly differentiated cancer cells are obviously abnormal, with large differences from normal cells; moderately differentiated is between well differentiated and poorly differentiated; undifferentiated means Large atypia makes it difficult to determine the site of origin of these tumors; dedifferentiation is used to describe tumors composed of two different types of cancer cells, one is well differentiated and the other is poorly differentiated or undifferentiated. Well-differentiated and moderately differentiated cancers grow slowly; poorly and undifferentiated cancers are more aggressive, grow faster, and tend to spread to other parts of the body.
　　Tumor grading
　　Tumor grading mainly refers to the degree of abnormality of tumor cells and tissues observed under a microscope compared to normal cells and tissues. Generally speaking, it refers to the degree of malignancy of the tumor, which is also one of the indicators reflecting the speed of tumor growth and spread. Each level of differentiation may “correspond” to a grade: well-differentiated, moderately differentiated, poorly differentiated, and undifferentiated correspond to G1, G2, G3, and G4, respectively; Low grade, poorly differentiated and undifferentiated into high grade. Because the histologic features of different tumors can vary widely, different grading systems may be used for different tumors. However, in general, most tumors are divided into grades 1 to 4 (some grading systems are divided into grades 1 to 3), as detailed below.
　　G1: Tumor cells and tissue look like healthy cells and tissue, called a well-differentiated tumor. Such tumors are considered low-grade and less malignant.
　　G2: The tumor cells and tissues are somewhat abnormal, do not look like normal cells and tissues, and grow faster than normal cells. This is called a moderately differentiated tumor. Tumors are considered intermediate-grade, with a relatively high degree of malignancy.
　　G3: The tumor cells and tissues are clearly abnormal, called poorly differentiated tumors, which are considered high-grade and more malignant.
　　G4: The tumor cells and tissues look the most abnormal and are called undifferentiated tumors. These tumors are considered the highest grade, most malignant, and grow and spread more quickly.
　　Tumor staging
　　Tumor staging mainly refers to the size of the primary tumor, the extent of the involvement, and the degree of spread of tumor cells in the patient’s body. In layman’s terms, it refers to the stage of tumor development, whether it is early or late. The “TNM staging system” consists of three basic elements, namely, T staging, N staging, and M staging. T refers to the situation of the primary tumor; N refers to the situation of regional lymph nodes affected by tumor cells; M refers to the situation of distant metastasis of tumor cells. When the conditions of T, N, and M are determined, the tumor can be staged, that is, the commonly heard stages I, II, III, and IV. Sometimes, the stage of the tumor is subdivided, so the patient may also see stages Ia, IIb, etc. For example, lung cancer mainly refers to the size of the tumor, whether it invades the bronchi, pleura, chest wall, great blood vessels, esophagus, vertebral body, etc., which are successively set as T1-T4. If the lesion is small, no invasion of surrounding tissues and organs (T1), no lymph node metastasis (N0) and distant metastasis (M0) are found in surgery and imaging examination, the stage is stage I. For luminal tract tumors, gastric cancer, and colorectal cancer, the depth of lesion invasion from superficial to deep is the mucosal layer, submucosa layer, muscularis propria, and serosa layer, and whether the surrounding tissues and organs are invaded. This is the main basis for T staging. , and also sequentially set to T1-T4. For example, if the esophageal cancer has invaded the muscular layer (T2), 5 lymph node metastases (N2) are found by surgery and pathology, and no distant metastasis is found by imaging examination (M0), the tumor is stage T2N2M0 IIIA.
　　Generally speaking, the earlier the stage, that is, stage I and II, it means that the tumor is in the early stage and the situation is still controllable; the stage III and IV means that the tumor is in the middle and late stage, and the treatment of the tumor is difficult at this time, and the prognosis will be relatively poor. Difference.
　　There are
　　mainly histological type and gross type. Due to the influence of morphology under the microscope and the subjective judgment of pathologists, inconsistencies in histological typing are inevitable. The complexity of the tumor determines that morphological typing alone is not enough. Poorly differentiated tumors also need the assistance of immunohistochemistry to distinguish them, such as lung squamous cell carcinoma and adenocarcinoma. Different types of tumors may have different responses to conventional treatments such as chemotherapy and radiotherapy. In addition, tumors often hide a large number of protein, genomic differences, which is the molecular classification of tumors. In addition, even tumors with the same type, grade, and stage show completely different characteristics and survival responses due to differences in their molecular phenotypes, and molecular typing has attracted increasing clinical attention. With the rapid development of high-throughput gene sequencing technology, precision medicine has opened a new era of pathological examination combined with molecular typing diagnosis and treatment. Lymphoma, lung cancer, gastric cancer, colorectal cancer, breast cancer, endometrial cancer and other malignant tumors are all based on molecular classification in further clinical decision-making, choose appropriate surgery, immunization, targeted therapy, and accurately evaluate the prognosis of patients and recurrence risk.
　　Most cancers develop according to the process of “precancerous lesion-carcinoma in situ-invasive carcinoma-metastatic carcinoma”. It may take several years to develop from carcinoma in situ to invasive carcinoma. Therefore, early prevention and treatment of tumors is more expensive. Typing, grading, staging, and typing are important parameters and dimensions for evaluating tumor biological behavior, invasion and metastasis, and clinical progression, and are important factors that affect patient survival. Of course, the outcome of tumors is still affected by many factors, but with the development of diagnosis and treatment techniques, many tumors have become chronic diseases with good prognosis.