Measurement of tumor size
1.Clinical measurement of primary tumor size: Physical examination and imaging techniques (mammography, ultrasound and MRI) can be used to clinically determine tumor size. It should be noted that some special types of cancer are difficult to accurately determine the size by imaging, and it is also difficult to distinguish infiltrating carcinoma from carcinoma in situ.
2.Pathological measurement of primary tumor size: only the infiltrative component is calculated, and the in situ cancer part should be removed. For example, the intraductal carcinoma (carcinoma in situ) component is 4 cm, while the infiltrating carcinoma component is only 0.5 cm. The tumor should be classified as pT1a according to the size of infiltrating carcinoma.
3. For smaller invasive carcinomas that can be accommodated in one wax block, microscopic measurement is the most accurate pT measurement technique; for larger invasive carcinomas that need to be divided into multiple wax blocks, it is more accurate to measure the tumor size in general, because it is difficult to guarantee that the tumor tissue sections divided into different wax blocks are from the same all sides, and the error of blind summation is larger. For tumors with a high proportion of carcinoma in situ, the principle of combining imaging, bulk and microscopy should be followed.
4.Regardless of the size of carcinoma in situ, as long as there is no infiltrative component, it is classified as Tis. and then classified as ductal carcinoma in situ or lobular carcinoma in situ. Cases with both DCIS and LCIS are classified as DCIS. ductal intraepithelial neoplasia and lobular intraepithelial neoplasia are also mentioned in the new version of TNM staging, which have not yet been widely used, so it is important to pay attention to the correspondence between different terms. Currently, the tumor size of DCIS is easy to measure, while LCIS is more difficult.
5. The diagnosis of inflammatory breast cancer requires typical skin involvement occupying at least 1/3 of the skin area of the breast. histologic findings of cutaneous lymphovascular carcinoma emboli are evidence to support the diagnosis but are not required, and only histologic evidence of cutaneous lymphovascular involvement without typical clinical presentation is not sufficient to diagnose inflammatory breast cancer.
Measurement of regional lymph node metastasis
1. The definition of isolated tumor cells in lymph nodes is more stringent: the size of foci of tumor cells in clusters must not exceed 0.2 mm; for dispersed non-confluent tumors, the number of tumor cells in a single tissue section of each lymph node must not exceed 200.
The definition of sentinel lymph nodes is also stricter: if the number of lymph nodes detected in general³6, they can no longer be called “sentinel” lymph nodes.
3. The subclavian lymph nodes (axillary apical lymph nodes, grade III axillary lymph nodes) are distinguished from the axillary and mid-axillary lymph nodes (grade I and II axillary lymph nodes). It should be noted that ipsilateral supraclavicular lymph nodes also belong to regional lymph nodes and metastasis occurs as N3c, but if the tumor metastasizes to contralateral internal breast lymph nodes, contralateral cervical lymph nodes or contralateral axillary lymph nodes, it belongs to M1.
Measurement of distant metastasis
A negative clinical history and examination is sufficient to indicate that the case is M0 and does not require overly refined imaging or other tests. The current staging system does not consider occult metastases, and MX should be used sparingly (distant metastases cannot be assessed).
1. New M0 (i+) group: It is defined by the presence of isolated, disseminated tumor cells in the bone marrow or peripheral blood, or by the incidental finding of lesions up to 0.2 mm in size in other tissues (e.g. prophylactic ovariectomy specimens). If there are no clinically and/or imaging obvious metastases, M0(i+) does not change the tumor stage and is temporarily regarded as M0. Its clinical significance needs to be studied in depth.
2. If neither neoadjuvant management nor evidence of disease progression is performed within 4 months of the diagnosis of breast cancer, but distant metastases are found on postoperative imaging, the staging should be modified accordingly. However, if new metastases appear afterwards, they should be considered as recurrence and staged according to recurrent tumor.
TNM staging after neoadjuvant therapy
1. The application of neoadjuvant therapy for breast cancer and the degree of tumor remission after treatment both affect the prognosis of patients, therefore, the post-neoadjuvant pathological staging is also generated accordingly, and this staging and the preoperative clinical staging are two different and co-existing staging systems.
2. The pre-treatment clinical tumor size should be determined based on clinical or imaging findings; while the post-treatment T should be determined based on a combination of clinical, imaging (ycT) or pathological findings. There is a controversy about the definition of ypT, and it is unclear whether the size of all infiltrating lesions or the size of a single maximal infiltrating lesion should be measured. ypT value is still adopted to measure a single maximal continuous infiltrating lesion, and the prefix m can be added for multiple lesions. fibrotic tissue within the tumor bed is not counted as tumor size.
3. For those diagnosed with inflammatory breast cancer before neoadjuvant therapy, even if the inflammatory manifestations are in complete remission after treatment, they are still classified as inflammatory breast cancer.
4. ypTNM should indicate the degree of patient response to neoadjuvant therapy (complete remission, partial remission, no remission), and the basis for determining the degree of remission (physical examination, imaging techniques, pathological examination) should be stated.
Although some scholars believe that the definition of complete remission is the complete disappearance of the tumor (including invasive cancer and carcinoma in situ), when the AJCC formulated this version of TNM staging, it was proposed that those with only residual carcinoma in situ also belong to complete remission, based on the fact that the presence of carcinoma in situ has an impact on the choice of local treatment, but has no impact on the patient’s prognosis.
6, Those with lymph node metastases £0.2 mm after neoadjuvant therapy are classified as ypN0 (i+), however, such patients are not pathologically in complete remission.
7. If the patient was M0 before treatment, the presence of metastasis after treatment suggests tumor progression. If the patient belonged to M1 before treatment, even complete remission after neoadjuvant therapy still belongs to stage IV, which is not related to the remission status after treatment.
TNM staging started in 1959, when modern comprehensive treatment of tumors was not yet available; therefore, TNM staging is crucial for the treatment of tumors (mainly surgical resection). In the following 50 years, research in tumor biology has made many achievements and systemic treatments have been updated. In the case of breast cancer, for example, TNM staging is no longer the main determinant of treatment modality. How to integrate the TNM staging system as well as other prognostic factors and treatment determinants has also become a focus of attention. In the new version of the staging system for esophageal cancer, the tumor type, grading and even site have been integrated with TNM to develop prognostic groupings. In breast cancer, tumor histological grading or molecular markers have not been incorporated into the TNM staging system, but it is recommended that these test results be reported together with TNM staging, and biological grouping of breast cancer is expected to be seen in the near future.