Many patients with suspected malignant tumors have to undergo many tests before treatment, including CT, MRI and other imaging tests. Why do patients still need to do puncture, bronchoscopy, or even go to surgery for mediastinoscopy and thoracoscopy to get biopsy specimens for pathological diagnosis after so many tests? Why is pathological diagnosis so important?
For tumor patients, disease diagnosis ultimately depends on bronchoscopy or surgical resection and pathological examination of the specimens obtained for judgment. Pathological diagnosis is the “gold standard” for tumor diagnosis, other examinations are only helpful for doctors to detect and judge the disease, or follow up the treatment effect during the treatment process. In other words, any other examinations, such as CT, MRI, etc., even if a mass or lesion is found on the image, it cannot ultimately determine the nature and type of lesion, and the diagnosis has to rely on pathological diagnosis. This is a very crucial basis in the process of tumor treatment.
What information is included in a complete pathological diagnosis?
A complete pathological diagnosis includes four aspects of information.
1. Basic information of the patient, such as name, gender, age and pathology number. Among them, the pathology number is a unique number that each patient has in the hospital where the examination is performed and is very important. In addition, each hospital has the patient’s case number or ID number in the basic information, depending on the situation.
2. The content of the report, i.e., the way and place of origin of the specimen sent for examination. That is, it needs to be indicated from which organ the specimen originated and by which means it was obtained, such as puncture, lumpectomy or surgical resection.
3, the content of the pathology report. The content of the pathology report is the most important part of the entire pathological diagnosis, containing the type and nature of the lesion found through the test. The specimen obtained by surgical resection also contains the extent of tumor invasion, whether lymph nodes have metastasis and the presence of vascular aneurysm emboli. In addition, if the tumor lesion is atypical, the differential diagnosis should be added in the pathology report, and the differential diagnosis of tumor is often achieved by immunohistochemistry.
4.Molecular typing. For lung cancer, molecular typing is also a very important part of the pathological diagnosis report. However, the specific content of molecular typing report may be sent in a separate report or attached to the pathology report, forming the fourth part.
What is the meaning of “immunohistochemistry” in the pathology report?
Immunohistochemistry, or immunohistochemical testing, is a common test used in pathology diagnosis. It is used to identify antigens in tissue cells and to study their localization, characterization, and quantification by sectioning and staining specimens, whether small or large, and then developing the color of a chromogenic agent labeled with antibodies according to a chemical reaction.
Immunohistochemistry is useful for differential diagnosis of tumors in pathological diagnosis, determination of lung cancer types, and even for subsequent treatment of lung cancer. In addition, immunohistochemistry can be used to determine the molecular typing of lung cancer, i.e., genetic testing using immunohistochemical methods.
What does “-” or “-” stand for?
A “-” means a positive stain in immunohistochemistry, i.e., a genetic mutation, and a “-” means a negative stain, i.e., no genetic mutation. Both “-” and “-” have clinical significance in the differential diagnosis, and it does not mean that “-” is good and “-” is bad. -” is bad.
What is the meaning of EGFR and ALK, which are often found in immunohistochemistry results?
Yes, EGFR and ALK are two common molecular types in lung cancer, and it is recommended worldwide that lung cancer patients must be tested for these two genes, because once a positive mutation is detected, patients will have targeted drugs with good efficacy to use. Therefore, if molecular pathology testing is necessary, both genes should be routinely tested.
Do all patients need to have genetic testing for EGFR and ALK?
There are clear guidelines and expert consensus recommendations for genetic testing for EGFR and ALK. The Chinese Guidelines for the Diagnosis and Treatment of EGFR and ALK Positive NSCLC recommend that all adenocarcinomas or lung cancers with adenocarcinoma components require EGFR and ALK gene testing in principle. In addition, genetic testing was not previously recommended for squamous carcinoma, but now a new edition of the guidelines states that since squamous carcinoma may be mixed with some adenocarcinoma in the small specimens obtained, ALK genetic testing is recommended for patients diagnosed with squamous carcinoma using pathological testing of small specimens, if they are non-smoking young women and negative for other genes.
What does EGFR-E746 (-) and EGFR-L858 (-) mean in the report? What does it suggest when guiding treatment?
EGFR is a common mutated gene in lung cancer, and there are many fragments in this gene, and the abnormality of each fragment may have some significance in guiding clinical medication. most of the gene fragments in EGFR belong to sensitivity mutation, and some belong to non-sensitivity mutation. EGFR-E746 and EGFR-L858 are the loci tested for some fragments in the EGFR gene test. When EGFR-E746 and EGFR-L858 show “+”, it means there is a gene mutation, and if it shows ” -“, it means that there is no mutation. In addition to these two test loci, other loci should be tested to see if the gene fragments corresponding to the test loci are mutated. When mutations are detected in certain fragments, patients must promptly consult their clinicians or pathologists for professional advice on whether a positive mutation in that fragment is suitable for use of targeted drugs.
Does ALK(+) mean that a patient needs targeted therapy?
The current expert consensus in China recommends immunohistochemistry (IHC), polymerase chain reaction (PCR), and fluorescence in situ hybridization (FISH) to detect the ALK gene. Whenever any of the recommended methods detects positive ALK, it indicates that the patient needs targeted therapy. One of the more commonly used immunohistochemistry methods is Ventana IHC, and a positive ALK test by Ventana IHC can be followed up with targeted therapy directly without other molecular tests.
Many patients are found to be inoperable when lung cancer is detected, how to make pathological diagnosis for such patients?
No matter pathologists or clinicians, as oncologists, for the diagnosis of tumor patients, without pathological diagnosis, any clinical diagnosis cannot be the final diagnosis. Therefore, when a lung cancer patient has reached an advanced stage and has lost the chance of surgery, he or she must find ways to get biopsy specimens as much as possible, such as obtaining specimens through bronchoscopy or puncture, or doing lymph node biopsy for superficial lymph node metastasis. Only when a pathological diagnosis is obtained can follow-up treatment be carried out based on the diagnosis, otherwise all treatment is blind and unfounded.