Sentinel node. Diagnosis at the Clínica
When cancer progresses, it tends to disseminate through the blood and lymphatic vessels. The sentinel node is the first lymph node that the tumour cells encounter when attempting to disseminate through the lymph.
Once removed, the lymph node is subjected to an examination by a pathologist who will determine whether it appears affected or not by tumour cells. In the results are positive, the disease could have extended to other areas of the patient’s body.
The oncologist must then assess this information and then prescribe the most appropriate treatment.
The procedure for detecting the sentinel node and thereby its involvement begins the day before the operation, by performing a lymphoscintigraphy on the patient.
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Analysis of the sentinel node provides information on the extent of the disease, in the most selective manner possible, to determine the most effective and appropriate treatment that is tailored to each case.
In cases of breast cancer, the main advantage is avoiding the complete extirpation of the axillary lymph nodes, thereby avoiding the complications in this arm such as fluid retention, swelling (lymphoedema [SP]), lack of forearm skin sensitivity and reduced arm movement.
This allows breast surgery to be less aggressive for the patient and for the indicated treatment plan to be the most appropriate possible, resulting in a better recovery and a very good quality of life after the operation.
In melanoma, the lymph node is the first site affected in metastases or the spread of the disease to other organs. Therefore, the extirpation of the sentinel node is indicated within the surgery. The procedure is essential for healing.
The injection of the radiopharmaceutical should be performed half an hour before proceeding to the lymphoscintigraphy. The following day during the operation, a dye (methylene blue or others) is injected into the tumour. The dye migrates to the first lymph node or sentinel node of the area closest to the tumoral mass.
The substance stains the lymph node or sentinel nodes blue, leaving them visually labelled, making it easier for the surgeon to find. By using a probe connected to a gamma radiation detector, the specialist locates the sentinel node that contains the radiopharmaceutical injected the day before. The probe emits a beep that becomes more intense the higher the concentration of the radioactive isotope detected.
The surgeon can thereby accurately determine the location of the sentinel node and remove it for subsequent analysis. Once removed, the lymph node is subjected to examination by a pathologist, who will determine whether it appears affected or not by tumour cells.