Biopsy of the sentinel lymph node before chemotherapy
To avoid loss of information about the tumor's condition and its implications, it is essential to perform a biopsy of the sentinel lymph node before the initiation of chemotherapy, even if it was already done before the breast surgery.
The decision to recommend chemotherapy may be based solely on the tumor's characteristics, including its size and biological features (such as hormone receptor status). In cases where the tumor's characteristics do not clearly indicate the need for chemotherapy, the presence of affected lymph nodes may lead to such a recommendation. Additionally, when chemotherapy is already decided based on tumor characteristics alone, the involvement of lymph nodes may alter the type of chemotherapy to be administered.
Radiation therapy is given as an addition to breast-conserving surgeries as part of local treatment. The decision for post-mastectomy radiation therapy is recommended when there is a relatively high risk of local recurrence. This risk is present in tumors with a diameter of 5 cm or larger, inflammatory tumors, and cases where the tumor involves the skin or penetrates the chest wall muscles. These factors are generally known with good accuracy before surgery.
Another indication for radiation therapy after complete surgery is the involvement of four or more lymph nodes in the axilla. This information may be obtained after surgery and can also dictate the addition of radiation to the internal mammary nodes, in addition to the regular radiation to the chest wall and the nearby lymph nodes. It should be noted that in an approach with sentinel lymph node surgery, there is always the possibility that it will not be successful, and a full axillary dissection will be required, where radiation therapy is not automatic and depends on the extent of lymph node involvement.
In cases of neoadjuvant therapy, lymph node involvement in the tumor may disappear. In this situation, valuable information about the disease's extent may be lost.
There are two main approaches to the biopsy of the sentinel lymph node in neoadjuvant therapy:
The first approach emphasizes the importance of obtaining complete information about the lymph nodes' condition to determine the prognosis for healing. This information is crucial for the patient and, in certain situations, may dictate the therapeutic approaches, such as the type of chemotherapy and the need for radiation after the treatment ends with complete surgery. Therefore, according to this approach, the surgery is performed in two parts: in the first, the sentinel lymph nodes are identified, and if they are affected by the tumor, an axillary dissection is performed. Subsequently, the patient undergoes the prescribed treatment, usually chemotherapy. If the tumor is small enough, a partial mastectomy will be performed in the second surgery.
This way, no information about the lymph nodes' condition will be lost, at the cost of two surgeries instead of the option of a single surgery. It is essential to mention that some argue that after chemotherapy, the biopsy of the sentinel lymph node may not be accurate. There may be a situation where the identified sentinel lymph node was affected, in addition to other lymph nodes. Due to local factors, chemotherapy may cause the tumor in the sentinel lymph node to disappear, while the effectiveness of the treatment in other lymph nodes may be less, and residual tumor cells may remain there. In such a case, a false result of the biopsy will be obtained. According to this approach, if a sentinel lymph node biopsy was not performed before the initiation of neoadjuvant therapy, a formal axillary dissection should be performed.
Another approach claims that the biopsy of the sentinel lymph node is accurate even after chemotherapy. Additionally, treatment decisions should be based on the condition after the treatment: if the patient arrived at complete surgery, the decision for additional radiation will be based on the lymph nodes' condition after chemotherapy. In our experience, the error rate of biopsy of the sentinel lymph node is significantly higher than usual after chemotherapy. Therefore, we usually perform the biopsy of the sentinel lymph node before the initiation of neoadjuvant therapy.