Dr Francois Malherbe talks about the use of Sentimag for sentinel lymph node biopsy in early-stage breast cancer.
Breast cancer patients in South Africa will have a new surgical option that eliminates exposure to radioactive materials and offers a less invasive, more flexible alternative for sentinel lymph node biopsy.
Breast cancer begins when normal cells in the breast change and abnormal growth occurs. A malignant breast cancer can spread to other parts of the body. This spread occurs when cancer cells break off from the main tumour and enter the body’s blood or lymphatic system. Lymph flows through tiny tubes, called lymphatic vessels, that drain into lymph nodes. The lymph nodes trap the cancer cells travelling away from the original tumour. When cancer spreads through the lymphatic system, the lymph node or group of lymph nodes the cancer reaches first is called the ‘sentinel’ lymph node.
It is important to know whether the cancer has spread to the lymph nodes because it affects the type of treatment that the patient will receive. Patients with cancer spread to the lymph nodes are more likely treated with chemotherapy and radiotherapy in addition to surgery of the breast. The other important reason to know whether lymph node spread has occurred is because it has a big impact on staging and prognosis of breast cancer patients.
Traditionally doctors assessed cancer spread to the lymph nodes by doing an axillary lymph node dissection. During an axillary node dissection, all the axillary nodes are removed. However, this procedure is associated with high rates of lymphoedema, nerve damage, shoulder pain and loss of mobility in the arm and shoulder.
To limit these side effects, some patients in whom the treating surgeon cannot palpate any abnormal lymph nodes and has normal axillary lymph nodes on an ultrasound, a sentinel node biopsy is recommended. During a sentinel node procedure, a low-activity radioactive substance and a blue dye are injected into the tumour, usually the day before the surgery. The substance injected will travel in the lymphatic ducts and as it reaches the first lymph nodes it will be filtered out. During surgery, the surgeon will then be able to see blue discoloured nodes and detect radioactivity in the sentinel lymph nodes with a machine, called a gamma probe. Only the ‘sentinel’ nodes are removed, which usually mean that less than four axillary nodes are removed, limiting the side effects of axillary surgery.
Currently there is a trend in breast cancer treatment, for patients with certain types of breast cancer, to have chemotherapy before they have their surgery. This is called neo-adjuvant chemotherapy. Some patients who are not candidates for a sentinel node biopsy might become eligible for a sentinel node biopsy after chemotherapy, if they have a good response to treatment. Because of this and the fact that breast cancers are diagnosed earlier, more patients are now eligible for a sentinel node biopsy than ever before.
The main reason many women are not having sentinel node biopsies in South Africa is because the radioactive substance used to detect the nodes can only be administered in a nuclear medicine facility, which is usually not available outside of the main cities.
A new technology called Sentimag, which uses a very sensitive magnetic detector to find the sentinel node after the injection of a magnetic tracer into the breast, has the potential to change this. Sentimag is approved for use in Europe, Australasia and now in South Africa. Numerous studies show that it is not inferior to conventional sentinel node biopsy techniques using nuclear medicine particles. The main advantage of Sentimag is that women can now have a sentinel node biopsy performed outside of the main cities. The other advantage is that patients no longer need painful injections into their breast before the surgery. This is now all done in theatre while the patient is asleep for their breast surgery.
Sentimag certainly has the potential to improve access to sentinel node biopsy for many more women, both in the public and private sectors, in South Africa.
For more information on the Sentimag and Sienna system, please contact Julie Belloni at Sysmex on 076 404 1914.
MEET OUR EXPERT – Dr Francois Malherbe
Dr Francois Malherbe FCS(SA) is a specialist breast and endocrine surgeon working at Groote Schuur Hospital and UCT Private Academic Hospital in Cape Town. He has a special interest in oncoplastic breast conserving surgery for breast cancer.