Man has been struggling to treat cancer long before we knew of the existence of DNA, genes, mutations and the whole complex gamut of changes that lead to cancer. The best that could be done until very recently was to try and cut it out. This approach presented several problems.
First, most patients with cancer who were heroic or desperate enough to submit to the surgeon’s knife were already beyond cure.
Secondly, most cancers were not externally visible and many of those that were, such as head and neck cancers, were inoperable. Having got beyond these two issues, many subjected to surgery without anaesthesia died of shock, and of those who survived many died of infection. The successes were anecdotal.
With the advent of anaesthesia and anti-sepsis, things got better but there was still a poor understanding of the biology of cancer.
Halstead’s radical mastectomy which was the accepted surgical gold standard for the treatment of breast cancer between the late 19th and mid-20th century and beyond, subjected thousands of women to a mutilating procedure based on the false premise that the more healthy tissue that was removed around the tumour, the better the outcome. I have a depressing image of these women from my student and junior days.
Today we know that outcome is largely dependent on two factors: tumour biology, which we cannot influence, and stage at diagnosis and treatment, which we certainly can.
Beyond surgery, new radiotherapy techniques and an ever-increasing number of new drugs with individual patient selection have not only improved cure rates but also allowed a decrease in the extent of surgical operations.
The radical mastectomy removed the whole breast, as well as the chest wall (pectoral) muscles, leaving a chest wall covered by skin, later made thin and fragile by the addition of radiotherapy. The removal of the pectoral muscles weakened the arm.
But this was only one part of the operation. The second part involved the removal of as much tissue as possible from the armpit(axilla) of the same side. The aim of this was to remove as many lymph nodes as could be reached, again in the mistaken belief that this would improve cure rates.
This part of the operation, known as an axillary dissection, was all too often followed by the development of gross lymphoedema (swelling) of the upper limb, producing a grotesque, heavy, uncomfortable limb prone to recurrent infections which only made the swelling worse.
Large, randomised trials carried out in the 1970s and 1980s clearly demonstrated that a simple mastectomy was no worse than a radical one in controlling cancer, thus sparing the pectoral muscles and eventually confining the radical mastectomy to the dustbin of medical history.
For the smaller tumours, which today constitute the majority in Malta and the Western world, it was shown that a wide local excision of the primary tumour with only a few millimetres of surrounding healthy tissue followed by radiotherapy produces the same local recurrence rate as a simple mastectomy.
There still remain some indications for a total mastectomy, for example, multiple tumours in the same breast or a large tumour in a small breast but these now constitute a minority.
This, combined with techniques of breast reconstruction both at the time of primary surgery or later, has greatly altered the cosmetic and psychological outcome of breast cancer surgery. But what about the second part of the operation, that on the axilla?
Once the procedure to remove the primary had become a relatively minor one, the axillary dissection came to present the main cause of morbidity.
The need to carry out an axillary dissection has today been drastically reduced by the introduction of sentinel node biopsy. Unless there is gross involvement of the axilla with cancer, the axillary part of the operation is largely a staging procedure rather than a therapeutic one. It gives us information on one important prognostic criterion, namely whether the cancer has affected the axillary nodes and to what extent. On this basis (and others), the oncologist will decide the nature of post-operative medical treatment and areas to be radiated.
That information can be equally obtained by removing and examining the axillary sentinel node (or two or three nodes). This is the node/nodes to which the tumour primarily drains. If this node is not involved by cancer, the axilla is taken as clear, thus sparing the need for further traumatic surgery. If positive for cancer, one can proceed to an axillary dissection to count how many other nodes are affected, but if imaging does not indicate gross disease in the nodes, even this is largely unnecessary.
As the axilla contains between 20 and 40 nodes, the problem lies in finding the right one to remove and examine. A tracer injected into the tumour or even the breast will first find its way to the sentinel node. Next, one has to find the tracer in that node as this will identify the node to be removed and examined. The first technique used to identify the sentinel involved injecting a tracer of methylene blue into the breast and finding the blue dye in the axilla. This was not terribly accurate.
Next came an injection of technetium, whose radioactive presence in the sentinel node could be detected by a radioactivity probe. Accuracy improved. This technique is still often combined with the methylene blue method as a double check.
Saint James Hospital has now introduced a system that does away with the radioisotope and instead uses a magnetic liquid tracer (Magtrace). This is injected, conveniently, with the patient under anaesthesia 20 minutes prior to starting the surgery.
The sentinel node/nodes are detected by a magnetic probe, as well as secondarily by the colour change (brown) they undergo when they take up the tracer. The latter is more of a confirmatory feature. The tracer can be administered up to 30 days prior to surgery, though logistically and for the patient’s comfort, it seems more sensible to do this immediately prior to surgery.
It is a system now widely used in several oncology centres in over 50 countries, including the Royal Marsden hospital but is a first for Malta.
Stephen Brincat is director of oncology, Saint James Hospital Group.