The treatment of breast cancer involves a multi-disciplinary approach. The aims of treatment are to obtain local control (reduce the risk of local recurrence), lymph node staging and obtaining systemic control (reduce the risk of disease developing elsewere i.e. metastases).
1. LOCAL CONTROL
Breast cancers need to be excised from the breast in such a way to reduce the risk of local recurrence. If breast cancer recurs, there is often an associated increase risk of spread elsewhere in the body. Up until the late 1970s the main form of treatment was a radical mastectomy which involved removing the entire breast, much of the musculature on the chest wall and most of the axillary (armpit) lymph nodes. This surgery often had a very poor cosmetic outcome with associated problems with shoulder movement. There was also a very significant risk of lymphoedema (swelling of the arm). Studies indicated that the overall survival of patients was similar whether they had a radical mastectomy or a less radical procedure that spared the chest wall muscles and therefore prevented much of the shoulder morbidity. By the 1980s, it became apparent through a number of studies that patients with ‘small’ tumours (less than 3-4 cm in diameter) had exactly the same survival outcome and disease free survival if they underwent a breast conserving procedure when compared to a mastectomy. It was also determined that people who underwent a breast conserving procedure (lumpectomy) had a higher incidence of recurrence (2-3 times increase risk) if they did not have radiotherapy following the procedure. The modern treatment for the majority of breast cancers is for a wide local excision (lumpectomy) followed by a course of radiotherapy which usually lasts six weeks (30 treatment doses over five days a week).
Breast conserving surgery can be considered when tumours are small, unifocal (in only one part of the breast) and when there has been no previous breast conserving surgery with radiotherapy. A mastectomy however would need to be considered if tumours were very large, centrally placed, multifocal or multicentric (more than one tumour in different quadrants of the same breast) and where there had previously been breast conserving surgery with radiotherapy. Usually, radiotherapy cannot be given again to the same region of the body. Any part of the body can usually only receive a certain dosage of radiotherapy before there is irreversible DNA damage. This usually means that if a patient has recurrence after a lumpectomy and radiotherapy, they would then need to consider a mastectomy for appropriate local control.
2. LYMPH NODE STAGING
Up until the last decade, the gold standard of treatment for lymphatic staging was a Level 1 and 2 axillary clearance. The axilla (armpit) is conventionally divided into three Levels (Level 1, Level 2 and Level 3) with Level 1 being at the lower most portion of the axilla. A routine axillary clearance could harvest anywhere from 10-25 lymph nodes. These lymph nodes are sent to the pathology laboratory for histological assessment. The lymph node status is the most important prognostic factor in breast cancer. Therefore an accurate assessment of the lymph nodes is crucial.
Fortunately with the advent of breast screening, over 80-90% of patients are lymph node negative (do not have evidence of spread to the lymph nodes). This has lead to a trend for less invasive surgery as routine removal of Level 1 and 2 lymph nodes in all patients would mean that 80-90% of patients have had the surgery for no significant benefit. Indeed there are often significant complications associated with lymph node surgery (see complications of breast surgery).
For breast cancers that are considered clinically node negative at diagnosis, the current gold standard treatment is a sentinel lymph node biopsy. The sentinel lymph node is the first draining node (or nodes) for a particular location in the breast. The rationale is that if the sentinel node can be located for the location of the tumour site, then this will reflect the overall lymph node status of the axilla. If the sentinel lymph node is negative, then no further surgery will be required as the surrounding lymph nodes should also be negative. Unfortunately, if the sentinel node is positive, then current world wide opinion is that patients should return for a formal axillary clearance as there may be other lymph nodes in the vicinity that are also positive. With smaller tumours now being diagnosed, the majority of patients undergoing a sentinel lymph node biopsy would expect to have negative nodes and therefore only require one surgical procedure to their axilla.
The sentinel lymph node can be detected by various means. This could either involve injection of a mild radio-isotope prior to surgery and thus allowing a scintigram (a picture of the sentinel node) to be obtained preoperatively. In the operating theatre, Patent Blue V dye is injected around the tumour site and in most circumstances, the sentinel node can be identified using one or either of these techniques or a combination of these techniques. In 2-3% of patients, a sentinel node cannot be identified in which case these patients will need to undergo a formal axillary clearance to obtain appropriate nodal staging. If successful, the sentinel lymph node biopsy procedure has fewer complications, a shorter operating time and the patient can usually be discharged the day after surgery without requiring indwelling drains.
Patients who are clinically node positive at the time of diagnosis (have malignant lymph nodes palpable or are diagnosed by breast imaging) will need to undergo a full axillary clearance. These patients will often undergo further testing in hospital with a bone scan and a CT scan of the brain, chest and abdomen to exclude the possibility of further disease. Patients who have undergone a full axillary clearance will usually need to be discharged with a drain in-situ (to be removed at the consulting rooms a week after surgery).
3. SYSTEMIC CONTROL
The mortality rate of breast cancer has dropped by between 20-30% in the last two to three decades. Although screening has certainly contributed to this reduction in mortality rate, the other factor behind the reduction in mortality rate is the extensive use of systemic treatments in more patients. This means in the 21st century, more patients are offered systemic treatment which works by eliminating or arresting microscopic cells that are circulating throughout the body. This treatment can include chemotherapy, hormonal therapy or antibody therapy (Herceptin). Often it can be a combination of all or some of these treatments, depending upon the type of tumour and other factors such as the health of the patient and their age. In previous times, moving to chemotherapy may have signaled a last ditch attempt at treating an advanced or terminal stage cancer. The modern treatment of adjuvant systemic therapy will confer a significant benefit to many patients overall survival. Modern chemotherapy treatments are fair better tolerated with the use of a number of agents that help control some of the more disturbing side effects such as nausea.
All surgical procedures are accompanied by a risk of complications. More information on possible complications of Breast surgery can be found here.