Cancer is a disease where the normal cellular regulators malfunction and instead of the cells dying off as programmed they continually divide without their normal control, accumulating into a mass (tumour). As the tumour grows, it promotes the formation of blood vessels to bring in oxygen and nutrients, however these vessels are ‘leaky’ and can allow the cancer cells to leave the tumour site and travel through the blood stream and lymphatic system to other parts of the body. This process is called metastasis. It is thought that the majority of breast cancers develop as the end result of a continuum of change within the breast tissue as depicted below. These changes usually take many years to progress to invasive carcinoma, and many never progress that far.
• invasive breast cancer
The majority of these arise in the breast ducts (70%) and are therefore known as ductal cancers (or NOS). About 20% of cancers develop in the glands at the ends of the ducts and are called lobular cancers. The remaining 10% are called special type cancers and are discussed later. These two main types of breast cancer tend to behave in a similar fashion although lobular cancers are more often multifocal (more widespread throughout the breast rather than causing an obvious mass - thus accounting for the increased difficult in detection mammographically) and bilateral (in both breasts). The most important factors in determining how well the cancer will behave is thus not the tumour type but its prognostic features.
• prognostic features
There are 3 major prognostic features, which can be combined into an index to give an indication of disease severity (the Nottingham Prognostic Index -NPI) although this must be interpreted with some caution as the index is a statistical value that cannot tell you how you will fare (only the average outcome for 100 women with identical disease). The pathology report will contain information on all of features:
1. lymph node status (ie metastatic involvement)
2. histological grade: I, II, III (low -- intermediate -- high)
3. tumour size
There are also several minor prognostic features which include:
1. oestrogen/progesterone receptor status (ER /PR)
2. Herceptin receptor status (HER2)
3. tumour subtype (ductal, lobular, etc)
4. lymphovascular invasion -- LVI (presence of tumour cells in the small vessels around the tumour, in transit to the lymphnodes)
• special types cancers
As mentioned previously, these account for about 10% of cancers. The majority are less aggressive than ductal cancers per se, with the notable exception of inflammatory carcinomas:
5. adenoid cystic
Whilst these tend to present as breast lumps, with the final diagnosis often only confirmed on histology, inflammatory carcinomas deserve special mention. Blockage of the skin lymphatic channels leads to swelling and redness and thus it can be mistaken for a breast infection.
Paget’s disease, whilst not a special type of cancer, also presents in an unusual way with nipple crusting and bleeding and can be mistaken for eczema of the nipple. The underlying cause is either DCIS or an invasive carcinoma affecting the ducts behind the nipple.
• clinical staging
There are 2 main clinical staging systems:
(1) TNM: (where T is for Tumour size, N is for lymph Node involvement and M is for Metastasis) which can be both a clinical & histological staging system. It is important as a way of accurately describing the tumour and, for example, allowing similar groups to be analysed to assess outcomes in treatment trials.
(2) Manchester system: which is a clinical staging method describing whether or not the tumour is confined to the breast.
Axillary surgery is undertaken for two main reasons. Firstly, to determine if any cancer has spread to the lymph nodes (staging) and secondly, to ensure removal of any such affected nodes and thus reduce the chance of local disease recurrence.
1. A complete clearance of the axilla (a level III dissection). This involves removing all the lymph nodes and may necessitate dividing small pectoralis minor muscle, although this does not result in any demonstrable weakness. The dissection is continued internally to the root of the neck and usually 20 or more nodes are removed.
2. A level I/II dissection. This involves removing the majority of the nodes, including those behind the pectoralis muscle without dividing pectoral minor and removes, on average, 10-20 nodes.
3. A level I dissection. The lower axilla is dissected and about half the total nodes are removed up to the edge of pectoralis minor.
4. An axillary sample. Six or more nodes 'cherry picked' from the level I area.
5. Sentinel Node Biopsy.
6. No axillary dissection
Current best practice suggests a sentinel node biopsy in the first instance or, if there is known nodal involvment from cytology, a level I/II axillary dissection should be performed on all patients with invasive cancers. There is no clear evidence that more extensive surgery is of benefit, except in a few circumstances, and this full clearance is associated with a higher rate of post surgical side effects, especially arm swelling (lymphoedema) and shoulder stiffness.
Patients with ductal carcinoma-in-situ (DCIS) alone should not undergo an axillary node dissection; although in some circumstances a sentinel node biopsy is indicated. This is assessed on an individual basis and should be discussed with you.
• sentinel node biopsy
In an effort to minimise the morbidity (arm swelling, stiff shoulder and altered sensation) associated with standard axillary surgery contemporary practice is moving towards identifying and removing only the key (sentinel) node/s. Many international studies have shown the sentinel node can be correctly identified in more than 95% of cases and, if clear of tumour, the likelihood of any other (i.e. non-sentinel) nodes being involved is less than 5%.
The procedure involves injection of a radioisotope in to the breast. The overall radiation involved is less than one chest X-ray and the vast majority of the dose is removed with the tumour and any residual activity is depleted within 36 hours of surgery. If used, the blue dye can stain the skin leading to a temporary tattooing effect, which can last for weeks or even months. Urine can also be tinged with blue for several hours after surgery. Cases of allergic reaction to the blue dye have been reported very rarely. If the sentinel node/s are positive an operation to remove the remaining lymph nodes will be recommended.
Surgery that aims to maintain quality of life and an acceptable breast appearance whilst at the same time being uncompromising on oncological effectiveness. The origins of oncoplastic surgery date to the 1980s with the rise of breast conserving surgery instead of a mastecomy as a surgical option. In more recent years the utilisation has been extended with the use of neoadjuvant chemotherapy (prior to surgery to shkink the tumour). There are three main techniques:
• glandular redistribution
• mastopexy / reduction mammaplasty
• volume restoration