Breast Cancer Radiotherapy
External Beam Radiotherapy
External beam radiotherapy (EBRT) is given in a way almost unrecognisable compared to 5 or 10 years ago. EBRT is very much technology and engineering-based, and there have been remarkable advances in recent years. The benefits to cancer patients are far-reaching, and breast cancer patients in particular will benefit.
Breast cancer EBRT is given typically over 6-7 weeks, 5 days a week. Each treatment takes about 15 minutes, and is just like having an x-ray.
There are several critical aspects of breast cancer EBRT. These should be some of the questions you ask your treating radiation oncologist. If you read (and understand!) the following, you are lucky. It is rare that patients are given the opportunity to learn about these issues.
1. Voluming the breast with CT
Voluming is the process by which doctors mark out the breast or at-risk part of the breast. This occurs at simulation, which is the process of scanning the breast with a CT scan, then outlining the tissue to be targeted in 3 dimensons. In the past (and at many departments even today), patients were only volumed with x-rays using a "conventional simulator". However the problem is that x-rays do not clearly show the breast, so it is impossibly to accurately ensure the correct tissue is being treated or excluded from treatment. For this reason, all patients having breast cancer radiotherapy should seriously consider having a CT-simulation for voluming. It is expected that using CT-simulation increases likely cure and decreases side-effects. If you are not offered CT-simulation, you should seriously consider finding a centre that does.
2. Considering lymph node treatment
Patients who have lymph nodes in the axilla that are positive are at risk of having the supraclavicular lymph nodes being positive. All breast cancer patients with positive lymph nodes (whether you have had a mastectomy, lumpectomy or wide excision) should have a discussion with their radiation oncologist about supraclavicular fossa lymph (SCF) node treatment pros and cons. In Australia, some radiation oncologists do not offer SCF lymph node treatment, however in other countries such as the USA, it is recommended for many patients. You should ask your radiation oncologist exactly what the risk of lymph node involvement is, and whether you will be offered the choice of SCF lymph node radiotherapy.
3. Giving radiotherapy more slowly
In the past, patients were usually treated with radiotherapy by giving 2 Gy per day (Gy is the measurement of dose). This is given for, say, 30 treatments, to give a total dose of 60Gy (2 Gy x 30 = 60Gy). It is possible that by giving the radiation more slowly (at 1.8 Gy per day instead of 2.0 Gy per day), that the risk of serious long term side-effects of radiotherapy may be decreased. Studies are not conclusive, however decreasing serious side-effects is a very important advance in treatment. This issue remains controversial.
4. 3D conformal and intensity-modulated radiotherapy (IMRT)
Modern computing and engineering now allows us to treat the breast or chest wall and miss most normal tissues. Old techniques (such as the use of conventional simulation) should be avoided, as studies show worse dose distribution within the tissue, potentially leading to worse side-effects. Prof Shakespeare believes that as a minimum, CT-simulation and 3D planning should be used, and in many cases IMRT can be considered. Again, if your radiation oncologist does not offer 3D CT-simulation or IMRT, you should find one who does. There is further informationa bout CT-simulation and 3D conformal radiotherapy for breast cancer.
5. Prone breast radiotherapy
One of the problems larger-breasted women face is that when they lie on their back for radiotherapy, their breast falls over the chest wall. This means that when we treat with radiotherapy, we treat a lot of extra normal tissue in order to cover the breast. This may well result in worse side-effects including breast swelling and pain, rib fractures, lung damage and heart damage. One solution is to treat medium and large-breasted patients face down (i.e. "prone"). This allows the breast to hang off the chest wall, and means that radiation can potentially avoid treating as much heart, lung and ribs (in some cases we can completely exclude these critical tissues). In addition, the breast may be treated with a more even dose, meaning potentially less breast pain and swelling. This is a very important advance in breast patient care, and women should ask about this new technique which is offered in a few centres of excellence in Australia (although is widely available in the USA). More information on prone breast radiotherapy can be found here.
6. Daily x-rays during treatment
Prof Shakespeare's own research shows that every patient should have an x-ray every single day of radiotherapy treatment, to ensure that the breast is being treated. We know that the breast position moves (for example with breathing), so there is no point "treating blindly" without checking the breast's position. In many radiation centres, x-rays are only done once a week or less: this seems a very poor option, since every day, patients' positions change. It has been very well documented that if you do not do a check x-ray every single day, you may well be missing your mark. More information on daily x-rays can be found here.
The following is a patient who had both of her breasts treated with breast conservation plus radiation 10 years ago. She has no side-effects and is cured. This is what we aim to achieve in our patients.
