What is Radiation Therapy?
Radiation therapy is also known as DXT (Deep X-ray Therapy) or radiotherapy is an adjuvant treatment for some types of cancer. In breast cancer it is used after surgery to help prevent recurrence of the cancer at its original site. Most modern radiotherapy units use Cobalt-60 as the source of the radiation. This is much the same as that used for a standard diagnostic x-ray but at a much higher dose. If you need radiation as a part of your cancer treatment, the timing and approach to reconstruction can be coordinated in order to give you the best aesthetic result. Although radiation complicates breast reconstruction, most patients can still achieve an acceptable outcome with proper planning.
Who will need Radiation Therapy?
The following circumstances are absolute requirements for breast radiation:
- All forms of “breast conserving surgery” including lumpectomy, quadrantectomy and hemi-mastectomy. This is necessary in every case, regardless of tumour size or biology as it has been documented that the local recurrence rate without radiation is 4-fold higher (9% vs. 38%).
- Multiple positive lymph nodes (tumour present in the nodes). Present protocols dictate if there are 4 or more positive nodes, radiation is definitely required. In some cases, with 1-3 positive nodes and additional poor prognostic factors, radiation may still be recommended.
- Locally advanced disease. If the tumour is larger than 5cm in diameter or the tumour has invaded the underlying chest wall or the skin, or there is so called “inflammatory breast cancer”, radiation will be required. In these patients, immediate breast reconstruction may not be ideal because of the adverse effects radiation can have on the reconstructed breast. Indeed, in some such cases, reconstructive surgery often has the goal of reconstructing the chest wall to allow radiation to proceed rather than the goal of making a breast mound.
- Inadequate surgical margins. If the tumour has been resected with less than 10mm of normal tissue, or there is DCIS present at the margin, the risk of local recurrence is higher. If it is technically possible to remove this tissue surgically, then an additional operation is warranted. In cases it is not technically possible, radiation will be required.
- Combinations of the above. In cases where multiple poor prognostic factors exist but each is alone insufficient to require radiation, the oncologist may recommend radiation based in their assessment of the risks and benefits.
Can the need for Radiation Therapy be predicted before surgery?
Despite pre-operative evaluation and breast imaging it is not possible to always predict who will need radiation before the surgery. This is because pathology information provided after evaluation of the specimen will help determine if radiation is needed.
What does Radiation Therapy do to the tissues?
Although radiation is effective on tumour cells, there is unfortunately, a negative effect on normal cells. Thus, despite its life-saving benefits, radiation therapy can be the source of potential problems when it comes to breast reconstruction. Radiation causes damages to the capillary blood supply as well as to the cells responsible for wound healing (fibroblasts). This results in a significantly greater risk of complications following surgery, such as infection, delayed healing, wound breakdown, fat necrosis, as well as implant related problems such as extrusion and capsular contracture.
Does Radiation Therapy hurt?
While receiving the radiation there is typically no sensation. As the radiation dose increases, some of the so called “acute effects” become apparent. These may cause variable degrees of discomfort and even pain. Most modern radiation treatments are skin-sparing. One of the first effects of radiation is increased pigmentation around the hair follicles. This may lead to general “tanning” or darkening of the skin as radiation stimulates melanin production. Later temporary hair loss in the radiated field occurs. Sweat glands and sebaceous glands may stop functioning and the skin becomes thin, dry and itchy. Frequently, skin sensitivity is increased. In severe cases the skin may under superficial ulceration (moist desquamation) which is painful and may even become infected. This generally heals within 3 weeks after stopping radiation.
What are the visible effects of Radiation Therapy?
The above biological effects of radiation will have an impact on the final aesthetic outcome of the reconstructed breast. The effects of radiation may not be apparent initially and their final clinical effect may only become apparent as long as 3 years after the radiation. Even if the radiation was performed many years ago, its effect on the reconstruction may only become evident after many months. In general, some of the adverse long term aesthetic effects are: shrinkage of the breast (about 25% volume loss is expected), firmness, discolouration, fine capillary blood vessel development (telangiectasia), distortion and deformation and occasionally chronic pain. It is impossible to predict which of these effects will occur and to what extent.
What about Radiation Therapy and Silicone Implants?
Radiation is particularly problematic when using tissue expanders or silicone implants. There is a significantly increased rate of all complications related to foreign material in the face of radiation. Various studies in the medical literature have shown the rate of major complications and failed reconstruction to be in the order of 36% to 54% of cases. Although it is not impossible to consider an alloplastic reconstruction in radiated tissues, the potential complication rates, coupled with the increased likelihood of capsular contracture, make the use of an implant a suboptimal choice for women in who radiation is planned or those with a history of prior radiation. When the patient’s anatomy allows it, a better choice for breast reconstruction is a delayed autogenous tissue flap.
What happens if I need Radiation Therapy after starting Reconstruction?
If it is decided that radiation is required and the patient has already begun the process of immediate reconstruction, the negative effects of radiation therapy on the reconstructed breast will need to be managed. This form of management has recently been dubbed “breast restoration”. For patients with a tissue expander in place, radiation will affect the quality of the breast skin overlying the expander. The skin may recover enough to allow exchange of the expander for a final implant. If the skin does not sufficiently recover, or if other problems arise, such as significant capsular contracture, it may be necessary to “salvage” the reconstruction with the use of a flap. One alternative is to use a latissimus dorsi flap to provide extra skin and soft tissue which is non-irradiated, while retaining the implant as part of the reconstruction. Another alternative is to abandon the implant reconstruction altogether, and to proceed with an autogenous flap alone, such as TRAM flap. A new modality, which has only recently received approval by the American Society of Plastic Surgeons (ASPS) is the use of fat injections. In this technique, fat is harvested from the abdomen or thighs with a special liposuction cannula and processed before being re-injected into the area of radiation damage. This supplies new and non-irradiated stem cells, which improve both tissue quality and stimulate tissue capillary re-growth.
For patients with an autogenous flap reconstruction that is then radiated, both the skin and the underlying subcutaneous fat will be affected. The fat may undergo a process of “fat necrosis” which results in firm and occasionally tender lumps or persistent wound drainage. In some mild cases continued evaluation with an ultrasound or MRI may be all that is required as the process does tend to settle with time. It is often difficult to determine if an area of firmness is just fat necrosis or if it is tumour recurrence and in these cases a biopsy may need to be done. In severe cases additional surgery will be required to excise these areas. Some residual dents and deformities may be amenable to correction by fat injection as described above.