Radiation is almost always delivered after the diagnosis of breast cancer when the breast is conserved (i.e. not removed) by a mastectomy. Remember, radiation is considered a local treatment modality just as surgery is. The aim is to treat the area at risk locally (in the breast). There are indications for treatment after mastectomy as well.
After surgery, radiation can decrease the chance of the cancer returning in the breast. The role of radiation is to treat any cancer cells not detected or removed by surgery. It kills cancer cells by destroying the ability to multiply. Surrounding normal tissues which are healthy may also get radiation and have some damage. Healthy normal cells are better able to heal from radiation injury than cancer cells because they have maintained the ability to repair radiation induced damage.
So the key questions are: What are the options for treatment with radiation? How does one chose the type of radiation to get the cancer killed but keep healthy tissues healthy?
This is where your cancer team comes in and is so important in weighing the pluses and the minuses of all the radiation options they have to offer. The doctors look at the mammograms, MRI and PET/CT if performed. They will evaluate the pathology report very carefully and take that into consideration when evaluating the size of the tumor, margins of resection, molecular markers/aggressiveness of the tumor, and any lymph node involvement. They consider the size of the breast vs. size of the tumor, age of the patient and even the prior medical problems. All of these factors will be weighed into the treatment decision.
The options are based on all the above parameters and include the following: whole breast radiation (WBI) with standard conformal radiation or IMRT (intensity modulated) to try to decrease radiation to normal structures such as the heart in left sided breast cancers; accelerated partial breast (APBI) radiation which concentrates on the lumpectomy with a margin of normal tissue. Some centers also use intraoperative radiation also called (IORT). Keep in mind that WBI usually takes at least 6 weeks to complete and is daily, APBI takes 1 week but is twice daily and IORT usually takes one treatment.
The present standard of care is to give whole breast radiation daily (M-F) for several weeks, but ongoing research suggests that it may be safe to give radiation to part of the breast….the so called highest risk area/lumpectomy.
Because APBI is still being studied, it is used more selectively than WBI. There are 2 different approaches to APBI with pros and cons to each. APBI can be done with external radiation coming from a standard treatment machine or through implant therapy also called breast brachytherapy. With breast brachytherapy, a temporary implant is placed in the breast by the surgeon. This implant looks like a whisk made of small flexible tubes or another type looks like a balloon. The idea is to fit this device to the surgical cavity. In effect with the implant the patient is being treated from the inside going outward and is the most sparing of normal tissues. The radiation is placed into this device for about 10 min via a small radioactive seed, twice per day for 5 days. After the radiation is delivered the implant is removed with a little local anesthesia and the radiation is complete in 5 days. This is all done as an out-patient. Most people like this method because the treatments are completed in 5 days. The long-term results are looking promising when compared to the more standard weeks of whole breast radiation. In general patient who are candidates for partial breast radiation are over 50, small tumors less than 3 cm, clear margins and negative lymph nodes. The real advantage with this method is the amount of normal tissue sparing since a small rim of normal tissue is treated around the lumpectomy cavity. With external radiation, in order to get to the surgical cavity radiation traverses through more normal tissue.
The decision to use whole breast or partial breast radiation can be a complicated one. Your cancer team is best poised to help you with this decision based on the facts. When I first started in this field many women were still getting mastectomies. Slowly the field started accepting breast conservation with whole breast radiation as an equal option to mastectomy in certain scenarios. The trend for recommending mastectomies started to reverse. We now are faced with another trend….the ability to scale back on the amount of tissue radiated. This can make decisions more complex but how wonderful to have more options. If only I had that crystal ball to see down the road 25 years from now. I hope you found this information helpful. There is much information available on all of these modalities but please let your physician help guide you on the best sites for more extensive information. Be well.