The majority of breast cancer patients undergo radiation treatment (radiotherapy) after undergoing breast conserving surgery such as lumpectomy and some high-risk women also have radiation after having a mastectomy. Radiation treatment is designed to destroy any remaining cancer cells in the breast after surgery. Radiation is effective in improving breast cancer survivorship; many studies have found that radiation protects against breast cancer recurrence. Certain foods have been found to increase the anti-cancer effects of radiation whereas others could interfere with it. Some foods can also ameliorate radiation's side effects. Please see our article on what to eat during radiation treatment for information on this topic.

Impact of radiotherapy on breast cancer prognosis

Numerous studies have reported that radiation treatment reduces the risk of recurrence in the breast that was treated and that this translates into a survival advantage. This is true for both invasive breast cancer and ductal carcinoma in situ (DCIS). Radiation is especially important when surgical margins are close or positive for residual tumor cells.

There has been a trend toward omitting radiation after breast-conserving surgery in recent years. Unfortunately, this is occurring among vulnerable populations (African-American, Latina, older, uninsured) and among women who have an increased risk of breast cancer recurrence. This trend represents a serious health care concern because of the potential increased risk of local recurrence and breast cancer-related death.

The positive impact of radiation treatment has been underestimated because it takes five years for the survival benefit to become apparent. In addition, two hypotheses have resulted in a tendency to de-emphasize the importance of radiation after breast conserving surgery. The first hypothesis is that since radiation is a local treatment which prevents locoregional recurrence, any such recurrence will likely be caught and treated in any event. However, it has been shown that approximately one in four local recurrences eventually will lead to stage IV disease and death. The second hypothesis is the idea that if a cancer has the tendency to spread, it will have done so even before the lumpectomy, so that radiation treatment will be too late to stop it. However, recent study results have shown that radiation appears to help prevent late recurrences.

Timing of radiotherapy

It is important that radiation treatment be started within a few weeks of breast cancer surgery. One study found a continuous relation between the time period between lumpectomy and radiation and local recurrence in older women, suggesting that starting radiation as soon as possible could minimize the risk of local recurrence.

Sequential treatment is the current standard for early-stage breast cancer; chemotherapy is given first, followed by radiation treatment. However, a major 2011 study found that simultaneous chemotherapy and radiation (synchronous chemoradiation) after surgery reduces local recurrence and can be given without greatly increasing the treatment side effects. This study might result in a change in the standard for women who need to undergo both chemotherapy and radiation.

Types of radiotherapy

While five to six weeks of whole breast external beam radiotherapy is the most common type of radiation treatment, various other forms of radiation are also being used or are under development. These include accelerated partial breast irradiation, targeted intraoperative radiotherapy, and radioactive implants (brachytherapy). Common features of these new treatments are that the radiation is delivered to a smaller area and for a shorter period of time.

One large 2012 study reported that brachytherapy had comparable survival outcomes as whole breast radiation. However, rates of side effects and mastectomy were higher in women undergoing brachytherapy, which is inconsistent with hoped-for advantages of what is in some respects less extensive treatment. The five-year rate of mastectomy was 3.95% for women treated with brachytherapy compared to 2.18% for whole breast irradiation. Brachytherapy was associated with more infections (16.20%) than whole breast irradiation (10.33%). In addition, brachytherapy was associated with more noninfectious postoperative complications, as well as breast pain, fat necrosis, and rib fractures than whole breast irradiation. However, five-year overall survival was 87.66% for brachytherapy compared to 87.04% for whole breast irradiation, results which were equivalent.

Breast cancer seeding in the needle tract is a possible, although rare, complication of core needle biopsy used to diagnose breast cancer. There is a theoretical risk of local recurrence if the needle tract is not removed during subsequent surgery or irradiated. This risk might increase if some form of partial breast irradiation is used instead of whole breast radiotherapy.

Side effects of radiation treatment

Radiation treatment harms the skin. This can result in skin damage that ranges from mild to severe, but which normally heals after treatment ends. Next to skin damage, fatigue is the most common side effect of radiation treatment, followed by nausea, vomiting and loss of appetite. While most women recover their pre-treatment energy level within a few months of completing treatment, fatigue can be persistent in a large minority of patients. Women irradiated for left-sided tumors also have increased risks of heart and lung damage, although these risks appear to have diminished in recent years because of improvements in the delivery of radiation.

Exercise during radiation treatment

Regular exercise has been shown to reduce fatigue in cancer patients undergoing radiotherapy. However, one study suggested that intense or prolonged physical activity a couple of days before the start of radiation or chemotherapy has significant potential to reduce the benefits of the treatments. Based on the available evidence, light to moderate aerobic could be beneficial to reduce fatigue during radiation treatment.