Women diagnosed with early-stage breast cancer who have lumpectomy usually have radiation therapy after surgery. Radiation therapy after lumpectomy lowers the risk of the breast cancer coming back (recurrence) and makes lumpectomy as effective as mastectomy. Radiation can be delivered to the entire breast (called whole-breast irradiation) or to just the area of the breast where the cancer was (called partial-breast irradiation).
A study compared partial-breast irradiation to whole-breast irradiation and found no differences in survival or the risk of the cancer spreading to other parts of the body (metastatic recurrence). Still, there was a difference in the risk of the cancer coming back in the same breast or the lymph nodes near the same breast (locoregional recurrence). The results were presented at the 2009 American Society of Clinical Oncology (ASCO) Annual Meeting.
The researchers analyzed the results from three earlier studies. All of the 1,140 women in the studies had been diagnosed with early-stage breast cancer and had had lumpectomy followed by radiation therapy. Some of the women got whole-breast irradiation and some received partial-breast irradiation. The women who got partial-breast irradiation:
- had the same survival rate
- had the same risk of the cancer coming back in another place in the body besides the breast
- were more than twice as likely to have the cancer come back in the same breast
- were more than 3 times as likely to have the cancer come back in the lymph nodes near the breast that had the original cancer
compared to women who had whole-breast irradiation.
The researchers explained that the higher risk of the cancer coming back in the same breast or lymph nodes near the same breast could have been because the original studies had a flaw in their design. More research is needed to see if this higher risk of locoregional recurrence continues to happen with partial-breast irradiation.
Whole-breast irradiation is the most common type of radiation therapy used to treat breast cancer. Whole-breast irradiation is delivered by an external bream of radiation. A large machine, called a linear accelerator, aims a beam of high-energy radiation at the breast area affected by the cancer. Whole-breast irradiation usually is given 5 days a week for 5 to 7 weeks as an outpatient procedure.
External partial-breast irradiation is a less common type of radiation therapy that focuses only on the area where the cancer was, meaning the rest of the breast area receives little or no radiation. Studies are comparing the benefits of external partial-breast irradiation to whole-breast irradiation.
Most partial-breast irradiation is delivered internally, rather than externally. Internal partial-breast irradiation, also called brachytherapy, uses small pieces of radioactive material ("seeds") that are placed in small tubes or catheters around the area where the cancer was. The area that's near the site of the original cancer is the area that is at highest risk of recurrence. Brachytherapy usually is given for 5 to 7 days, a much shorter time than external radiation. Brachytherapy systems require a skilled and experienced medical team and available radioactive materials.
Partial-breast irradiation currently is used less frequently than whole-breast irradiation. Still, internal partial-breast irradiation is appealing to many women because the treatment time is shorter (1 week versus 5 to 7 weeks). If radiation therapy is part of your treatment plan, it may seem easier to rearrange your daily routine for 1 week compared to almost 2 months. Internal partial-breast irradiation also can be more convenient for people who live far away from a treatment center. This study gives doctors the confidence that partial-breast irradiation provides benefits that are mostly comparable to whole-breast irradiation.
If surgery and radiation therapy are part of your treatment plan, you and your doctor will talk about which surgery and which radiation therapy method makes the most sense for you. For some women, external whole-breast irradiation is the best approach. For others, internal partial-breast irradiation therapy may be a good option. The Breastcancer.org Radiation Therapy section offers more information, including how radiation works to treat breast cancer and what to expect during and after treatment.