Accelerated partial breast irradiation (APBI)
Accelerated partial breast irradiation (APBI) is a targeted radiation therapy that serves as an alternative to traditional radiation after a lumpectomy for breast cancer. By focusing radiation on the area surrounding the lumpectomy site, APBI significantly reduces treatment time from several weeks to approximately five days, which may enhance patient convenience and compliance. While many doctors consider it an experimental procedure, it may be suitable for specific patients based on established criteria set by radiation oncology experts.
Patients undergo a careful positioning process to ensure the targeted area receives the appropriate radiation dose, utilizing higher radiation amounts than conventional methods. Common side effects may include fatigue, pain, and localized skin changes, though most are relatively mild. Research indicates that APBI has comparable recurrence rates to traditional therapies, prompting ongoing studies to further evaluate its effectiveness across diverse patient populations. Overall, APBI represents a promising option in the evolving landscape of breast cancer treatment, though discussions with healthcare providers are essential to determine its suitability for individual cases.
On this Page
Accelerated partial breast irradiation (APBI)
CATEGORY: Procedures
DEFINITION: Accelerated partial breast irradiation (APBI) is an alternative to traditional radiation therapy after lumpectomy that can reduce the time of treatment from weeks to days. It is considered an experimental procedure by many doctors.
Cancers treated: Breast cancer
Why performed:Radiation therapy is given after a lumpectomy to kill any remaining cancer cells in the breast. Accelerated partial breast irradiation is an alternative therapy that delivers radiation in a way that reduces the time and number of treatments required. Radiation therapy usually requires outpatient center or clinic visits five days a week for six or seven weeks. APBI reduces the amount of time required for treatment to about five days in total.
Patient preparation: Accelerated partial breast irradiation was considered a new treatment in 2009, when an American Society for Radiation Oncology (ASTRO) task force released a consensus statement regarding the use of APBI. According to the consensus statement, patients who met certain requirements could be considered suitable for APBI outside of a clinical trial. The task force also recommended sets of criteria for categorizing patients in a "cautionary" group, for whom the use of APBI requires caution and care, and an "unsuitable" group, for whom APBI is not usually recommended outside of a clinical trial (B. Smith et al. 2009). A clinical trial is a carefully controlled study, supervised by doctors who are also researchers, that is designed to investigate the risks or benefits of a new or experimental procedure. Different types of APBIs are being investigated in clinical trials, using different methods and techniques. As a result, the patient preparation for APBI will differ depending on the specifics of the therapy. In general, the preparation for APBI is the same as for any other radiation therapy treatment.
Steps of the procedure: Just as with traditional radiation therapy, the actual time elapsed during treatment of accelerated partial breast irradiation is usually very short. The time that it takes to get the equipment and patient prepared, however, may be significant. First, the patient and the patient’s breast are positioned appropriately for the machine. During traditional radiation therapy, the entire breast receives radiation. During APBI, however, the only part of the breast that receives radiation is the area around the lumpectomy site. Therefore, the breast must be positioned very exactly so the correct area receives the radiation. To place the breast in the correct position, the cancer care team may label the breast with a marker or a tattoo. The patient should check with her cancer care team to see if these marks are temporary.
Once the breast and equipment are correctly positioned, a dose of radiation is given to the breast. Radiation machines deliver beams of high-energy particles to the tissue that destroy cancer cells. Accelerated partial breast irradiation uses amounts of radiation during treatment that are higher than those used by traditional radiation therapy. This is part of the reason the treatment time of APBI is so short.
After the procedure: After the procedure, the patient may experience fatigue, pain, or swelling in the breast. Aftercare depends on the procedure that is used. Patients should discuss aftercare with their cancer care team before the day of the first procedure so that anything needed, such as transportation home after the procedure, can be arranged in advance.
Risks: Risks are associated with any procedure involving radiation. With an experimental therapy such as APBI, ongoing clinical trials are trying to determine any long-term side effects that may result from the procedure. Most studies, however, have found risks associated with APBI to be relatively mildnot greater than risks associated with traditional radiation therapy, and decreasing over time. The ASTRO task force's 2009 consensus statement reported interstitial brachytherapy had the longest reported follow-up, but that follow-up data remained limited for other APBI techniques. The task force also reported that the best APBI delivery technique had yet to be determined due to insufficient data regarding comparative effectiveness and toxicity (B. Smith et al. 2009). This consensus statement was partially updated in 2017, and focused primarily on the factor of ageparticularly as it pertained to instances of recurrence.
The most common side effects of APBI are believed to be fatigue, skin changes similar to sunburn in the treated area, swelling in the breast, breast heaviness, and breast discoloration. The creation of small, hard nodes in the breast is also possible. These nodes are not dangerous, but they can occasionally be mistaken for a return of the breast cancer when felt or seen on a mammogram. A very rare but extremely serious possible complication of any radiation to the breast is the development of angiosarcomaan aggressive form of cancer.
Results: Studies comparing women who received APBI and those who received traditional radiation therapy after lumpectomy have generally found comparable rates of recurrence, even after many years. Researchers, however, are still conducting more studies and clinical trials. Most studies have been conducted only on very specific groups of womenmore research is being done to study the larger population of women with breast cancer to help determine whether APBI is a technique that could be beneficial to all women, and should be integrated into standard breast cancer treatment practices. The results that any individual woman experiences after APBI will depend on many different factorsgenetics, the type of original cancer, and the size of the original cancer.
In 2024, an article by the National Cancer Institute suggested new methods for combining the beneficial impacts of immunotherapy in conjunction with radiation therapy. While much current research has been done on the subject of immunotherapy as a replacement for radiation, the article suggested that both together can be very effective. Researchers from the University of Chicago first radiated tumors in test mice. This caused levels of myeloid-derived suppressor cells (MDSCs) to decrease. MDSCs are used by the human body to direct T-cells, which are capable of destroying functional cells, away from healthy tissues. Cancer cells exploit this characteristic as defenses provided by T-cells are reduced. The smaller levels of MDSC caused by the radiation, induced T-cells to remain active and to attack cancerous tumors. The MDSCs were also augmented by gene therapies. The activated T-cells then sought out other tumors in the body to destroy.
Bibliography
"Accelerated Partial Breast Irradiation: Update of an ASTRO Evidence-Based Consensus Statement." IntraOp, 2 May 2018, intraop.com/clinical-research/accelerated-partial-breast-irradiation-update-of-an-astro-evidence-based-consensus-statement. Accessed 13 June 2024.
Pasqualini, Jorge R., Breast Cancer: Prognosis, Treatment, and Prevention. 2d ed., New York, Informa, 2008.
Reynolds, Sharon. “Manipulating an Immune Cell May Make Radiation Therapy More Effective, Study Suggests” National Cancer Institute, 12 Feb. 2024, www.cancer.gov/news-events/cancer-currents-blog/2024/radiation-cancer-bambi-immune-response. Accessed 13 June 2024.
Smith, Benjamin D et al. “Accelerated Partial Breast Irradiation Consensus Statement from the American Society for Radiation Oncology (ASTRO).” International Journal of Radiation Oncology, Biology, Physics vol. 74, no. 4, 2009, pp. 987-1001. doi:10.1016/j.ijrobp.2009.02.031. Accessed 13 June 2024.
Smith, Terry L. Breast Cancer: Current and Emerging Trends in Detection and Treatment. New York, Rosen, 2006.
Torosian, Michael H., ed. Breast Cancer: A Guide to Detection and Multidisciplinary Therapy. Totowa, Humana, 2002.
“Treating Breast Cancer.” American Cancer Society, 2024, www.cancer.org/cancer/types/breast-cancer/treatment.html. Accessed 13 June 2024.
Winchester, David J., et al. Breast Cancer. 2nd ed., Hamilton, Decker, 2006.