March 27, 2025 — For women with early-stage breast cancer, breast-conserving therapy (BCT) including radiation therapy (RT) leads to progressive reduction in breast size over time , reports a study in the April issue of Plastic and Reconstructive Surgery® , the official medical journal of the American Society of Plastic Surgeons (ASPS). The journal is published in the Lippincott portfolio by Wolters Kluwer .
"Our findings suggest that women undergoing BCT/RT may lose approximately 20% of breast volume within a year, with continued reductions through five years," comments Chris Reid, MD, of University of California San Diego. "Anticipating these changes may help guide patient expectations and assist surgical planning to restore women after breast cancer treatment."
New data on changes in breast size after BCT for early breast cancer
Breast-conserving therapy – consisting of limited surgery (lumpectomy) and RT – is the preferred treatment for many women with early-stage breast cancer. It offers survival rates similar to those of mastectomy, with more favorable physical, psychological, and quality of life outcomes.
However, RT has adverse effects on breast tissue, including breast shrinkage due to radiation-induced tissue atrophy and fibrosis. While this long-term side effect is well-recognized, there are few data on the extent or time course of breast volume loss after BCT.
Dr. Reid and colleagues measured changes in breast volume in 113 patients who underwent BCT/RT for early-stage (T1) breast cancer between 2005 and 2023. Measurements were made using mammograms obtained before and after BCT and up to five years later. The researchers also examined the impact of initial breast size and other factors on volume loss.
Reflecting the size of the tumor, breast volume decreased by an average of 9.2% after lumpectomy. Breast volume continued to decrease over time, even after the immediate side effects of radiation resolved. After one year, the average decline in breast volume was 19.3%, in addition to the tissue removed at surgery.
Implications for patient expectations and treatment planning
"Additional volume change was observed yearly for five years," the researchers write. By that time, the average decrease in breast size was 26.6%. Consistent with previous studies of breast shrinkage following BCT, "progressive volume loss was seen in all patients."
Women with larger breasts and relatively smaller tumor volumes (measuring less than 10% of breast volume) had greater total breast shrinkage: 29.5%, compared to 21.7% for those with smaller breasts. Other factors associated with greater volume loss included smoking, diabetes, and receiving cytotoxic chemotherapy in addition to RT.
The study provides new evidence on breast shrinkage after BCT. Expected breast shrinkage is approximately 20% within the first year, progressing to about 26% by five years. Especially with the growing emphasis on patient satisfaction in evaluating the outcomes of breast cancer treatment, the findings highlight the need to discuss long-term changes in breast volume in patients receiving undergoing BCT/RT.
The greater volume loss in patients with larger breasts raises concerns about breast asymmetry – which is a common concern after BCT. "Anticipating these changes may help guide patient expectations and assist surgeons in planning reconstructive procedures to attain symmetry posttreatment," Dr. Reid comments. The authors discuss key areas for further research, including the effects of different treatment techniques on breast volume changes and the need for more objective approaches to measuring breast volume.
