Researchers from the University of California San Francisco studied 400 women who had breast cancer surgery and followed them monthly for six months to determine the prevalence of persistent pain in the breast and to characterize distinct breast pain phenotypes. This was the first study to identify subgroups of patients with distinct, persistent breast pain following breast cancer surgery.

They also evaluated study participants for differences within pain classes based on demographic, preoperative, intraoperative and perioperative characteristics. Persistent pain was evaluated using the Breast Symptom Questionnaire, which obtained information about the occurrence of breast pain and patients' ratings of pain intensity. The results of the study showed that 31.7 percent of the study participants said they had no breast pain, 43.4 percent had mild pain, 13.3 percent had moderate pain, and 11.6 percent reported having severe pain that lasted for six months. The findings suggest that 1 in 4 women will experience significant and persistent pain in the first six months following breast cancer surgery.

Four non-modifiable demographic characteristics were associated in the severe pain group: younger age, less education, non-white ethnicity and lower income. Consistent with previous studies, younger age was associated with higher risk of being in all three classes of pain groups used in the study.

The major modifiable variables were preoperative breast pain, changes in breast sensations, severity of post-operative pain, number of lymph nodes removed, and having auxillary lymph node dissection (ALND). The authors noted that the data suggest that improvements in post-operative pain management are necessary to reduce the occurrence of persistent breast pain.