Chronic pain after breast reconstruction surgery is a common complaint, but its considerable incidence means that the operation itself may not be to blame, according to a study of almost 2,000 women recruited from the Mastectomy Reconstructive Outcomes Consortium (MROC).

In the February issue of The Breast , investigators from the University of Michigan, Ann Arbor and Memorial Sloan Kettering Cancer Center, New York, wrote that almost half of the study subjects had some level of pain before their operations and that, at 2 years afterward, their pain had increased but not in a clinically meaningful way. This finding is consistent with earlier research, which investigators noted found that “one-fourth to one-half of women who undergo postmastectomy report persistent pain months and years after surgery.”

“Average clinical pain severity was strikingly similar for preoperative and postoperative assessments,” said lead author Randy S. Roth, PhD , of the University of Michigan, and his coauthors. “Postoperative levels of pain, acute postoperative pain and (marginally) level of depression held consistent relationship at 2-year follow-up with all outcome measures.”

The prospective, multicenter cohort study of 1,996 women was undertaken over 5 years. Most patients had immediate (92.7%) and bilateral (53.8%) reconstruction; 47.6% had sentinel lymph node biopsy and 25.9% had axillary lymph node dissection. Most had no adjuvant therapy: 70.3% received no radiation and 52.7% no chemotherapy.

At 2 years, the Numerical Pain Rating Scale (NPRS) measured what Dr. Roth and his coauthors called a “significant increase in pain intensity” – from an average rating of 1.1 to 1.2, an increase of 9%. However, the absolute change and standard deviation (1.7 for both intervals) “suggest that this was not a clinically meaningful change.” The researchers also recorded more complaints of bodily discomfort after 2 years, “but the statistical parameters again indicate little clinically meaningful differences from preoperative status.”

Pain ratings measured with the McGill Pain Questionnaire showed a significant decrease in the MPQ affective pain rating, from 1.6 preoperatively to 0.8 at 2 years (P less than .001), and virtually no change in the MPQ sensory rating, from 3.2 to 3.1.

The researchers drew some conclusions about demographic profiles and pain after breast reconstruction. Older age was associated with more severe pain on NPRS, and higher body mass index was linked with chronic postsurgical pain for the MPQ sensory rating, NPRS score, and body discomfort scores.

Treatment characteristics associated with chronic postsurgical pain (CPSP) include radiation therapy during or after reconstruction and chemotherapy before reconstruction. Chemotherapy during or after reconstruction was associated with higher MPQ affective rating scores at 2 years (P = .011), as was chemotherapy both before and during or after reconstruction (P = .001). The latter also was linked to higher NPRS scores (P = .0015).

The type of surgery also was a factor in CPSP, the researchers wrote. Both MPQ sensory and affective ratings were higher in women who had free transverse flap surgery, or deep or superficial inferior epigastric perforator surgery than in women who had tissue expander/implant reconstruction. Lymph node status and timing of surgery had no impact on chronic pain.

One noteworthy finding, Dr. Roth and his coauthors wrote, is that “careful examination of our data suggests that CPSP following breast reconstruction may be of less clinical concern as a direct consequence of breast reconstruction than suggested by previous investigations of major surgery, including mastectomy and breast reconstruction.” Future studies of chronic postsurgical pain in breast reconstruction “will require greater methodological rigor” to reach more sound conclusions to use in patient counseling.

Dr. Roth and his coauthors had no financial relationships to disclose.

SOURCE: Roth RS et al. Breast 2018;37:119-25 .