Association Between Danish Guideline Treatments for Breast Cancer and Physiotherapy-Relevant Late Effects: A Nationwide Cohort Study.

BACKGROUND

Breast cancer survival has improved substantially, yet many women continue to experience late effects that may require physiotherapy. Shoulder impairment, lymphedema, and fatigue are among the most common physiotherapy-relevant late effects following primary breast cancer treatment. Understanding how guideline treatments for breast cancer influence these impairments is essential for the early identification of high-risk patients and the development of targeted rehabilitation strategies.

PURPOSE: To investigate the association between Danish guideline treatments for breast cancer and the risk of three physiotherapy-relevant self-reported late effect dimensions 3-7 years postoperatively.

METHODS

National cohort study of 5729 women who underwent surgical treatment for primary breast cancer between 2015 and 2019. Participants completed a questionnaire 3-7 years postoperatively addressing shoulder impairment, lymphedema, and fatigue. Treatment codes were extracted from the Danish National Patient Registry and categorized according to Danish guideline regimens for surgery and radiotherapy. Logistic regression analyses, adjusted for relevant confounders, were performed to estimate associations, and absolute risks were calculated.

RESULTS

Compared with breast-conserving surgery (BCS) and sentinel lymph node biopsy (SLNB) with radiotherapy, treatment combinations involving mastectomy or axillary lymph node dissection (ALND) with radiotherapy were associated with approximately threefold higher odds of self-reported late effects. The highest risk was observed after mastectomy and SLNB with radiotherapy (ORadj 3.10, 95% CI 2.48-3.88), followed by mastectomy with ALND and radiotherapy (ORadj 2.90, 95% CI 2.02-4.15) and BCS with ALND and radiotherapy (ORadj 2.76, 95% CI 2.25-3.39). Shoulder impairment was consistently the most frequent self-reported late effect across all treatment types.

DISCUSSION: Guideline treatments involving mastectomy, and/or ALND in combination with radiotherapy substantially increased the risk of self-reported late effects, particularly shoulder impairment. These findings highlight the need for early targeted physiotherapy interventions and improved detection strategies to mitigate late effects in breast cancer survivors.