Breast skin V40 predicted lymphedema after breast-conserving therapy

KEY POINTS

• This retrospective cohort included 116 patients treated with partial mastectomy followed by whole-breast RT. Median age was 63 years, 70.7% received hypofractionation, 81% received a sequential boost, and 19% underwent regional nodal irradiation.
• Clinical breast lymphedema developed in 28/116 patients (24.1%). Diagnosis required both symptoms such as swelling, heaviness or discomfort and corresponding examination findings including edema, skin thickening or peau d’orange.
• Breast skin was defined as the superficial 5 mm of the whole breast. On multivariable analysis, a skin V40 >90 cc was independently associated with breast lymphedema, with OR 3.91 (95% CI 1.17–13.04; p=.026).
• Increasing age was also independently associated with risk (OR 1.05 per year; p=.032), whereas fractionation, regional nodal irradiation and BMI were not independently predictive in the primary model. Skin V40 >90 cc remained significant across sensitivity analyses.
• Mammographic skin thickness provided an objective imaging signal. The average increase between baseline and 6-month mammography achieved an AUC of 0.774, with an optimal cutoff of 0.85 mm, 93% sensitivity and 61% specificity for clinical breast lymphedema.
• Longitudinal mammography showed persistently greater skin thickening in affected treated breasts. The trajectory differed significantly by lymphedema status over time, supporting skin thickness as more than a single-timepoint measurement.
• Among 12 patients receiving multiple sessions of lymphedema-directed physical therapy, mean skin thickness decreased from 3.5 to 2.6 mm. In six patients with serial LLIS data, scores improved from 23.8 to 8.5, although these treatment findings were exploratory and highly selected.

CLINICAL TAKEAWAY

SOURCE

International Journal of Radiation Oncology, Biology, Physics