Breast irradiation causes pallor in the nipple-areolar complex in women with Celtic skin type (result from the St. George and Wollongong randomised breast boost trial)

INTRODUCTION: The nipple-areolar complex (NAC) has special histological properties with higher melanocyte concentration than breast skin. To date, there are no data describing the late effects on the NAC following breast-conserving therapy (BCT). This study evaluated colour changes in the NAC in patients treated with breast-conserving surgery and adjuvant radiotherapy after 5 years. METHODS: Digital photographs obtained at 5 years following breast irradiation from the St. George and Wollongong (SGW) trial (NCT00138814) were evaluated by five experts using an iPad® (Apple Inc., Cupertino, CA, USA) application specifically created for this study. The SGW trial randomised 688 patients with Tis-2, N0-1, M0 carcinoma to the control arm of 50 Gy in 25 fractions and boost arm of 45 Gy in 25 fractions and 16 Gy in 8 fractions electron boost. RESULTS: A total of 141/372 (38%) patients had altered NAC (86% lighter, 10% darker). Patients with Celtic skin type had increased likelihood of having an altered NAC (odds ratio (OR), 1.75 (CI 1.1-2.7, P = 0.011)). On subgroup analysis, those with Celtic skin type receiving biologically equivalent dose (BED) Gy3 ≥ 80 Gy had OR of 3.03 (95% CI 1.2-7.5, P = 0.016) for having altered colour. There was a dose response with more profound changes seen in the NAC compared with irradiated breast skin if BED Gy3 ≥ 80 Gy with OR of 2.42 (95% CI 1.1-5.6, P = 0.036). CONCLUSION: In this Caucasian BCT population, over 30% of patients developed lighter NAC and more commonly in women with Celtic skin type. The degree of this effect increased with higher radiation dose.