The Impact of Subtype Distribution in Inflammatory Breast Cancer Outcome

Abstract

Objective: Inflammatory breast cancer (IBC) has an unfavourable prognosis despite the advances made in the treatment of breast cancer. Our studyaimed to define immunohistochemistry-based surrogate subtype distribution to determine whether the breast cancer subtype accompanied survivaloutcome differences in IBC.Materials and Methods: Medical records of female breast cancer patients with non-metastatic inflammatory breast cancer admitted to our clinicbetween March 2000 and December 2015 were retrospectively reviewed. Patient demographics, clinical and pathological feature of the primarytumour, adjuvant treatment options and survival data were analysed. Intrinsic breast cancer subtypes were defined according to ER, PR, HER-2 andki-67 status.Results: We identified 129 non-metastatic inflammatory breast cancer patients. Median follow-up was 73 months. 10 (7.7%) were luminal A-like,67 (51.9%) were luminal B-like, 37 (28.6%) were HER-2 positive, and 15 (11.6%) were triple negative (TNBC) by immunohistochemistry. Therewere no statistically significant differences between subtypes in terms of histological type, grade, tumour size and lymph node status. Median diseasefree survival was 47 months (95% confidence interval [CI] 29.2-82.6) and median overall survival was 75 months (95% CI 64.7-90.8). Triplenegative breast cancer showed poorer outcome than other subgroups. Presence of TNBC disease was associated with poorer outcome compared toluminal A (HR: 0.19, 95% CI 0.04-0.92, p: 0.039), luminal B (HR: 0.34, 95% CI 0.15-0.74, p: 0.007) and HER-2 positive subgroups (HR: 0.40,95% CI 0.17-0.94, p:0.037). Luminal A patients had a trend to have a better overall survival which did not reach to a statistical significant difference.Conclusion: Our study put forth that IBC have a poor prognosis irrespective of breast cancer surrogate subtype distribution. Luminal A, the mostfrequent subtype of breast cancer was the least common in our IBC patient group. TNBC had the worst outcome when compared to other breastcancer subtypes.