Clinical Implication of HER2 Status in Hormone Receptor-Positive Mucinous Breast Cancer

• Published in: Annals of surgical oncology 2019-07, Vol.26 (7), p.2166-2174
• Main Authors: Gwark, Sung-chan, Lee, Han Shin, Lee, Youngjoo, Lee, Sae Byul, Sohn, Guiyun, Kim, Jisun, Chung, Il Yong, Ko, Beom Seok, Kim, Hee Jeong, Son, Byung Ho, Ahn, Jin-Hee, Jung, Kyung Hae, Kim, Sung-Bae, Lee, Hee Jin, Gong, Gyung-Yub, Ahn, Sei Hyun, Lee, Jong Won
• Format: Article
• Language: English
• Subjects: Adenocarcinoma, Mucinous - metabolism; Adenocarcinoma, Mucinous - mortality; Adenocarcinoma, Mucinous - pathology; Adenocarcinoma, Mucinous - therapy; Adult; Aged; Aged, 80 and over; Breast cancer; Breast Neoplasms - metabolism; Breast Neoplasms - mortality; Breast Neoplasms - pathology; Breast Neoplasms - therapy; Breast Oncology; Chemoradiotherapy - mortality; Chemotherapy; Epidermal growth factor; ErbB-2 protein; Female; Follow-Up Studies; Humans; Medicine; Medicine & Public Health; Metastases; Middle Aged; Monoclonal antibodies; Oncology; Prognosis; Receptor, ErbB-2 - metabolism; Receptors, Estrogen - metabolism; Receptors, Progesterone - metabolism; Retrospective Studies; Surgery; Surgical Oncology; Survival; Survival Rate; Targeted cancer therapy; Trastuzumab; Tumors; Young Adult
• ISSN: 1068-9265; 1534-4681
• DOI: 10.1245/s10434-019-07332-9

Purpose Mucinous carcinoma (MC) is a rare breast cancer with favorable outcome. Unlike typical breast cancer, the current guidelines do not recommend chemotherapy or anti-human epidermal growth factor receptor 2 (HER2) therapy for hormone receptor (HR)-positive MC, regardless of HER2 status. We evaluated the prognostic implication of HER2 status in HR-positive MC. Methods We retrospectively reviewed the data of 471 patients with pure MC (stages I–III) who underwent curative surgery. We analyzed 5-year disease-free survival (DFS) and distant metastasis-free survival (DMFS), according to clinicopathological characteristics. Results The median follow-up duration was 79.0 months. Overall, the 5-year DFS rate was 95.7% and the 5-year DMFS rate was 96.2%. Nodal status was the only significant factor for DFS (relative risk [RR], 3.40; 95% confidence interval [CI] 3.40–9.67, p  = 0.021). Among HR-positive/node-negative patients with tumor size ≥ 3 cm, HER2-positive patients showed significantly worse DFS (RR, 8.76; 95% CI 1.45–52.76, p  = 0.018) and DMFS (RR, 11.37; 95% CI 1.37–74.70, p  = 0.011). This finding was consistently significant, when combining both “HR-positive/node-negative/tumor size ≥ 3 cm” and “HR-positive/node-positive” MC (n = 125) for DFS (RR, 4.30; 95% CI 1.43–12.97, p  = 0.009) and DMFS (RR, 4.93; 95% CI 1.63–14.90, p  = 0.005). Intriguingly, within this subgroup, among HER2-positive tumors, whereas 5-year DFS was 60.2% in patients who did not receive trastuzumab, 100% of those who received trastuzumab were disease free ( p  = 0.053). Conclusions In HR-positive, node-negative MC with tumor size ≥ 3 cm, patients with HER2-positive MC showed worse survival, suggesting a potential role of an anti-HER2 strategy in this subgroup.