Open Access

ARTICLE

Prolonged Survival in Patients with Human Epidermal Growth Factor Receptor-2-Overexpressed Metastatic Breast Cancer after Targeted Therapy is Dominantly Contributed by Luminal-Human Epidermal Growth Factor Receptor-2 Population

Keiichi Kontani^1,*, Kana Kuraishi¹, Shin-ichiro Hashimoto¹, Shoko Norimura², Nozomi Hashimoto¹, Masahiro Ohtani³, Naomi Fujiwara-Honjo⁴, Manabu Date⁵, Koji Teramoto⁶, Hiroyasu Yokomise¹

1 Department of Thoracic, Breast and Endocrine Surgery, Kagawa University Faculty of Medicine, 1750-1 Miki-cho, Kita-gun, 761-0793, Japan
2 Department of Surgery, Takamatsu Red Cross Hospital, 4-1-3 Ban-cho, Takamatsu, 760-0017, Japan
3 Kagawa Health Service Association, Health Care Center, 148 Fuseishi, Takamatsu, 761-8071, Japan
4 Department of Radiology, Osaka Neurosurgery Hospital, 378-1 Sanmyo-cho, Takamatsu, 761-8083, Japan
5 Department of Surgery, Date Hospital, 588-8 Kanko-cho, Takamatsu, 760-0076, Japan
6 Department of Surgery, Shiga University of Medical Science, 1-1 Seta, Otsu, 520-2191, Japan

* Corresponding Author: Keiichi Kontani. Email:

Oncologie 2021, 23(2), 229-239. https://doi.org/10.32604/Oncologie.2021.016277

Received 22 February 2021; Accepted 14 May 2021; Issue published 22 June 2021

Abstract

The prognosis of patients with human epidermal growth factor receptor-2 (HER2)-overexpressed metastatic breast cancer (MBC) has improved drastically following the development of anti-HER2 therapies. We question what factors are involved in the improved outcome by the treatment. One hundred and two MBC patients who received chemotherapy were classified into groups according to breast cancer subtype: luminal/HER2-negative (n = 50), HER2 (n = 26), and triple-negative subtypes (n = 26). Clinicopathologic features and clinical outcomes of the groups were compared. Disease-free intervals in the triple-negative group were significantly shorter than those in the other two groups. Age, tumor grade, the number of disease sites, and prior chemotherapeutic regimens did not differ among the groups. As a result, median overall survival was significantly longer in the HER2 and luminal/HER2-negative groups than in the triple-negative group (114, 68, and 18 months, respectively, p < 0.001). To determine key factors underlying favorable outcomes of the HER2 group, the HER2 group was further divided into two subgroups, luminal-HER2 and non-luminal-HER2 groups, according to their hormone receptor status, and clinical outcomes were compared. Median overall survival from the time of diagnosis of MBC in the luminal-HER2 group was significantly longer than that in the non-luminal-HER2 group (not reached and 39 months, respectively, p = 0.048), and was as favorable as shown in the luminal/HER2-negative group. In conclusion, the prognosis and survival of patients with HER2-overexpression receiving anti-HER2 therapy improved considerably in the luminal-HER2, but not in the non-luminal-HER2 group.

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