Adjuvant trastuzumab without chemotherapy for treating early HER2-positive breast cancer in older patients: A propensity score-adjusted analysis of a prospective cohort study
Masataka Sawaki,
Naruto Taira,
Yukari Uemura,
Tsuyoshi Saito,
Shinichi Baba,
Kokoro Kobayashi,
Hiroaki Kawashima,
Michiko Tsuneizumi,
Noriko Sagawa,
Hiroko Bando,
Masato Takahashi,
Miki Yamaguchi,
Tsutomu Takashima,
Takahiro Nakayama,
Masahiro Kashiwaba,
Toshiro Mizuno,
Yutaka Yamamoto,
Hiroji Iwata,
Tatsuya Toyama,
Koichiro Tsugawa,
Takuya Kawahara,
Hirofumi Mukai
Affiliations
Masataka Sawaki
Department of Breast Oncology, Aichi Cancer Center Hospital, Nagoya, Japan; Corresponding author. Department of Breast Oncology, Aichi Cancer Center Hospital. 1-1 Kanokoden, Chikusa-ku, Nagoya, 464-8681, Japan.
Naruto Taira
Department of Breast and Thyroid Surgery, Kawasaki Medical School, Okayama, Japan
Yukari Uemura
Biostatistics Section, Department of Data Science, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan
Tsuyoshi Saito
Department of Surgery, Japanese Red Cross Saitama Hospital, Saitama, Japan
Shinichi Baba
Department of Surgery, Sagara Hospital, Kagoshima, Japan
Kokoro Kobayashi
Department of Medical Oncology, The Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan
Hiroaki Kawashima
Department of Surgery, Aomori City Hospital, Aomori, Japan
Michiko Tsuneizumi
Department of Breast Surgery, Shizuoka General Hospital, Shizuoka, Japan
Noriko Sagawa
Department of Breast Surgery, Kyoundo Hospital, Tokyo, Japan
Hiroko Bando
Department of Breast and Endocrine Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
Masato Takahashi
Department of Breast Surgery, Hokkaido University Hospital, Sapporo, Japan
Miki Yamaguchi
Department of Breast Surgery, JCHO Kurume General Hospital, Kurume, Japan
Tsutomu Takashima
Department of Breast and Endocrine Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan
Takahiro Nakayama
Department of Breast and Endocrine Surgery, Osaka International Cancer Institute, Osaka, Japan
Masahiro Kashiwaba
Department of Breast Surgery, Adachi Breast Clinic, Kyoto, Japan
Toshiro Mizuno
Department of Medical Oncology, Mie University Hospital, Tsu, Japan
Yutaka Yamamoto
Department of Breast and Endocrine Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
Hiroji Iwata
Department of Breast Oncology, Aichi Cancer Center Hospital, Nagoya, Japan
Tatsuya Toyama
Department of Breast Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
Koichiro Tsugawa
Department of Breast and Endocrine Surgery, St. Marianna University School of Medicine, Kawasaki, Japan
Takuya Kawahara
Clinical Research Promotion Center, The University of Tokyo Hospital, Tokyo, Japan
Hirofumi Mukai
Department of Breast and Medical Oncology, National Cancer Center Hospital East, Kashiwa, Japan
Purpose: To gauge the effects of treatment practices on prognosis for older patients with HER2-positive early breast cancer, particularly to determine whether adjuvant trastuzumab alone can offer benefit over no adjuvant therapy. This is a prospective cohort study which accompanies the RESPECT that is a randomized-controlled trial (RCT). Methods: Patients who declined the RCT were treated based on the physician's discretion. We studied the 1) trastuzumab-plus-chemotherapy group, 2) trastuzumab-monotherapy group, and 3) non-trastuzumab group (no therapy or anticancer therapy without trastuzumab). The primary endpoint was disease-free survival (DFS), which was compared using the propensity-score method. Relapse-free survival (RFS) and health-related quality of life (HRQoL) were assessed. Results: We enrolled 123 patients aged over 70 years (median: 74.5). Treatment categories were: trastuzumab-plus-chemotherapy group (n = 36, 30%), trastuzumab-monotherapy group (n = 52, 43%), and non-trastuzumab group (n = 32, 27%). The 3-year DFS was 96.7% in trastuzumab-plus-chemotherapy group, 89.2% in trastuzumab-monotherapy group, and 82.5% in non-trastuzumab group. DFS in non-trastuzumab group was lower than in trastuzumab-plus-chemotherapy and trastuzumab-monotherapy groups (propensity-adjusted hazard ratio; HR: 3.29; 95% CI: 1.15–9.39; P = 0.026). The RFS in non-trastuzumab group was lower than in trastuzumab-plus-chemotherapy and trastuzumab-monotherapy groups (propensity-adjusted HR = 7.80; 95% CI: 2.32–26.2, P < 0.0001). There were no significant intergroup differences in the proportions of patients showing HRQoL deterioration at 36 months (P = 0.717). Conclusion: Trastuzumab-treated patients had better prognoses than patients not treated with trastuzumab without deterioration of HRQoL. Trastuzumab monotherapy could be considered for older patients who reject chemotherapy.
