Ten-Year Follow-up Clinical Outcomes and the Role of Adjuvant Chemotherapy in HER2-Positive Patients with Microinvasive Breast Cancer
- Author:
Yeokyeong SHIN
1
;
Soo-Young LEE
;
Hyehyun JEONG
;
Jin-Hee AHN
;
Kyung Hae JUNG
;
Sung-Bae KIM
;
Hee Jeong KIM
;
Jong Won LEE
;
Byung Ho SON
;
BeomSeok KO
;
Ji Sun KIM
;
Il Yong CHUNG
;
Hee Jin LEE
;
Gyungyub GONG
;
Sae Byul LEE
;
Jae Ho JEONG
Author Information
- Publication Type:Original Article
- From:Cancer Research and Treatment 2026;58(1):151-158
- CountryRepublic of Korea
- Language:English
-
Abstract:
Purpose:Although human epidermal growth factor receptor 2 (HER2) positivity is prevalent in microinvasive breast cancer (MIBC), data focused on HER2-positive MIBC are limited. We investigated the clinical course and long-term outcomes of HER2-positive MIBC and evaluated the role of adjuvant chemotherapy.
Materials and Methods:The study included patients with curatively resected pT1mi pN0 HER2-positive breast cancer between January 2000 and January 2020. Treatments and survival outcomes, including invasive breast cancer-free survival (IBCFS), distant recurrence-free survival (DRFS), and overall survival (OS) were analyzed.
Results:The analysis included 799 female patients. The median age was 51 years (range, 23 to 79 years), and 51.6% (n=412) were premenopausal. Multifocality was confirmed in 17.3% (n=138), and estrogen receptor (ER) positivity in 29.8% (n=238). Adjuvant chemotherapy was administered to 17.5% (n=140), with doxifluridine in 96.4% of cases. One patient (0.1%) received trastuzumab. With a median follow-up of 119.0 months (95% confidence interval [CI], 114.0 to 127.0), the 8-year IBCFS, DRFS, and OS were 91.2% (95% CI, 89.1 to 93.3), 97.5% (95% CI, 96.4 to 98.7), and 98.8% (95% CI, 98.0 to 99.6), respectively. No significant differences were observed between patients with and without adjuvant chemotherapy. The lack of differences in IBCFS by chemotherapy was consistent across subgroups, including pre-/postmenopausal patients, grade 1-2/3 tumors, and ER-negative disease.
Conclusion:A clinically meaningful proportion of HER2-positive MIBC patients experience IBCFS events with long-term follow-up. Adjuvant chemotherapy did not improve survival, potentially due to the use of an outdated, ineffective regimen. The role of modern adjuvant regimens, particularly those incorporating HER2-targeted therapy, warrants further exploration.
