Invasive lobular breast cancer in young patients without adjuvant systemic treatment: 15-year survival outcomes.

Authors

R A B Voorthuis, M Opdam, N D Ter Hoeve, M da Silva, M Christgen, G Dackus, P V Diest, P W B Derksen, F S Hilbers, S C Linn

Published in

Breast cancer research and treatment. Volume 218. Issue 3. Aug 06, 2026. Epub Aug 06, 2026.

Abstract

Invasive lobular carcinoma (ILC) of the breast typically affects older women. As a result, there is limited research on prognosis and prognostic factors in young women with ILC. Here we set out to determine the long-term outcome and prognostic factors of women under 40 years of age with lymph node-negative (N0), hormone-receptor positive (HR+)/human epidermal growth-factor receptor 2 negative (HER2-) ILC who did not receive adjuvant systemic treatment (chemo- and/or endocrine therapy).
Through the Netherlands Cancer Registry we selected all systemically untreated patients younger than 40 years with HR+/HER2-, N0, early breast cancer diagnosed in the Netherlands from 1989-2000. At the time, node-negativity was considered a favorable prognostic marker and guidelines recommended no adjuvant systemic therapy for this subgroup. Distant recurrence-free survival (DRFS), recurrence-free survival (RFS) and overall survival (OS) were assessed according to the STEEP criteria. Uni- and multivariable Cox proportional hazard models were used to assess prognosis, calculating hazard ratios (HR) with confidence interval (CI).
Of the n = 1138 selected patients, n = 95 were histologically classified as ILC and n = 805 as invasive breast cancer of no special type (BC-NST), n = 238 were classified as other breast cancer subtype. In ILC, tumor grade was not associated with DRFS/RFS or OS (HR for DRFS 1.40, 95%CI 0.42-4.63). However, the presence of lymphovascular invasion (LVI) (adjusted HR DRFS 2.81, 95%CI 1.14-6.94, p < 0.05) and multifocality (adjusted HR DRFS 3.28, 95%CI 1.49-7.22, p < 0.01) were. When comparing DRFS, RFS and OS in matched low-risk luminal A-like ILC vs. BC-NST, we observed a trend for worse 15-year survival in ILC (15-year DRFS 63% in ILC vs. 74% in BC-NST; HR 1.50, 95%CI 0.98-2.29, p = 0.06).
In these young patients with systemically untreated N0 ILC we show that grade was not prognostic at 15 years follow-up, whereas LVI and multifocality were. Furthermore, ILC had a numerically worse 15-year survival than matched luminal A-like BC-NST.

PMID:
42560578
Bibliographic data and abstract were imported from PubMed on 06 Aug 2026.

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