The large randomized trials on trastuzumab for primary breast cancer (BC) included few old patients. With exception of endocrine treatment, trials on adjuvant therapy for the old group specifically are scarce.
To compare adjuvant treatment, recurrences and survival in old and older-old patients with primary HER2 positive BC.
Patients ≥ 70 years with diagnose of primary HER2 positive BC from 2008 through 2015 were included in this retrospective non-randomized investigation. Standard clinical and biological data (age, surgery, tumor size, nodal status, histopathological grade, vascular invasion, expression of hormone receptors, recurrences and death) were extracted from patient’s charts. Comparisons were performed according to age (old; 70-74 years vs older old; ≥ 75 years) and treatment with trastuzumab or not. Patients that initiated adjuvant trastuzumab but did not complete one year (n = 8) were included in the trastuzumab group in survival analyzes. Recurrence-free survival (RFS) and overall survival (OS) were calculated in uni- and multivariate analyses.
A total of 115 patients were registered, eleven patients had distant metastasis and seven were omitted from all treatment including primary surgery due to serious concomitant illness and a poor general condition leaving 97 patients for analysis. There were no differences between the groups (70-74; n = 40), (≥75; n = 57) in tumor size (p = 0.86), nodal status (p = 0.10), ER (p = 0.25), PgR (p = 1.0) or vascular invasion (p = 1.0). A lower proportion of patients ≥ 75 years received adjuvant trastuzumab (21% versus 70%, p < 0.001). Adjuvant trastuzumab improved RFS (p = 0.027) and OS (p = 0.002) in univariate analyses. The corresponding figures in multivariate analysis adjusted for tumor size, nodal status and grade were RFS (p = 0.0052) and OS (p = 0.0003) respectively. Brain was the most common site of distant metastasis (15% of patients at first recurrence).
We show a large difference in delivered adjuvant treatment between old and older old patients with a small proportion of patients aged 75 years or more receiving HER2 directed therapy that resulted in a worse survival. The vast majority can complete the planned treatment. Our results indicate that brain metastases is common also among older patients.

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