OBJECTIVES: To identify women with inoperable or metastatic breast cancer (BC) positive for human epidermal growth factor receptor 2 (HER2+), characterize them and assess their comorbidities, overall survival and healthcare integrated costs from the Italian National Health System’s (INHS) perspective.

METHODS: From the Fondazione ReS (Ricerca e Salute) database, in 2017, women aged ≥18 with BC-HER2+ (in-hospital BC diagnosis and specific trastuzumab/lapatinib supply from 2013 to 2019) with a new in-hospital diagnosis of metastasis, or newly BC diagnosed but without any mastectomy in the following year, were selected. Age, comorbidities, 1-year healthcare resources consumption, and 2-year overall survival (Kaplan Meier analysis) and costs charged to the INHS were assessed, by the 2-year treatment group (trastuzumab/another chemotherapy as first-line, no chemotherapy).

RESULTS: From 5 million inhabitants in ReS database in 2017, of 615 patients with BC-HER2+ (12.2% of BC-women), 198 had new metastases or were inoperable (index dates): 159, 16 and 23 were treated with trastuzumab (mean age 57±12; 56.6% with ≥1 comorbidity), another (57±11; 56.2%) and no chemotherapy (65±13; 78.2%), respectively. Within 1-year follow-up: about all patients were treated with ≥1 concomitant drug (mainly systemic corticosteroids); 29.6%, 12.5% and 47.8% of trastuzumab, another and no chemotherapy-treated cohort, respectively, were hospitalized; about all and 78.3% trastuzumab/another and no chemotherapy-treated patients, respectively, benefited from outpatient specialist care. Within 2-year follow-up: 87.4%, 37.5% and 21.7% of trastuzumab, another and no chemotherapy-treated cohort, respectively, survived; on average, the INHS spent €92,738 (vs €61,054 the first year), €17,048 (€18,829) and €1,656 (vs €7,033) per patient treated with trastuzumab, another and no chemotherapy, respectively.

CONCLUSIONS: Despite limitations due to the exclusive use of administrative healthcare data, a slightly underestimated prevalence of women with BC-HER2+ was found, and the high burden of this condition on the INHS, in terms of comorbidities and healthcare resource consumption and costs, was confirmed.