A simulation model drawing on real-world data from Brazil’s public health system (SUS) estimates how many deaths from stage II-III HER2-positive breast cancer could be avoided if access were widened to two anti-HER2 therapies already used elsewhere: adjuvant T-DM1 and perioperative pertuzumab.
What was already known
Limited access to contemporary anti-HER2 therapies within Brazil’s public system may contribute to avoidable mortality among women with early HER2-positive breast cancer. Quantifying the impact of incorporating these treatments helps guide health-policy and resource-allocation decisions.
What this work adds
The authors developed a static decision-tree microsimulation model with an 8-year time horizon. The study population came from nationwide real-world data in the DATASUS system, which captures all patients treated within the SUS. Three strategies were compared: the current SUS standard (perioperative trastuzumab only); incorporation of adjuvant T-DM1 in patients with residual invasive disease after neoadjuvant therapy; and a gold-standard regimen including perioperative pertuzumab plus response-guided adjuvant T-DM1. Clinical inputs were drawn from the NeoSphere, APHINITY and KATHERINE trials, and a probabilistic sensitivity analysis with 100,000 simulations was performed.
Main results
A total of 22,432 women with stage II-III HER2-positive breast cancer were identified. The projected mean number of deaths at 8 years was 3,606 (95% CI: 3,082-4,180) under the SUS standard; 2,672 (95% CI: 2,244-3,147) with adjuvant T-DM1; and 2,390 (95% CI: 2,034-2,790) with the gold-standard regimen. Incorporating T-DM1 was associated with 934 fewer deaths (a 25.9% relative reduction), while full adoption of the gold-standard strategy was associated with 1,216 fewer deaths (33.7%).
What it means
The authors conclude that expanding access to adjuvant T-DM1 and perioperative pertuzumab within the SUS could meaningfully reduce mortality and narrow disparities in outcomes for Brazilian women with early HER2-positive breast cancer. These are modelled estimates — not observed counts — so the figures should be read as projections conditional on the model’s assumptions. The underlying message, however, is that gaps in access to treatment can translate into measurable gaps in survival.
Reference: Mattar A, Cavalcante FP, Correa-Netto NF, Silveira I, Pavanel EB, La Scala CSK, et al. Impact of anti-HER2 therapies on potentially avoidable deaths from stage II and III HER2-positive breast cancer in the Brazilian public healthcare system. The Breast, 2026. DOI/link
