Initial chemotherapy dose reductions and subsequent treatment delivery in stage I–IIIA breast cancer
Year: 2026
Type: article
Study design: Observational Study
Abstract: BACKGROUND: For most cytotoxic drugs, guidelines recommend body-surface-area-based dosing, yet some patients start with reduced doses, potentially reflecting tolerability concerns. The relationship between first-cycle dose reductions and subsequent delivery is unclear. METHODS: The authors analyzed data from women with stage I-IIIA breast cancer treated with adjuvant chemotherapy. Sankey diagrams illustrated trajectories from first-cycle dose proportion (FCDP) to average relative dose intensity (ARDI, ratio of received to expected dose intensity across the regimen), and cumulative dose proportion (CDP, ratio of total received to expected dose). Poisson regression estimated adjusted prevalence ratios for reduced FCDP (<95% vs. ≥95%) and three outcomes: ARDI reduction beyond initial FCDP, receiving fewer cycles, and CDP reduction beyond initial FCDP. Analyses assessed effect modification by age, body mass index (BMI), and comorbidities. Dosing was analyzed for cytotoxic and HER2-targeted therapy. RESULTS: A total of 8772 (90.8%) patients started with FCDP ≥95%; most maintained ARDI ≥95% (65.1%) and CDP ≥95% (79.9%). In multi-variable models, FCDP <95% was not significantly associated with further ARDI or CDP reductions or receipt of fewer cycles. BMI modified these associations (p-interaction = .004 for fewer cycles; p-interaction = .03 for CDP), with positive associations among overweight but not obese or normal-weight patients. FCDP <95% was linked to a lower likelihood of further ARDI reductions for both therapy types and lower likelihood of cumulative dose reduction in HER2-targeted therapy. CONCLUSIONS: Early dosing decisions shaped subsequent chemotherapy delivery. Most patients who began at full dose maintained consistent dosing, whereas early reductions did not stave off subsequent changes, underscoring the need to balance safety with adequate dose intensity.
Source: Cancer
DOI: 10.1002/cncr.70294
Authors: Maria J. Monroy‐Iglesias, Kelli O’Connell, Jenna Bhimani, Victoria S. Blinder, Rachael P. Burganowski‐Doud, Isaac J. Ergas, Grace B. Gallagher, Jennifer J. Griggs, Narre Heon, Tatjana Kolevska, Yuriy Kotsurovskyy, Candyce H. Kroenke, Cecile A. Laurent, Raymond Liu, Kanichi G. Nakata, Sonia Persaud, Janise M. Roh, Yashasvini Sampathkumar, Sara Tabatabai, Emily Valice, Peng Wang, Erin J. Aiello Bowles, Elisa V. Bandera, Lawrence H. Kushi, Elizabeth D. Kantor
Institutions: Memorial Sloan Kettering Cancer Center, Kaiser Permanente Washington Health Research Institute, Kaiser Permanente Northern California, University of Michigan, Michigan Medicine, Kaiser Permanente, Kaiser Permanente Vallejo Medical Center, Kaiser Permanente San Francisco Medical Center, Rutgers Cancer Institute
Language: English
Subfield: Cancer Research
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7131242293