Time to treatment initiation for breast cancer: A systematic review and meta-analysis of studies from 21 countries

Breast cancer is the most common cancer among women globally, accounting for one in four cancer cases and one in six cancer deaths. Timely initiation of treatment after diagnosis is critical to improving survival outcomes. However, delays in treatment initiation remain widespread, influenced by health system constraints, socio-demographic factors, and the COVID-19 pandemic. Despite growing recognition of this issue, no prior study has comprehensively quantified global evidence on diagnosis-to-treatment delays in breast cancer. Our objective was to systematically review and synthesize global evidence on time to treatment initiation (TTI) among patients with breast cancer, and to estimate pooled mean delays and the proportion of patients experiencing delays at predefined cutoffs (30, 60, and 90 days).

This systematic review and meta-analysis was conducted following PRISMA 2020 guidelines. Four databases (PubMed, Scopus, Web of Science, and Embase) were searched from inception to October 15, 2025. Eligible observational studies reported TTI as mean/median days or as proportions of patients with delayed initiation. Data were pooled using DerSimonian-Laird random-effects models. Subgroup analyses were performed by publication period, WHO region, study setting, and World Bank income group. A sensitivity analysis excluded United States datasets. Risk of delay was compared by stage at diagnosis. Risk of bias was assessed with the Joanna Briggs Institute checklist.

Sixty studies (analyzed as 62 datasets) involving 3644,548 breast cancer patients from 21 countries were included. The pooled mean TTI was 51.7 days (95% CI: 46.5-56.9; I² = 99.9%). At the 30-day cutoff, 37% (95% CI: 25-49%) of patients experienced delays; at 60 days, 17% (95% CI: 11-22%); and at 90 days, 4% (95% CI: 3-5%). The United States contributed 32 datasets and 70.1% of participants. Excluding these datasets raised the pooled mean TTI to 75.0 days (95% CI: 44.5-105.5). Mean TTI was 39.8 days in high-income countries and 79.7 days in low- and middle-income countries (p = 0.07). Delays beyond 90 days affected 2.6% and 26.5% of patients, respectively (p < 0.001). Stage at diagnosis was not associated with delay.

Delays between diagnosis and treatment initiation are common, with more than one-third of patients waiting over 30 days. The pooled estimate reflects mainly high-income settings. Delays are longer, and very long delays more frequent, in low- and middle-income countries, where evidence remains sparse. Agreed TTI benchmarks, stronger oncology services, and more primary studies from low- and middle-income countries are priorities to close the cancer care gap.