Trends in use of magnetic resonance imaging and partial breast irradiation between 2011–2022 in the Netherlands: A population-based study

Purpose: This study aimed to investigate whether the introduction of partial breast irradiation (PBI) was associated with increased MRI use in the Netherlands from 2011 to 2022, and examined the impact of MRI on treatment and outcomes. Methods: Women aged ≥50 who underwent surgery (without preoperative systemic therapy) for cT1-2N0M0 breast cancer or DCIS between 2011 and 2022 were selected from the Netherlands Cancer Registry. Logistic regression was used to analyze associations between MRI and treatment or surgical radicality, stratified by tumour type. Subgroup analyses were performed in patients meeting ASTRO PBI criteria (unifocal cT1, grade 1/2, ER-positive, pure DCIS ≤ 2,5 cm). Results: Among 119,768 patients, 35,863 (30 %) received MRI, increasing from 24 % (2011) to 37 % (2022). PBI use increased from 3 % (2017) to 21 % (2022). MRI was not associated with the probability of receiving PBI (OR 0.98, 95 % CI:0.90–1.07). In patients with invasive breast cancer, MRI was associated with fewer DCIS-involved margins (OR 0.81, 95 % CI:0.74–0.89), but a higher probability of mastectomy (OR 1.29, 95 % CI:1.24–1.34). In patients with an ASTRO-defined PBI indication, MRI use was associated with a decreased likelihood of receiving PBI in invasive cancer (OR:0.66, 95 % CI:0.60–0.72) and DCIS (OR:0.80, 95 % CI:0.75–0.85). Conclusion: This study shows rising trends in PBI and MRI use in the Netherlands from 2011 to 2022. MRI reduced PBI eligibility and enhanced surgical precision by less involved margins in patients with cT1N0 breast cancer without PST.