Real-world patient-reported outcomes in stage II/III rectal cancer in the Netherlands.

65Background: In a real-world (RW) study, tumor characteristics and outcomes differed between patients (pts) with mismatch repair deficient (dMMR) and proficient (pMMR) stage II/III rectal cancer (RC) from the Netherlands¹. To address the scarcity of quality-of-life (QoL) data, particularly for dMMR RC, longitudinal patient-reported outcomes (PROs) from this study are presented. Methods: We retrospectively analyzed pts with stage II/III RC and known MMR status treated during 2015–2022 from the Netherlands Cancer Registry and Prospective Dutch Colorectal Cancer cohort. QoL (EORTC-QLQ-C30/CR29), fatigue (MFI-20), and work ability index (WAI) PROs were collected pre-treatment (tx; baseline [BL]) and at 3, 6, 12, 18, and 24 months (mo) post-BL. High C30 and WAI scores indicate better functioning; high CR29 and MFI-20 scores indicate worse symptoms/fatigue. Results: Of 7937 eligible pts, 1313 had ≥1 PRO (dMMR 21/182 [12%]; pMMR 1292/7755 [17%]). Pt and tx characteristics were comparable between the PRO and overall cohort, but the PRO cohort had better WHO performance status (0: 78% vs 68%), with less advanced stage (cT4: 11% vs 15%). For both, most pts received neoadjuvant tx and resection (68% vs 61%). PRO data are shown in the Table. Overall, QoL decreased during the first 12–18 mo of tx before returning to BL levels. PRO data from dMMR pts were too limited to study whether mean QoL and trends over time differ from pMMR pts. Conclusions: This is the first study to assess RW PROs over time in this pt population by MMR status. While numbers of dMMR pts were low, these findings are relevant to the QoL of pts with stage II/III dMMR and pMMR RC, particularly the QoL decline up to 18 mo after initiating tx. These analyses suggest QoL is driven by disease and tx rather than MMR status, as similar trends were observed. 1. Lunenberg R, et al. Int J Cancer 2025 [in print]. Funding: GSK.