Medication-Documented Systemic Anticancer Treatment in Colorectal Cancer: A Single-Centre Routine-Data Study

Background/Objectives: Real-world colorectal cancer (CRC) treatment is documented across multiple routine hospital data domains, which complicates interpretation of treatment-pattern studies. We characterised medication-documented systemic anticancer treatment patterns in CRC and evaluated the consistency of the routine data sources used to ascertain them. Methods: This retrospective observational study included 1310 encounters from 627 patients with C18—C20 diagnosis codes from 1 March to 30 April 2026. Semicolon-delimited medication entries were normalised to named agents. Patient-level medication-derived treatment patterns were characterised among 54 patients with at least one named antineoplastic documented during the fixed study window, without assuming representativeness of the full CRC-coded cohort; oral prescriptions were analysed separately as complementary evidence. Results: Twenty patients (37.0%) had cytotoxic component(s) only, 20 (37.0%) targeted/immune-checkpoint-inhibitor (ICI) plus cytotoxic components, 12 (22.2%) targeted/ICI components without cytotoxic co-documentation, and 2 (3.7%) other antineoplastic agents only. At the first treatment-documented encounter, 24/54 (44.4%) had at least two named antineoplastic agents co-documented. Thirty-three patients (61.1%) had medication-positive treatment documentation in at least two encounters, and 30/33 (90.9%) had the same documented class set across these encounters. Procedure- and medication-based indicators agreed in 890/891 interpretable encounters (99.89%; Cohen’s kappa 0.9953, 95% CI 0.9839–1.0000). Conclusions: Routine hospital medication data showed heterogeneous medication patterns among CRC-coded patients, frequently with multi-component and repeated documentation. Procedure and medication indicators share a hospital workflow; their near-complete concordance describes internal consistency and cannot exclude joint under-capture or establish clinical accuracy or treatment appropriateness.