LAUSR

Creative Commons CC BY: This article is distributed under the terms of the Creative Commons Attribution 4.0 License (https://creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). Neoadjuvant therapy increases esophageal cancer survival.1 Data on oncological treatments in the Finnish Cancer Registry (FCR) are in research often used to estimate whether patients received neoadjuvant treatment or not. Nordic national registry data are generally valid,2,3 but no studies on using oncological treatment data in the FCR to estimate neoadjuvant treatment exist. The aim was to evaluate the completeness and concordance of FCR data, compared with neoadjuvant treatment according to patient records. This population-based nationwide study in Finland included all patients undergoing esophagectomy for cancer during 2010 to 2016. The ethical committee in Northern Ostrobothnia (EETMK 115/2016), and other relevant bodies and agencies approved the study.4 The FCR maintains an accurate national registry of all cancers in Finland.5 Oncological treatments in the FCR by modality are reported with specifications: “curative, palliative, or unclear intent” and “under or over 4 months from diagnosis.” Whether each modality is neoadjuvant or adjuvant therapy is not specified. Patients receiving any oncological treatment during 4 months from diagnosis in FCR were classified neoadjuvant treated, as all underwent surgery. Neoadjuvant treatment modalities were classified into (1) chemotherapy, (2) radiotherapy, and (3) chemoradiotherapy. The Finnish National Esophago-Gastric Cancer Cohort (FINEGO) was the “gold standard” comparison, described in detail elsewhere.4 The main variable of interest was neoadjuvant therapy (yes/no). Second, modalities were assessed separately. Positive predictive value (PPV), concordance, and completeness were calculated. Of the 562 patients who underwent esophagectomy, 555 (98.8%) had patient records available. Cancer registry record was found for 488 (86.8%) patients. Of the 562 patients, 241 (42.9%) were excluded due to missing FCR data, resulting in 321 (57.1%) patients with complete data on received neoadjuvant treatment. For neoadjuvant treatment modality, there were 306 (54.4%) patients with complete data. The proportions of received neoadjuvant therapy were similar between included patients and those with missing FCR data. For those with FCR record, oncological treatment data completeness was 65.8%. PPV and Research letter: Oncological treatment reported by the Finnish Cancer Registry compared to given neoadjuvant treatment in patients undergoing esophagectomy for cancer—A nationwide study