Background Patients with potentially curable esophageal cancer can be treated with neo-adjuvant chemoradiotherapy followed by surgery or definitive chemoradiotherapy with curative intent. For frail older patients choosing the appropriate oncological treatment can be difficult, and data on geriatric deficits as determinants of treatment outcomes are not yet available. Objectives To describe the prevalence of geriatric deficits and to study their association with treatment discontinuation and mortality in older patients with potentially curable esophageal cancer. Material and Methods A cohort study was conducted in a Dutch tertiary care hospital including patients aged >= 70 years with primary stage I-IVA esophageal cancer. Geriatric screening and assessment data were collected. Outcomes were treatment discontinuation and one year all-cause mortality. Results In total, 138 patients with curable esophageal cancer were included. Mean age was 76.1 years (standard deviation 4.7), 54% had clinical stage III and 24% stage IVA disease. Most patients received neo-adjuvant chemoradiotherapy and surgery (41%), 32% definitive chemoradiotherapy and 22% palliative radiotherapy. Overall, one year all-cause mortality was 36%. Geriatric screening and assessment was performed in 94 out of 138 patients, of which 60% was malnourished, 20% dependent in Instrumental Activities of Daily Living (IADL) and 52% was frail. Malnutrition was associated with higher mortality risk (Hazard Ratio, 3.2; 95% Confidence Interval, 1.3-7.7)) independent of age, sex and tumor stage. Seventy-six out of 94 patients were treated with chemoradiotherapy, of which 23% discontinued treatment. Patients with IADL dependency and Charlson Comorbidity Index >= 1 discontinued treatment more often. Conclusion All-cause mortality within one year was high, irrespective of treatment modality. Treatment discontinuation rate was high, especially in patients treated with definitive chemoradiotherapy. Geriatric assessment associates with outcomes in older patients ...