BACKGROUND: Cancer screening can reduce late-stage diagnoses, expand treatment options, and improve cancer outcomes. We modelled how introducing a multi-cancer early detection (MCED) screening programme in England could impact cancer treatment patterns. METHODS: The proportions of cancers (19 types, diagnosed 2014-2019) treated with resection, radiotherapy, and systemic anti-cancer therapy (SACT) were applied to modelled stage-specific cancer incidence data with and without addition of MCED screening to existing screening. We modelled an initial screening round (first screen for individuals aged 50-79 years) and a steady-state programme (annual screening from age 50-79 years). RESULTS: Assuming test parameters are accurate, if MCED screening is introduced in England, more cancers would require resection compared with current annual usage (steady-state: +8900, +10.0%). The number of cancers receiving radiotherapy would decrease overall (-1200; -2.0%) due to a decrease in palliative radiotherapy (-2100; -23.0%); the number of cancers treated with curative radiotherapy would increase slightly (+932; +2.1%). Fewer cancers would receive cytotoxic chemotherapy (-5300, -9.8%) and non-cytotoxic SACT (-530, -12.2%). Increased use of curative treatment combinations is also predicted. CONCLUSIONS: Changes to future service delivery and workforce planning will be needed for the full benefits of an MCED screening programme to be realised.