There were over 5,500 cancellations at Regional Hospital Mullingar according to CHI.
Claims that 800 chemotherapy appointments for children and young people were cancelled last year are being disputed.
The Sinn Fein leader Mary-Lou McDonald told the Dail yesterday a 250,000 hospital appointments were cancelled in 2023, including the chemo sessions for children.
That figure also includes over 5,500 cancellations at Regional Hospital Mullingar last year.
However Children's Health Ireland says the majority of those cancellations were made for 'patient specific reasons' based on 'clinical decisions'.
These include a patient being too unwell or no longer needing the treatment.
Sinn Fein's Health Spokesperson David Cullinane says concerned CHI is now challenging the data it provided to the HSE.
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