Table 1 Patient data eligibility criteria

Inclusion criteria

 Aged ≥18

 Vitamin C deficiency (due to the underlying cancer disease or treatment)

 Previously confirmed cancer diagnosis with previous or current radiation- and/or chemotherapy

 Total lymphocyte count <1500/μL

 Treatment with iv vitamin C 7.5 g once a week, for a total of 4 doses

 Patient's statement of agreement to use and publish their data for the observational study

Exclusion criteria (anamnestic)

 Patients who received colony-stimulating factor

 Patients not completing all four doses of iv vitamin C

 Oxalate-urolithiasis, nephrolithiasis

 Renal insufficiency

 Iron-storage disease (thalassemia, hämochromatosis, sideroblastic anaemia)

 Erythrocytic glucose-6-phosphate-dehydrogenase-deficiency

 Pregnancy and lactation