VDR and nephrolithiasis: Administration of vitamin D3 would supposedly stop stroma formation to make the PDAC more accessible for chemotherapy as well as high-dose vitamin C. To avoid kidney stones in combination with high-dose vitamin C, the cholecalciferol concentration should be checked at least every two months (target range 40–50 ng/mL) to rule out hypervitaminosis D. These effects could possibly be avoided with the alternative use of vitamin D receptor agonists.