This study focuses on the numerical investigation of the cooling effect caused by blood vessels on magnetic nanoparticle hyperthermia (MNPH) therapy. The MNPH is simulated on the physical models constructed from DICOM images using the open-source 3D-Slicer software. The physical model comprises cancerous tissue, blood vessels, and surrounding liver tissue. Intratumoral injection of magnetic nanoparticles (MNPs) is used to deliver MNPs at the center of the tumor volume. MNPs, after injection, are considered uniformly distributed within 25% of the tumor volume. In order to perform the parametric study, the tumor's position with respect to the blood vessel is changed. For all cases, magnetic hyperthermia treatment is administered for the duration of 1 hour. The magnetic field parameters for MNPH are: frequency 150 kHz and magnetic field amplitude 20.5kA/m. The therapeutic effect is evaluated based on the percentage of tumor volume exceeding the therapeutic threshold temperature of 43°C. The results indicate that there is a significant increase in the cooling effect when the tumor is in close proximity to the blood vessel. This reduces the effectiveness of MNPH. However, this cooling effects diminish when tumor is away from major blood vessel.