“…The GPU implementations of discrete/continuous models, such as the particle automata model (PAM) (Panuszewska et al, 2018; Wcisło et al, 2013; Worecki and Wcisło, 2012) and agent-based models (Jagiella et al, 2017; Wang et al 2015a, 2015b; Zhang et al 2011), where the tissue is represented by the cell–cell interactions while oxygen, tumor angiogenic factors (TAF), and nutrients concentrations are calculated by integrating reaction–diffusion equations, allow us for simulating rather small tumors in a mesoscopic scale, that is, a few millimeters in diameter. As shown in Jagiella et al (2017), the evolution of N = 10 6 cells (tumor and healthy ones) in 3-D involves 3–4 days of CPU time (5–6 min on HPC cluster with 1000 CPU cores (Jagiella et al, 2017)).…”