**5. Concluding Remarks**

Over recent years, the molecular mechanisms behind HFD-induced prostate cancer development and progression have been studied using pre-clinical models. Although several lines of evidence have proposed its relationship with potential mechanisms, such as growth factor signaling, lipid accumulation, inflammation, and endocrine modulation, the current data still remains inconclusive. In addition, the studies presented herein have used various types of models and diet sources, suggesting the need for increases vigilance when communicating and interpreting information. Therefore, it is important to consider the predictability and limitation of each preclinical model when translating experimental results into clinical practice. Although information from pre-clinical models remain important for deeper understanding and exploration of novel treatment targets, further studies are needed to validate the impact of dietary fat and obesity on prostate cancer development and progression.

**Author Contributions:** Conceptualization, Data collection and Writing—Original Draft Preparation, S.N.; Reviewing: T.N., H.S., M.H. and A.K. Writing—Review and Editing, T.H.; Supervision, T.I. and T.H.

**Acknowledgments:** This study was supported in part by research grants from the MEXT/JSPS (Kakenhi, 16H02679, 16K10992, 19K09663) and the Japan Agency for Medical Research and Development (AMED) (grant 18gm0710002h0706).

**Conflicts of Interest:** The authors declare no conflict of interest.
