Shortly after the powerful role that immunotherapies play in the battle against cancer were discovered, we are wowed by new findings almost everyday in the field. It is not surprising that the effect of human immune systems could have on tumors are influenced by many other factors, given the how complex the immune system is. (Cancer types, mutation rates/neoantigen loads of the tumors, gut µbiota of individuals, tumor intrinsic signatures all count here.) However, I'm surprised when two new studies simultaneously suggested that fasting/ calorie restriction is an influencer of immune surveillance. In the latest issue of Cancer Cell , Di Biase et al. and Pietrocola et al. both showed that mice undergoing calorie-restricted diet had improved tumor control performance compared with those that had normal food. Treating mice with calorie-restriction was even more effective when combined with traditional chemotherapies like mitoxantrone and doxorubicin. The finding stays true...