intermittent fasting and particularly long term fasting have shown to be particularly efficacious natural way to ward off cancer. On the diet piece Spirulina is a great food to act to any diet.

https://www.osher.ucsf.edu/patient-care/self-care-resources/cancer-and-nutrition/frequently-asked-questions/cancer-and-fasting-calorie-restriction/

https://www.cancertutor.com/spirulina-cancer-fighting-sea-algae/