Our goal was to contribute as much as we could to the treatment effort, and so we focused on diet and rest.
Namely we removed all sugar and glutamine (animal products), and took care of all household tasks: cleaning, cooking, getting to appointments, etc.
Each cycle when we would get the blood test results we would add items to the diet to address any numbers that were falling.
For example, increasing iron, folate and b-complex rich foods like lentils to support platelet production.
There is a lot to be said about where chemo and radiation treatments are these days, and I am thankful for the medical interventions.
The drug treatment designed by the doctors, and our efforts at home, led to the tumor shrinking at such a rate that my family member is considered a statistical anomaly, and their blood protein markers are at below normal levels; down from 27x the normal level when we started treatment.
This book is a great resource: https://www.howtostarvecancer.com/the-book/
In addition to diet advice it also covers a lot of new or experimental treatments for nearly all cancers.
I truly believe diet can make a huge impact on addressing cancer.
Good luck.