@melcanada
When considering complementary or alternative treatments, be open-minded yet skeptical. Learn about the potential benefits and risks. As per the disclaimer for Mayo Clinic Connect https://connect.mayoclinic.org/blog/about-connect/tab/disclaimer/
"All information shared by members on the Mayo Clinic Connect, such as messages, images, advice, URLs, and any other material, is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding your health. Never disregard professional medical advice or delay in seeking it because of something you have read on the community."

To help with your research, I found this article by a radiation oncologist who practising integrated cancer care in Australia. In particular, I think you may appreciate the studies she cites.
– Supplemental Mushrooms https://www.drcarolhaddad.com/blog/supplemental-mushrooms

One of my favorite websites for finding evidence-based info about herbs and supplements is Memorial Sloan Kettering Cancer Center (MSK) complementary therapies database:
– Search About Herbs (cancer specific) https://www.mskcc.org/cancer-care/diagnosis-treatment/symptom-management/integrative-medicine/herbs/search

Here's what they have on Chaga Mushroom https://www.mskcc.org/cancer-care/integrative-medicine/herbs/chaga-mushroom

Keep in mind that natural substances can also have toxicities, adverse side effects and treatment interactions.

Luckily, more and more cancer centers and oncology specialists are open to discussing and integrating complementary medicine. I hope your oncologist is someone with whom you can speak openly about your interest and use of integrative and complementary medicine. Does your cancer center have a integrative medicine department?

May I ask, what form is the Calcium in? I don't mean capsule or pill, but like Magnesium it may be Magnesium Oxide vs Magnesium Malate, Glycinate. Some are easier/harder on digestion, some absorb better and I believe some doesn't accumulate in arteries, etc... thanks much for any insight, etc.

All the best!