I don't know, all steroids surpress the immune system, which is needed to fight cancer. I believe this particular steroid is given because it reduces covid symptoms(especially lung inflamation).

Excert from following article: This drug works by dampening down the body's immune system. Moreover, it helps treat different diseases, including inflammation or swelling in the body, such as in allergic and asthmatic patients where inflammation is in the airways and lungs, or among patients with sore and inflamed joints (Jiang, K. et al., 2017).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7836247/
It's possible that curcumin far exceeds the anti-inflamitory powers of the steroid and it is proven to also strengthen the immune system. While organized medicine has resisted holistics, they are now realizing the need for it's power to heal.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8572027/

I should add that I tested positive for Covid after know exposure during my chemotherapy. After 5 days I tested negative and continued therapy. I have never had any Covid symptoms.