My beloved son-in-law died last week from a very aggressive liver cancer that spread to his kidneys. He was 55. Had one Novavax, which is not MRNA, so that probably did not cause cancer.
I'm sorry for your loss.
I didn't know anything about Novavax, so I searched for it. I'm not going to say that it does or doesn't cause cancers, but it does contain spike proteins. This is from the Yale Medicine page (yalemedicine.org):
How it works: Unlike the mRNA and vector vaccines, this is a protein adjuvant (an adjuvant is an ingredient used to strengthen the immune response). While other vaccines trick the body’s cells into creating parts of the virus that can trigger the immune system, the Novavax vaccine takes a different approach. It contains the spike protein of the coronavirus itself, but formulated as a nanoparticle, which cannot cause disease. When the vaccine is injected, this stimulates the immune system to produce antibodies and T-cell immune responses.