Is there anything that can be done about neurofibromatosis? Either to slow or stop the growth of new tumors? Reduce the size of existing ones?

not usually. Many women with nf1 note increase in growth of preexisting tumors during pregnancy.Adults with nf1 acquire more tumors with age.Nfs develop gradually over time, may continue to grow in size for period of time.Nothing person can do to prevent. Nf. May be removed by surgery or occasionally by laser. If neurofibroma is removed, may or may not grow back.No effect by foods, smoking, caffeine or heat.
Depends. Neurofibromatosis is a systemic disease. If a neurofibromas is in a dicey location and can cause serious damage then sometimes chemotherapy is recommended if surgery is risky. Trouble some lumps can be removed surgically.