The polyps are most likely caused by fungal candida and chronic inflammation. I had a patient who would 60 polyps removed each year. They did the Candida Plan and haven't had any polyps return since, and that was 20 years ago. They were able to restore their sense of smell, as well.
My sister had chronic sinus issues until doing the Plan, and others, too.
In 1999, researchers at the Mayo Clinic found that 96% off sinus infections were fungal.