Is there any way to cure ethnoidal nasal polyps other than surgery?

Polyps: depending on the extent of the polyps, some medical treatments may work. Such as sterodi saline sinus rinses, anti inflammatory medications, etc. if you have nasal allergies, it may be worth it for you to consult one and treat them as it amy diminsih their recurrence

Agree: with Dr Mumneh, will add that leukotriene modifying agents are particularly effective. In certain cases, "aspirin desensitization" therapy works wonders. Before using the intranasal steroids, sometimes oral/systemic steroids are given to get more immediate control. Note also the polyps typically recur after surgical removal (unless medically treated)