Prostate cancer that has become resistant to hormone treatment and that does not respond to radiation or chemotherapy requires new methods of treatment.

Most research on prostate cancer focuses on cure rates, but increasingly researchers are paying attention to the quality of a man's life after prostate cancer treatment.

According to NHK, Akihito, who was treated for prostate cancer in 2003 and underwent heart surgery in 2012, plans to make a formal announcement shortly.