I thought throat cancer had a higher survival rate? (provided it hasn’t metastasized?)
It depends on what he means by "throat" cancer. If it's a head and neck cancer that's in his oropharynx area, there's a better chance of outcome than if it were in his esophagus.
At his age, he is also in a prime range for head & neck cancer from an HPV infection. The prognosis for this type of cancer is also 90% or better for a recovery.
If radiation is used, there's a chance his ability to sing could be affected for more than a year. Radiation is harsh, to this area of the body.