Treatment
zaslal Frank (confidential) v Fórum Nemecko
He needs to get a visa first - depending on the duration of treatment most likely a tourist visa. He can apply for that at the German embassy.
Then he should contact suitable hospitals or sanatoriums and ask about available treatments and costs.
He'd have to finance his stay and treatment from his own pocket - temporary visitors are excluded from German health insurance, and international ones exclude pre-existing conditions.