he felt like "a million bucks" = he felt like he was equal to A LOT OF MONEY?
Context:
According to a family spokesman, the Senator told his wife shortly after the operation that he felt like "a million bucks", reported the Associated Press.
Malignant glioma are often fatal and occur in about 1 in every 9,000 people in the US.
Doctors have not said exactly what type of tumour Kennedy was diagnosed with, there have been media speculations that it is likely to be a glioblastoma multiforme, which is more prevalent in older people.