ritallin mayhy impreove more severe fatigue in those with more advanced disease
 

from medscape:
The stimulant methylphenidate does not significantly decrease cancer-related fatigue, according to the results of a phase 3 study published online July 12 in the Journal of Clinical Oncology.

However, the drug was more beneficial than placebo to patients with more advanced fatigue and/or more advanced disease, but these findings of a benefit came from a subset analysis within the study and therefore are not fully proven.

Methylphenidate, which is marketed as Ritalin, among other trade names, is approved by the US Food and Drug Administration for the treatment of attention deficit hyperactivity disorder and narcolepsy.