Primary objective:
-To determine the effectiveness of patient controlled methylphenidate as compared to placebo for the management of cancer related fatigue as determined by the Functional Assessment of Chronic Illness Therapy (FACIT)-F Fatigue score
Secondary objective
* To assess the efficacy of as needed methylphenidate on pain, sedation and quality of life.
* To assess the potential side effects of methylphenidate on appetite, insomnia and anxiety
