The study will be conducted in two phases, the initial Study phase to administer the radio-labeled 14C-eribulin and collection of PK samples, and the Extension Phase when the patients will continue to receive non-radio-labeled eribulin. In the initial Study phase, patients will receive a single 2 mg flat dose of 14C-eribulin (approximately 80 to 90 microCuries) administered on Cycle 1 Day 1 as an intravenous (IV) bolus injection or infusion over 2-5 minutes. Following this initial dose, patients will remain in the research unit until Day 8 to complete sample collections of urine, blood and feces for PK analysis and determination of 14C-eribulin concentrations between Days 1 and 8.