The incidence of cancer increases with advanced age. Unfortunately, there is a significant lack of evidence regarding the safety and efficacy of treatments. The oncology community also lacks information regarding which older patients are most likely to benefit from treatment without undue toxicities. Interventions to lower symptoms and reduce long-term complications from cancer and cancer treatment in older patients are urgently needed. Establishing research priorities in geriatric oncology could help guide researchers and focus efforts on interventions that have the highest likelihood of improving outcomes. The Cancer and Aging Research Group, in partnership with the National Institute on Aging and National Cancer Institute, held linked conferences as part of a U13 grant in September of 2010 and November of 2012, summarising the gaps in knowledge in geriatric oncology and recommending ways to close these gaps. The overall purpose of this review is to highlight the important research priorities in geriatric oncology from the literature and from the previous U13 meetings. More evidence regarding the treatment of older cancer patients is urgently needed given the rapid aging of the population.