Drugs that reduce the symptoms but do not cure dementia were developed four decades after drugs that cure some cancers became available, the Alzheimer's Society said.
The charity called on global leaders to commit to driving forward research when they gather for the first G8 dementia summit.
Delegates at the event, which will be held in London on Wednesday, will discuss looking for effective therapies and new research as well as efforts to slow the impact of dementia.
An Alzheimer's Society spokesman said: "Just as President Nixon galvanised the world in 1971 with his war on cancer with the National Cancer Act, the charity calls for similar action to tackle the global dementia crisis."
Jeremy Hughes, chief executive of the charity, said: "The G8 summit could be the defining moment for dementia that people look back on many years in the future, as many do now for Nixon's declaration on cancer.
"It is shocking how dementia research is decades behind cancer.
"Currently there are six times more UK researchers working on cancer than dementia. Now is the time for action and for governments worldwide to step up and commit to a collaborative plan. Many cancers can now be cured, so it is time to find a cure for the millions living with dementia worldwide."
Prime Minister David Cameron said he wanted to use Britain's presidency of the G8 to encourage an international drive to tackle dementia.
Mr Cameron has said dealing with the condition is a personal priority and announced a UK plan on research, care and awareness last year. He has also said funding for dementia research will increase to around £66 million by 2015.
Dementia is a syndrome associated with continuing decline of the brain and its abilities. Current estimates say 35.6 million people globally live with dementia, including 800,000 in the UK.
With an ageing population, the World Health Organisation has estimated the number could reach 115.4 million in 2050. In the UK, there are likely to be nearly a million people with the condition by the end of 2020, experts have predicted.