Aging societies, especially in rich countries, and improved diagnosis and treatment are boosting both the absolute number of older cancer patients as well as their proportion of all victims of the disease.
"There are not enough healthcare professionals who have skills and knowledge in both cancer and the best care and treatment for the elderly," Kathy Redmond, editor of "Cancer World", told the European Cancer Conference meeting this week in Barcelona.
In the three decades to 2030, according to the World Health Organisation (WHO), the number of persons with cancer aged 65 or older will have doubled.
"There is still far too much complacency on this issue," she told AFP, describing the impending explosion of aged cancer patients as a "time bomb."
New cancer cases around the world are expected to increase from 10.9 million in 2002 to about 16 million in 2020, according to the WHO, with the corresponding deaths per year jumping from 6.7 million to 10.3 million.
The elderly, Redmond told AFP, face a host of health problems specific to advanced age.
Non-adherence to oral, long-term cancer therapies, for example, is emerging as a significant problem in oncology.
"There's an enormous lack of awareness about the scope of non-compliance in cancer," she said. "The elderly are at higher risk because they are more likely to have literacy and memory problems, and less likely to receive comprehensive information about their treatment."
More and more of the elderly, living in isolation, are likely to lack the social networks -- family and friends -- that can help ensure that drugs are properly taken, she added.
By 2050 Europe will have twice as many persons 65 and older as children 15 and under, she said, citing United Nations figures.
Another problem facing older cancer patients is what Redmond calls "ageism."
"There is a problem with persistent negative attitudes toward the elderly," resulting in less than optimal care," she said. "Under-treatment and sub-optimal practices mean that otherwise healthy older cancer patients are dying unnecessarily."