Since the 21st century, the aging of the population began
to accelerate. Although the aging of the population is still
concentrated in developed countries,many developing countries
have entered the era of an aging population. The United
Nations predict that population aging will occur mainly in
developing countries in the next 35 years [1]. The World
Health Organization (WHO) categorized 60–74-year-olds as
the younger elderly, 75–89-year-olds as the elderly, and ≥90-
year-olds as elderly elderly or macrobian elderly, while the
National Comprehensive Cancer Network (NCCN) defined
the 65–75-year-olds as the younger elderly, 76–85-year-olds
as the elderly, and >85-year-olds as themacrobian elderly