TOKYO -- The National Cancer Center (NCC) on May 30 published for the first time a detailed estimate of cancer incidence among those belonging to the adolescent and young adult (AYA) generation aged 15-39.
The analysis, now available on the center's website, indicates that those in their 20s tend to develop ovarian or testicular cancer, while breast cancer is the most common form of the disease among those in their 30s.
It is the first time that such data has been released for the generation, for which there is a less sufficient support system in comparison to children aged 14 or younger, or for the middle-aged or elderly.
The estimate is based on data collected by 27 prefectures on local cancer patients from 2009 through 2011 that had been deemed to meet international precision standards and covered 36.8 percent of the total population of Japan. The center also updated data on children's cancers for the first time since 2007.
According to the analysis, some 21,400 people of the AYA generation were newly diagnosed with cancer per year over the three-year period. Incidence rates per 100,000 people by age group were 12.3 for children, 14.2 for ages 15-19, 31.1 for ages 20-29 and 91.1 for ages 30-39. Estimates on the number of diagnosed cancer patients nationwide per year is about 2,100 for 14 or younger, roughly 900 for ages 15-19, some 4,200 for those in their 20s and about 16,300 for those in their 30s.
The type of cancer with the highest incidence rate by age group was leukemia for children and those aged from 15 to 19. But the ratio of germ cell and gonadal tumors, such as ovarian or testicular cancer, doubled in the 15-19 age group, and topped the list for those in their 20s. Among patients in their 30s, there were more people with breast or cervical cancer, which are more typically seen among middle-aged or older women.
Kota Katanoda, chief of NCC's division of cancer statistics integration, says that he does not have a clear-cut answer as to why the types of cancer people tend to suffer differ by age. Still, he explained that those in their late teens and 20s are possibly affected by puberty.
"Those in their 30s perhaps see higher rates of developing breast cancer because of the influence of female hormones," he added.
(Japanese original by Kaori Gomi, Medical Welfare News Department)