Global Cancer Burden in Young Adults Differs From That in Other Age Groups

A new study published in The Lancet found that the global cancer burden among 20-39 year-olds differs from that seen in younger and older ages and varies by age, sex, developmental level, and geographic region.

While lower among this age group than in older ages, the burden of cancer affecting this age group has rarely been studied in depth.

“These cancers are a bridge between pediatric and adult oncology, and represent a distinct spectrum of disease among young adults who have a large proportion of their expected lifespans remaining, contribute substantially to the economy, and have an important role in caring for their families,” wrote the authors.

The study defined the years of young adult cancer between 20 and 39 years. The reason for this age range is its relation to biological and physiological maturity; patients have passed puberty but have not yet experienced effects of hormonal decline, immune response deterioration, or organ dysfunction associated with chronic health conditions.

The authors used global, regional, and country-specific data estimates of the number of new cancer cases and cancer-associated deaths in 2012 from the International Agency for Research on Cancer’s GLOBOCAN 2012.

The authors calculated age-standardized incidence and mortality rates (ASR) per 100,000 people per year at the global and country level. Case fatality, which measures the severity of a disease, was estimated by dividing the mortality ASR by the incidence ASR. To establish patterns in the cancer burden, the authors compared low-, middle- and high-income countries.

Results showed 975,396 new cases of cancer and 358,392 cancer-associated deaths. The disease was more common in women. The incident ASR was 43·3 new cancer cases per 100,000 people per year, and the mortality ASR was 15·9 cancer-associated deaths per 100,000 people per year.

The annual burden was significantly higher among young adults relative to children and adolescents, with 4 times the rate of new cancers and approximately 3 times the rate of cancer-associated deaths. However, the rates of cases and deaths were lower than that of middle-age and late-adulthood groups.

The most common types of cancer in new cases were female breast cancer, cervical cancer, liver cancer, leukemia, thyroid cancer, and colorectal cancer. For mortality rates in women, female breast cancer, liver cancer, leukemia, and cervical cancer were the most common contributors.

The burden of infection-associated cancers was greater in regions under transition, and cancer incidence was elevated in very high-HDI regions compared with low-HDI regions. However, the mortality burden was 3 times higher in low-HDI regions, which reflects differences in cancer profiles and inferior outcomes.

“Because young adult cancer patients exhibit a combination of features observed in younger and older patients, progress needs to be achieved through a combination of the methods that led to the improvements in these other groups,” concluded the authors.