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Delineating the age ranges used to define adolescents and young adults.

TO THE EDITOR: We were extremely pleased to see Journal of Clinical Oncology promoting awareness of the unique treatment issues that involve adolescents and young adults diagnosed with cancer by publishing an issue devoted to this topic on November 10, 2010. As noted in the overview by Thomas et al, this is an emerging field with implications for a broad array of health care providers and the health care system itself. Challenges particular to cancer outcomes in this group include biologic variation in tumors, treatment effectiveness and tolerance, adherence, fertility preservation, and early death. Because these challenges vary by age among adolescents and young adults, we were interested to note the substantial variability in the age ranges used by authors to define this group. A majority of authors adopted the strategy of describing ages in cited studies or reports without explicitly stating the age range they intended to address. Perhaps the best example of this was in the article by Veal et al, who described epidemiologic data consistently beginning at age 15 years but with varying cutoffs at ages 24, 29, and 39 years of age. These authors also presented a summary table of clinical pharmacology studies in adolescents and young adults in which participants’ ages ranged from 0.04 to 54 years. The authors of the overview described adolescents and young adults as “between the ages of 15 and 40.” Several authors explicitly stated age ranges. Butow et al adopted the World Health Organization definition of ages 12 to 24 years, whereas Wein et al and Ferrari et al described the age range as 15 to 29 years, with the possibility of including up to age 39 years. The challenge of defining age ranges for adolescents and young adults in the oncology context is not exclusive to the November 10, 2010, issue of JCO. The National Cancer Institute’s Adolescent and Young Adult Oncology Progress Review Group considered the issue carefully and focused their work on individuals diagnosed with cancer from ages 15 to 39 years. Yet a Surveillance, Epidemiology and End Results monograph about cancer epidemiology in adolescents and young adults published in the same year used a range of age 15 to 29 years. Other journals have feature issues that are similar to the November 10, 2010, issue of JCO, and have used a number of age ranges to describe the adolescent and young adult group. For example, in the May-June 2005 issue of Current Problems in Pediatric and Adolescent Health Care, the group was defined as “15 to approximately 30” years of age, although the only available survival statistics were from a group of patients who were 20 to 39 years of age. Professional organizations also differ; the Children’s Oncology Group’s Adolescents and Young Adults Committee defines the group as including age 15 to 29 years, whereasneedsofpatientsage15to39yearsareaddressed in the recently launched Focus Under Forty educational efforts of the American Society of Clinical Oncology and LIVESTRONG. Public data sources, clinics, and research studies vary widely in the age characterization of adolescents and young adults. Inconsistencies in defining an age range for adolescents and young adults are understandable given the realities of the complex biologic and psychosocial developmental processes experienced in the lengthy transition from childhood to adulthood in Western cultures. Treadgold and Kuperberg addressed this issue in the November 10, 2010, issue of JCO and noted that adolescents and young adults are not a “homogeneous entity.” They went on to point out the important differences in “lived experience” across the age span, which they define on the basis of emerging consensus as the “early teen years to the end of the thirties.” We sympathize with the challenges faced in defining appropriate age ranges for adolescents and young adults in the oncology context. Yet we also fear that failing to clearly delineate age ranges could be a substantial barrier to advancing clinical care and research for a population known to be at risk for poorer cancer outcomes than those diagnosed with cancer at younger or older ages. Thus, we urge that all communications from this emerging field explicitly define the age range being addressed and the rationale for that range. In addition to facilitating comparisons of clinical experiences and research findings from groups of adolescents and young adults, presenting a rationale for each age range selection will help identify situations in which the entire group can reasonably be considered together versus those in which narrower age ranges may be more appropriate. Without explicit age range definitions that are grounded in careful thought, progress in oncology care and research for adolescents and young adults may be slowed.