# Age‐Specific Trends in Carcinoma Incidence Among Adolescents and Young Adults in the United States, 1975–2021

## TL;DR

Carcinoma rates are rising among U.S. adolescents and young adults, especially in those aged 15–19, highlighting a need for further research into causes and prevention.

## Contribution

This study reveals detailed age- and sex-specific trends in carcinoma incidence among adolescents and young adults in the U.S. from 1975 to 2021.

## Key findings

- Carcinoma incidence increased by 0.61% per year in adolescents and young adults (15–39) from 1975 to 2021.
- The largest relative increase occurred in adolescents aged 15–19 (1.66% per year).
- The rise in carcinoma incidence was observed across all 5-year age groups and both sexes.

## Abstract

The incidence of carcinomas among adolescents and young adults (AYAs; ages 15–39) is rising. However, most research treats AYAs as a single group, potentially obscuring important age‐ and sex‐specific trends. This study examined long‐term trends in carcinoma incidence among AYAs in the U.S., overall and by 5 year age groups.

We conducted a population‐based, retrospective time‐series analysis using data from eight U.S. cancer registries in the Surveillance, Epidemiology and End Results database. The study included 128,255 AYAs diagnosed with malignant carcinoma between 1975–2021. Average annual percent change (AAPC) in incidence rates was estimated using Joinpoint regression, stratified by age, sex, and carcinoma subtype.

A total of 128,255 individuals, aged 15–39, who were diagnosed with carcinoma between 1975–2021; 77.5% of AYA carcinoma cases occurred in females. The overall incidence of carcinomas increased by 0.61% (CI: 0.43–0.80) per year in AYAs from 1975 to 2021, with similar increases observed in females (AAPC: 0.68%; 95% CI, 0.50–0.87) and males (AAPC: 0.71%; 95% CI, 0.45–0.97). When stratified by age group, overall carcinoma incidence increased in each 5‐year group; the largest relative increase was in those aged 15–19 (AAPC: 1.66%; 95% CI, 0.71–2.62) and the smallest was in those aged 35–39 (AAPC: 0.48%; 95% CI, 0.22–0.74).

Carcinoma incidence is increasing in the AYA population within each 5‐year age group, including among adolescents, a group in which these cancers have historically been rare. These findings highlight the urgent need to investigate the causes of this increase to guide targeted prevention and early detection efforts.

This study analyzed long‐term trends in carcinoma incidence among U.S. adolescents and young adults (ages 15–39) using cancer registry data from 1975 to 2021. The study found that carcinoma incidence increased steadily over time in both males and females and across all 5 year age groups, with the largest relative rise among adolescents aged 15–19. These findings point to the need for research on the causes of this increase to inform prevention and early detection strategies.