OBJECTIVES:Cancer in young adults represents a great challenge, both biologically and socially, and understanding the unique characteristics of neoplasms in this age group is important to improving care. We aimed to evaluate the most common carcinomas and their characteristics, such as histological type and clinical stage, in young adults in the largest cancer hospital in Latin America.METHODS:The hospital registry was consulted for the period between 2008 and 2014. Young adults were defined as individuals aged 18 to 39 years, and older adults were defined as individuals aged 40 years and older. Differences between age groups were assessed through chi-square tests.RESULTS:Of the 39,389 patients included, 3,821 (9.7%) were young adults. Among the young adults, the most frequent cancer types were the following: breast, lymph node, colorectal, thyroid, testicle, hematopoietic and reticuloendothelial, uterine cervix, brain, soft tissue and stomach; these sites accounted for 74.5% of the observed tumors. Breast, colorectal and stomach cancers were more frequently diagnosed at advanced stages in young adults than in older adults (p<0.001). The most common histological types were infiltrating ductal carcinoma (86.12%) for breast cancer, adenocarcinomas not otherwise specified (45.35%) for colorectal cancer, squamous cell carcinoma not otherwise specified (65.26%) for uterine cervix cancer, signet ring cell adenocarcinomas (49.32%) for stomach cancer and adenocarcinomas not otherwise specified (50.79%) for lung cancer.CONCLUSION:Young adults are diagnosed with cancer at more advanced stages, indicating that health professionals should be aware of cancer incidence in this age group. It is necessary to develop a better understanding of cancer in young adults and to implement dedicated health care strategies for these patients.