A Study Highlights Genomic Differences Between Young-Adult and Older-Adult Cancers

A new study suggests that several genetic features may play a key role in identifying more effective treatment options for young-adult cancer patients (aged <50). By systematically comparing the genomes of 14 cancer types affecting both young and older adults, researchers concluded that younger patients with skin, colon, or other cancers may need treatments markedly different from those typically given to older patients.

Why Study the Genetics of Young- and Older-Adult Tumors?

According to at least two recent studies, cancer diagnosis rates are rising in young adults. However, as the authors of this study point out, much of what is known about treating different cancers is based on studies in older patients. This reliance on information from older cancer patients creates a clear knowledge gap that needs to be filled for younger patients. 

To address this, researchers compared genomic data from 14 tumor types in 1,757 adult patients younger than 50 with data from 3,608 patients older than 50.

The data came from The Cancer Genome Atlas, a project funded by the US National Cancer Institute. For each tumor, researchers systematically compared genetic mutations, chromosomal changes, tumor immune-system factors, and the potential to be treated with a known anticancer therapy. They then validated the results using additional samples from the International Cancer Genome Consortium.

- Related topic: Why are cancer rates increasing among young adults and adolescents?

Key Findings

Overall, the findings showed that each young-adult tumor type could be distinguished from its counterpart in older patients by a specific set of genomic markers.

For example, the relative frequencies of well-known mutations found in lower-grade gliomas varied considerably with patient age. In contrast, endometrial (uterine) tumors in young adults tended to have more mutations than those in older patients.

However, some common trends were seen across cancer types. Most importantly, the findings suggested that young adults’ immune systems responded differently to most tumors. This included responses from macrophages and dendritic cells, which are often used by anticancer immunotherapies.

Finally, the researchers examined treatments targeting the BRAF gene’s cancer-causing mutations and found several differences in how younger- and older-adult tumors might respond to different treatment options. For example, anti-BRAF drugs appeared more likely to provide effective treatment options for young adults with skin cancer than for older people with the same tumors. In contrast, older patients with colon cancer may benefit more from anti-BRAF treatment options than younger patients.

The authors made these findings accessible to other cancer researchers. They also plan to collaborate with others to test new ideas for fighting tumors in young adults.

At the Icahn School of Medicine at Mount Sinai, in the laboratory of Assistant Professor of Genetics and Genomic Sciences Kuan-lin Huang, a former graduate student, William Lee, led the study.