Survival rates associated with blood cancers such as leukemia, lymphoma, and multiple myeloma have risen for patients of all ages in recent years, but this increase has been relatively smaller in adolescents and young adults—those aged 15-40—than in children and older adults. There are likely to be multiple reasons for this, researchers say, but at least part of the answer lies in the basic biology of tumors—differences in the genetic makeup of cancers in young adults that make such cancers less responsive to standard therapies.

In acute lymphocytic leukemia (ALL), researchers have recently identified a genetic subtype, known as Philadelphia chromosome-like (Ph-like) ALL, that becomes more prevalent with age and possibly peaks in young adulthood. and has a poorer prognosis in adolescents and young adults, says Daniel DeAngelo, MD, PhD, director of Clinical and Translational Research for the Adult Leukemia Program at Dana-Farber. Ph-like ALL has a pattern of gene activity similar to a subtype called Philadelphia chromosome-positive (Ph+) ALL.

In a study published in 2014, researchers profiled the genomic activity of tumor cells from 1,725 patients ages one through 39 with precursor B-cell ALL, the most common form of ALL involving B cells. The analysis showed that 294 of the patients had Ph-like ALL, and that its prevalence increased with age. Patients in the older age groups—adolescents and young adults—generally didn’t fare as well after treatment as younger patients did.

While it can be difficult to identify patients with Ph-like ALL, researchers hope to be able to develop targeted treatment strategies for this group of patients, DeAngelo says.

The trend of smaller survival improvements among adolescents and young adults is also evident in lymphoma. Since Hodgkin lymphoma, which is diagnosed in about 8,000 people every year in the United States, is primarily a disease of adolescence, it is difficult to compare treatment outcomes among different age groups, says Ann LaCasce, MD, MMSc, director of the Dana-Farber/ Partners CancerCare Fellowship Program in Hematology/Medical Oncology.

By contrast, non-Hodgkin lymphoma, which is diagnosed in about 70,000 people in the U.S. every year, occurs in all age groups. When it arises in young adults, it is often in a form known as diffuse large B-cell lymphoma, a particularly fast-growing, aggressive type of the disease. Children with non-Hodgkin lymphoma receive intensive therapy, usually with very good results, LaCasce remarks. In adults, treatment approaches vary depending on whether the disease is aggressive or highly aggressive.

While treatment outcomes are generally good for patients with lymphoma, much work remains to be done to better understand the underlying biology of the disease—specifically its genomic profile and interactions with the immune system—in adolescents and young adults, LaCasce says. Such knowledge will be key to developing more effective treatments.

This article was originally published on December 18, 2017, by Dana-Farber Cancer Institute. It is republished with permission.