Young Americans with cancer have a far better prognosis than once thought due to a surprising new discovery about the role of HIV/AIDS, fundamentally altering a longstanding narrative about their cancer mortality, according to new findings by USC scientists.

For decades, some researchers believed cancer survival rates were dismally low among adolescents and young adults in the United States. But a review of long-term data by researchers at the Keck School of Medicine of USC and the Los Angeles Cancer Surveillance Program shows that 15- to 39-year-olds had the best survival of any age group for many years, and maintained that lead until pediatric cancer survival caught up.

That fact shows clearly once the rise and fall of HIV/AIDs-related cancers are considered—a re-evaluation not done before. The findings appear in the Oct. 15 Journal of the National Cancer Institute.

“Those earlier statistics were not wrong. They just weren’t re-examined until now,” said senior author Dennis Deapen, director of the Los Angeles cancer registry and a professor of clinical preventive medicine at the Keck School of Medicine. “We need accurate cancer survival statistics to evaluate treatment results and set clinical guidelines and research priorities. When we talk to patients, we want to provide hope, backed by data.”

Young adults’ cancer survival rates: A puzzle solved

Pediatric cancer is considered a medical success story, with survival rates soaring from 20% to 80% in recent decades. In contrast, survival for 15- to 39-year-olds with cancer took a disturbing dip between 1975 to 1997, which puzzled scientists for many years.

The new analysis adjusts for Kaposi’s sarcoma and lymphomas, which were a consequence of the HIV/AIDS epidemic in the United States in the 1980s and 1990s, before the widespread availability of antiretroviral therapy.

Overall, 5-year survival for all cancers among children and adolescents and young adults is now 80%.

The USC analysis concurs with a 2014 National Cancer Institute report concluding that young people with cancer have generally good outcomes because of their better overall health, greater ability to recover from cancer treatment, and lower mortality from other causes, compared to older adults.

Young people with cancer face difficulties

About 70,000 adolescents and young adults are diagnosed with cancer in the United States every year. Researchers caution that this group still faces a host of unique challenges, including later diagnosis, difficulty accessing treatment, low participation in clinical trials, and psychosocial after effects.

“It’s exciting to have some good news come out of the cancer surveillance data,” said Lihua Liu, an associate professor of clinical preventive medicine at USC and the study’s lead author. “Our findings confirm the importance and benefit of cancer research and accessing cutting-edge treatment. It highlights the need for research of adolescent and young adult survivorship and their psychosocial challenges.”