Rare Cancers Present Unique Challenges

teen girl in head scarf lies in hospital bed and talks to nurse

About 1 in 5 cancer diagnoses in the US is for a rare cancer, according to a report prepared by American Cancer Society researchers. The report defines rare cancer types as those diagnosed in fewer than 6 cases per 100,000 per year. The report was published May 19, 2017 in CA: A Cancer Journal for Clinicians, a peer-reviewed journal of the American Cancer Society.

“Cancer is always difficult, but being diagnosed with a rare cancer presents additional challenges,” said Carol E. DeSantis, MPH, lead investigator of the report and American Cancer Society Director of Breast and Gynecological Cancer Surveillance, Intramural Research. “It’s challenging for patients and their families to find information and support when the doctor is uncertain what kind of cancer you have.”

As a group, rare cancers are more difficult to diagnose than common cancers and often involve numerous physician visits and misdiagnoses while the more common causes for symptoms are ruled out. As a consequence, they are more likely to be diagnosed at later stages, which can make them even harder to treat. In addition, treatment options for rare cancers are often more limited and less effective than for common cancers. This is partly because there is less clinical research and fewer clinical trials for rare cancers, as it is harder to enroll enough people for a study.

There is also limited information published about the burden of rare cancers in the US. Authors of the report used data from the North American Association of Central Cancer Registries and the Surveillance, Epidemiology, and End Results (SEER) program to comprehensively examine contemporary incidence rates, stage at diagnosis, and survival for more than 100 rare cancer types.

Rare cancers in young people

The proportion of rare cancers is greater among children, adolescents, and young adults. Rare cancers account for most of the diagnoses (71%) in those aged younger than 20, and 39% of the diagnoses in those ages 20 to 39. Rare cancers accounted for about 17% to 20% of cancers diagnosed in adults ages 40 and older.

Five-year relative survival is significantly higher among children, adolescents, and young adults with rare cancers (about 80%) than among adults ages 40 and older with rare cancers (60% or less). However, patients with a rare cancer diagnosis have poorer survival than those with a common cancer diagnosis across all age groups.

Reducing the burden

“Continued efforts are needed to develop interventions for prevention, early detection, and treatment to reduce the burden of rare cancers, write the authors. “Such discoveries can often advance knowledge for all cancers.”

Strategies to enroll more people in clinical trials include international collaboration and changes in study designs that would maximize findings with smaller numbers of patients. In 2011, the International Rare Cancers Institute was established as a joint initiative among research institutes in the US, Europe, and Canada. In 2014, the National Clinical Trials Network was launched in the US with a focus on the study of rare cancers. 

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

The Burden of Rare Cancers in the United States. Published May 19, 2017 in CA: A Cancer Journal for Clinicians. First author Carol E. DeSantis, MPH, American Cancer Society, Atlanta Ga.


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