One In Five Cancers Is A Rare Cancer

The Take Home:

1-   One in Five Cancers Diagnosed in the United States is a rare type of cancer. This includes 20% of all cancers that are diagnosed.

2-  Rare cancers are diagnosed at later stages leading to poor quality of life and decreased survival.

3-  Research and treatments for rare cancers are lacking.


How rare are rare cancers?  According to a new report, published in CA: A Cancer Journal for Clinicians, a peer-reviewed journal of the American Cancer Society, in the United States about one in five cancer diagnoses is a rare type of cancer.  The report also finds that rare cancers account for more than two in three cancers occurring in children and adolescents. The authors of the report also said that the proportion of rare cancers is likely to grow as we increase the use of molecular markers to classify cancers.

Those of us who do have some type of rare cancer know that having one presents us with many additional challenges not faced by the “run of the mill cancer survivor."  These challenges affect both us, the cancer survivor, as well as our healthcare teams.  

For most rare cancers, research to identify the causes for our cancers or to develop strategies for their prevention or early detection is limited or nonexistent. Experience has also shown us that rare cancers are often very challenging to diagnose, often requiring us to make numerous visits to many different doctors.  We experience high rates of misdiagnoses, all leading us to have substantial delays in receiving a correct diagnosis. 

This problem is then made more significant because our treatment options are very limited and less effective than those available for more common cancers.  A search of the clinical trial databases clearly shows that there is significantly less research, including less pre-clinical studies and fewer clinical trials being run looking at rare cancers. 

These delays and our limited treatment options translate to our receiving a diagnosis with our cancers having progressed to later stages, increasing our symptoms and decreasing our survival. 

Those of us with rare cancers who do not live close to select high-volume cancer centers are often left without experienced healthcare professionals to treat us as well as not being able to access any of the limited numbers of trials that might be available.  

To better understand the actual burden of rare cancers,  Carol E. DeSantis, MPH, 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 181 rare cancers (defined as an incidence of fewer than 6 cases per 100,000 individuals per year) in the United States.

Their research concluded that approximately 20% of people diagnosed with cancer in the United States are diagnosed with a rare cancer. The researchers also found that rare cancers make up a larger proportion of cancers diagnosed in Hispanic (24%) and Asian/Pacific Islander (22%) patients compared with non-Hispanic blacks (20%) and non-Hispanic whites (19%). They also found that more than two-thirds (71%) of cancers occurring in children and adolescents are rare cancers compared with less than 20% of cancers diagnosed in people aged 65 years and older.

Among solid tumors, 59% of rare cancers are diagnosed at regional or distant stages compared with 45% of common cancers. Presumably, because of this later stage of diagnosis, the 5-year relative survival is poorer for people with a rare cancer compared with those diagnosed with a common cancer among both males (55% vs 75%) and females (60% vs 74%). However, the 5-year relative survival is substantially higher for children and adolescents diagnosed with rare cancer (82%) than for adults (46% for ages 65-79 years).

Rare cancers need to receive more focus.  We need to find ways to increase bench science research as well as later stage translational research.  The numbers of diagnosed rare cancers are significant (20% of those diagnosed), they are diagnosed at later stages, and we do not have adequate, proven and approved treatments. 

Discoveries about rare cancers should also provide us with insights and discoveries that will also advance our knowledge base about other cancers.   

Article: The burden of rare cancers in the United States, Carol E. DeSantis, MPH, Joan L. Kramer, MD, Ahmedin Jemal, DVM, Ph.D., CA: A Cancer Journal for Clinicians, doi: 10.3322/caac.21400, published online 19 May 2017.

Joel T. Nowak, MA, MSW wrote this Post.  Joel is the CEO/Executive Director of Cancer ABCs.  He is a Cancer Thriver diagnosed with 5 primary cancers - Thyroid, Metastatic Prostate, Renal, Melanoma and a rare cancer, Appendiceal Cancer.