How Common Is MDS in the US, and What Age Is Typical?

Overall, myelodysplastic syndrome (MDS) is considered a relatively rare condition in the general United States population, with an estimated annual incidence (number of newly diagnosed cases per year) of 4 to 5 new cases per 100,000 people ^[1][2]. MDS is primarily a disease of aging ^[2]. The typical age at diagnosis is in the 70s, with studies reporting a median age (meaning half of patients are younger and half are older) between 70 and 76 years old ^[2][3]. Because it is strongly tied to advancing age, the condition is very uncommon in children and young adults, but becomes much more frequent in older age groups ^[2].

Age and Sex Trends

While the overall incidence across all ages is low, the likelihood of developing MDS increases sharply as people get older. For people aged 65 and older, the incidence rate jumps to approximately 25 newly diagnosed cases per 100,000 people annually ^[2].

Reported incidence is also higher in men than in women. Men are diagnosed with MDS almost twice as often as women, with an overall rate of about 5.4 cases per 100,000 person-years in men compared to 2.9 cases per 100,000 in women ^[2].

Racial and Ethnic Patterns

Information from the Surveillance, Epidemiology, and End Results (SEER) program—a major US cancer registry system—shows that reported diagnosis rates vary across racial and ethnic groups depending on a person’s age:

• Older Adults: Among patients aged 50 and older, MDS is diagnosed more frequently in non-Hispanic White individuals than in non-Hispanic Black or Hispanic individuals ^[4].
• Younger Adults: In people under the age of 50, this trend is reversed in the SEER data. In this younger age group, non-Hispanic Black individuals had a 49% higher reported incidence rate than non-Hispanic White individuals ^[4].

It is important to understand that these statistics come from specific registry datasets and study periods. Differences in these numbers do not necessarily mean there are inherent biological differences in risk; they can also reflect variations in healthcare access, diagnostic practices, and population factors ^[4].

Why True Numbers May Be Higher

The official cancer registry numbers are generally considered a “lower bound” estimate, meaning the true number of people who develop MDS is likely higher than what statistics report ^[5][6]. Several factors contribute to this:

• Underdiagnosis and Mild Symptoms: Early MDS often has very mild symptoms (or no symptoms at all) and might only be noticed as low red blood cells (anemia), low white blood cells, or low platelets on routine blood work. Because mild anemia has many possible causes, and older adults often have other health conditions, some MDS cases may never be formally diagnosed ^[5]. Persistent unexplained low blood counts always require a clinician’s evaluation.
• Different Ways of Counting (Incidence vs. Prevalence): While incidence tracks new diagnoses, prevalence tracks how many people are currently living with the condition. When researchers looked at Medicare billing claims rather than official cancer registries, they estimated a prevalence of 75 to 162 per 100,000 older adults ^[6]. This claims-based estimate includes people living with the disease over a period of time and may include coding errors, so it cannot be directly compared to annual incidence rates ^[6].

• Reporting History: MDS has long been recognized as a disease, but the US did not officially require it to be tracked as a reportable cancer in registries like SEER until 2001 ^[5]. Consequently, historical tracking is limited compared to other cancers.
• Changing Definitions: The medical criteria used to define and code different subtypes of MDS frequently evolve as experts learn more about the genetics of the disease ^[7][8]. For example, a noticeable drop in reported new cases after 2010 was largely due to changes in how the condition was medically coded and defined in registries, not necessarily fewer people getting sick ^[1][9].
• Therapy-Related Cases: A small percentage of individuals develop therapy-related MDS, an uncommon classification that occurs after receiving specific types of cytotoxic chemotherapy or radiation therapy for an earlier cancer ^[10]. Changes in how these secondary cases are classified can also shift overall MDS statistics ^[10].

Demographics Alone Do Not Determine Your Outcome

While statistics can tell us who is most likely to develop MDS in a population, demographic trends do not dictate your personal prognosis. Age and overall fitness certainly influence which treatments you might tolerate (such as a stem cell transplant), but they do not determine the underlying biology of your disease.

To understand your unique situation, your medical team will look at the specific features of your disease: the percentage of immature cells (blasts) in your bone marrow, your specific chromosome changes, genetic mutations, and how low your blood counts are ^[11]. Doctors combine these factors using validated scoring systems like the IPSS-M (Molecular International Prognostic Scoring System) to accurately assess your risk and guide your personalized treatment plan ^[11].