First Report of National Estimates of the Incidence of Myelodysplastic Syndromes and Chronic Myeloproliferative Disorders from the U.S. SEER Program.

BACKGROUND: Incidence rates for myelodysplastic syndromes (MDS) and chronic myeloproliferative disorders (CMD) in the United States were unavailable prior to the addition of these stem cell malignancies to the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program and other central cancer registries in 2001. Description of national incidence rates for 2001–2003 will provide an important baseline for future studies of secular trends and allow for the examination of rates by selected demographic factors to define risk profiles of these malignancies in the American population.

METHODS: Incidence rates of MDS and CMD were calculated for 18 SEER areas between 2001–2003. These rates were stratified by disease subtype using the FAB classification (including chronic myelomonocytic leukemia [CMML]) with the addition of the WHO deletion 5q category, sex, age at diagnosis and race. Based on the observed SEER incidence rates, counts were estimated for the entire U.S. population.

RESULTS: In 2003, 2,538 cases of MDS and 1,421 cases of CMD were observed for all 18 SEER areas combined. Similar numbers of cases were observed in 2001 and 2002. Age-adjusted incidence rates for 2001–2003 were significantly higher among males than females for MDS (4.5 per 100,000 in males vs. 2.7 per 100,000 in females, p <0.0001) and CMD (2.4 per 100,000 in males vs. 1.7 per 100,000 in females, p<0.0001). This gender rate difference was observed consistently across all disease subtypes, including refractory anemia (2.0 per 100,000 in males vs. 1.2 per 100,000 in females (p<0.0001). Incidence rates were significantly associated with age at diagnosis for both MDS (p=0.01) and CMD (p=0.001), and were highest among White, non-Hispanics (2.4 per 100,000 for CMD; 4.2 per 100,000 for MDS). An estimated national total of 14,648 cases of MDS (including CMML) and CMD were diagnosed in 2003, with overall incidence rates for MDS and CMD of 3.1 and 1.9 per 100,000, respectively. The MDS incidence rate for the U.S. is remarkably similar to those previously reported from European countries including England and Wales (3.6 per 100,000), Germany (4.1 per 100,000), Sweden (3.6 per 100,000) and France (3.2 per 100,000). Estimated incidence rates in the U.S. were greater among men than women for all diseases, including CMML (0.40 per 100,000 in males versus 0.3 per 100,000 in females, p< 0.0001). Disease incidence increased with age for MDS, CMD, and CMML, although the increase was greatest for MDS, with an approximate five-fold difference in estimated rates for those diagnosed at ages 60–69 years vs. 80 years and older (7.4 per 100,000 vs. 36.3 per 100,000). The increase in MDS incidence with age was greater for males than females, whereas the age-related increase in CMD and CMML incidence was similar across sexes. Rates of CMD, MDS and CMML were all estimated to be highest among White, non-Hispanics.

CONCLUSION: Male sex and advanced age are important risk factors for the development of CMD and MDS. Diagnostic recording differences may underestimate the total annual U.S. MDS and CMD case burden. Future prevention intervention and disease causality studies of MDS and CMD should target high-risk groups.