Rates of Mantle Cell Lymphoma are Steadily Rising

Roxanne Nelson

July 09, 2008

July 9, 2008 — Over the past decade, the incidence of mantle cell lymphoma has been steadily increasing in the United States. According to a report published online July 9 in Cancer, the disease also occurs far more frequently within specific subgroups. White Americans, males, and people older than 50 years were found to have a significantly higher incidence of the disease.

The researchers also found that, in the majority of cases, mantle cell lymphoma was diagnosed at a late stage, and that there were considerable geographic variations in the incidence rate.

The overall incidence of non-Hodgkin's lymphoma (NHL) has been progressively rising, and is currently the fifth most common cancer in the United States. In 2007, there were an estimated 63,190 new cases and 15,280 deaths from NHL. Mantle cell lymphoma is an uncommon but distinct type of lymphoma, but it was not established as such until 1992.

Very little is currently known about the incidence of mantle cell lymphoma and its associated factors. In this study, researchers sought to examine the incidence of this disease since it was first recognized as a distinct lymphoma subtype, and to identify factors associated with incidence patterns. Michael Wang, MD, assistant professor of medicine at the University of Texas MD Anderson Cancer Center, in Houston, and colleagues used Surveillance, Epidemiology, and End Results (SEER) tumor registries to identify patients who had been diagnosed with mantle cell lymphoma between 1992 and 2004.

During this period, 87,166 patients were diagnosed with NHL; of this group, 2459 (2.8%) had confirmed mantle cell lymphoma. They noted that the age-adjusted incidence rate for mantle cell lymphoma was lowest in 1992 (0.27 per 100,000), and highest in 2004 (0.69 per 100,000), the last year for which data were available. The 2004 rate was nearly 2.5 times higher than the 1992 rate.

"The cause of this remarkable increase in the age-adjusted incidence rate in [mantle cell lymphoma] over a 13-year period is unknown," they write. The higher rate may not be due to improvements in detection or in the pathologic recognition, since the increase is primarily seen in stage 4 disease. The observed increase was also unlikely due to changes in the diagnostic criteria, as that remained relatively unchanged between 1992 and 2004.

In fact, the age-adjusted incidence rate for stages 1, 2, and 3 disease remained fairly consistent during the study period; annual percent changes were –3.06%, 2.31%, and 4.88%, respectively. For stage 4, the incidence showed a dramatic increase over time, with an annual percent change of 10.22%.

The increase in incidence was also more pronounced in men than in women. In 1992, the age-adjusted incidence rate was 0.34 per 100,000 for men and 0.21 per 100,000 for women; by 2004, this rate had significantly changed (1.01 per 100,000 for men and 0.44 per 100,000 for women). In 2004, the rate for men was more than twice that for women, and the steady rise in incidence observed over the 13-year period was mainly due to the increased rates in men. The annual percent change was 7.79% for men and 2.53% for women.

Incidence rates also increased with age, with the highest occurring in people older than 80 years. The annual percent change in patients 50 to 59 years, 60 to 69 years, 70 to 79 years, and older than 80 years was 4.73%, 7.65%, 6.41%, and 7.98%, respectively; the trend in incidence rates remained flat among people younger than 50 years.

The researchers also observed variations in race and geographic location. White Americans had a higher rate than any other race (0.61 per 100,000). The annual percent change from 1992 to 2004 was 6.31% for whites, but only 1.28% for blacks. The Seattle/Puget Sound area haad the highest rate (0.67 per 100,000), whereas Alaskan natives had the lowest incidence rate (0.10 per 100,000). Los Angeles, San Francisco–Oakland, Iowa, New Mexico, and Seattle also experienced a significant increase in the incidence of mantle cell lymphoma between 1992 and 2004.

The annual percent change for mantle cell lymphoma was 5.87%, which is higher than that for NHL (0.2%), diffuse large B-cell lymphoma (0.17%), and follicular lymphoma (1.23%). The mortality rate for mantle cell lymphoma also increased over time, indicating that despite the availability of numerous therapies, the outcome for this disease has not substantially improved.

The researchers note that although this current study demonstrates parallel curves for incidence and mortality, their data do not reflect the use of the newer, highly effective therapies that have become available since 2004. Mantle cell lymphoma has the worst prognosis of all lymphomas but, since 2004, new biologic agents have shown promise in more effectively treating this disease.

"Therefore, a better understanding of the epidemiology of mantle cell lymphoma, the development of novel agents, more research funding, and increased public awareness are all needed to change the natural history of mantle cell lymphoma," the authors write.

Cancer. Published online before print July 9, 2008

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