Study Shows Significant Disparities in Worldwide Rates of Non-Hodgkin Lymphoma

A study exploring worldwide patterns of non-Hodgkin lymphoma (NHL) incidence and mortality in 2020 identified significant disparities between mortality rates in higher-income Western countries and those in low- and middle-income countries in regions of Africa, Western Asia, and others. The findings suggest access to diagnosis and treatment must improve to reduce NHL mortality on a global scale.

NHL comprises more than 60 types of immune system neoplasms, and known risk factors include infections, immunosuppression, high doses of radiation or chemotherapy, organ or stem cell transplantation, and autoimmune diseases. Patients living with HIV are more likely to develop NHL, and it is the most common AIDS-related cancer.

The new research, published in International Journal of Cancer, relied on estimates of NHL incidence and mortality from the GLOBOCAN 2020 database, which was developed by the International Agency for Research on Cancer and includes 185 countries.

“NHL is an important group of malignancies that are highly treatable and in part potentially curable, and assessing the worldwide burden is crucial for estimating the impact on the global and national health systems, advocating for the development of effective and equitable national cancer plans, and in developing directions for future research,” the authors wrote.

In 2020, there were an estimated 544,352 new cases of NHL diagnosed globally and an estimated 259,793 deaths. Of those cases, 24.9% were in Eastern Asia, 15.1% were in North America, and 9.7% were in South Central Asia.

As far as incidence, the rates were highest in Australia and New Zealand, North America, Northern Europe, and Western Europe, all of which had corresponding age-standardized rates (ASR) of incidence higher than 10 per 100,000 person-years. The highest mortality rates, however, occurred in African regions, Western Asia, and Oceania.

The lowest rates, all less than 4 per 100,000 person-years, occurred in South Central Asia for men, while women in South Central and Southeast Asia, Middle Africa, and Central America had the lowest incidence rates. Overall, males had higher rates of NHL than females.

Despite higher incidence rates in high-income regions, mortality was disproportionately high in lower-income regions of Africa, Western Asia, Melanesia, Micronesia, and Polynesia at more than 3 deaths per 100,000 person-years related to NHL. “The large variations and the disproportionately higher mortality in low- and middle-income countries can be related to the underlying prevalence and distribution of risk factors and to the level of access to diagnostic and treatment facilities,” the authors wrote.

In the highest-income countries, advanced treatments such as stem cell transplantation, immunotherapy, and targeted therapies have improved prognosis in recent years. The 5-year survival rate in these countries can be greater than 70%, while middle-income countries have an estimated survival rate of 30% to 50%; there are no population-based data on survival in low-income countries.

“The disparities in NHL incidence and mortality rates by world region and country in our study, where the highest mortality rates were observed in low- to middle-income countries, can thus mainly be attributed to inequalities in the health system and cancer care performance, as well as the availability of cancer diagnostic and treatment resources,” the authors wrote.

Despite its limitations, including differing quality of evidence between countries in the GLOBOCAN database, the findings reveal disparities between countries that must be addressed to improve NHL outcomes worldwide.

Reference

Mafra A, Laversanne M, Gospodarowicz M, et al. Global patterns of non-Hodgkin lymphoma in 2020. Int J Cancer. Published online June 13, 2022. doi:10.1002/ijc.34163