Blood Cancer Among Arabs and Jews in the Middle East

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For years now, different rates of lymphoma among Palestinians and Israelis have been causing occasional blips on the radar in the coverage of lymphoma worldwide. Are the rates of lymphoma truly different between Israelis and Palestinians? If so what could account for these differences?

Non-Hodgkin Lymphoma Globally, and in Israel

The two main categories of lymphoma, a cancer of the lymphocyte-white blood cells, are Hodgkin lymphoma and non-Hodgkin lymphoma, or NHL.

Of the two, NHL is the more common, and that is the type of lymphoma discussed here.

NHL incidence rates have increased globally from 1950–2000, actually tripling in the over-65 age group. As reported in 2012, Israel had the unwelcome distinction of being first in the world in NHL incidence rates, where NHL is the fifth most common cancer in Israel. It was also reported that, on average each year, if you take 100,000 individuals, about 15.7 Jewish men and 11.8 Jewish women will develop NHL, while only 10.4 and 10.0 male and female Israeli Arabs, respectively, develop the disease. Though rates are lower among Israeli Arabs, if you look at Lebanon, which is in close geographic proximity to Israel, they are ranked second in the world in the highest rates of NHL, just behind Israel. The Palestinian Cancer Registry in 2014 reported that NHL was the seventh most common among West Bank Palestinian men and ninth among women.

Genes, Environment, and Risk of NHL

First of all, what caused rates of NHL skyrocket over the 50 years from 1950 to 2000? That is a question for which there are many different theories, however, to many researchers, the rise strongly suggests environmental factors. However, rates of certain types of lymphomas are also believed to vary with genes, family history, and ethnicity.

There is a particularly interesting situation with respect to Jewish Israelis and Arab Palestinians in that they represent genetically and culturally different populations living in very close geographic proximity. They share the same ecosystem, yet they have different lifestyles, health behaviors, and medical systems.

Noting this interesting mix, a group of researchers, Kleinstern and colleagues, set out to examine medical history, environmental and lifestyle risk factors for NHL—and specifically NHL that arises from B-lymphocytes, a common form of lymphoma in Israelis and Palestinians. They reviewed the pathology reports, and only patients with lymphomas that were positive for CD20 or other B-cell markers were included in their study.

Lymphoma in Israeli Jews and Palestinian Arabs

Findings from the study by Kleinstern and colleagues are some of the first to describe NHL patterns more specifically in this tiny, yet high profile corner of the world. In the United States, DLBCL is the most common lymphoma. The same is true for both Israeli Jews and Palestinian Arabs, however the distributions of each type of B-cell NHL are distinct.

There were three basic categories of B-cell NHL these researchers were looking at:

  • Diffuse large B-cell lymphoma (DLBCL)
  • Follicular lymphoma (FL)
  • Mantle zone lymphoma (MZL)

Looking at the pathology reports, researchers found that Israeli Jews had patterns that were similar to those typical of Western populations. In contrast, Palestinian Arabs had more DLBCL (71 percent), and higher proportions of DLBCL than in Saudi Arabia (51 percent) or Jordan (62 percent).

They also noted that Jordan’s population is similar genetically and culturally to the Palestinian Arabs, while a study in Lebanon—a country with high NHL rates—reported 44 percent DLBCL, which is more like the rates among Israeli Jews.

Gardening and Pesticides

Gardening as a hobby was linked to B-cell NHL and DLBCL only for Palestinian Arabs. More Palestinian Arabs gardened (47.7 percent) versus the Israeli Jewish population (36.7 percent). The authors noted that most West Bank homes have gardens, used mainly for fruit, olive trees and vegetables, and not for flowers or lawns, while the majority of Israeli Jews live in apartment buildings.

Oddly, gardening identified explicitly as “vegetable gardening” was linked to B-NHL and DLBCL, but only for Israeli Jews. The authors felt that gardening may reflect exposure to pesticides in both populations, but noted that other exposures, such as to UV radiation via sun exposure are also possible.

Bottom Line

This study was able to describe some of the differences between two populations living in close proximity to one another, and both genetic and environmental influences seemed likely to be in play, including infections, lifestyle, and family history exposures.

There was evidence to suggest that there may be significant differences in the causes of B-NHL lymphoma in these two populations.

However, one of the tangible successes of this investigation, in addition to its findings, was also undoubtedly the fact that it was conceived, planned and practically realized/achieved, which was captured succinctly by the authors in the paper’s conclusion:

“This study reflects a unique joint scientific effort involving Israeli and Palestinian investigators, and demonstrates the importance of cooperative research even in politically uncertain climates.”

Sources:

Kleinstern G, Seir RA, Perlman R, et al. Ethnic variation in medical and lifestyle risk factors for B cell non-Hodgkin lymphoma: A case-control study among Israelis and Palestinians. PLoS One. 2017; 12(2): e0171709.

World Health Organization.Globocan 2012: Estimated cancer incidence, mortality and prevalence worldwide in 2012, fact sheets by cancer.

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