BETHESDA, MD—A new report revealed a possible link of industrial solvents or benzene to hematopoietic cancers, specifically hairy cell leukemia.
The article in Military Medicine sought to inform clinicians of the updated epidemiology with regard to clinical findings for HCL.1
Uniformed Services University of the Health Sciences-led researchers explained that the industrial solvents benzene and trichloroethylene (TCE) are known carcinogens and had contaminated the drinking water at Marine Corps Base Camp Lejeune, NC, from the 1950s to 1980s.
“Benzene and TCE are linked to the hematopoietic cancers acute myelocytic and lymphocytic leukemia and chronic lymphocytic leukemia,” the authors pointed out. Now, they reported the case of a veteran stationed at Marine Corps Base Camp Lejeune during this period who developed HCL, a rare form of lymphocytic leukemia.
The report reviewed his presentation, medical history, solvent exposure and literature on the carcinogenicity of benzene and TCE, with researchers suggesting this patient represents a possible link of TCE or benzene to HCL. The case also informs clinicians of the updated epidemiology with regard to clinical findings for HCL.”
HCL is an uncommon indolent malignancy of B cells that accounts for 2% of all leukemias, according to background information in the article. It added that clonal B-cell lymphocytes develop BRAF-V600E kinase-activating mutations that cause rearrangements of immunoglobulin genes that infiltrate the reticuloendothelial system.
Classical presentation of HCL includes pancytopenia, aplastic anemia, large mononuclear cells with cytoplasmic projections, and splenomegaly, according to the study team, which added, “Etiology is unclear, though suggestions include occupational and environmental exposures.”
At the same time, the authors discussed the carcinogenicity of several industrial solvents, including benzene and trichloroethylene (TCE). In an International Agency for Research on Cancer (IARC) report, benzene and TCE demonstrated sufficient evidence that they are linked to carcinogens in humans and animals. The article added that human exposure is largely through water sources and in occupations, including dry cleaning, metalworking and construction.
HCL has a median age of onset of 55 years and is three to four times more likely in males, according the authors, with genetics playing little role in the disease. The leukemia has a higher incidence among Caucasians and lower incidence among Asians, Africans and Arabs.
While occupational and environmental risk factors with regards to HCL are still unknown, there appeared to be a link with exposure to cattle farms, pesticides, petroleum products and ionizing radiation, researchers wrote.
In the case presented in the report, the patient is a 59-year-old male veteran with a history of Type II diabetes mellitus, hypertension and a current smoker who presented to establish care. He reported three months of fevers, chills, drenching night sweats, general malaise and fatigue. The patient’s medical exposure history for smoking is significant—a current smoker at half-pack/day with a 40 pack-year. The patient also served in the military at Marine Corps Base Camp Lejeune for five years in the 1970s, although he denied work on farms, with pesticides or petroleum products and radiation work.
“Our patient’s history was negative for these exposures, though he reported a work history as a plumber. He denied exposure to industrial solvents in his workplace,” according to the study. B-cell malignancies as a whole are linked with exposure to pesticides, herbicides and organic chemicals.
The authors noted that HCL classically presents with splenomegaly and hypocellular bone marrow on aspirate, adding, “His lack of splenomegaly is becoming more common owing to early diagnosis with hematologic studies. Peripheral lymphadenopathy is uncommon, and abdominal lymphadenopathy correlates with duration of disease. Atypically, this patient has a considerable tobacco history of 40 pack-years, and HCL has an inverse relationship with smoking.”
What is mysterious, they said, is that, despite benzene and TCE’s known carcinogenicity, there is no known link between HCL and these solvents. The article pointed out that a single study of the affected Camp Lejeune population showed an increased incidence of leukemia, which was extracted from death certificates of the residents but included no HCL codes.
“Of note, this study showed a hazard ratio for hematopoietic cancers of 1.05 with upper confidence limit, lower confidence limit, and P-values of 0.82, 1.33 and 0.57, respectively,” the authors advised. “More recent studies show declines in B-cells with exposure to benzene and TCE.”
“HCL is an uncommon indolent B-cell malignancy with possible exposure links to cattle farms, pesticides, petroleum products and ionizing radiation,” the researchers concluded. “There is no known link between HCL and industrial solvents, but data on this topic are sparse. This case of a veteran with HCL exposed to drinking water contaminated with these solvents presents a possible link. Further study is needed to determine environmental and occupational exposure risk factors in HCL.”
- Green-Lott AM, Singaraju R, Liu ML, Ascensao J. Hairy Cell Leukemia and Ground Water Contamination With Industrial Solvents: a Case Report. Mil Med. 2020 Aug 14;185(7-8):e1338-e1340. doi: 10.1093/milmed/usz484. PMID: 32239156.