Military Service in Vietnam/Korea and Serum Dioxin Levels Do Not Affect the Outcomes of Patients Diagnosed with Plasma Cell Dyscrasias

Exposure to dioxin, a contaminant found in herbicides has been associated with increased risk of cancers including multiple myeloma and postulated to cause poorer survival in the exposed population. Military personnel, especially those who had served in Vietnam and Korea have an increased risk of dioxin (which contaminated the herbicide Agent Orange which was sprayed during these wars) exposure. We looked at the impact of dioxin exposure and blood levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) which is the most toxic of the poly-chlorinated dioxins on the survival outcomes of military veterans diagnosed with plasma cell dyscrasias (PCD).

A prospective analysis of newly diagnosed and existing myeloma patients was done. Information regarding the patient and disease characteristics, the military record, and outcomes were collected. Approximately 60 ml of heparinised peripheral blood was collected and immediately frozen at −20 degrees. These samples were shipped to Eurofins Laboratory, Hamburg, Germany for dioxin level measurement. Patients' blood lipid levels were also measured and the dioxin toxic equivalent (Teq) was calculated. Overall survival (OS) was calculated from the date of diagnosis till death (Kaplan Meier method). Cox regression and log rank analysis were used to look for prognostic variables.

Fifty two (52) patients of PCD were available for analysis. Majority had a diagnosis of multiple myeloma. Forty one underwent treatment including stem cell transplant in 16 (Table 1 shows the patient characteristics, laboratory results and treatment outcomes). During a median follow up of 54 months (2–348), 21 patients died (progressive myeloma: 12(23%), cardiac failure: 3 (5.7%), infections: 1 (1.9%), acute myeloid leukemia: 1 (1.9%), pulmonary embolism: 1 (1.9%) and unknown: 3 (5.7%). The median OS was 111 mos (95% CI 56–155) and the estimated survival at 5 yrs was 69.5% (+/− SE 0.067). The 5 yr OS was negatively impacted by abnormal cytogenetics (40.3 % vs. 75.5%; p=0.012), and service in the army (non-army vs. army: 83% vs. 40%; p=0.032). Patients who had served in Vietnam had outcomes similar to others; Korean War veterans had a poorer OS, but this was not statistically significant (5 yr OS 68% vs. 48%; p=0.1). There was no association between TCDD levels or the Teq with OS. Abnormal cytogenetics was the only significant factor on multivariate analysis.

We did not find an association between military service in Korea/Vietnam or serum dioxin levels and poor survival in military veterans diagnosed with Plasma cell dyscrasias. However, a study of a larger sample of myeloma patients with similar service and exposure histories maybe warranted.

No relevant conflicts of interest to declare.