corresponding to service in support units (OR 1.50, 95% CI 1.02-2.21), combat-support units (OR 1.18, 95% CI 0.65-2.15), or combat units (OR 1.25, 95% CI 0.63-2.45).

With respect to soft-tissue and other sarcomas, the same eight cancer registries showed that 342 men had confirmed cancers compared with the 1776 controls. The OR for soft-tissue and other sarcomas in Vietnam-theater veterans compared with Vietnam-era veterans is a nonsignificant 0.74 (95% CI 0.39-1.41) with the same adjustment factors as for NHL (Selected Cancers Cooperative Study Group 1990b). Again, there was no trend in cancer risk in men who served in support units (OR 0.76, 95% CI 0.37-1.53), combat-support units (OR 1.03, 95% CI 0.44-2.41), or combat units (OR 0.76, 95% CI 0.25-2.28).

Combining data from the eight cancer registries shows that 28 of the 310 men with Hodgkin’s disease had served in Vietnam, two of the 48 with nasal carcinoma, three of the 80 with nasopharyngeal carcinoma, and eight of the 130 with primary liver cancer (Selected Cancers Cooperative Study Group 1990c). Although the power of the study was good for Hodgkin’s disease (96%), it was less robust for the other cancers. In comparisons of Vietnam-theater veterans with Vietnam-era veterans with the same adjustments as for NHL, the OR was 1.23 for Hodgkin’s disease (95% CI 0.65-2.32), 0.31 for nasal carcinoma (95% CI 0.04-2.20, additionally adjusted for occupational exposures), and 0.53 for primary liver cancer (95% CI 0.14-1.94, additionally adjusted for occupational exposures); the OR for nasopharyngeal carcinoma could not be calculated with conditional logistic regression. There was no trend (p = 0.17) in risk of Hodgkin’s disease related to serving in Vietnam in a support unit (OR 1.58, 95% CI 0.90-2.77), a combat-support unit (OR 0.50, 95% CI 0.14-1.76), or a combat unit (OR 0.94, 95% CI 0.34-2.59). The relationship of combat to the other three cancers was not assessed.

Although the authors did not sample blood for possibly elevated dioxin levels, they asserted that, based on their locations and occupations during the war, the Vietnam-veteran study participants were not at greater risk of exposure to Agent Orange than the nondeployed veterans. Those studies are limited by the small sample sizes for some cancers.

Postservice mortality was assessed in 10,716 Marines who served in Vietnam and 9346 Marines who were not deployed to Vietnam (Watanabe and Kang 1995). An analysis of death certificates showed that as of 1991, for Marines who had served in Vietnam, there were no statistically significant increases in all-cancer mortality (rate ratio 1.08, 95% CI 0.84-1.39), cancer of the larynx (rate ratio 2.60, 95% CI 0.27-25.0), lung cancer (rate ratio 1.12, 95% CI 0.71-1.76), or lymphosarcoma and reticulosarcoma (rate ratio 1.21, 95% CI 0.27-5.41). No statistically significant increase was seen for all cancers or for lung cancer. The relative-risk (RR) estimates based on the Cox proportional-hazards model were 1.20 (95% CI 0.93-1.55) for all cancers and 1.33 (95% CI 0.84-2.10) for lung cancer, adjusted for year of birth and military rank. Death certificates were obtained from VA regional offices, federal records centers, and state vital-statistics offices. Comparisons with the U.S. male population showed slightly increased standardized mortality ratios for laryngeal cancer and for lymphosarcoma and reticulosarcoma, but the increases were not statistically significant. The authors considered the latent period for many cancers to be 15-20 years but found no difference in RRs in cancer deaths whether veterans were followed for less than or more than 16 years. The authors suggested that there may have been insufficient observation time since the war to detect excess deaths from cancer and that there was insufficient statistical power to detect rare causes of death. They also noted that many of the Marines were posted to areas in Vietnam where Agent Orange was used.

A similar study of cancer mortality was conducted in female Vietnam veterans (Dalager et al. 1995). The vital status of 4586 female Vietnam veterans and 5325 female Vietnam-era



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