Cohort mortality study of prostate cancer among chemical workers

Towards reliable diagnostics of prostate cancer via breath

Early detection of cancer is a key ingredient for saving many lives. Unfortunately, cancers of the urogenital system are difficult to detect at early stage. The existing noninvasive diagnostics of prostate cancer (PCa) suffer from low accuracy (< 70%) even at advanced stages. In an attempt to improve the accuracy, a small breath study of 63 volunteers representing three groups: (1) of 19 healthy, (2) 28 with PCa, (3) with 8 kidney cancer (KC) and 8 bladder cancer (BC) was performed. Ultrabroadband mid-infrared Fourier absorption spectroscopy revealed eight spectral ranges (SRs) that differentiate the groups. The resulting accuracies of supervised analyses exceeded 95% for four SRs in distinguishing (1) vs (2), three for (1) vs (3) and four SRs for (1) vs (2) + (3). The SRs were then attributed to volatile metabolites. Their origin and involvement in urogenital carcinogenesis are discussed.

Nested case-control study of occupational chemical exposures and prostate cancer in aerospace and radiation workers

BACKGROUND

To date, little is known about the potential contributions of occupational exposure to chemicals to the etiology of prostate cancer. Previous studies examining associations suffered from limitations including the reliance on mortality data and inadequate exposure assessment.

METHODS

We conducted a nested case-control study of 362 cases and 1,805 matched controls to examine the association between occupational chemical exposures and prostate cancer incidence. Workers were employed between 1950 and 1992 at a nuclear energy and rocket engine-testing facility in Southern California. We obtained cancer-incidence data from the California Cancer Registry and seven other state cancer registries. Data from company records were used to construct a job exposure matrix (JEM) for occupational exposures to hydrazine, trichloroethylene (TCE), polycyclic aromatic hydrocarbons (PAHs), benzene and mineral oil. Associations between chemical exposures and prostate cancer incidence were assessed in conditional logistic regression models.

RESULTS

With adjustment for occupational confounders, including socioeconomic status, occupational physical activity, and exposure to the other chemicals evaluated, the odds ratio for low/moderate TCE exposure was 1.3; 95%CI = 0.8 to 2.1, and for high TCE exposure was 2.1; 95%CI = 1.2 to 3.9. Furthermore, we noted a positive trend between increasing levels of TCE exposure and prostate cancer (P-value for trend = 0.02).

CONCLUSION

Our results suggest that high levels of TCE exposure are associated with prostate cancer among workers in our study population.

Cohort mortality study of employees at the Celanese plant in Pampa, Texas

BACKGROUND

The mortality experience of chemical workers from the Pampa, Texas Celanese Ltd. plant through 1991 has been previously reported. This study updates that effort and presents an additional seven years of data and follow-up that provided 268 additional cohort members and 71 new deaths.

METHODS

Mortality was determined through December 31, 1998, the period for which the National Death Index could provide information on deaths. The mortality experience of Celanese Ltd. employees was compared to that of the general population of the United States. All cause and cause-specific standardized mortality ratios (SMRs) were calculated.

RESULTS

For the entire cohort, several causes of death including all causes (SMR = 65.9; 95% confidence interval (CI) = 56.9-76.0), heart disease (SMR = 69.1; 95% CI = 53.6-87.8), and all malignant neoplasms (SMR = 74.2; 95% CI = 56.3-95.9) were significantly less than expected. SMRs were also calculated separately for white men, non-white men, and women. Unlike the initial study, the SMR for prostate cancer among white males was not significantly elevated (SMR=176.1; 95% CI = 76.0-347.0) and was much lower than the prior SMR of 330.4. This suggests that the initial findings, which were based on a small number of deaths, were likely due to chance.

CONCLUSIONS

Overall, Celanese Ltd. employees from the Pampa plant have significantly lower than expected SMRs for several causes of death, and no causes of death that are significantly elevated.

Occupation and prostate cancer risk in Sweden

To provide new leads regarding occupational prostate cancer risk factors, we linked 36,269 prostate cancer cases reported to the Swedish National Cancer Registry during 1961 to 1979 with employment information from the 1960 National Census. Standardized incidence ratios for prostate cancer, within major (1-digit), general (2-digit), and specific (3-digit) industries and occupations, were calculated. Significant excess risks were seen for agriculture-related industries, soap and perfume manufacture, and leather processing industries. Significantly elevated standardized incidence ratios were also seen for the following occupations: farmers, leather workers, and white-collar occupations. Our results suggest that farmers; certain occupations and industries with exposures to cadmium, herbicides, and fertilizers; and men with low occupational physical activity levels have elevated prostate cancer risks. Further research is needed to confirm these findings and identify specific exposures related to excess risk in these occupations and industries.