Overall Lab cancer rates lower than Bay Area norms, surveillance report finds
Considerably less cancer was found among Lab employees than would be
expected based on Bay Area rates, according to the findings in the Health
Services Department’s Cancer Surveillance Project. The project reports
cancer rates among LLNL employees.
Drs. Jim Seward and Mort Mendelsohn of the Lab, and Don Whorton, a private physician and epidemiologist, presented the findings to Lab employees Wednesday. Mendelsohn also provided an update on his mortality rate study, which was originally released in March.
"Healthy lifestyle patterns and cancer screening activities are probably important contributors to the observed low cancer rates," said Seward, director of Health Services.
The results of the current project indicate very low rates of invasive cancers for both men and women at LLNL. Among men, there are very low rates for several types of cancer including oral cancer, lung cancer, gastrointestinal cancer and lymphomas. Among women, rates of genital tract cancers, including cervical cancer, were particularly low.
For more than 20 other types of cancers, rates were below or similar to those expected for the general population. Breast and prostate cancer rates were very close to the expected levels. Two cancers that were elevated among LLNL men included testicular cancer and melanoma, although the melanoma rates have become normal in recent years.
The report is a follow-up to a 1985 state cancer incidence study showing a statistically significant number of malignant melanoma — skin cancer — cases among LLNL employees from 1969-80. The total melanomas at LLNL over the 1974-97 period remain high (84 actual vs. 54 expected). However, the results of the project indicate that, despite elevations in the ‘70s and early ‘80s, LLNL’s melanoma rate has dropped since that time.
"LLNL melanoma rates are now similar to the Bay Area rates," said Seward, "and this is due in part to our educational campaigns focusing on sun protection and the Lab’s Mole Patrol screening program."
There have been several studies to look for workplace causes for melanoma at LLNL, but there has been no consistent finding relating the melanomas to any exposure on-site. Analyses have consistently supported the association with personal characteristics (mole count, body coloring and solar sensitivity).
The Cancer Surveillance Project is an initiative to understand the occurrence of different types of cancer among employees. With funding from the DOE Office of Health Programs, the Laboratory hired Dr. Whorton to do the cancer analysis. In addition to updating information on the occurrence of melanoma, Health Services initiated the project as a means for developing targeted cancer prevention and early detection programs.
The report covers the 24-year time period of 1974-97 (the last year information was available), in which 637 out of 17,785 LLNL employees were diagnosed with cancer. Of the 637 cases of either invasive or in situ (surface-level only) cancers reported, 437 were in males, 200 were in females. The statistics from the survey were broken down by type of cancer, by year, by age and by gender.
The project shows a statistically significant higher incidence rate in testicular cancer, with 21 observed cases during the 24-year period, while the expected number was only 10 cases. Seward indicated that this finding is not surprising, since research on testicular cancer has consistently indicated that professional and white collar workers have a 1.5-2.5 times increased risk for this cancer. The reason for the socio-economic distribution in testicular cancers is not known, but it points to probable lifestyle factors rather than occupational ones. Health Services plans to investigate the options to learn more about the 21 LLNL cases that have occurred since 1974.
Due to confidentiality protections, HSD does not know the identity or the occupations of the LLNL cases.
Testicular cancer is a cancer usually found in males between 25 and 34 years. Other risk factors for this cancer include un-descended testicles, prenatal exposure to prescribed estrogens, and chromosomal disorders.
"Employee anonymity in the report was preserved in the way the data was gathered," Seward explained.
LLNL provided the California Cancer Registry (CCR) a computer file containing names of 17,785 employees who worked for at least six consecutive months from 1974-97. (Supplemental labor information was unavailable.) The CCR then matched those names with any cancer reported to them during that time period and provided the data without names or other identifiers. The CCR did not release any data on cancers with less than six cases.
The findings of the Cancer Surveillance Project are confirmed by a related study on mortality in LLNL employees and retirees. Mort Mendelsohn and Dan Moore summarized their mortality study in the March 16 edition of Newsline (see the Web at: http://www.llnl. gov/llnl/06news/NewsReleases/2001/NR-01-03-08.html. They found reductions in cancer mortality that were almost identical to those seen in the incidence work.
Likewise, they found striking reductions of all causes of death (below 50 percent of U.S. levels) and of many specific causes, such as circulatory mortality (at 40 percent of U.S. levels), In calculations done subsequently, they estimate for the years of the study, 1984-1996, that Laboratory workers and retirees had five years of added life expectancy compared to the U.S. population.
"These are very striking indications of the good health of our populations," Mendelsohn said.
Employees interested in learning more about the project can access the full report at the HSD Website, http://www-r.llnl.gov/healthserv /. The Website also provides information on testicular cancer and HSD’s various cancer-screening services. Interested individuals may also contact Jim Seward, 3-6903, or Kathleen Noonan, 3-8999.
This project could not have been completed without help from the following individuals whom HSD thanks for their assistance: Mark Costella, Ed Cunniffe, Marleen Emig, John Futterman, Don Graves, Barbara Kornblum, and Lynda Seaver who participated in the LLNL Employee Advisory Group; Cliff Strader, Bonnie Richter and Heather Stockwell of the DOE Office of Health Programs who provided funding and support; Bob Schlag, Sandy Liu and Bill Wright of the California Cancer Registry; and Joe Bartelt, LLNL Administrative Information Systems.