© 1999 by Oxford University Press
Journal of the National Cancer Institute, Vol. 91, No. 20, 1703,
October 20, 1999
© 1999 Oxford University Press
IN THIS ISSUE |
Human herpesvirus 8 (HHV8) infection is associated with all forms of Kaposi's sarcoma (KS). A cluster of HHV8 genes (ORFK13-72-73 locus) may contribute to KS by encoding proteins, such as the latency-associated nuclear antigen; v-cyc-D, a viral homologue of the cellular cyclin D; and an anti-apoptotic protein, v-FLIP, which inhibits programmed cell death. Stürzl et al. (p. 1725) examined expression of these genes in tissues obtained from KS patients at different disease stages. They found that the messenger RNA encoding v-cyc-D and v-FLIP is abundantly expressed in KS spindle cells of late-stage nodular lesions but not in early lesions. Thus, apoptosis is relatively frequent in HHV8-infected cells in early lesions but low or absent in the late-stage nodular lesions. These data suggest that the anti-apoptotic v-FLIP protein of HHV8 may contribute to KS progression.
Human Herpesvirus 8 and Transfusions
A number of viruses may be spread by blood transfusion, possibly including some with carcinogenic potential. Human herpesvirus 8 (HHV8), which is associated with Kaposi's sarcoma, is sexually transmitted, but other routes of exposure likely exist. It is not known whether transfusions are a source of exposure. Engels et al. (p. 1773), studying a blood-donor population in Jamaica, screened blood from donors and recipients for the presence of HHV8 antigens. Twenty-seven of the 1010 donors screened were HHV8 positive, but none of the 19 recipients of blood from the 27 positive donors were found to be infected—except for one subject who was HHV8 positive before transfusion. The authors conclude, based on these and other data, that screening for HHV8 by blood banks is not currently indicated.
Serum 
-Tocopherol and Lung Cancer Risk
The relationship between blood levels of -tocopherol, the predominant form of vitamin
E, and the risk of developing lung cancer has been unclear, with different studies giving
conflicting results. To better understand this association, Woodson et al. (p. 1738) examined the relationship between subsequent lung cancer incidence and serum levels
of the vitamin in blood samples collected at the start of the Alpha-Tocopherol, Beta-Carotene
Cancer Prevention (ATBC) Study—in which 29,133 male smokers from Finland received
dietary supplementation daily with -tocopherol, ß-carotene, both, or neither for 5-8
years. The researchers observed a 19% reduction in lung cancer incidence among men in
the highest compared with the lowest fifths of the subjects in terms of initial serum
-tocopherol level. The risk appeared particularly reduced among younger men, those with
less cumulative tobacco exposure, and possibly those receiving -tocopherol
supplementation.
"Our data are compatible with a beneficial influence of higher vitamin E status on lung cancer development and indicate a possibly stronger effect among persons who have accumulated lower levels of lung carcinogens from chronic cigarette smoking."—Woodson et al.
Gene Therapy in a Rabbit Model
Several approaches to cancer gene therapy have yielded promising results in rodents. Further research in large animal models will decide the usefulness of these approaches in humans. Gnant et al. (p. 1744) have gone the next step by investigating the pattern of transgene expression and vector elimination in a rabbit model of disseminated liver metastases after systemic gene delivery using a thymidine kinase-negative vaccinia virus vector. Recombinant virus vector encoding for the luciferase reporter gene was injected into tumor-bearing rabbits, and luciferase activity was measured at multiple time points thereafter. Luciferase expression was increased in tumors by at least 16-fold as compared with other tissues and was maintained for approximately 1 week, providing evidence for tumor-specific gene delivery. The authors conclude that the period of transgene expression is limited, but a therapeutic window of 1 week may be sufficient for an enzyme/prodrug gene therapy approach, thus encouraging the use of such vectors in clinical settings.
PSA Testing in Older Men
Prostate-specific antigen (PSA) measured in serum is widely used as a screening tool for the
detection of prostate cancer. However, the majority of PSA testing that occurs in the population
eventually proves unnecessary because most men who undergo repeated testing never develop
prostate cancer, and most men with elevated PSA levels do not have cancer discovered at biopsy.
Carter et al. (p. 1733) have conducted a prospective cohort study to evaluate
the possibility of identifying older men with very low PSA levels for whom further PSA testing
could be reduced because of a low risk of future prostate cancer diagnosis. They report that, for
men who reach the age of 60 or 65 years with low PSA measurements (
0.5 ng/mL or 1.0
ng/mL, respectively), discontinuation of regular PSA testing may not lead to an increase in the
rate of undetected prostate cancer and could lead to substantially lower health care costs.
"Identification of those men who are unlikely to benefit from further PSA testing could markedly reduce health care costs and treatment-associated morbidity."—Carter et al.
Diet and Risk of Non-Hodgkin's Lymphoma
Researchers have previously found associations between decreased immune responses and dietary intake of certain types of fat and protein and between a suppressed immune system and risk of non-Hodgkin's lymphoma. Zhang et al. (p. 1751) report findings from the Nurses' Health Study on possible associations between diet and risk of the disease. On the basis of 199 incident cases of non-Hodgkin's lymphoma among 88,410 women followed for 14 years, the researchers found statistically significant associations between frequent intake of beef, pork, or lamb as a main dish and increased risk of the disease and between high intake of trans unsaturated fat and increased risk of the disease.
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