© 1999 by Oxford University Press
Journal of the National Cancer Institute, Vol. 91, No. 7, 575,
April 7, 1999
© 1999 Oxford University Press
IN THIS ISSUE |
Head and neck squamous cell carcinoma (HNSCC) with an unknown primary tumor site presents as a cervical lymph node metastasis without an obvious mucosal lesion. Califano et al. (p. 599) have investigated whether localization of the primary tumor site can be achieved by detecting, in histologically benign mucosa, genetic alterations identical to those found in the metastatic lesion. Microsatellite analysis was performed on metastatic tumors and histologically benign surveillance biopsy specimens from 18 patients. In 10 patients, at least one surveillance biopsy specimen exhibited genetic alterations identical to those in the metastatic lesion, and three of these patients subsequently developed HNSCC in the same or adjacent mucosal region. Thus, microstaellite analysis may represent a clinically useful tool for detecting occult primary tumor sites.
DNA Damage and Early Smoking
Wiencke et al. (p. 614) report that the levels of DNA adducts (chemical modifications) caused by exposure to tobacco smoke—which are thought to predict the risk of developing lung cancer—are related to the age at which a smoker takes up the tobacco habit. The researchers collected smoking histories, samples of nontumorous lung tissue, and blood samples from 143 lung cancer patients. They measured DNA adduct levels in the tissue samples and analyzed these results in light of data from the smoking histories. They found that the impact of different risk factors may differ in current and former smokers. In current smokers, for example, the recent number of cigarettes smoked per day is the most important factor. In former smokers, it is the age of smoking initiation: the earlier a person began smoking, the higher the risk. The authors suggest that smoking during adolescence may cause physiologic changes that allow DNA adducts to persist longer. Alternatively, they say, early smoking may produce more adducts.
In an editorial, Spitz et al. (p. 578) try to place the results of Wiencke et al. into context. They point out that the ability to identify current and former smokers with the highest risks of developing cancer has substantial implications for cancer prevention. They conclude that the study by Wiencke et al. fits one more piece into the lung cancer risk assessment puzzle.
Colorectal Cancer Risk Factors
In a prospective case-control study nested in the Physicians' Health Study, Ma et al. (p. 620) examined whether there was an association between plasma levels of insulin-like growth factor (IGF)-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) and colorectal cancer. In this study, plasma samples were collected at baseline from 14 916 men without cancer. After 12 years, the authors measured these compounds in the baseline plasma samples from 193 men who were diagnosed with colorectal cancer during this period and from 318 matched control subjects. They found that the men who 12 years earlier had the higher levels of plasma IGF-I had an increased risk of colorectal cancer. Additionally, they report that the men with higher levels of plasma IGFBP-3 had a lower risk of colorectal cancer. They conclude that circulating levels of IGF-I and IGFBP-3 appear to be related to the risk of developing colorectal cancer.
In an editorial, Burroughs et al. (p. 579) write that the study by Ma et al. provides perhaps the best epidemiologic evidence to date that plasma levels of IGF-I and IGFBP-3 are associated with cancer risk. The editorialists caution, however, that these results must be duplicated with other prospectively collected samples.
Ovarian Abnormalities and Cancer Risk
To determine whether premalignant lesions can be identified for ovarian cancer, Stratton et al. (p. 626) examined ovaries that were removed from 37 women with a family history of ovarian cancer at a time before genetic testing became available. The authors report that, when these women were genetically tested, 11 women had a mutated BRCA1 or BRCA2 gene and 26 women did not. The authors found no morphologic difference between ovaries from these groups for any of the features studied. They conclude that many of the "abnormalities" described in "normal" ovaries are variations of the normal and are not associated with the development of ovarian cancer.
The p53 Gene Family
Many identified genes have been found to belong to gene families, which are comprised of members with varying degrees of relatedness. Until recently, the p53 tumor suppressor gene (also known as TP53) seemed to lack relatives. However, several laboratories have now identified two p53-related genes, i.e., p73 and p51 (the latter also known as p40, p63, KET, or p73L). In a review, Kaelin (p. 594) details the identification and preliminary characterization of these p53 family members and discusses what is known about alteration of these genes in human cancers.
Fruits, Vegetables, and Bladder Cancer
Studies examining fruit and vegetable intake and bladder cancer risk have been inconsistent, especially with regard to the types of fruit and vegetable. Michaud et al. (p. 605) examined total fruit and vegetable intake and intake of subtypes in relation to bladder cancer risk in a large, male prospective cohort study. Total intake of cruciferous vegetables was inversely associated with bladder cancer risk, but intakes of yellow or green leafy vegetables or carotenoid-rich vegetables were not. Most of the individual cruciferous vegetables were inversely related to risk, but only the associations for broccoli and cabbage were statistically significant.
Prolactin and Breast Cancer
Breast development is regulated in part by the hormone prolactin, which, when administered to animals, increases the rate at which mammary tumors form. Drawing participants from the prospective Nurses' Health Study, Hankinson et al. (p. 629) conducted a nested case-control study of serum prolactin levels and the risk of developing breast cancer. The study included 306 postmenopausal women who were diagnosed with breast cancer subsequent to providing blood samples for hormone analysis and 448 control subjects, who were matched to the patients on the basis of age, use of postmenopausal steroid hormones, and the time of day and month of blood collection. The researchers report that they found a statistically significant positive association between the plasma level of prolactin and postmenopausal breast cancer risk.
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