International journal of cancer. Journal international du cancer
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Comparative Study
Mutations of the p53 gene in oral squamous-cell carcinomas from Sudanese dippers of nitrosamine-rich toombak and non-snuff-dippers from the Sudan and Scandinavia.
Using PCR-SSCP/DNA sequencing methods, we analyzed 14 oral squamous-cell carcinomas (OSCCs) and 8 pre-malignant oral lesions from different Sudanese patients for prevalence of mutations in exons 5 to 9 of the p53 gene in relation to toombak-dipping status. OSCCs (14 from Sudan, 28 from Scandinavia), and 3 pre-malignant oral lesions from Sudanese non-dippers were used as controls. A statistically significant increased incidence in mutations of the p53 gene was found in OSCCs from toombak dippers (93%; 13/14), as compared with those from non-dippers in Sudan (57%; 8/14) and in Scandinavia (61%; 17/28) respectively. ⋯ No mutations were found in any of the non-malignant oral lesions in relation to dipping or non-dipping status. These findings suggest that (i) the use of toombak plays a significant role in induction of increased p53 gene mutations, (ii) mutations observed were similar to those induced by tobacco-specific N-nitrosamines (TSNAs) in experimental animal models and those already reported in toombak dippers, (iii) types of mutations associated with TSNAs were similar in the exposed and the control groups, (iv) a novel mutation in exon 6 was found in the OSCCs from toombak dippers, (v) the p53 exons 5 (codon 130), 6 (codons 190, 216) and 7 (codons 229, 249, 252) mutations are probable hot spots for toombak-related OSCCs. Further studies are necessary to validate the increased incidence and exon locations of the p53-gene mutations as a biomarker of malignant transformation in populations in which the oral use of tobacco is habitual.
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Epidemiologic studies have suggested an increased risk for ovarian cancer associated with the use of talcum powder in genital hygiene, but the biologic credibility of the association has been questioned. We conducted a population-based case-control study in eastern Massachusetts and New Hampshire involving 563 women with newly diagnosed epithelial ovarian cancer and 523 control women selected either by random digit dialing or through lists of residents. Use of body powders was assessed through personal interview and the exposure odds ratio (OR) for the use of talc in genital hygiene was calculated. ⋯ Relative to women who never used body powder or used it only in non-genital areas, the OR (and 95% confidence interval) associated with genital exposure to talc was 1.60 (1.18 and 2. 15) after adjustment for age, study location, parity, oral contraceptive use, body mass index and family history of breast or ovarian cancer. Exposure prior to rather than after a first livebirth appeared to be more harmful, and the association was most apparent for women with invasive serous cancers and least apparent for those with mucinous tumors. We conclude that there is a significant association between the use of talc in genital hygiene and risk of epithelial ovarian cancer that, when viewed in perspective of published data on this association, warrants more formal public health warnings.