Characteristics of small breast and/or ovarian cancer families with germline mutations in BRCA1 and BRCA2

For families with a small number of cases of breast and/or ovarian cancer, limited data are available to predict the likelihood of genetic predisposition due to mutations in BRCA1 or BRCA2. In 104 families with three or more affected individuals (average 3.8) seeking counselling at family cancer clinics, mutation analysis was performed in the open reading frame of BRCA1 and BRCA2 by the protein truncation test and mutation-specific assays. In 31 of the 104 families tested, mutations were detected (30%). The majority of these mutations (25) occurred in BRCA1. Mutations were detected in 15 out of 25 families (60%) with both breast and ovarian cancer and in 16 out of 79 families (20%) with exclusively cases of breast cancer. Thus, an ovarian cancer case strongly predicted finding a mutation (P < 0.001). Within the group of small breast-cancer-only families, a bilateral breast cancer case or a unilateral breast cancer case diagnosed before age 40 independently predicted finding a BRCA1 or BRCA2 mutation (P = 0.005 and P = 0.02, respectively). Therefore, even small breast/ovarian cancer families with at least one case of ovarian cancer, bilateral breast cancer, or a case of breast cancer diagnosed before age 40, should be referred for mutation screening.

The use of 4-aminobiphenyl hemoglobin adducts and aromatic DNA adducts in lymphocytes of smokers as biomarkers of exposure

Two biomarkers of exposure to cigarette smoke, 4-aminobiphenyl-hemoglobin (Hb) adducts and aromatic DNA adducts in lymphocytes, were determined from a population of 55 smokers and 4 nonsmokers. The levels of these adducts were related to daily cigarette consumption and also to (calculated) tar and nicotine intake. The Hb adduct levels seemed to correspond best to the number of cigarettes (cig) smoked, but at a cigarette consumption of >30 cig/day, a saturation effect was observed. Lymphocytic DNA adducts also correlated well with cigarette and tar consumption; for this type of adduct, a saturation level was reached at a dose of approximately 15-20 cig/day. From a subpopulation, a second sample was obtained after 2 months, and the adduct levels were compared with their initial adduct levels. Strong correlations were found between the first and second DNA adduct measurements (r = 0.84). In another subpopulation, resampling was performed after 6 months. No correlation between DNA adduct levels in the first and last samples was found, but 4-aminobiphenyl Hb adduct levels were strongly correlated (r = 0.78), the absolute quantities measured being comparable (paired t test: t = -1.27, P = 0.22, n = 15). We found no influence of GSTM1 and NAT2 polymorphisms on Hb adduct formation and of GSTM1 polymorphism on aromatic DNA adduct formation. A significantly lower aromatic DNA adduct level was observed for intermediate acetylators when compared to slow acetylators.

32P-postlabelling of aromatic DNA adducts in white blood cells and alveolar macrophages of smokers: saturation at high exposures

DNA adducts may serve as a molecular dosimeter of exposure to cigarette smoke-associated carcinogens such as polycyclic aromatic hydrocarbons (PAH). Target tissues for cigarette smoke-induced carcinogenesis are rarely accessible; therefore, peripheral blood cells or cells obtained by bronchoalveolar lavage (BAL) may be used as surrogate sources of exposed DNA. However, the relationship between cigarette smoke exposure and aromatic-DNA adducts in white blood cells and BAL cells is still unclear. In this study, we examined DNA adduct formation in lymphocytes and BAL cells in several populations of smoking individuals by means of 32P-postlabelling. Significant correlations between the amount of cigarettes smoked per day and the level of aromatic-DNA adducts were found in lymphocytes. In BAL cells, DNA adduct levels were associated with age (p = 0.05) and gender (p = 0.10) after adjustment for smoking behaviour. Adduct formation levelled off at higher exposure levels, suggesting less efficient adduct formation; decreases in the formation of adducts per unit of exposure were found in lymphocytes (r(s) = -0.80, p < 0.001) and BAL cells (r(s) = -0.72, p < 0.001). To assess intra-individual variation in adduct levels at constant smoking behaviour, sampling was repeated after a period of 2 and 6 months. In lymphocytes, repeated measurements with an interval of 2 months were highly correlated (r = 0.84, p = 0.009, n = 8), whereas repeated measurements with an interval of 6 months showed no correlation (r = 0.30, p = 0.27, n = 16). Repeated measurements in BAL cells showed a significant correlation after 6 months (r = 0.68, p = 0.03, n = 10). Furthermore, in a group of occupationally exposed aluminium workers, adduct levels in total white blood cells were correlated with the average concentrations of PAH in the ambient air of workers who smoked cigarettes, whereas in non-smokers, no such relationship was found. We conclude that cigarette smoking may directly or indirectly influence DNA adduct levels and saturation of DNA adduct formation may occur, leading to non-linear dose-response relationships.

Smokers and urinary genotoxins: implications for selection of cohorts and modulation of endpoints in chemoprevention trials

Urinary genotoxicity assays measure the internal dose of genotoxic carcinogens, thereby providing a particularly sensitive endpoint for selecting cohorts of individuals exposed to cigarette smoke or other mutagens excreted with urines, as well as for evaluating the modulation of this parameter after administration of chemopreventive agents. Mutagenicity of urines was investigated in smoking Italian volunteers, who received oral N-acetylcysteine (NAC) at the same doses which are usually prescribed for the long-term treatment of chronic bronchitis. The daily excretion of mutagens, concentrated on XAD-2 columns and tested in Salmonella typhimurium YG1024 with S9 mix, was significantly and remarkably decreased by NAC in the majority of the subjects examined so far. Time-course experiments showed that this effect starts since the first day of drug administration and reverses when treatment is withdrawn. In addition, NAC administration almost totally prevented urinary genotoxicity in one subject whose concentrated urines induced a differential lethality in Escherichia coli strains having distinctive DNA repair capacities. The decrease of urinary genotoxicity produced by NAC in the majority of smokers correlates with the ability of this thiol to prevent tumors and to affect a variety of intermediate biomarkers in animal models. Modulation of the urinary excretion of mutagens is one of the biomarkers evaluated in two ongoing Phase II chemoprevention trials. One study involves the oral administration of NAC in Dutch smokers. The pretreatment urine samples of all the subjects so far recruited are clearly mutagenic. The other study involves the oral administration of the dithiolethione oltipraz to individuals living in the Qidong County of the People's Republic of China, an area of high endemy for HBV infection and of high exposure to aflatoxins. Additionally, a large proportion of the recruited male subjects are smokers. A total of 500 urine specimens will be assayed from 240 subjects according to a complex protocol arranged in three consecutive phases.

Toxicity grading systems. A comparison between the WHO scoring system and the Common Toxicity Criteria when used for nausea and vomiting

BACKGROUND

The Common Toxicity Criteria adopted by the NCI in the USA for grading toxicity in cancer clinical trials have been compared to the WHO scoring system which is still in use in Europe.

PATIENTS & METHODS

Sixty-six patients undergoing emetic chemotherapy at the Netherlands Cancer Institute completed questionnaires, 32 according to the WHO criteria and 34 to the Common Toxicity Criteria, on the severity, frequency and duration of gastro-intestinal toxicity. Their answers were then compared to the scores coded by research nurses and physicians. The nurses coded acute toxicity when the patients were discharged, and the doctors coded overall toxicity when the patients returned for the subsequent course of chemotherapy. To evaluate the coding systems, an estimate was made of the percentage agreement between the patients' answers and the nurses' and doctors' ratings.

RESULTS

The percentage agreement of the Common Toxicity Criteria with the patients' own experiences of nausea and vomiting was considerably better than that of the WHO score. The Gamma statistic confirmed this. The Common Toxicity Criteria have now been adopted for grading toxicity in studies of the Early Clinical Trials Group of the EORTC and are recommended for use in other clinical trials.