Polymorphisms in immunoregulatory genes, smoky coal exposure and lung cancer risk in Xuan Wei, China

We conducted a population-based case-control study in Xuan Wei, China, where lung cancer rates are among the highest in China due to exposure to indoor coal combustion products, to evaluate the association between polymorphisms in immunoregulatory genes and lung cancer risk. A total of 122 incident primary lung cancer cases and 122 individually matched controls were enrolled in Xuan Wei, China. Fifty single-nucleotide polymorphisms (SNPs) in 23 immunoregulatory genes involved in inflammation were genotyped and analyzed by logistic regression to assess the risk of lung cancer. A global test of association for 42 SNPs, which excluded eight SNPs that were in very tight linkage disequilibrium with other SNPs, was statistically significant (P = 0.01), suggesting that overall genetic variation in this pathway contributes to lung cancer risk. In addition, the IL1B -1060TT (i.e. -511TT) genotype was associated with increased lung cancer risk compared with the CC genotype [odds ratio (OR) = 2.27, 95% confidence interval (CI) = 1.05-4.91]. The IL8RA Ex2+860 GC or CC (OR = 0.27, 95% CI = 0.11-0.67), ICAM1 Ex2+100 AT or TT (OR = 0.39, 95% CI = 0.18-0.88) and IL12A Ex7+277 GA or AA (OR = 0.43, 95% CI = 0.22-0.84) genotypes were associated with decreased lung cancer risk. The protective effect of the IL8RA variant was stronger among subjects with high cumulative smoky coal use (> or = 130 tons) (OR = 0.11, 95% CI = 0.03-0.44; P(interaction) = 0.03). In conclusion, genetic variation in immunoregulatory genes may play an important role in the development of lung cancer in this population.     

Smoky coal exposure, NBS1 polymorphisms, p53 protein accumulation, and lung cancer risk in Xuan Wei, China

Lung cancer rates in Xuan Wei County are among the highest in China and have been associated with exposure to indoor smoky coal emissions that contain high levels of polycyclic aromatic hydrocarbons (PAHs). The NBS1 gene product participates in DNA double-strand break repair and DNA damage-induced checkpoint activation, which are critical for maintaining genomic integrity. The p53 tumor suppressor gene is known to play key roles both in the maintenance of genomic stability in mammalian cells and in DNA damage surveillance. We examined the association between two common NBS1 polymorphisms (Leu34Leu, Gln185Glu) and lung cancer risk in a population-based case-control study in Xuan Wei, China. Individuals homozygous for the NBS1 34Leu or NBS1 185Glu variants were found to have an increased risk of lung cancer (odds ratio [OR] 2.15, 95% confidence interval [CI]: 0.91-5.10 and OR 2.53, 95% CI: 1.05-6.08, respectively). A haplotype containing the variant alleles from both NBS1 SNPs was associated with increased risk of lung cancer compared with the most common haplotype. Further, the associations were particularly pronounced among cases with over expression of p53 protein. These results suggest that NBS1 could be important in the pathogenesis of lung cancer in this population. However, additional studies in other populations with substantial environmental exposures to PAHs are needed to confirm our findings.     

K-ras mutations in lung carcinomas from nonsmoking women exposed to unvented coal smoke in China

Lung cancer mortality rate in nonsmoking women in Xuan Wei (XW) County is the highest in China. The XW lung cancer rate is associated with exposure to coal smoke, containing high concentrations of polycyclic aromatic hydrocarbons (PAHs), in unvented homes. Here we investigated codon 12 K-ras mutations in lung tumors or sputum samples from 102 XW lung cancer patients (41 nonsmoking women and 61 smoking men). In addition, we analyzed specimens from 50 lung cancer patients (14 nonsmoking women, 33 smoking men and three nonsmoking men), from Beijing and Henan (B&H), where natural gas is the main domestic fuel. K-ras mutations were found in nine women (21.9%) and 14 men (22.9%) from XW, with G to T transversions accounting for 66.7 and 85.7%, respectively. Among B&H patients, one woman (7.1%) and six men (16.7%) had K-ras mutations, with G to T transversions accounting for 66.7% of the mutations in the men. Therefore, the frequency and type of K-ras mutations in XW nonsmoking women are similar to those of K-ras mutations found in both XW and B&H smoking men. On the other hand, the mutation frequency in XW women is higher than, although not statistically significant from, that in the B&H nonsmoking women (P=0.28, two-sided Fisher's Exact Test). These results suggest an association between exposure to coal smoke and the increased K-ras mutation frequency in XW nonsmoking female lung cancer patients. They also suggest that the mutagens and/or mechanisms of mutations in these nonsmoking women are similar to those responsible for K-ras mutations in cigarette smoking lung cancer patients, which are probably induced largely by chemicals such as PAHs.     

K-ras and p53 mutations in hereditary non-polyposis colorectal cancers

Genetic instability related to defective DNA mismatch repair genes may be involved in the pathogenesis of carcinoma in Hereditary Non-Polyposis Colorectal Cancer (HNPCC). To test that the targets of genetic instability could include critical transforming genes involved in colon tumor progression, we examined 23 colorectal carcinomas in patients with HNPCC in order to detect somatic mutations in K-ras and p53 genes. Using single strand conformation polymorphism followed by direct DNA sequencing, we detected 4 mutations in K-ras gene (17%) and 3 in p53 gene (13%) which change the aminoacid sequence of the protein p53. This is significantly lower than in sporadic cancer. Our data suggest that colon cancer in HNPCC might partly involve a distinct pathogenetic mechanism that involves other genes than those altered in sporadic tumors. Int. J. Cancer 74:94–96. © 1997 Wiley-Liss, Inc.     

Detection of p53 mutations in sputum smears precedes diagnosis of non-small cell lung carcinoma

Little progress has been made in reducing lung cancer mortality by applying conventional methods to early diagnosis and screening. Recent advances in molecular oncology, however, have provided tools which may be of use in this area. p53 gene mutation is the most common gene alteration in the development of lung cancer. Conventional cytologic analysis of sputum is an insensitive test for the diagnosis of lung cancer. In this study, we attempted to establish a polymerase chain reaction (PCR)-based assay for assessing the possibility of early detection of p53 mutation in archival Papanicolaou-stained cytologic sputum smears. Ten sputum smear slides were collected prior to clinical diagnosis from 10 lung cancer patients who had been confirmed to have p53 mutations in surgically resected lung tumors. We successfully obtained sufficient amounts of RNA from each sputum smear specimen for amplification of PCR and direct sequencing. Only one patient was found to have p53 mutation at codon 286; the other nine patients had wild type p53 genes. This result supports the possibility that detection of p53 mutations in cytologic sputum smears is an available strategy for the early diagnosis of lung cancer.     

Distribution of p53 and K-ras mutations in human lung cancer tissues

Studies were performed to examine the mutational pattern of K-ras exons 1 and 2 and p53 exons 5-8 in lung cancer tissues from 27 Chinese patients (10 smokers, 17 non-smokers) using single-stranded conformational polymorphism and DNA sequencing. K-ras mutations were found in 13/27 tumors (48%); all mutations were clustered in exon 1 and distributed between codons 9 and 32. The frequency and number of patients with K-ras mutations between smokers and non-smokers were not different, except that a high frequency of G --> A transitions (11/11) was found in non-smokers. Among cell types, K-ras mutations were found in 7/13 (54%) squamous cell carcinoma (SC) and 5/12 (42%) adenocarcinoma (AC) patients. A --> T transversions (all six transversions) were present only in SC. In p53, 18/27 (67%) tumors contained mutations in exons 7 and 8, frequently at codons 226, 270, 275 and 281. The number of tumors with p53 mutations in smokers (70%) and in non-smokers (65%) was similar, and the mutation frequency did not differ except for a higher number of G --> A (6/7) and T --> C (5/6) transitions in non-smokers. Among cell types, the number of tumors with p53 mutations was 9/13 (69%) in SC and 8/12 (67%) in AC. The A --> G (11/16) transitions and A --> C (4/4) transversions in p53 were more frequent in SC than in AC (P < 0.04 for A --> G; P < 0.02 for A --> C). The varying mutation patterns in both the K-ras and p53 genes between smokers and non-smokers and among cell types suggest that other than cigarette smoke, environmental and dietary factors may also be involved in the genesis of lung cancer among these patients.      

K-ras, p53 mutations, and microsatellite instability (MSI) in gallbladder cancer

Despite the considerable progress in understanding the molecular pathology of carcinogenesis, the genetic mechanisms underlying the development and progression of gallbladder cancer (GC) are poorly understood. The survival of GC patients is generally poor. Therefore, it is very useful to define valuable prognostic factors. The most extensively studied oncogenes in gallbladder carcinogenesis are ras, commonly mutated in neoplasms of the gastrointestinal tract. K-ras oncogene is altered in a subset of gallbladder patients and mainly in those having anomalous junction of the pancreaticobiliary tract. Most of the studies of genetic abnormalities in GC have focused on p53 gene. p53 mutation/overexpression and/or LOH is present in more than 50% of gallbladder carcinomas, suggesting an important role in their pathogenesis. However, these results have not any predictive value yet. Moreover, the involvement of an alternative molecular pathway, that of microsatellite instability (MSI), is found in a limited group of GC patients. Additional research is necessary to establish its possible relation to defects of the mismatch repair (MMR) system and its proposed prognostic significance. Further elucidation of the molecular events specific to GC will help to identify novel molecular targets for the diagnosis and clinical management of the patients.     

Frequent K-ras mutations and absence of p53 mutations in mucin-producing tumors of the pancreas

Mucin-producing tumors of the pancreas (MPT) are characterized by the prodcution of much mucin and a benign course after surgical treatment. We examined 16 cases of MPT and 20 cases of “common” pancreatic duct cell carcinomas (DCC) in regard to K-ras and p53 mutations. The mutations were detected by constant denaturant gel electrophoresis in combination with other techniques using PCR products amplified from the samples microdissected from the tissue sections. K-ras codon 12 mutations were identified in all MPT and in 95% of DCC. On the other hand, p53 mutations were found in four of 20 (20%) DCC, and p53 was immunocy-tochemically overexpressed in 3 of the 4 mutated cases. However, no p53 mutations and no p53 overexpression were identified in the 16 MPT. These results indicate that, although the K-ras codon 12 mutations may be almost essential for the development of both MPT and DCC, p53 mutations seemed to be involved mainly to the latters. © Wiley-Liss, Inc.     

肺癌患者癌组织和痰液细胞中p53和K-ras基因突变的研究

目的 检测肺癌组织和肺癌患者痰液脱落细胞中ｐ５３、Ｋ－ｒａｓ基因突变情况,比较联合检测ｐ５３、Ｋ－ｒａｓ和单一检测ｐ５３或Ｋ－ｒａｓ基因在肺癌诊断中的价值。方法 应用ＰＣＲ－ＳＳＣＰ－银染法检测了５９例肺癌组织、癌旁肺组织、１４全肺部良性病变肺组织及患者痰液脱落细胞中ｐ５３基因第５～８外显子、Ｋ－ｒａｓ基因第１外显子突变。结果 肺癌组织中ｐ５３基因突变率为３７．３％（２２／５９）,痰液脱落细胞为３     

p53 and K-ras mutations in lung cancers from former and never-smoking women

Somatic p53 mutations are common in lung cancer. Active cigarette smoking is positively correlated with the total frequency of p53 mutations and G:C to T:A transversions on the nontranscribed (DNA coding) strand. Mutational hotspots within the p53 gene, e.g., codon 157, have been identified for tobacco-related lung cancer, whereas these same mutations are found rarely in other cancers. Such data implicate specific p53 mutations as molecular markers of smoking. Because limited data exist concerning the p53 mutation frequency and spectra in ex-smokers and nonsmokers, we have analyzed p53 and K-ras mutations in 126 lung cancers from a population-based case-control study of nonsmoking (n = 117) or ex-smoking (n = 9) women from Missouri with quantitative assessments of exposure to environmental tobacco smoke. Mutations in the p53 gene were found in lung cancers from lifetime nonsmokers (19%) and ex-smokers (67%; odds ratio, 9.08; 95% confidence interval, 2.06-39.98). All deletions were found in tumors from patients who were either ex-smokers or nonsmokers exposed to passive smoking. The G:C to A:T transitions (11 of 28; 39%) were the most frequent p53 mutations found and clustered in tumors from lifetime nonsmokers without passive smoke exposure. The incidence of K-ras codon 12 or 13 mutations was 11% (14 of 115 analyzed) with no difference between long-term ex-smokers and nonsmokers. These and other results indicate that p53 mutations occur more commonly in smokers and ex-smokers than in never-smokers. Such comparisons provide additional evidence of genetic damage caused by tobacco smoke during lung carcinogenesis.     

Indoor coal combustion emissions, GSTM1 and GSTT1 genotypes, and lung cancer risk: a case-control study in Xuan Wei, China.

The lung cancer mortality rate in Xuan Wei County, China is among the highest in the country and has been associated with exposure to indoor smoky coal emissions that contain high levels of polycyclic aromatic hydrocarbons. This risk may be modified by variation in metabolism genes, including GSTM1, which encodes an enzyme known to detoxify polycyclic aromatic hydrocarbons. To investigate the relationship between GST genotypes and lung cancer risk in Xuan Wei County, we analyzed GSTM1 and GSTT1 genotypes in a population-based case-control study. A total of 122 lung cancer patients and 122 controls, individually matched by age, sex, and home fuel type, were studied. Compared to subjects who used less than 130 tons of smoky coal during their lifetime, heavier users (> or =130 tons) had a 2.4-fold (95% confidence interval, 1.3-4.4) increased risk of lung cancer. The GSTM1-null genotype was associated with a 2.3-fold (95% confidence interval, 1.3-4.2) increased risk of lung cancer. Furthermore, there was some evidence that smoky coal use was more strongly associated with lung cancer risk among GSTM1-null versus GSTM1-positive individuals. In contrast, the GSTT1 genotype was not significantly associated with lung cancer risk. Our data suggest that the GSTM1-null genotype may enhance susceptibility to air pollution from indoor coal combustion emissions.     

Analysis of K-ras p53 and c-raf-1 mutations in beryllium-induced rat lung tumors

Beryllium (Be) metal and several of its analogues have beenshown to be carcinogenic in rats. In addition, workers employedat Be processing plants have been shown to have a slight excessof lung cancer. In this study, a single inhalation exposureto Be metal produced a 64% incidence of lung tumors in the F344/Nrat. The most frequent tumor type observed was adenocarcinoma.These Be metal-induced lung carcinomas were examined for geneticalterations in the K-ras, p53, and c-raf-1 genes. DNA isolatedfrom lung neoplasms was analyzed by PCR amplification and directDNA sequence analysis, immunohistochemical analysis and Southernblot analysis. No K-ras codon 12,13 or 61 mutations were detectedin 24 lung tumors by direct sequencing. Using a more sensitiveK-ras codon 12 mutation selection assay, K-ras codon 12 GGT-GTTtransversions were detected in two of 12 adeno-carcinomas. Theseresults suggest that activation of the K-ras protooncogene isboth a rare and late event, possibly stemming from genomic instabilityduring the progression of some Be-induced rat adenocarcinomasof the lung. No mutant p53 nuclear immunoreactivity was observedin any Be-induced tumor. Because immunohistochemical analysisof the p53 protein only detects missense mutations, exons 5–8of this gene were also analyzed by direct DNA sequencing. Inorder to perform the p53 sequence analysis, it was necessaryto first characterize and sequence the/p53 intron sequencesflanking exons 5–8 and their splice sites. Details ofthis expanded intron DNA sequence information are given here.No mutations were detected within exons 5–8 of the p53gene. No rearrangement of the c-raf-1 protooncogene was detectedby Southern blot analysis. These results indicate that the mechanismsunderlying the development of Be-induced lung cancer in ratsdo not involve gene dysfunctions commonly associated with humannon-small-cell lung cancer.     

Mouse skin tumorigenicity studies of indoor coal and wood combustion emissions from homes of residents in Xuan Wei, China with high lung cancer mortality

The rural Xuan Wei County, Yunnan Province, China, has an unusually high lung cancer mortality rate that cannot be attributed to tobacco smoke or occupational exposure. The lung cancer rate is associated with 'smoky' coal, in contrast to wood or 'smokeless' coal burned in unventilated homes. This study was conducted to characterize and compare mouse skin tumorigenicity of the coal and the wood combustion emissions and to link the animal data to human lung cancer. Indoor air particles (less than 10 microns) were collected from a central commune where the lung cancer mortality rate is high and smoky coal is the major fuel used and also from a south-western commune where lung cancer mortality rate is low and where wood or smokeless coal are the major fuels used. The organic extracts of these indoor air particles from smoky coal, smokeless coal and wood combustion were analysed for polycyclic aromatic hydrocarbons and assayed for skin tumor initiation activity and complete carcinogenicity in SENCAR mice. The results showed that the organic extract of the emission particles from smoky coal combustion is the most active in tumor initiation among the three combustion emission samples followed by smokeless coal and then wood. The organic extract of the particles from smoky coal combustion was shown to be a potent complete carcinogen, whereas the wood extract was relatively inactive as a complete carcinogen. The extract of particles from the smokeless coal combustion was not tested for complete carcinogenicity because of inadequate supply. Eighty-eight percent of the mice treated with the smoky coal extract showed carcinomas, averaging 1.1 carcinomas per tumor-bearing mouse at the end of the 77 week study. These findings were in agreement with the epidemiological data, which showed that the Xuan Wei residents using smoky coal as a major fuel in homes had a high lung cancer mortality rate. This study demonstrates that the results of the tumorigenicity assays in mice were in agreement with human lung cancer data.     

p53 overexpression and K-ras codon 12 mutations in submucosal invasive depressed-type colorectal cancer

We examined histological findings, p53 overexpressions and K-ras codon 12 mutations and the histology of submucosal invasive (sm) colorectal cancers. Sixty specimens of sporadic sm cancer were obtained by surgical resection or endoscopic polypectomy. p53 expression was examined by immunohistochemical staining using the streptavidin-biotin method. K-ras codon 12 mutations were detected by polymerase chain reaction (PCR) and dot blot hybridization. These tumors were classified as depressed-type or polypoid-type sm cancers. Among 60 sm cancer samples, depressed-type sm cancers were found in 9 (15%) and polypoid-type sm cancers were found in 51 (85%). The frequency of p53 expression was significantly higher in depressed-type [7/9 (78%)] as compared to polypoid-type [18/51 (35%)] sm cancers (p<0.05). The frequency of K-ras codon 12 point mutations was significantly lower in depressed-type [0/9 (0%)] as compared to polypoid-type [23/51 (45%)] sm cancers (p<0.05). We conclude that the development of depressed-type cancers may involve a distinct genetic pathway.     

Detection of p53 mutations in precancerous gastric tissue

Intestinal-type gastric cancer is preceded by gastritis and intestinal metaplasia. There is uncertainty regarding the stage at which genetic alterations in the p53 gene occur. Reactive oxygen species (ROS) may participate in the production of mutations and the inactivation of p53 is due to infection by the bacterium Helicobacter pylori. We have investigated whether alterations of the p53 gene can be detected in gastritis and intestinal metaplasia using the restriction site mutation assay. We also assessed the potential contribution of ROS to p53 inactivation using electron spin resonance spectroscopy (ESR) and correlated with the presence of H. pylori. In all, 35% of the gastritis samples and 45% of the intestinal metaplasia samples were found to contain mutations in exons 5-8 of the p53 gene. Electron spin resonance spectroscopy analysis showed a significant increase in free radical levels in gastritis samples compared with normal, intestinal metaplasia and cancer samples, suggesting that free radicals present in gastritis may contribute to p53 mutations. There was no significant difference in free radical levels between the H. pylori-positive and -negative groups. However, a small subpopulation of the H. pylori-negative patients had much higher levels of free radicals. This suggests a more prominent role for other factors in ROS production.     

Analysis of p53, K-ras,c-kit,and beta-catenin gene mutations in sinonasal NK/T cell lymphoma in northeast district of China

Recently we reported the different frequenties of p53 and c-kit gene mutations among sinonasal NK/T cell lymphoma (NKTCL) in Korea, north China (Beijing), and Japan, suggesting some racial, environmental, or life-style differences as a possible cause of nasal tumorigenesis. In this study, gene mutations in p53, c-kit , K-ras, and β-catenin gene were analyzed by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) followed by direct sequencing in 20 cases of sinonasal NKTCL from northeast China (Shen Yang). Age of patients ranged from 5 to 63 (median, 40.0) years. p53 gene mutations were found in eight of 20 cases (40%), with exon 4 involvement in 10% of cases. The majority was missense mutations and G:C to A:T transition was predominant. The frequency of the c-kit and K-ras gene mutations was low (5%), while that of the β-catenin gene was six of 20 cases (30%). From these findings, it is concluded that nasal NKTCL in northeast China shared common features with that in Korea in the younger onset of disease compared to that in Japan and lower frequency of p53 gene mutations with infrequent exon 4 involvement compared to that in Japan and north China. These differences might be caused by migration of susceptible populations or some environmental confounding factors. (Cancer Sci 2003; 94: 297–301)     

p53, K-ras, c-kit and beta-catenin gene mutations in sinonasal NK/T-cell lymphoma in Korea and Japan

Mutations of p53, K-ras, c-kit, and beta-catenin gene were examined in 100 cases of sinonasal NK/T-cell lymphoma (NKTCL) from Korea and Japan. Age of patients ranged from 12 to 72 (median 41.0) in Korea and 27 to 82 (median 61.0) years in Japan. Gene mutations were analyzed on paraffin-embedded specimens by PCR-SSCP followed by direct sequencing. p53 is a well-known tumor suppressor gene. c-kit gene encodes a receptor tyrosine kinase, which plays a crucial role in proliferation and differentiation of hematopoietic stem cells. Mutations of K-ras and beta-catenin are frequently observed in cancers. Thirteen of 42 (31.0%) cases from Korea and 36 of 58 (62.1%) from Japan had p53 mutations, showing significant differences in the incidence of p53 mutation between two countries. Of the Japanese cases 18 (31.0%) had mutations in exon 4, while only 3 cases (7.1%) were found in Korea cases (p<0.01 by chi2 test). K-ras, c-kit and beta-catenin mutations were also found in higher incidence in Japanese cases. In conclusion, different frequency of p53 mutations with different pattern of exon involvement and difference in age of disease onset is evident between sinonasal NKTCL in Korea and Japan.     

Lung tumor KRAS and TP53 mutations in nonsmokers reflect exposure to PAH-rich coal combustion emissions

We determined the TP53 and codon 12 KRAS mutations in lung tumors from 24 nonsmokers whose tumors were associated with exposure to smoky coal. Among any tumors studied previously, these showed the highest percentage of mutations that (a) were G --> T transversions at either KRAS (86%) or TP53 (76%), (b) clustered at the G-rich codons 153-158 of TP53 (33%), and (c) had 100% of the guanines of the G --> T transversions on the nontranscribed strand. This mutation spectrum is consistent with an exposure to polycyclic aromatic hydrocarbons, which are the primary component of the smoky coal emissions. These results show that mutations in the TP53 and KRAS genes can reflect a specific environmental exposure.     

直肠癌p53、K-ras基因突变与临床病理的相关性研究

目的　探索p5 3、k ras基因同时突变对直肠癌的恶性行为升级的作用及其临床意义。方法　用PCR SSCP方法检测直肠癌细胞p5 3、K ras基因突变 ,分析该基因突变与临床病理因素及预后的关系。结果　直肠癌细胞p5 3、K ras基因突变与临床病理因素无关 ,生存率也无统计学差异。结论　直肠癌细胞p5 3、K ras基因突变对癌细胞恶性生物学行为升级无明显的促进作用 ,p5 3、K ras基因同时突变也无协同促癌作用 ,也不影响病人的预后。     

Differences in K-ras and p53 gene mutations among pancreatic adenocarcinomas associated with regional environmental pollution

BACKGROUND: Variations in genetic mutations in pancreatic carcinoma between different geographical regions have not been studied extensively, especially in developing countries where pancreatic cancer is relatively rare. METHODS: We studied the molecular pathology of 54 pancreatic adenocarcinomas from Egyptian patients residing in a heavily polluted region of the eastern Nile River delta and compared the findings with 45 tumors from patients residing in low-pollution regions. RESULTS: Rates of K-ras mutation in codon 12 and of p53 mutation in exons 5-8 were higher in tumors of patients from the high-pollution region as compared with the low-pollution regions (61.5 versus 34.2%, respectively, for K-ras, P = 0.01; 25.9 versus 11.6%, respectively, for p53, P = 0.08). There were also distinct differences in the specific types of K-ras and p53 mutations between the two regions. The ratio of G-to-T k-ras transversion mutation (codon 12) relative to wild-type was significantly higher in tumors from the high-pollution region (0.90) than tumors from the non-pollution site (0.28) (P = 0.03). Relative to tumors with wild-type, the ratio of p53 mutations in exons 5, 7 or 8 to wild-type in tumors from the high-pollution region was significantly higher than the ratio from the non-pollution site (0.28 versus 0.03, P = 0.01). Logistic regression showed that G-to-T transversion mutation in K-ras was predicted by the region of residence of the patients. CONCLUSIONS: Our study reveals that there are differences in the frequencies and types of K-ras and p53 mutations found in pancreatic adenocarcinomas of patients in high-pollution and low-pollution regions in Egypt and suggests that environmental factors may explain these differences. We speculate that gene-environment interactions in pancreatic carcinogenesis also occur in other populations.