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.     

Smoking, passive smoking and lung cancer cell types among women in Poland.

A case-control study involving 242 women with histologically confirmed lung cancer and 352 healthy controls, was conducted in Cracow, Poland between 1991 and 1997. Subjects were interviewed about their exposure to smoking, passive smoking and other suspected risk factors, according to a structured questionnaire. Multivariate analysis has shown that cigarette smoking was the most strongly active risk factor in female lung cancer. The strongest influence of this factor was observed with reference to small cell carcinoma and squamous cell carcinoma. It has also been observed that passive smoking exposure during childhood before the age of 18, significantly increased risk of squamous cell carcinoma, small cell carcinoma and all cell types combined. A similar effect was observed for adenocarcinoma, but there was no statistical significance.     

Life course socioeconomic conditions, passive tobacco exposures and cigarette smoking in a multiethnic birth cohort of U.S. women

Low socioeconomic status (SES) and exposure to passive tobacco smoke are associated with increased risk of smoking in adults, but the influences of these factors in earlier life periods on adult smoking behavior are not well understood. We investigated the relationship of SES and passive tobacco exposure over the lifecourse with adult smoking status in a multiethnic cohort of U.S. women (n = 262, average age = 41.8), using prospective data on maternal smoking during pregnancy and childhood SES, and follow-up data on current smoking, adult SES and household tobacco exposure. Low adolescent and adult SES consistently increased the risk of current smoking, but most associations were not statistically significant in multivariable models. Blue collar parental occupation at birth increased the risk of smoking, particularly for current smoking relative to former smoking (odds ratio [OR] = 2.7, 95% confidence interval [CI] = 1.2–5.9). After adjusting for SES, current and former smokers were more likely than never smokers to have exposures to prenatal tobacco (OR = 4.4, 95% CI = 2.1–9.4 and OR = 2.0, 95% CI = 1.0–4.2, respectively) and adult household tobacco (OR = 2.7, 95% CI = 1.3–5.8 and OR = 2.4, 95% CI = 1.2–4.8, respectively). Our results show that early life conditions have enduring influences on women’s smoking behavior in middle adulthood, even after considering similar types of conditions in later life periods. We would like to thank Julie Flom for her contribution to the New York Women’s Birth Cohort.     

Contemporary lung cancer trends among U.S. women.

The age-standardized lung cancer incidence rate among women in the United States has decreased for each of the last 3 years for which data are available (1999-2001). We conducted this study to assess the stability and near-term sustainability of this decrease. We examined temporal trends in age-specific lung cancer incidence by calendar year and birth cohort and measured trends in the age-standardized rate in each geographic area within the Surveillance, Epidemiology, and End Results (SEER) Program using joinpoint regression analyses. Age-standardized lung cancer incidence rates have peaked or are decreasing in all geographic areas within SEER, although the decline is statistically significant only in San Francisco-Oakland. Age-specific incidence rates are decreasing in six of the seven 5-year age groups between ages 50 and 84 years in all areas of SEER combined. Rates in these age groups contribute nearly 95% of the total age-standardized incidence rate; consequently, trends in incidence at these ages will determine future trends in the overall age-standardized incidence rate for the next 20 to 25 years. Birth cohort patterns suggest that the decrease in the age-standardized rate will continue for at least 20 years, but will be slowed by aging of women born in the late 1950s and early 1960s. Given calendar year and birth cohort age-specific incidence patterns, the early decline in lung cancer incidence among women is likely to persist through at least 2025. Sustaining the downward trend beyond 2025 will require continued reductions in smoking initiation among children and increases in cessation among addicted smokers.     

EGFR and K-Ras mutations in women with lung adenocarcinoma: implications for treatment strategy definition

Background

We aimed at investigating the outcomes of female patients with stage IIIB-IV adenocarcinoma of the lung according to EGFR and K-Ras mutational status.

Methods

One hundred and three consecutive female patients genotyped at a single Italian Institution were analyzed. Patients were planned to receive first-line platinum-based chemotherapy (CT) and a salvage treatment with anti-EGFR tyrosine-kinase inhibitors (TKIs) was proposed irrespective of tumor mutational status. EGFR (exons 18–21) and K-Ras (exon 2, codons 12–13) mutations were evaluated by real-time PCR and pyrosequencing. The association of mutational status with clinical variables and treatment benefit was investigated by chi-square test and log-rank test.

Results

EGFR and K-Ras mutations were found in 31 (30%) and 13 (15%) cases, respectively. Sixty-six patients received platinum CT: no correlation was observed between EGFR or K-Ras mutational status and response rate (RR) (p > 0.05). However, patients treated with first-line CT harboring EGFR activating mutations experienced a significantly reduced progression-free survival (PFS) in comparison with wild-type ones (4.4 vs. 6.4 months, respectively; HR 0.597, 95% CI 0.287-0.975; p = 0.048). Thirty-nine patients received salvage treatment with erlotinib: EGFR activating mutations were significantly correlated with RR (60% vs. 12.5%; p = 0.004) and PFS (11.4 vs. 4.5 months; HR 0.491, 95% CI 0.216-0.936; p = 0.044). Responses to erlotinib were not reported among women with K-Ras mutant tumors, while 50% of those with wild-type K-Ras achieved an objective remission (p = 0.296). Median PFS (3.5 vs. 8.8 months; HR 0.284, 95% CI 0.015-0.510; p = 0.010) and OS (3.9 vs. 19.8 months; HR 0.158, 95% CI 0.001-0.075; p < 0.001) were significantly shorter among K-Ras mutant patients treated with TKI.

Conclusions

In our population of Caucasian women with advanced lung adenocarcinoma we observed that the presence of EGFR activating mutations correlates with a significant reduction in the benefit from first-line platinum-based CT, emphasizing the importance of an upfront use of anti-EGFR TKIs in this patient subset. K-Ras mutations seem to correlate with a detrimental effect from anti-EGFR TKI, but this finding deserves further investigation.     

Quantification of EGFR mutations in primary and metastatic tumors in non-small cell lung cancer

Background

EGFR mutation detection has been widely applied in the prediction of TKIs therapy in Non-Small Cell Lung Cancer (NSCLC). Metastatic tumors rather than primary tumors were usually assayed for those patients in advanced stages. Although the difference of EGFR mutation status in primary and metastatic tumors has been reported, the quantitative difference (ratio of mutated EGFR among total EGFR) in primary and metastatic tumors as well as in different sites of primary tumors was not clear.

Methods

Genomic DNA in Formalin Fixed-Paraffin Embedded samples of primary and metastatic tumors of 50 NSCLC patients was extracted. Real-time fluorescent PCR was performed to quantify the EGFR mutation ratios.

Results

The EGFR mutation ratios detected in different sites of primary tumors were highly concordant, whereas the EGFR mutation ratios in metastatic tumors were lower than those in primary tumors.

Conclusions

Randomly chosen sample may reliably represent the type and ratio of mutations of EGFR in primary tumors. EGFR mutation ratios in primary tumors and metastatic tumors are different. If metastatic tumors are used for the detection of EGFR mutation, the sensitivity of the detection assay must be considered.     

Lifetime residential and workplace exposure to environmental tobacco smoke and lung cancer in never-smoking women, Canada 1994-97

Although the risk of lung cancer among never-smokers living with a spouse who smokes has been extensively studied, the impact of lifetime residential and workplace environmental tobacco smoke has received less attention. As part of a large population-based case-control study of lung cancer, we collected lifetime residential and occupational passive smoking information from 71 women with lung cancer and 761 healthy control subjects, all of whom reported being lifetime nonsmokers. The adjusted odds ratio (OR) for lung cancer associated with residential passive exposure only was 1.21 (95% confidence interval [CI] 0.5-2.8). Although more years of and more intense residential passive smoke exposure tended to be associated with higher risk estimates, no clear dose-response relationship was evident. The OR for women with passive exposure as a child and as an adult was 1.63 (95% CI 0.8-3.5) and for those only exposed as an adult 1.20 (95%CI 0.5-3.0). Exposure to environmental tobacco smoke only in the workplace was associated with an adjusted OR of 1.27 (95% CI 0.4-4.0). Risks associated with increasing occupational exposure year tertiles were 1.24, 1.71 and 1.71. Total smoker-years of residential and occupational exposure combined resulted in a statistically significant trend (linear test for trend p = 0.05) with ORs for tertiles of exposure of 0.83, 1.54 and 1.82. Our results are consistent with the literature suggesting that long-term, regular exposure to either residential or occupational environmental tobacco smoke is associated with increased lung cancer risk in never-smoking women.     

非小细胞肺癌原发灶与脑转移灶EGFR基因突变状况的一致性研究

目的 探讨非小细胞肺癌（NSCLC）原发灶与脑转移灶的表皮生长因子受体（EGFR）基因突变状况,分析两者之间是否存在一致性。方法 收集2003年1月至2011年12月31例NSCLC脑转移患者的肺原发灶和脑转移灶石蜡包埋组织标本,应用DNA直接测序法进行EGFR突变分析,如发现两者突变不一致则进一步采用增殖阻碍突变系统 （ARMS）验证。结果 31例NSCLC肺原发灶中,8例存在19外显子E746-A750缺失突变、4例为21外显子L858R点突变;在31例脑转移灶样本中,8例为19外显子E746-A750缺失突变,3例存在21外显子L858R点突变,EGFR突变类型在脑转移灶和肺原发灶的分布差异无统计学意义 （P=0.793）。共有16.1％ （5／31）的肺原发灶和脑转移灶EGFR突变状况不一致,其中男性4例,女性1例;3例腺癌 （2例脑转移灶19外显子缺失突变而肺原发灶阴性突变,1例肺原发灶21外显子点突变而脑转移灶阴性突变）,1例鳞癌和1例非典型类癌 （均为脑转移灶阴性突变而肺原发灶19外显子缺失突变）。结论 NSCLC原发病灶及脑转移灶EGFR基因突变存在不一致性。     

Smoking, passive smoking and histological types in lung cancer in Hong Kong Chinese women

In a case control study in Hong Kong, 445 cases of Chinese female lung cancer patients all confirmed pathologically were compared with 445 Chinese female healthy neighbourhood controls matched for age. The predominant histological type was adenocarcinoma (47.2%). The relative risk (RR) in ever-smokers was 3.81 (P less than 0.001, 95% CI = 2.86, 5.08). The RRs were statistically significantly raised for all major cell types with significant trends between RR and amount of tobacco smoked daily. Among never smoking women, RR for passive smoking due to a smoking husband was 1.65 (P less than 0.01, 95% CI = 1.16, 2.35) with a significant trend between RR and amount smoked daily by the husband. When broken down by cell types, the numbers were substantial only for adenocarcinoma (RR = 2.12, P less than 0.01, 95% CI = 1.32, 3.39) with a significant trend between RR and amount smoked daily by the husband. The results suggest that passive smoking is a risk factor for lung cancer, particularly adenocarcinoma in Hong Kong Chinese women who never smoked.     

Residential radon exposure and lung cancer: an overview of published studies.

A possible link between presumed or measured household radon exposure and lung cancer is reviewed on the basis of published epidemiologic studies. Evidence of a link is reported as a result of studies in Sweden; findings are inconsistent elsewhere. A number of methodological problems were found. Many of the studies are ecological in design and are, therefore, primarily hypothesis generating. A number of studies lack any data on the number of lung cancers and are, therefore, difficult to evaluate. Some other studies provide results that are internally inconsistent. Of the case/control studies, there are many with minimal or no information on active and passive smoking, occupation, family history of cancer, and diet. The case/control studies are generally small in size and of low statistical power. Exposure classifications are nonstandardized, inconsistent in their findings, and often gross in their characterization of radon concentrations. Relatively few of the studies actually measured radon exposure. Some of the studies showed significant positive associations either with geological characteristics, water supply contamination, or house type. No significant associations were found with residence near uranium or radium processing waste. Where radon levels were measured, a relatively small percentage of studies found a statistically significant positive association with lung cancer. Overall, the evidence for an association between residential radon exposure and lung cancer is weak. There is a need for a more decisive case/control epidemiologic study of this problem.     

K-ras mutations in human adenocarcinoma of the lung: Association with smoking and occupational exposure to asbestos

We investigated point mutational activation of the ras genes (K-ras codons 12, 13 and 61; N-ras codons 12, 13 and 61; H-ras codons 12 and 61) in primary, resected lung cancer by dot blotting and oligonucleotide hybridization. K-ras mutations were found in 14 (29%) of the 48 lung tumour specimens examined, but no N-ras or H-ras mutations were found. The highest frequency of K-ras mutation was observed in adenocarcinoma: 12 of the 21 samples studied (57%) had a mutation, which is one of the highest frequencies reported for lung adenocarcinoma. The commonest type of mutation in these lung tumour samples consisted of transversions: we observed 11, of which 8 (57% of all mutations) were G to T transversions. Most of the 48 patients studied had a history of heavy smoking, either with or without evidence of occupational exposure to asbestos. Statistical analysis revealed-in addition to the highly significant association between the adenocarcinoma type of lung cancer and K-ras mutation-a clear association of K-ras mutations with heavy life-time smoking (≥50 pack-years of cigarette smoking; odds ratio (OR) 4.9, 90% CI 1.2 - 19.5, multivariate analysis). In addition, occupational asbestos exposure showed an elevated, but non-significant, OR of 2.2 (90% CI 0.6 - 8.7) with the presence of K-ras mutation. We conclude that the occurrence of K-ras mutations in adenocarcinoma of the lung is frequent, and that such mutations are associated with heavy life-time exposure to tobacco smoke, possibly in combination with occupational exposure to asbestos fibres.     

p53 mutations in non-small cell lung cancer in Japan: association between mutations and smoking.

The p53 gene has been implicated as a tumor suppressor gene involved in the pathogenesis of lung cancer. Our previous study revealed that the p53 gene is frequently mutated with a distinct nucleotide substitution pattern in small cell lung cancer specimens in Japanese patients. In this study, we examined 30 primary, resected non-small cell lung cancer samples in Japanese patients using complementary DNA-polymerase chain reaction and sequencing. Mutations changing the p53 coding sequence were found in 14 of 30 tumor samples (47%), while G:C to T:A transversions which are uncommon in other cancers such as colon cancer were the most frequently observed mutations, in agreement with an earlier report on non-small cell lung cancer in American patients. Furthermore, the present study shows for the first time that in univariate and multivariate analyses, the presence of p53 mutations is closely associated with lifetime cigarette consumption.     

p53 mutations in human lung tumors.

Mutation of one p53 allele and loss of the normal p53 allele [loss of heterozygosity (LOH)] occur in many tumors including lung cancers. These alterations apparently contribute to development of cancer by interfering with the tumor suppressor activity of p53. We directly sequenced amplified DNA in the mutational hot spots (exons 4-8) of p53 in DNA samples from 40 lung cancers. Most (31 of 40) samples were preselected for LOH in the region of p53. We detected 23 p53 mutations within these exons in 22 lung cancers; no p53 mutations were found in normal tissue of the patients. One-half of the mutations were G to T transversions on the nontranscribed strand, consistent with mutagenesis by tobacco smoke. Mutations of C to A on the nontranscribed strand, which would result from G to T mutations on the transcribed strand, were detected only in one sample. Three of 23 mutations were nonsense mutations; to date, nonsense mutations of p53 have not been reported in lung cancer. Mutation of this p53-coding region was detected in 20 of 27 small cell lung cancer samples, representing a 70% occurrence. Mutation of the p53 gene is apparently very frequent in small cell lung cancers. When LOH in the p53 region could be determined, complete concordance occurred between a sample having both a p53 mutation and LOH in the region of p53 (18 of 18 samples). Twelve samples of lung cancer had LOH in the region of p53, but the samples had no detectable p53 mutations, suggesting either alterations outside the known mutational hot spots of p53 or alterations of another unidentified tumor suppressor gene in the region of p53.     

Concomitant EGFR and KRAS mutations in ALK-rearranged lung cancer

We would add here new information on the subset of NSCLC with concomitant ALK rearrangement and mutations not only in EGFR, as described by Won JK et al in the February issue of Annals of Oncology, but also in KRAS.KRAS mutations in ALK rearranged NSCLC do seem to represent a novel mechanism of primary resistance to crizotinib that merits further confirmation on larger series of cases.     

Environmental tobacco smoke, genetic susceptibility, and risk of lung cancer in never-smoking women

BACKGROUND: Exposure to environmental tobacco smoke (ETS) is considered to be a major lung cancer risk factor for never smokers. We investigated the hypothesis that never-smoking women who are exposed to ETS and develop lung cancer are a genetically susceptible population. METHODS: Archival tumor tissues were analyzed from 106 never-smoking women enrolled in a case-control study of ETS (and other personal and environmental factors) and lung cancer risk. We analyzed germline polymorphisms in genes that have been associated with cancer susceptibility and whose products activate (cytochrome P450 1A1 [CYP1A1]) and detoxify (glutathione S-transferases M1 [GSTM1] and T1 [GSTT1]) chemical carcinogens found in tobacco smoke. RESULTS: When compared with never smokers who had no ETS exposure and developed lung cancer (n = 55), never smokers with exposure to ETS who developed lung cancer (n = 51) were more likely to be deficient in GSTM1 activity (i.e., were GSTM1 null) because of a genetic polymorphism in the GSTM1 gene (odds ratio = 2.6; 95% confidence interval = 1.1-6.1). A statistically significant rising trend in risk occurred with increasing ETS exposure (two-sided P =. 02), reaching a more than sixfold excess risk in those exposed to 55 pack-years of ETS (ETS pack-year = ETS produced by an active smoker, within a confined space such as a room, who smokes one pack of cigarettes a day for a year). No evidence was found of associations between GSTT1 deficiency or the CYP1A1 valine variant and lung cancer risk due to ETS exposure. CONCLUSIONS: A common genetic polymorphism divides the population of never smokers into two groups of approximately equal size, one (homozygous carriers of the GSTM1 null allele) that has a statistically significant greater risk of lung cancer from ETS than the other (heterozygous or homozygous carriers of the wild-type GSTM1 allele).     

Common genetic variation in TP53 is associated with lung cancer risk and prognosis in African Americans and somatic mutations in lung tumors.

Lung cancer is primarily caused by tobacco smoking, but susceptibility is likely modified by common genetic variation. In response to many forms of cellular stress, including DNA damage, the p53 protein functions to induce cell cycle arrest, DNA repair, senescence, or apoptosis. We hypothesized that common TP53 haplotypes modulate pathways of lung carcinogenesis and lung cancer susceptibility or prognosis. To investigate our hypothesis, 14 polymorphisms in TP53, including haplotype tagging and coding single nucleotide polymorphisms, were genotyped in two studies from the greater Baltimore, Maryland area. One study is a case-control study and the second is a case-only study for which TP53 mutational spectra data are available. African Americans with Pro-T-A-G-G haplotypes of the combined TP53 polymorphisms TP53_01 (rs1042522), TP53_65 (rs9895829), TP53_66 (rs2909430), TP53_16 (rs1625895), and TP53_11 (rs12951053) had both an increased risk for lung cancer (odds ratio, 2.32; 95% confidence interval, 1.18-4.57) and a worsened lung cancer prognosis (hazards ratio, 2.38; 95% confidence interval, 1.38-4.10) compared with those with Arg-T-A-G-T haplotypes. No associations of TP53 polymorphisms with lung cancer were observed in Caucasians. In the case-only study, several polymorphisms in TP53 and TP53 haplotypes, overlapping regions of TP53 associated with risk and prognosis in African Americans, were associated with increased odds of somatic TP53 mutation in lung tumors in Caucasians. In conclusion, common genetic variation in TP53 could modulate lung cancer pathways, as suggested by the association with lung cancer in African Americans and somatic TP53 mutation frequency in lung tumors.     

Cigarette smoking and lung cancer: modeling total exposure and intensity.

Investigators typically analyze cigarette smoking using smoking duration and intensity (number of cigarettes smoked per day) as risk factors. However, odds ratios (OR) for categories of intensity either adjusted for, or jointly with, duration of smoking may be distorted by differences in total pack-years of exposure to cigarette smoke. To study effects of intensity, we apply a linear excess OR model to compare total exposure delivered at low intensity for a long period of time with an equal total exposure delivered at high intensity for a short period of time to data from a large case-control study of lung cancer. The excess OR per pack-year increases with intensity for subjects who smoke < or =20 cigarettes per day and decreases with intensity for subjects who smoke >20 cigarettes per day. The intensity patterns are homogeneous by histologic type of lung cancer, suggesting that observed differences in risks by histologic type are related to total smoking exposure or smoking duration and not smoking intensity. At lower smoking intensities, there is an "exposure enhancement" effect such that for equal total exposure, the excess OR per pack-year increases with intensity. At higher smoking intensities, there is a "reduced potency" or "wasted exposure" effect such that for equal total exposure, the excess OR per pack-year decreases with intensity (i.e., smoking at a lower intensity for longer duration is more deleterious than smoking at a higher intensity for shorter duration).     

Survival in operable non-small-cell lung cancer: role of p53 mutations, tobacco smoking and asbestos exposure

Validated markers are needed to identify operable lung cancer patients with poor prognosis. About one-half of non-small-cell lung cancers (NSCLCs) carry a mutation in the p53 tumor-suppressor gene. We examined 101 NSCLC patients for surgical stage, completeness of resection, tobacco smoking, asbestos exposure, age, gender and p53 gene mutations as prognostic factors after a follow-up period of 4 years. Cox's multivariate regression model was applied to quantify the associations with overall and cancer-related survival. Patients with a wild-type p53 gene had an overall 4-year survival of 43% and those with a mutated p53 gene, 35%. In squamous-cell carcinoma, stage and heavy smoking, defined as the median of pack-years smoked, had prognostic significance for overall survival. Only stage was associated with poor cancer-related survival. Asbestos exposure was not associated with overall survival or cancer-related survival in squamous-cell carcinoma or adenocarcinoma. In adenocarcinoma, p53 mutation, in addition to stage, emerged as a significant predictor of poor cancer-related survival.