Alan Ng

National University of Singapore, Singapore, Singapore

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Publications (6)26.31 Total impact

  • Article: Aspirin and non-aspirin non-steroidal anti-inflammatory drug use and risk of lung cancer.
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    ABSTRACT: There is evidence that aspirin and non-aspirin non-steroidal anti-inflammatory drug (NSAID) have anti-carcinogenic properties, but their effect on lung cancer, in particular in never-smokers, is unclear. Information on past or current use of anti-inflammatory medication was obtained in 398 Chinese female primary lung cancer cases and 814 controls in a hospital-based study in Singapore. 65% of cases and 88% of controls were never-smokers. Controls were excluded if they had been admitted for conditions associated with aspirin or NSAID use (n=174). Regular aspirin use (twice a week or more, for a month or more) was associated with a reduced risk of lung cancer (adjusted odds ratio [OR] 0.50, 95% confidence intervals [95%CI] 0.31-0.81 in non-smokers; OR 0.38, 95%CI 0.16-0.93 in smokers). Regular use of non-aspirin NSAID, paracetamol, steroid creams and steroid pills was uncommon and no association with lung cancer was detected. Our results suggest that aspirin consumption may reduce lung cancer risk in Asian women and are consistent with current understanding of the role of cyclooxygenase in lung carcinogenesis.
    Lung cancer (Amsterdam, Netherlands) 04/2012; 77(2):246-51. · 3.14 Impact Factor
  • Article: Female reproductive factors, gene polymorphisms in the estrogen metabolism pathway, and risk of lung cancer in Chinese women.
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    ABSTRACT: The authors examined relations between reproductive factors and 5 estrogen pathway gene polymorphisms (CYP17 rs743572, CYP19A1 rs10046, ERβ rs1256049, ERβ rs4986938, and COMT rs4680) among 702 Singapore Chinese female lung cancer cases and 1,578 hospital controls, of whom 433 cases (61.7%) and 1,375 controls (87.1%) were never smokers. Parity (per child, odds ratio (OR) = 0.92, 95% confidence interval (CI): 0.87, 0.97) and menstrual cycle length (for ≥30 days vs. <30 days, OR = 0.50, 95% CI: 0.32, 0.80) were inversely associated with lung cancer in never smokers, while age at first birth (for ages 21-25, 26-30, and ≥31 years vs. ≤20 years, ORs were 1.54, 2.17, and 1.30, respectively), age at menopause (for ages 49-51 and ≥52 years vs. ≤48 years, ORs were 1.37 and 1.59; P(trend) = 0.003), and reproductive period (for 31-33, 34-36, 37-39, and ≥40 years vs. ≤30 years, ORs were 1.06, 1.25, 1.45, and 1.47; P(trend) = 0.026) were positively associated. Among smokers, parity was inversely associated with lung cancer, but there was no association with other reproductive factors. The COMT rs4680 A allele was positively associated with lung cancer in never smokers (for G/A or A/A vs. G/G, OR = 1.46, 95% CI: 1.12, 1.90) but not in ever smokers. No associations were seen with other polymorphisms. These results support a risk-enhancing role of estrogens in lung carcinogenesis among never smokers.
    American journal of epidemiology 02/2012; 175(6):492-503. · 5.59 Impact Factor
  • Article: Meat consumption and risk of lung cancer among never-smoking women.
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    ABSTRACT: The relationship between diet and lung cancer, apart from the protective effect of fruit and vegetables, is poorly understood. Reports on the role of dietary components such as meat are inconsistent, and few studies include sufficient numbers of nonsmokers. We examined the relationship between meat consumption and never-smoking lung cancer in a hospital-based case-control study of Singapore Chinese women, a population with low smoking prevalence. Three hundred and ninety-nine cases and 815 controls were recruited, of whom 258 cases and 712 controls were never smokers. A standardized questionnaire (which included a food frequency questionnaire module) was administered by trained interviewers. Among these never smokers, fruit and vegetable intake were inversely associated with lung cancer risk. Seventy-two percent of meat consumed was white meat (chicken or fish). Meat consumption overall was inversely associated with lung cancer [adjusted odds ratio (OR), 0.88, 0.59 for second, third tertiles, P (trend) = .012]. An inverse relationship between fish consumption and lung cancer (adjusted OR, 0.81, 0.47 for 2nd, 3rd tertiles, P (trend) < .001) was observed. No association was seen between consumption of processed meats and lung cancer, nor between dietary heterocyclic amines and lung cancer. Our data suggest that fish consumption may be protective against lung cancer in never smokers.
    Nutrition and Cancer 08/2011; 63(6):850-9. · 2.78 Impact Factor
  • Article: Polymorphisms in inflammatory pathway genes, host factors and lung cancer risk in Chinese female never-smokers.
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    ABSTRACT: Inflammation appears to be important in lung carcinogenesis among smokers, but its role among never-smokers is not well established. We hypothesized that inflammatory medical conditions and gene polymorphisms interact to increase lung cancer risk in never-smokers. We interviewed 433 Singaporean female never-smoker lung cancer patients and 1375 hospital controls, and evaluated six polymorphisms in the interleukin 1-β, interleukin 6 (IL6), cyclooxygenase-2, peroxisome proliferator-activated receptor-γ and interleukin 1-β receptor antagonist (IL1RN) genes. Tuberculosis was associated with a non-significant elevated risk of lung cancer [odds ratio (OR) 1.58, 95% confidence interval (CI) 0.95-2.62]. There was no effect of asthma, atopy or chronic productive cough individually. However, the presence of one or more of these conditions (asthma, cough or atopy) increased risk (OR 2.24, 95%CI 1.15-4.38) in individuals possessing the T/T genotype at interleukin 1-β -31T/C, but not in those possessing the C/T (OR 0.87, 95%CI 0.51-1.57) or C/C genotypes (OR 0.58, 95%CI 0.27-1.27), and in individuals having the *2 variable number of tandem repeat allele of IL1RN [OR 5.09 (1.39-18.67)], but not in those without (OR 0.93, 95%CI 0.63-1.35). The IL6-634 G allele increased the risk of lung cancer (OR 1.44, 95%CI 1.07-1.94). Lung cancer risk also increased with the number of polymorphism sites where at least 1 'risk' allele was present [interleukin 1-β -31T/C (T allele), IL1RN (*2 allele) and IL6-634C/G (G allele)] among those with asthma, cough or atopy (Ptrend 0.001) but not in those without (Ptrend 0.47). Our results suggest that the effect of inflammatory medical conditions on lung cancer in never-smokers is modulated by host genetic susceptibility and will need to be confirmed in other studies conducted in similar populations.
    Carcinogenesis 01/2011; 32(4):522-9. · 5.70 Impact Factor
  • Article: Using whole genome amplification (WGA) of low-volume biopsies to assess the prognostic role of EGFR, KRAS, p53, and CMET mutations in advanced-stage non-small cell lung cancer (NSCLC).
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    ABSTRACT: Progression of non-small cell lung cancer (NSCLC) from early- to late-stage may signify the accumulation of gene mutations. An advanced-stage tumor's mutation profile may also have prognostic value, guiding treatment decisions. Mutation detection of multiple genes is limited by the low amount of deoxyribonucleic acid extracted from low-volume diagnostic lung biopsies. We explored whole genome amplification (WGA) to enable multiple molecular analyses. Eighty-eight advanced-stage NSCLC patients were enrolled. Their low-volume lung biopsies underwent WGA before direct sequencing for epidermal growth factor receptor (EGFR), KRAS (rat sarcoma virus), p53, and CMET (mesenchymal-epithelial transition factor) mutations. Overall survival impact was examined. Surgically-resected tumors from 133 early-stage NSCLC patients were sequenced for EGFR, KRAS and p53 mutations. We compared the mutation frequencies of both groups. It is feasible for low-volume lung biopsies to undergo WGA for mutational analysis. KRAS and CMET mutations have a deleterious effect on overall survival, hazard ratios 5.05 (p = 0.009) and 23.65 (p = 0.005), respectively. EGFR and p53 mutations, however, do not have a survival impact. There also does not seem to be significant differences in the frequency of mutations in EGFR, KRAS, and p53 between early- and advanced-stage disease: 20% versus 24% (p = 0.48), 29% versus 27% (p = 0.75), 10% versus 6% (p = 0.27), respectively. In advanced-stage NSCLC, KRAS, and CMET mutations suggest poor prognosis, whereas EGFR and p53 mutations do not seem to have survival impact. Mutations in EGFR, KRAS and p53 are unlikely to be responsible for the progression of NSCLC from early- to late-stage disease. WGA may be used to expand starting deoxyribonucleic acid from low-volume lung biopsies for further analysis of advanced-stage NSCLC.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 02/2009; 4(1):12-21. · 4.55 Impact Factor
  • Article: An alternative approach to determining therapeutic choices in advanced non-small cell lung carcinoma (NSCLC): maximizing the diagnostic procedure and the use of low-volume lung biopsies.
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    ABSTRACT: Accurate mutational analysis, especially epidermal growth factor receptor (EGFR) mutations, of diagnostic biopsies from all Asian NSCLC patients is crucial to their clinical management, but faces problems. Here, we explore, within usual hospital constraints, the practicalities of incorporating mutational analysis in every newly diagnosed case of NSCLC, namely, maximizing tissue acquisition during the diagnostic procedure and determining the maximum quantity and quality of DNA sequence data available from these biopsies. Sixty-eight Chinese patients were enrolled. Thirty-five underwent surgical resections for early-stage tumors. Thirty-three underwent diagnostic procedures, i.e., needle aspirates under bronchoscopic or computed tomographic/fluoroscopic guidance, or forceps biopsies via bronchoscopy. Separate samples for research purposes were obtained from these 33 patients during the diagnostic procedure. All samples were analyzed for mutations in EGFR exons 18 to 21, p53 exons 4 to 9, and Kras exon 2. No deaths occurred in this study. Success rates in obtaining sequence data from surgical samples versus low-volume samples for EGFR, p53, and Kras were 100% versus 85%, 100% versus 82%, and 100% versus 85%, respectively. Sequencing nine polymerase chain reaction products from each low-volume sample resulted in the exhaustion of all extracted DNA from three samples. Acquiring a separate low-volume lung biopsy sample for mutational analysis in lung cancer patients during the diagnostic procedure is feasible and may be a valuable complement to the usual diagnostic workflow in future.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 06/2007; 2(5):387-96. · 4.55 Impact Factor