TP53 and KRAS2 Mutations in Plasma DNA of Healthy Subjects and Subsequent Cancer Occurrence: A Prospective Study

Abstract

In cancer patients, plasma often contains mutant DNA released by cancer cells. We have assessed the significance of plasma DNA mutations for subsequent cancer development in healthy subjects in a large longitudinal prospective study. The European Prospective Investigation into Cancer and Nutrition study was analyzed with a nested case-control design. Cases were nonsmokers or ex-smokers for >10 years and newly diagnosed with lung, bladder, or upper aerodigestive tract cancers or leukemia accrued after a median follow-up of 6.3 years. Controls were matched 2:1 for follow-up, age, sex, area of recruitment, and smoking status. KRAS2 mutations were detected by mutant-enriched PCR and sequencing (n = 1,098). TP53 mutations were detected by denaturing high-performance liquid chromatography, temporal temperature gradient electrophoresis, and sequencing (n = 550). KRAS2 or TP53 mutations were detected in 13 of 1,098 (1.2%) and 20 of 550 (3.6%) subjects, respectively, 16 of whom developed cancer on average after 18.3 months of follow-up. Among 137 subjects who developed bladder cancer, 5 had KRAS2 mutations [odds ratio (OR), 4.25; 95% confidence interval (95% CI), 1.27-14.15] and 7 had TP53 mutations (OR, 1.81; 95% CI, 0.66-4.97). There was a nonsignificant trend for association between TP53 mutations and bulky adducts in lymphocyte DNA (OR, 2.78; 95% CI,. This is the first report of TP53 or KRAS2 mutations in the plasma of healthy subjects in a prospective study, suggesting that KRAS2 mutation is detectable ahead of bladder cancer diagnosis. TP53 mutation may be associated with environmental exposures. These observations have implications for monitoring early steps of carcinogenesis. (Cancer Res 2006; 66(13): 6871-6)

EGFR and KRAS status of primary sarcomatoid carcinomas of the lung: Implications for anti‐EGFR treatment of a rare lung malignancy

“…33 All mutations were confirmed by a second independent PCR and sequencing reaction. Mutant-enriched PCR (ME-PCR) was also performed on all samples, as described by Gormally et al 34 This method allows the detection of low levels of mutant DNA against a background of wild-type sequences. Briefly, 2 successive restriction fragment length polymorphism analyses were performed, leading to enrichment in mutant sequence.…”

“…Primers and conditions have been published elsewhere. 34,35 Extensive measures were taken to prevent the cross contamination of samples. To avoid false positive results generated during successive PCR rounds, all analyses were repeated twice.…”

“…To avoid false positive results generated during successive PCR rounds, all analyses were repeated twice. Results were scored as ''positive'' or ''negative'' with respect to established cutoff sensitivity values as described by Gormally et al 34 Briefly, DNA from SW480 cells (containing KRAS mutation at codon 12) was diluted in increasing proportion of wildtype DNA and used as a standard. KRAS codon 12 ME-PCR could detect up to 0.1% of mutant DNA in wild-type DNA.…”

Molecular Signatures of Environmental Mutagens in Hepatocellular Carcinoma

“…In heavy smokers, mutations known to be induced by tobacco carcinogens are detected in CFDNA even in the absence of any deˆned lung pathology (51). In a prospective study on cancer risk in a cohort of neversmokers, we have shown that mutations in TP53 and in KRAS could be detected in CFDNA up to several years ahead of diagnosis of speciˆc cancers including bladder cancer (52). These mutations were interpreted as the result of ongoing carcinogenic exposure rather than of the shedding of DNA by undiagnosed, sub-symptomatic lesions.…”

Genomic tests: unreliable for cancer? A focus on circulating DNA and lung cancer

“…Some studies have also demonstrated that detection of genetic changes in CNA in healthy or at-risk individuals is correlated with risk of developing cancer [16,17]. These more recent reports suggest that genetic changes detectable in plasma DNA may be helpful in predicting cancer risk and move the technique much closer to clinical utility.…”