Identification of hypermethylated tumor suppressor genes in body fluids is an appealing strategy for the noninvasive detection of colorectal cancer. Here we examined the role of N-Myc downstream-regulated gene 4 (NDRG4) as a novel tumor suppressor and biomarker in colorectal cancer.
NDRG4 promoter methylation was analyzed in human colorectal cancer cell lines, colorectal tissue, and noncancerous colon mucosa by using methylation-specific polymerase chain reaction (PCR) and bisulfite sequencing. NDRG4 mRNA and protein expression were studied using real-time–PCR and immunohistochemistry, respectively. Tumor suppressor functions of NDRG4 were examined by colony formation, cell proliferation, and migration and invasion assays in colorectal cancer cell lines that were stably transfected with an NDRG4 expression construct. Quantitative methylation-specific PCR was used to examine the utility of NDRG4 promoter methylation as a biomarker in fecal DNA from 75 colorectal cancer patients and 75 control subjects. All P values are two-sided.
The prevalence of NDRG4 promoter methylation in two independent series of colorectal cancers was 86% (71/83) and 70% (128/184) compared with 4% (2/48) in noncancerous colon mucosa (P < .001). NDRG4 mRNA and protein expression were decreased in colorectal cancer tissue compared with noncancerous colon mucosa. NDRG4 overexpression in colorectal cancer cell lines suppressed colony formation (P = .014), cell proliferation (P < .001), and invasion (P < .001). NDRG4 promoter methylation analysis in fecal DNA from a training set of colorectal cancer patients and control subjects yielded a sensitivity of 61% (95% confidence interval [CI] = 43% to 79%) and a specificity of 93% (95% CI = 90% to 97%). An independent test set of colorectal cancer patients and control subjects yielded a sensitivity of 53% (95% CI = 39% to 67%) and a specificity of 100% (95% CI = 86% to 100%).
NDRG4 is a candidate tumor suppressor gene in colorectal cancer whose expression is frequently inactivated by promoter methylation. NDRG4 promoter methylation is a potential biomarker for the noninvasive detection of colorectal cancer in stool samples.
Information on clinically verified stroke and transient ischemic attack (TIA) following Hodgkin lymphoma is scarce. We quantified the long-term risk of cerebrovascular disease associated with the use of radiotherapy and chemotherapy in survivors of Hodgkin lymphoma and explored potential pathogenic mechanisms.
We performed a retrospective cohort study among 2201 five-year survivors of Hodgkin lymphoma treated before age 51 between 1965 and 1995. We compared incidence rates of clinically verified stroke and TIA with those in the general population. We used multivariable Cox regression techniques to study treatment-related factors and other risk factors. All statistical tests were two-sided.
After a median follow-up of 17.5 years, 96 patients developed cerebrovascular disease (55 strokes, 31 TIAs, and 10 with both TIA and stroke; median age = 52 years). Most ischemic events were from large-artery atherosclerosis (36%) or cardioembolisms (24%). The standardized incidence ratio for stroke was 2.2 (95% confidence interval [CI] = 1.7 to 2.8), and for TIA, it was 3.1 (95% CI = 2.2 to 4.2). The risks remained elevated, compared with those in the general population, after prolonged follow-up. The cumulative incidence of ischemic stroke or TIA 30 years after Hodgkin lymphoma treatment was 7% (95% CI = 5% to 8%). Radiation to the neck and mediastinum was an independent risk factor for ischemic cerebrovascular disease (hazard ratio = 2.5, 95% CI = 1.1 to 5.6 vs without radiotherapy). Treatment with chemotherapy was not associated with an increased risk. Hypertension, diabetes mellitus, and hypercholesterolemia were associated with the occurrence of ischemic cerebrovascular disease, whereas smoking and overweight were not.
Patients treated for Hodgkin lymphoma experience a substantially increased risk of stroke and TIA, associated with radiation to the neck and mediastinum. Physicians should consider appropriate risk-reducing strategies.
Merkel cell carcinoma is a rare malignancy of the skin. Integration of Merkel cell polyomavirus (MCPyV) DNA to the tumor genome is frequent in these cancers. The clinical consequences of MCPyV infection are unknown.
We analyzed formalin-fixed paraffin-embedded Merkel cell carcinoma tissue samples from 114 of 207 patients diagnosed with Merkel cell carcinoma in Finland from 1979 to 2004 for the presence of MCPyV DNA with the use of polymerase chain reaction (PCR), quantitative PCR, and DNA sequencing and examined associations between tumor MCPyV DNA status and histopathologic factors and survival. The median follow-up time after Merkel cell carcinoma diagnosis for subjects who were alive was 9.9 years (range = 4.9–21.9 years). All P values are two-sided.
MCPyV DNA was present in 91 carcinomas (79.8%). Compared with MCPyV DNA–negative cancers, MCPyV DNA–positive cancers were more often located in a limb (40.7% vs 8.7%, P = .015) and less frequent in patients who had regional nodal metastases at diagnosis (6.6% vs 21.7%, P = .043). Patients with MCPyV DNA–positive tumors had better overall survival than those with MCPyV DNA–negative tumors (5-year survival: 45.0% vs 13.0%, respectively; P < .001, two-sided log-rank test).
MCPyV infection is associated with clinical outcomes in patients with Merkel cell carcinoma. These findings lend support to the hypothesis that viral infection is frequently associated with the pathogenesis of Merkel cell carcinoma.
Adult survivors of childhood central nervous system (CNS) malignancies are at high risk for long-term morbidity and late mortality. However, patterns of late mortality, the long-term risks of subsequent neoplasms and debilitating medical conditions, and sociodemographic outcomes have not been comprehensively characterized for individual diagnostic and treatment groups.
We collected information on treatment, mortality, chronic medical conditions, and neurocognitive functioning of adult 5-year survivors of CNS malignancies diagnosed between 1970 and 1986 within the Childhood Cancer Survivor Study. Using competing risk framework, we calculated cumulative mortality according to cause of death and cumulative incidence of subsequent neoplasms according to exposure and dose of cranial radiation therapy (RT). Neurocognitive impairment and socioeconomic outcomes were assessed with respect to dose of CNS radiotherapy to specific brain regions. Cumulative incidence of chronic medical conditions was compared between survivors and siblings using Cox regression models. All tests of statistical significance were two-sided.
Among all eligible 5-year survivors (n = 2821), cumulative late mortality at 30 years was 25.8% (95% confidence interval [CI] = 23.4% to 28.3%), due primarily to recurrence and/or progression of primary disease. Patients who received cranial RT of 50 Gy or more (n = 813) had a cumulative incidence of a subsequent neoplasm within the CNS of 7.1% (95% CI = 4.5% to 9.6%) at 25 years from diagnosis compared with 1.0% (95% CI = 0% to 2.3%) for patients who had no RT. Survivors had higher risk than siblings of developing new endocrine, neurological, or sensory complications 5 or more years after diagnosis. Neurocognitive impairment was high and proportional to radiation dose for specific tumor types. There was a dose-dependent association between RT to the frontal and/or temporal lobes and lower rates of employment, and marriage.
Survivors of childhood CNS malignancies are at high risk for late mortality and for developing subsequent neoplasms and chronic medical conditions. Care providers should be informed of these risks so they can provide risk-directed care and develop screening guidelines.
Adding genotypes from seven single-nucleotide polymorphisms (SNPs), which had previously been associated with breast cancer, to the National Cancer Institute's Breast Cancer Risk Assessment Tool (BCRAT) increases the area under the receiver operating characteristic curve from 0.607 to 0.632.
Criteria that are based on four clinical or public health applications were used to compare BCRAT with BCRATplus7, which includes the seven genotypes. Criteria included number of expected life-threatening events for the decision to take tamoxifen, expected decision losses (in units of the loss from giving a mammogram to a woman without detectable breast cancer) for the decision to have a mammogram, rates of risk reclassification, and number of lives saved by risk-based allocation of screening mammography. For all calculations, the following assumptions were made: Hardy–Weinberg equilibrium, linkage equilibrium across SNPs, additive effects of alleles at each locus, no interactions on the logistic scale among SNPs or with factors in BCRAT, and independence of SNPs from factors in BCRAT.
Improvements in expected numbers of life-threatening events were only 0.07% and 0.81% for deciding whether to take tamoxifen to prevent breast cancer for women aged 50–59 and 40–49 years, respectively. For deciding whether to recommend screening mammograms to women aged 50–54 years, the reduction in expected losses was 0.86% if the ideal breast cancer prevalence threshold for recommending mammography was that of women aged 50–54 years. Cross-classification of risks indicated that some women classified by BCRAT would have different classifications with BCRATplus7, which might be useful if BCRATplus7 was well calibrated. Improvements from BCRATplus7 were small for risk-based allocation of mammograms under costs constraints.
The gains from BCRATplus7 are small in the applications examined. Models with SNPs, such as BCRATplus7, have not been validated for calibration in independent cohort data. Additional studies are needed to validate a model with SNPs and justify its use.