Colon cancer: association of histopathological parameters and patients' survival with clinical presentation

Available data correlating symptoms of colon cancer patients with the severity of the disease are very limited. In a population‐based setting, we correlated information on symptoms of colon cancer patients with several pathological tumor parameters and survival. Information on all patients diagnosed with colon cancer in Iceland in 1995–2004 for this retrospective, population‐based study was obtained from the Icelandic Cancer Registry. Information on symptoms of patients and blood hemoglobin was collected from patients' files. Pathological parameters were obtained from a previously performed standardized tumor review. A total of 768 patients entered this study; the median age was 73 years. Tumors in patients presenting at diagnosis with visible blood in stools were significantly more likely to be of lower grade, having pushing border, conspicuous peritumoral lymphocytic infiltration, and lower frequency of vessel invasion. Patients with abdominal pain and anemia were significantly more likely to have vessel invasion. Logistic regression showed that visible blood in stools was significantly associated with protecting pathological factors (OR range 0.38–0.83, p < 0.05). Tumors in patients presenting with abdominal pain were strongly associated with infiltrative margin and scarce peritumoral lymphocytic infiltration (OR = 1.95; 2.18 respectively, p < 0.05). Changes in bowel habits were strongly associated with vessel invasion (OR = 2.03, p < 0.05). Cox regression showed that blood in stools predicted survival (HR = 0.54). In conclusion, visible blood in stools correlates significantly with all the beneficial pathological parameters analyzed and with better survival of patients. Anemia, general symptoms, changes in bowel habits, acute symptoms, and abdominal pain correlate with more aggressive tumor characteristics and adverse outcome for patients.     

Association study between CYP24A1 gene polymorphisms and cancer risk

CYP24A1, an essential gene in regulation of vitamin D, has been reported to play an important role in enhancing immune activity and inhibiting tumorigenesis. Previous studies proposed that rs2585428, rs4809960, rs6022999 and rs6068816 in CYP24A1 gene might be greatly associated with cancer risk. To validate the findings, we here investigated the associations of these four polymorphisms and colorectal cancer (CRC) risk in a central Chinese population (426 colon cancer patients, 361 rectal cancer patients and 800 healthy controls). The genotyping was conducted by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and confirmed by sequencing. Our results revealed that the rs4809960 and rs6022999 were strongly associated with the CRC risk, especially with the colon cancer risk. Moreover, the analysis of haplotypes consisting of rs2585428(G > A), rs4809960(T > C), rs6022999(A > G) and rs6068816(C > T) indicated that haplotype ATGC significantly decreased the CRC risk, especially the colon cancer risk. Haplotype GCAT significantly increased the CRC risk, especially the rectal cancer risk. However, haplotype ACAC was only found to be associated with increased risk of CRC. To improve the statistical strength, an updated meta-analysis was further performed. The results showed that rs2585428 was associated with cancer risk in Caucasian population, rs4809960 was associated with breast cancer risk in Caucasian population, and rs6022999 was associated with cancer risk in Asian population. Collectively, the rs4809960 and rs6022999 may be the genetic biomarkers for prediction of colon cancer risk in Chinese population, the rs2585428 and rs6022999 may link to cancer susceptibility in Caucasian population and in Asian population respectly.     

P53 codon 72 genotypes in colon cancer. Association with human papillomavirus infection.

It has been reported that the p53Arg homozygous genotype could be a potential genetic risk factor for cancer. In this study we investigated the proportion of p53 codon 72 genotypes in patients with colon cancer and compared to a control population. A region of the p53 gene containing the polymorphic site was amplified by PCR and the genotypes were determined by restriction enzyme digestion. No significant difference was found between genotype frequencies in the study groups. Infection with human papilloma virus was also investigated in the tumor samples. HPV 18 and HPV 33 infection was observed in a considerable number of the tumor samples. Incidence of HPV infection did not show a correlation with the genotypes. Thus the p53 genotypes do not seem to be associated with risk of colon cancer or HPV infection.     

Genetic polymorphisms in the cytochrome P450 1A1, glutathione S-transferase M1 and T1, and susceptibility to colon cancer

Several polymorphic cytochrome P-450 and glutathione S-transferase (GST) enzymes are involved in the activation and detoxification of many potential carcinogens and may therefore be important in susceptibility to cancer induction. CYP1A1 MspI, GSTM1, and GSTT1 are polymorphic enzymes and some alleles have been correlated with an increased risk of developing some cancers. In the present study, we examined possible associations between genetic polymorphisms of CYP1A1 MspI, GSTM1, and GSTT1 and colon cancer in a United Kingdom population. An excess of CYP1A1 MspI, and GSTM1 null genotypes was observed amongst colon cancer patients, although this did not reach the level of statistical significance. We found no significant increase in the risk of colon cancer for either CYP1A1 MspI (OR = 1.39; 95%CI: 0.46-4.21) or GSTM1 null (OR = 1.41; 95%CI: 0.76-3.01) genotypes. Individuals with GSTT1 null genotype had no association with colon cancer (OR = 0.42; 95%CI: 0.09-2.02). No significant association was observed in the site of colon cancer (proximal vs. distal). This study suggests that the polymorphisms of CYP1A1 MspI, GSTM1, and GSTT1 are not associated with a significant risk of developing colon cancer in a United Kingdom population.     

The rectal mucosa-associated microflora in patients with ulcerative colitis.

The rectal mucosa-associated flora (MAF) of patients with ulcerative colitis has been studied in 25 patients with newly diagnosed disease, 20 with relapse of existing disease, and 44 who were in remission. Patients with active disease were re-examined twice during treatment. The MAF was simpler and less dense than the microflora of faeces. Obligate anaerobes usually predominated in the MAF although the ratio of obligate anaerobes to facultative species was lower than that found in faeces. Viable counts of the total flora and of its constituent genera varied considerably between patients. Counts of the total flora, of obligate anaerobes (including bifidobacteria, eubacteria and clostridia), and facultative organisms and micro-aerobes (enterobacteria and lactobacilli) were reduced in patients with active disease compared with those with inactive disease; corresponding carriage rates were also lower. Counts and carriage rates increased during treatment and approached those found in quiescent disease. The alterations in the MAF were especially marked in patients experiencing their first attack of ulcerative colitis. The relationship between these alterations and the aetiology and pathogenesis of this disease remains unclear.     

Streptococcus bovis/Streptococcus equinus complex fecal carriage, colorectal carcinoma, and infective endocarditis: a new appraisal of a complex connection

The proportion of group D streptococcal infective endocarditis (IE) (predominantly due to Streptococcus gallolyticus) and the incidence of colorectal cancer are higher in France than in most European countries. We assumed that this could be explained by a high group D streptococci (GDS) fecal carriage rate. The aims of this study were to re-assess the GDS fecal carriage rate in France and its relationship with colorectal cancer. Consecutive adult subjects who were to undergo a complete colonoscopy were invited to participate. GDS were searched in subjects’ stools before their colonoscopy using biomolecular techniques. Colonoscopic findings were sorted into four subgroups: normal colonoscopy, non-tumoral lesions, benign tumors, and premalignant/malignant tumors. GDS fecal carriages were calculated overall and in each subgroup and compared. The data from 259 subjects were analyzed. GDS were identified in the feces of 12 subjects, with the following distribution: S. lutetiensis (n?=?9), S. pasteurianus (n?=?2), and S. gallolyticus (n?=?1). This accounted for an overall GDS fecal carriage rate of 4.6 %. The GDS fecal carriage rate was 6 % in case of normal colonoscopy, 1.3 % in case of non-tumoral lesions, 3.2 % in case of benign tumors, and 11 % in case of premalignant/malignant tumors. These four percentages were not statistically different. The GDS fecal carriage rate was lower than expected, which did not confirm our working hypothesis. Most strains belonged to S. bovis biotype II, while S. gallolyticus was found only once. These findings suggest that different GDS play different roles in the etiopathogenesis of IE and colorectal cancer.     

Clinical predictive values of extended-spectrum beta-lactamase carriage in patients admitted to medical wards

We aimed to reassess, through clinical items, populations at risk for extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) carriage at admission to hospital and to assess the risk of further positive clinical culture of ESBL-E among carriers. We performed a 5-month cohort study in a medicine ward of a 500-bed university teaching hospital in the Parisian area of France. All admitted patients were prospectively enrolled for rectal swabbing and clinical data collection, including bacterial infection at admission and during stay. Variables associated with ESBL-E carriage were identified by univariate and multivariate analysis. Five hundred patients were included. The prevalence of ESBL-E was 6.6% (33/500) upon admission. Only previous carriage of multidrug-resistant bacteria (MDRB) was associated with carriage (odds ratio [OR]: 17.7, 95% confidence interval (CI) 5.8–54.2, p < 0.001), yet, the positive predictive value (PPV) was not higher than 50%. When prior MDRB carriage was not considered in the multivariate analysis, only prior antibiotic consumption was found to be associated with carriage at admission (OR: 2.2 [1.1–4.5], p = 0.02). Two patients had ESBL-E infection at admission, yet, no patient became infected with ESBL-E during their stay. The clinical prediction of ESBL carriage at admission in our wards was found to be poorly efficient for assessing the at-risk population.     

Prevalence and risk factor assessment of Tropheryma whipplei in a rural community in Gabon: a community-based cross-sectional study

Tropheryma whipplei is the causative agent of Whipple's disease and has been detected in stools of asymptomatic carriers. Colonization has been associated with precarious hygienic conditions. There is a lack of knowledge about the epidemiology and transmission characteristics on a population level, so the aim of this study was to determine the overall and age-specific prevalence of T. whipplei and to identify risk factors for colonization. This molecular epidemiological survey was designed as a cross-sectional study in a rural community in Central African Gabon and inhabitants of the entire community were invited to participate. Overall prevalence assessed by real-time PCR and sequencing was 19.6% (95% CI 16–23.2%, n = 91) in 465 stool samples provided by the study participants. Younger age groups showed a significantly higher prevalence of T. whipplei colonization ranging from 40.0% (95% CI 27.8–52.2) among the 0–4 year olds to 36.4% (95% CI 26.1–46.6) among children aged 5–10 years. Prevalence decreased in older age groups (p <0.001) from 12.6% (95% CI 5.8–19.4%; 11–20 years) to 9.7% (95% CI 5.7–13.6) among those older than 20. Risk factor analysis revealed young age, male sex, and number of people sharing a bed as factors associated with an increased risk for T. whipplei carriage. These results demonstrate that T. whipplei carriage is highly prevalent in this part of Africa. The high prevalence in early life and the analysis of risk factors suggest that transmission may peak during childhood facilitated through close person-to-person contacts.     

A germline E-cadherin mutation in a family with gastric and colon cancer

Inactivating mutations have been found in the cell-cell adhesion molecule E-cadherin (CDH1), which acts as a tumor suppressor gene in different kinds of cancers, e.g. primarily diffuse gastric cancer and lobular breast cancer. In this study, we screened for germline alterations in familial gastric and colon cancer cases. In total, 20 gastric and 18 colon cancer patients with both familial gastric and colon cancer were tested for germline E-cadherin alterations by using PCR/SSCP, specific restriction digestion test and sequencing. No pathogenic mutations were identified in the gastric cancer patients. In two colon cancer patients, a missense mutation in exon 12, codon 592 (Ala592Thr) was found. This alteration segregated with diffuse gastric cancer and colon cancer in one of the families. The prevalence of this alteration in the general population and colon cancer cases was almost the same. However, the fact that this alteration (Ala592Thr) segregated with colon cancer and diffuse gastric cancer in one big family, suggests that this E-cadherin missense alteration, beside predisposing to diffuse gastric cancer, also may play a role in colorectal carcinogenesis.     

Asymptomatic carriage of Neisseria meningitidis in a randomly sampled population.

To estimate the extent of meningococcal carriage in the Norwegian population and to investigate the relationship of several characteristics of the population to the carrier state, 1,500 individuals living in rural and small-town areas near Oslo were selected at random from the Norwegian National Population Registry. These persons were asked to complete a questionnaire and to volunteer for a bacteriological tonsillopharyngeal swab sampling. Sixty-three percent of the selected persons participated in the survey. Ninety-one (9.6%) of the volunteers harbored Neisseria meningitidis. The isolates were serogrouped, serotyped, tested for antibiotic resistance, and analyzed by multilocus enzyme electrophoresis. Eight (8.8%) of the 91 isolates represented clones of the two clone complexes that have been responsible for most of the systemic meningococal disease in Norway in the 1980s. Age between 15 and 24, male sex, and active and passive smoking were found to be independently associated with meningococcal carriage in logistic regression analyses. Working outside the home and having an occupation in transportation or industry also increased the risk for meningococcal carriage in individuals older than 17, when corrections for gender and smoking were made. Assuming that our sample is representative of the Norwegian population, we estimated that about 40,000 individuals in Norway are asymptomatic carriers of isolates with epidemic potential. Thus, carriage eradication among close contacts of persons with systemic disease is unlikely to have a significant impact on the overall epidemiological situation.     

Relation of meat, fat, and fiber intake to the risk of colon cancer in a prospective study among women

BACKGROUND. The rates of colon cancer in various countries are strongly correlated with the per capita consumption of red meat and animal fat and, to a lesser degree, inversely associated with the consumption of fiber. METHODS. We conducted a prospective study among 88,751 women 34 to 59 years old and without a history of cancer, inflammatory bowel disease, or familial polyposis who completed a dietary questionnaire in 1980. By 1986, during 512,488 person-years of follow-up, 150 incident cases of colon cancer had been documented. RESULTS. After adjustment for total energy intake, animal fat was positively associated with the risk of colon cancer (P for trend = 0.01); the relative risk for the highest as compared with the lowest quintile was 1.89 (95 percent confidence interval, 1.13 to 3.15). No association was found for vegetable fat. The relative risk of colon cancer in women who ate beef, pork, or lamb as a main dish every day was 2.49 (95 percent confidence interval, 1.24 to 5.03), as compared with those reporting consumption less than once a month. Processed meats and liver were also significantly associated with increased risk, whereas fish and chicken without skin were related to decreased risk. The ratio of the intake of red meat to the intake of chicken and fish was particularly strongly associated with an increased incidence of colon cancer (P for trend = 0.0005); the relative risk for women in the highest quintile of this ratio as compared with those in the lowest quintile was 2.49 (95 percent confidence interval, 1.50 to 4.13). A low intake of fiber from fruits appeared to contribute to the risk of colon cancer, but this relation was not statistically independent of meat intake. CONCLUSIONS. These prospective data provide evidence for the hypothesis that a high intake of animal fat increases the risk of colon cancer, and they support existing recommendations to substitute fish and chicken for meats high in fat.     

Incidence and origin of Clostridium difficile in neonates

The stools of 65 of 92 (71%) infants in a special care nursery yielded Clostridium difficile on culture. Ninety percent of stools collected after 6 to 35 days in the unit were positive, and 36% of these also contained toxin. When tested in vitro, 94% of the isolates produced toxin. Of 110 swabs collected from the environment of the unit, 9% were positive for C. difficile, but the stools of 12 nurses working on the unit were negative. Thirty-five vaginal swabs collected from mothers just before delivery were negative for C. difficile on culture, but 16 of their infants had C. difficile in their stools. It was concluded that there is a high carriage rate in the stools of neonates of C. difficile acquired progressively during the course of their stay in the special care unit. Infection is mainly from environmental sources rather than maternal transmission.     

An unexpected wide population variation of the G1733A polymorphism of the androgen receptor gene: data on the Mediterranean region.

The androgen receptor (AR) has been proposed as a candidate gene for several cancers (breast, prostate, uterine endometrium, colon, and esophagus). Ethnicity is considered an associated risk factor for some of these cancers. Several case-control genetic studies have been focused in samples of the main ethnic groups, but little is known about the distribution of risk polymorphisms in current populations with accurate ethnic and/or geographic origins. The A allele of the G1733A polymorphism of the AR gene has been associated with increased risk of prostate cancer. We provide data from this marker in 12 samples from 7 Mediterranean countries such as Spain, Italy (Sardinia), Greece, Turkey, Morocco, Algeria, and Egypt. A sample from Ivory Coast has also been analyzed. The A allele distribution shows a frequency in the Ivory Coast population (65.17%) that contrasts with the low values found in Northern Mediterraneans (mean average value of 13.98%). North African populations present two-times higher frequencies (average value of 27.19%) than Europeans. The wide population variation range found for the A allele strengthens the potential interest of further screening as a baseline to the design of future preventive and population health programs.     

Polymorphisms in the CLDN1 and CLDN7 genes are related to differentiation and tumor stage in colon carcinoma

Tight junction is composed of transmembrane proteins important for maintaining cell polarity and regulating ion flow. Among these proteins are the tissue‐specific claudins, proteins that have recently been suggested as tumor markers for several different types of cancer. An altered claudin expression has been observed in colon, prostatic, ovarian, and breast carcinoma. The aim of this study was to analyze the allele frequencies of three common single nucleotide polymorphisms (SNPs) in the genes for claudin 1 and claudin 7 in colon cancer (CC) patients and in a control population of healthy blood donors. Pyrosequencing was used to genotype the CLDN1 SNP rs9869263 (c.369C>T), and the CLDN7 SNPs rs4562 (c.590C>T) and rs374400 (c.606T>G) in DNA from 102 formalin fixed paraffin embedded (FFPE) colon cancer tissue, and 111 blood leukocyte DNA from blood/plasma donors. These results were correlated with clinical parameters such as TNM stage, tumor localization, tumor differentiation, complexity index, sex, and age. We found that there was a significant association between the CLDN1 genotype CC in tumor samples and a higher risk of colon cancer development (OR 3.0, p < 0.001). We also found that the CLDN7 rs4562 (c.590C>T) genotype CT had a higher risk of lymph node involvement (p = 0.031) and a lower degree of tumor differentiation (p = 0.028). In the control population, the allele frequencies were very similar to those in the HapMap cohort for CLDN7. The CLDN1 rs9869263 genotype (c.369C>T) was related to increased risk of colon cancer, and the CLDN7 rs4562 genotype (c.590C>T) was related to tumor differentiation and lymph node involvement in colon carcinoma. Further studies are warranted to ascertain their potential uses as biomarkers predicting tumor development, proliferation, and outcome in this disease.     

Proliferation state and polo-like kinase1 dependence of tumorigenic colon cancer cells

Tumor-initiating cells are responsible for tumor maintenance and relapse in solid and hematologic cancers. Although tumor-initiating cells were initially believed to be mainly quiescent, rapidly proliferating tumorigenic cells were found in breast cancer. In colon cancer, the proliferative activity of the tumorigenic population has not been defined, although it represents an essential parameter for the development of more effective therapeutic strategies. Here, we show that tumorigenic colon cancer cells can be found in a rapidly proliferating state in vitro and in vivo, both in human tumors and mouse xenografts. Inhibitors of polo-like kinase1 (Plk1), a mitotic kinase essential for cell proliferation, demonstrated maximal efficiency over other targeted compounds and chemotherapeutic agents in inducing death of colon cancer-initiating cells in vitro. In vivo, Plk1 inhibitors killed CD133(+) colon cancer cells leading to complete growth arrest of colon cancer stem cell-derived xenografts, whereas chemotherapeutic agents only slowed tumor progression. While chemotherapy treatment increased CD133(+) cell proliferation, treatment with Plk1 inhibitors eliminated all proliferating tumor-initiating cells. Quiescent CD133(+) cells that survived the treatment with Plk1 inhibitors could be killed by subsequent Plk1 inhibition when they exited from quiescence. Altogether, these results provide a new insight into the proliferative status of colon tumor-initiating cells both in basal conditions and in response to therapy and indicate Plk1 inhibitors as potentially useful in the treatment of colorectal cancer. Stem Cells2012;30:1819-1830.     

Aspirin use and reduced risk of fatal colon cancer.

BACKGROUND AND METHODS. Experiments in animals and two epidemiologic studies in humans suggest that aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) may be protective against colon cancer. We tested this hypothesis in a prospective mortality study of 662,424 adults who provided information in 1982 on the frequency and duration of their aspirin use. Death rates from colon cancer were measured through 1988. The possible influence of other risk factors for colon cancer was examined in multivariate analyses for 598 case patients and 3058 matched control subjects drawn from the cohort. RESULTS. Death rates from colon cancer decreased with more frequent aspirin use in both men and women. The relative risk among persons who used aspirin 16 or more times per month for at least one year was 0.60 in men (95 percent confidence interval, 0.40 to 0.89) and 0.58 in women (95 percent confidence interval, 0.37 to 0.90). The risk estimates were unaffected when we excluded persons who reported at entry into the study that they had cancer, heart disease, stroke, or another condition that might influence both their aspirin use and their mortality. Adjustment for dietary factors, obesity, physical activity, and family history did not alter the findings significantly. No association was found between the use of acetaminophen and the risk of colon cancer. CONCLUSIONS. Regular aspirin use at low doses may reduce the risk of fatal colon cancer. Whether this is due to a direct effect of aspirin, perhaps mediated by the inhibition of prostaglandin synthesis, or to other factors indirectly associated with aspirin use is unclear.     

Population prevalence of familial cancer and common hereditary cancer syndromes. The 2005 California Health Interview Survey

PurposeFamily history guides cancer prevention and genetic testing. We sought to estimate the population prevalence of increased familial risk for breast, ovarian, endometrial, prostate, and colorectal cancers and hereditary cancer syndromes that include these cancers.MethodsUsing the 2005 California Health Interview Survey data, a weak, moderate, or strong familial cancer risk was assigned to 33,187 respondents. Guidelines were applied to identify individuals with hereditary breast-ovarian cancer and hereditary nonpolyposis colon cancer.ResultsAmong respondents without a personal history of cancer, familial breast cancer was most prevalent; 7% had a moderate and 5% a strong familial risk. Older individuals and women were more likely to report family history of cancer. Generally, whites had the highest prevalence, and Asians and Latinos had the lowest prevalence. Among women without a personal history of breast or ovarian cancer, 2.5% met criteria for hereditary breast-ovarian cancer, and among individuals without a personal history of colorectal, endometrial or ovarian cancer, 1.1% met criteria for hereditary nonpolyposis colon cancer.ConclusionsWe provide population-based prevalence estimates for moderate and strong familial risk for five common cancers and hereditary breast-ovarian cancer and hereditary nonpolyposis colon cancer. Such estimates are helpful in planning and evaluation of genetic services and prevention programs, and assessment of cancer surveillance and prevention strategies.     

Long-term risk of colorectal cancer after excision of rectosigmoid adenomas.

BACKGROUND AND METHODS. Surveillance by repeated colonoscopy is currently recommended for patients with colorectal adenomas. We assessed the long-term risk of colorectal cancer after rigid-instrument sigmoidoscopy and polypectomy in 1618 patients with rectosigmoid adenomas (tumor of the rectum or distal sigmoid colon) who did not undergo surveillance. A total of 22,462 person-years of observation were accrued (mean, 14 years per patient). RESULTS. The incidence of subsequent rectal cancer in these patients was similar to that in the general population (standardized incidence ratio, 1.2; 95 percent confidence interval, 0.7 to 2.1). Most rectal cancers developed in patients whose adenomas had been inadequately removed; the risk was very low after complete removal. The risk of subsequent colon cancer depended on the histologic type, size, and number of adenomas in the rectosigmoid. Among 842 patients with a rectosigmoid adenoma that was tubulovillous, villous, or large (greater than or equal to 1 cm), colon cancer developed in 31 patients. The standardized incidence ratio was 3.6 (95 percent confidence interval, 2.4 to 5.0) overall and 6.6 (95 percent confidence interval, 3.3 to 11.8) if there were multiple rectosigmoid adenomas. Among the remaining 776 patients with only small, tubular adenomas (whether single or multiple), colon cancer developed in only 4 patients. The standardized incidence ratio in this group was 0.5 (95 percent confidence interval, 0.1 to 1.3). CONCLUSIONS. Follow-up colonoscopic examinations may be warranted in patients with tubulovillous, villous, or large adenomas in the rectosigmoid, particularly if the adenomas are also multiple. In patients with only a single, small tubular adenoma that is only mildly or moderately dysplastic (43 percent of our series), however, surveillance may not be of value because the risk of cancer is so low.     

Comparison of a direct fecal Shiga-like toxin assay and sorbitol-MacConkey agar culture for laboratory diagnosis of enterohemorrhagic Escherichia coli infection.

A direct fecal Shiga-like toxin assay (DSLTA) was used to prospectively screen 9,449 unselected stool samples, received at the British Columbia Provincial Health Laboratories and the Metropolitan Laboratories of Vancouver, for Shiga-like toxin I and Shiga-like toxin II. The results were compared with results of routine stool culture on sorbitol-MacConkey agar (SMAC) for Escherichia coli O157:H7. Of 80 specimens positive by either method, 59 (74%) and 74 (93%) were positive by SMAC and DSLTA, respectively; 53 (66%) were positive by both methods, 21 (26%) were positive by DSLTA only, and 6 (7%) were positive by SMAC only. On further screening, Shiga-like toxin-producing E. coli were detected in 8 (38%) of the 21 stools positive by DSLTA only, including serotypes O157:H7 (1 stool), O26:K60 (5 stools), O128:K67 (1 stool), and O103:H2 (1 stool). For the remaining 13 stools in which no SLTEC was found but DSLTA was positive, clinical information revealed that 11 of 12 patients had diarrheal illnesses, and 4 of these 11 had bloody diarrhea or hemolytic-uremic syndrome. Stools positive only by SMAC were collected earlier in the illness than stools positive by DSLTA, suggesting that free fecal toxin levels may be too low to detect at this time. Overall we found that DSLTA detected 19% more positive specimens than SMAC and that Shiga-like toxin-producing E. coli serotypes other than E. coli O157:H7 are causing disease in the province of British Columbia, Canada.     

HFE gene mutations in susceptibility to childhood leukemia: HuGE review.

The hereditary hemochromatosis (HHC) gene, HFE on chromosome 6p21.3, encodes a protein involved in iron homeostasis. HFE mutations have low penetrance with a mild effect on serum iron levels. Animal, twin, and population studies have shown that carrier state for C282Y can increase iron levels. A proportion of heterozygotes show slightly elevated serum iron levels. Increased serum iron has been suggested to increase the risk for oxidative damage to DNA. Epidemiologic studies established a correlation between iron levels and cancer risk. Case-control studies have reported associations between HFE mutations C282Y/H63D and several cancers, some of which in interaction with the transferrin receptor gene TFRC or dietary iron intake. Increased cancer risk in C282Y carriers is likely due to higher iron levels in a multifactorial setting. In childhood acute lymphoblastic leukemia (ALL), there is an association of C282Y with a gender effect in two British populations. No association has been found in acute myeloblastic leukemia and Hodgkin disease in adults. The childhood leukemia association possibly results from elevated intracellular iron in lymphoid cells increasing the vulnerability to DNA damage at a critical time window during lymphoid cell development. Interactions of HFE with environmental and genetic factors, most of which are recognized, may play a role in modification of susceptibility to leukemia conferred by C282Y. Given the population frequency of C282Y and the connection between iron and cancer, clarification of the mechanism of HFE associations in leukemia and cancer will have strong implications in public health.