N‐acetyl transferase 2 genotypes,meat intake and breast cancer risk

Heterocyclic amines (HAs) are carcinogens produced by high‐temperature cooking of meat and animal protein; metabolism of HA is influenced by polymorphisms in the N‐ acetyltransferase‐2 (NAT‐2) gene. Data from a variety of sources suggest that HA may play a role in human carcinogenesis. We examined the associations between meat intake and cooking method, acetylator genotype and breast cancer risk in a sub‐cohort of 32,826 women in the Nurses' Health Study who gave a blood sample in 1989–1990. Women who were diagnosed with breast cancer (n = 466) after blood draw and prior to June 1, 1994, were matched to 466 controls. Overall, rapid acetylators were not at increased risk of breast cancer compared with slow acetylators (multivariate OR = 1.1, 95% CI 0.8–1.5), and there were no associations between meat intake or cooking method of meat and breast cancer risk. Rapid acetylators with the highest red meat intake (one or more servings per day) were not at increased risk of breast cancer compared with slow acetylators with the lowest red meat intake (OR = 1.1, 95% CI 0.7–1.8). Frequent intake of charred meat among rapid acetylators (one or more times per week) was not associated with increased risk (OR = 1.2, 95% CI 0.6–2.3) compared with slow acetylators who ate charred meat less than once per month. We observed no significant associations for rapid acetylators who frequently consumed beef, pork or lamb cooked with high‐temperature cooking methods, such as barbecuing (OR = 0.9, 95% CI 0.4–1.9) or roasting (OR = 0.9, 95% CI 0.5–1.6). Our data suggest that HAs may not be a major cause of breast cancer, although we cannot exclude misclassification of HA intake as the reason for the lack of association. We observed no evidence of differential susceptibility to these exposures by NAT2 genotype. Int. J. Cancer 80:13–17, 1999. © 1999 Wiley‐Liss, Inc.     

Enhanced tumorigenesis of forestomach tumors induced by N‐Methyl‐N′‐nitro‐N‐nitrosoguanidine in rats with hypoinsulinemic diabetes

Hyperinsulinemia and hyperglycemia in prediabetic and diabetic patients are thought to increase the risk of developing neoplasms because insulin is a growth factor with pre‐eminent metabolic but also mitogenic effects. To determine the effect of hypoinsulinemic diabetic conditions on carcinogenesis, we examined N‐Methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG)‐induced forestomach carcinogenesis in hypoinsulinemic diabetic WBN/Kob rats aged about 45 weeks (DM) compared with non‐diabetic younger WBN/Kob rats (C1), non‐diabetic Wistar rats age‐matched to DM (C2), and non‐diabetic Wistar rats age‐matched to C1 (C3). All rats were treated with MNNG by gavage and were killed at 40 weeks after dosing. Various‐sized tumors were disseminated throughout the forestomach of all rats, and the ratio of the area of tumors to the whole forestomach area was 23.3% in the DM group and was higher than in the C1–3 (4.2–14.3%) groups. The incidence of carcinoma was much higher in the DM group (36.8%) than in the C1–3 (7.1–16.7%) groups, and the incidence of papilloma was also significantly higher in the DM group (84.2%) than in the C1–3 (28.5–50.0%) groups. The average thickness of the squamous epithelium in the non‐neoplastic mucosa was significantly greater in the DM group (50.8 μm) than in the C1–3 (29.6–37.9 μm) groups. Immunohistochemically, the Ki‐67‐positive index in the non‐tumorous mucosa of the DM group (42.0%) was significantly higher than that of the C1–3 groups (18.8–33.3%). These results suggest that prolonged hyperglycemic conditions without hyperinsulinemia enhance tumorigenesis of MNNG‐induced tumors by enhanced proliferative activity of the squamous epithelium in the rat forestomach. (Cancer Sci 2010)     

Attenuation by genistein of sodium‐chloride‐enhanced gastric carcinogenesis induced by N‐methyl‐N′‐nitro‐N‐nitrosoguanidine in Wistar rats

The effects of prolonged administration of genistein, a tyrosine‐kinase inhibitor, on sodium‐chloride‐enhanced induction of gastric carcinogenesis induced by N‐methyl‐N′‐nitro‐N‐nitrosoguanidine, and the labeling and apoptotic indices and vessel counts in the gastric mucosa and gastric cancers, were investigated in Wistar rats. After 25 weeks of the carcinogen treatment, rats were fed chow pellets containing 10% sodium chloride and were given s.c. injections of genistein at dosages of 15 mg/kg or 30 mg/kg body weight every other day. In week 52, the incidence of gastric cancers was significantly greater in rats fed sodium chloride than in untreated control rats. Prolonged administration of genistein at a dosage of 30 mg/kg, but not 15 mg/kg, body weight significantly reduced the incidence of gastric cancers, which was increased by oral treatment with sodium chloride. Genistein at the higher dose significantly decreased the labeling index and vessel counts of the antral mucosa and the gastric cancers (which were increased by treatment with sodium chloride) and significantly increased the apoptotic index of the antral mucosa and the cancers (which was lowered by the treatment with sodium chloride). These findings suggest that genistein attenuates gastric carcinogenesis promoted by sodium chloride, by inducing increased apoptosis and lower cell proliferation and angiogenesis of antral mucosa and gastric cancers. Int. J. Cancer 80:396–399, 1999. © 1999 Wiley‐Liss, Inc.     

In‐hospital mortality from liver resection for hepatocellular carcinoma

BACKGROUND:

There is a wide spectrum of disease burden in hepatocellular carcinoma accompanied by several options for surgical management. However, the associated mortality of such procedures is not well defined. Accurate predictions of patients' perioperative risk would be helpful to guide decision making.

METHODS:

The Nationwide Inpatient Sample was queried for data from 1998 to 2005. A cohort of patients who were discharged for hepatic procedures with a diagnosis of primary liver neoplasm was assembled. Procedures were categorized as hepatic lobectomy, wedge resection, or enucleation/ablation. Logistic regression and bootstrap methods were used to create an integer risk score for estimating the risk of in‐hospital mortality using procedure type, patient demographics, comorbidities, and hospital type. A randomly selected sample of 80% of the cohort (n = 2263) was used to create the score with validation conducted in the remaining 20% (n = 571).

RESULTS:

In total, 2834 patient discharges were identified. Overall in‐hospital mortality was 6.52%. Factors that were included in the final model were age, sex, Charlson comorbidity score, procedure type, and teaching hospital status. Integer values were assigned to these characteristics and were used to calculate an additive score. Four clinically relevant score groups were assembled to stratify the risk of in‐hospital mortality, with a 19‐fold gradient of mortality that ranged from 1.5% to 28.3%. In the derivation set, as in the validation set, the score discriminated well with c‐statistics of 0.75 and 0.73, respectively.

CONCLUSIONS:

The current results indicated that an integer‐based risk score can be used to predict in‐hospital mortality after surgery for hepatocellular carcinoma, and it may be useful for preoperative risk stratification and patient counseling. Cancer 2010. © 2010 American Cancer Society.     

‘Close Shave’ in liver resection for colorectal liver metastases

Introduction

The optimal size of clear liver resection margin width in patients with colorectal liver metastases (CRLM) remains controversial. The aim of this study was to investigate the effects of margin width on long-term survival after liver resection for CRLM with a policy of standard neo-adjuvant chemotherapy.

Methods

Consecutive patients (n = 238) who underwent liver resection for CRLM were included over a ten-year period. All patients with synchronous or early (<2 years) metachronous tumours were treated with neo-adjuvant chemotherapy. Data were recorded prospectively.

Results

Overall survival of the cohort at 1, 3 and 5 years were 90.3%, 68.1% and 56.1% respectively. The incidence of cancer involved resection margins (CIRM) was 5.8%. Patients with macroscopically involved resection margins had a poorer overall survival than those with microscopically involved margins (p = 0.04). Involved resection margins had a poorer overall survival (p = 0.002) than patients with clear margins. Width of clear resection margin did not affect long-term survival.

Conclusion

CIRM independently predicts poor outcome in patients with CRLM. Clear margin width does not affect survival. A standard policy of neo-adjuvant chemotherapy may be associated with a low incidence of CIRM and improved long-term outcome of sub-centimetre margin widths, resembling those with >1 cm resection margins.     

Novel mouse model for Gardner syndrome generated by a large‐scale N‐ethyl‐N‐nitrosourea mutagenesis program

Mutant mouse models are indispensable tools for clarifying the functions of genes and elucidating the underlying pathogenic mechanisms of human diseases. We carried out large‐scale mutagenesis using the chemical mutagen N‐ethyl‐N‐nitrosourea. One specific aim of our mutagenesis project was to generate novel cancer models. We screened 7012 animals for dominant traits using a necropsy test and thereby established 17 mutant lines predisposed to cancer. Here, we report on a novel cancer model line that developed osteoma, trichogenic tumor, and breast cancer. Using fine mapping and genomic sequencing, we identified a point mutation in the adenomatous polyposis coli (Apc) gene. The Apc1576 mutants bear a nonsense mutation at codon 1576 in the Apc gene. Although most Apc mutant mice established thus far have multifocal intestinal tumors, mice that are heterozygous for the Apc1576 mutation do not develop intestinal tumors; instead, they develop multifocal breast cancers and trichogenic tumors. Notably, the osteomas that develop in the Apc1576 mutant mice recapitulate the lesion observed in Gardner syndrome, a clinical variant of familial adenomatous polyposis. Our Apc1576 mutant mice will be valuable not only for understanding the function of the Apc gene in detail but also as models of human Gardner syndrome.     

Ikaros is a critical target during simultaneous exposure to X‐rays and N‐ethyl‐N‐nitrosourea in mouse T‐cell lymphomagenesis

Cancer risk associated with radiation exposure is considered the result of concurrent exposure to other natural and manmade carcinogens. Available data on the molecular characteristics of cancer after simultaneous exposure to radiation and chemicals are insufficient. In our study, we used a mouse thymic lymphoma (TL) model that was synergistically induced by simultaneous exposure to X‐rays and N‐ethyl‐N‐nitrosourea (ENU) at subcarcinogenic doses and analyzed the mutation frequency and spectrum of the TL‐associated genes Ikaros, Notch1, p53 and Kras. We found that the point mutation frequency in Ikaros was significantly increased to 47% for simultaneous exposure compared to 13 and 0% for X‐ray and ENU exposure alone, respectively. These mutations were mostly G:C > A:T at non‐CpG sites and T:A > C:G, both of which are characteristic of ENU mutagenesis. About half of the point mutations were accompanied by loss of heterozygosity (LOH), typical of X‐irradiation. The remaining half did not include LOH, which suggests that they were dominant‐negative mutations. In Notch1, the frequency of abnormalities was high (>58%) regardless of the treatment, suggesting that Notch1 aberration may be important for T‐cell lymphomagenesis. The p53 and Kras mutation frequencies were low for all treatments (<23%). Importantly, the frequency of TLs containing mutations in multiple genes, especially both Ikaros and Notch1, increased after simultaneous exposure. Thus, after simultaneous exposure, Ikaros is a critical target and is inactivated by ENU‐induced point mutations and/or X‐ray‐induced LOH in T‐cell lymphomagenesis. Furthermore, concomitant alterations of multiple tumor‐associated genes may contribute to enhanced lymphomagenesis after simultaneous exposure.     

Development of an early induction model of medulloblastoma in Ptch1 heterozygous mice initiated with N‐ethyl‐N‐nitrosourea

Mice heterozygous for the ptch1 gene (ptch1 mice) are known as a valuable model of medulloblastoma, a common brain tumor in children. To increase the incidence and reduce the time required for tumor development, allowing for evaluation of modifier effects on medulloblastoma in a short time, we attempted to develop an early induction model of medulloblastoma in ptch1 mice initiated with N‐ethyl‐N‐nitrosourea (ENU). Ptch1 mice and their wild‐type littermates received a single intraperitoneal injection of ENU (10, 50 or 100 mg/kg) on postnatal day 1 (d1) or 4 (d4), and histopathological assessment of brains was conducted at 12 weeks of age. The width of the external granular layer (EGL), a possible origin of medulloblastoma, after injection of 100 mg ENU on d1 or d4 was measured in up to 21‐day‐old mice. Cerebellar size was apparently reduced at the 50 mg dose and higher regardless of genotype. Microscopically, early lesions of medulloblastomas occurred with a high incidence only in ptch1 mice receiving 10 mg on d1 or d4, but a significant increase was not observed in other groups. Persistent EGL cells and misalignment of Purkinje cells were increased dose‐dependently. Although EGL was strikingly decreased after ENU injection, strong recovery was observed in mice of the d1‐treated group. In summary, neonatal treatment with ENU is available for the induction of medulloblastoma in ptch1 mice, and 10 mg of ENU administered on d1 appeared to be an appropriate dose to induce medulloblastoma.     

Actin and Vimentin proteins with N‐terminal deletion detected in tumor‐bearing rat livers induced by intraportal‐vein injection of Ha‐ras‐transfected rat liver cells

The introduction of the tumorigenic v‐Ha‐ras oncogene‐transformed rat liver epithelial cells (WBras), which is deficient in gap junctional intercellular communication (GJIC), into F344 rats, induces significant formation of hepatocellular tumors. GJIC plays a major role in maintaining tissue homeostasis. Using this in vivo tumor model system, we used 2‐dimensional electrophoresis with isoelectric focusing in the first dimension and SDS‐PAGE in the second dimension to globally identify proteins that are uniquely expressed in the livers of WBras‐treated rats as compared to the sham control. Immunoblotting was used to identify Ras and Connexin43, which were the positive and negative marker proteins, respectively, of the introduced WBras cells. As predicted, immunoblotting indicated that the whole liver of tumor‐bearing animals exhibited a decreased level of Connexin43 and an increased level of Ras. Connexin43 and GJIC were expressed and functional in normal liver, but not in the tumor. In addition to these 2 markers, an additional 4 proteins exhibited decreased levels and 2 proteins exhibited increased levels in the livers of tumor‐bearing animals. N‐Terminal sequencing analysis was used to identify these proteins, which were glucose‐regulated protein 78, 2 isoforms of heat shock protein 60, and the β‐chain of ATP synthase for the down regulated proteins, and β‐Actin with a 46 amino acid deletion from its N‐terminus and Vimentin with a 71 amino acid deletion from its N‐terminus for the up regulated proteins. These data offer potentially new markers of liver tumorigenicity, particularly, Vimentin. © 2008 Wiley‐Liss, Inc.     

New onset non‐alcoholic fatty liver disease after resection of pancreatic neuroendocrine tumors

Background and Objectives

Non‐alcoholic fatty liver disease (NAFLD) and non‐alcoholic steatohepatis (NASH) may occur after pancreatic resection due to exocrine pancreatic insufficiency (EPI). Patients with long‐term survival, such as after pancreatic neuroendocrine tumor (pNET) resection, are at risk of NAFLD/NASH. We aimed to determine the incidence and risk factors for new onset NAFLD/NASH and EPI after pNET resection.

Methods

Retrospective monocenter cohort study. Patients who underwent pNET resection (1992‐2016) were assessed for new onset NAFLD/NASH and EPI. Postoperative NAFLD/NASH was determined by a blinded abdominal radiologist, who compared pre‐ and postoperative imaging.

Results

Out of 235 patients with pNET, a total of 112 patients underwent resection and were included with a median follow‐up of 54 months. New onset NAFLD/NASH occurred in 20% and EPI in 49% of patients. Multivariate analysis showed that the only risk factor for new onset NAFLD/NASH was recurrent disease (OR 4.4, 95% CI 1.1‐16.8, P = 0.031), but not EPI (OR 0.94, 95% CI 0.3‐2.8, P = 0.911). The only risk factor for EPI was pancreatoduodenectomy (OR 4.3, 95% CI 1.4‐13.7, P = 0.012).

Conclusions

New onset NAFLD/NASH is occasionally found after pNET resection, especially in patients with recurrent disease, but is not related to EPI.     

Radiofrequency-assisted liver resection

BACKGROUND: Surgical resection remains the treatment of choice for primary, secondary liver cancer and a number of benign liver lesions. Complications are mainly related to blood loss. Radiofrequency-assisted liver resection (RF-LR) has been proposed in order to achieve minimal blood loss during parenchymal transection. PATIENTS AND METHODS: Between May 2005 and April 2007, 46 consecutive patients with various hepatic lesions underwent RF-LR using Radionics, Cool-Tip System. There were 28 men and 18 women with median age 65 years (range 54-76 years). Twelve major and 34 minor hepatectomies were performed for various diseases: hepatocellular carcinoma (n=19), metastatic carcinoma (n=23), focal nodal hyperplasia (n=2) and intrahepatic cholangiocarcinoma (ICC) (n=2). Hepatic inflow occlusion was not used. RESULTS: No perioperative death was documented. Median blood loss was 100ml (range 30-300cm(3)). Blood transfusion was required postoperatively in one patient. Median transection time was 35min (15-60min). Three patients developed biliary fistulas, four patients pleural effusions, one patient hyperbilirubinemia, two pneumonia and four wound infection. The median postoperative hospital stay was 6 days (range 4-10 days). In a median 12 month follow-up (range 3-24 months), four patients with colorectal metastases (CRM) and one patient with ICC developed recurrence. CONCLUSIONS: Cool-Tip RF device provides a unique, simple and safe method of bloodless liver resections and is indicated in cirrhotic patients with challenging hepatectomies (segment VIII, central resections).