Smokers as a high-risk group: data from a screening population.

GOAL: To determine the number of pack-years exposure associated with a 2-fold increase risk for significant colorectal neoplasia and to examine the risk of smoking in younger patients. BACKGROUND: Cigarette smoking has been shown to be a significant risk factor for colorectal neoplasia and may be used to stratify patients for screening or triaging of screening resources. However, more information is needed regarding the amount of exposure required to significantly increase by 2-fold an individual's risk for colorectal neoplasia. METHODS: Data collected for 2707 patients presenting for screening colonoscopy included tobacco use measured in pack-years and known risk factors for colorectal neoplasia. Our outcome was endoscopically detected significant colorectal neoplasia that included large (>1 cm) tubular adenomas, villous adenomas, multiple (3 or more) adenomas, high-grade dysplasia, and adenocarcinoma. RESULTS: Patients who smoked more than 30 pack-years were more than 2 times more likely to have significant colorectal neoplasia than patients who never smoked (odds ratio: 2.40; 95% confidence interval: 1.65-3.50). For patients aged 40 to 49 years, smokers were more likely than nonsmokers to have significant colorectal neoplasia (odds ratio: 2.71; 95% confidence interval: 1.05-6.97). CONCLUSIONS: Patients who have smoked more than 30 pack-years had a more than 2-fold increase for significant colorectal neoplasia as compared with nonsmokers. The increased risk was also observed in younger patients. Our data have implications for screening guidelines.

Audit of radiation dose delivered in time-resolved four-dimensional computed tomography in a radiotherapy department.

INTRODUCTION: To review the dose delivered to patients in time-resolved computed tomography (4D CT) used for radiotherapy treatment planning. METHODS: 4D CT is used at Peter MacCallum Cancer Centre since July 2007 for radiotherapy treatment planning using a Philips Brilliance Wide Bore CT scanner (16 slice, helical 4D CT acquisition). All scans are performed at 140 kVp and reconstructed in 10 datasets for different phases of the breathing cycle. Dose records were analysed retrospectively for 387 patients who underwent 4D CT procedures between 2007 and 2013. RESULTS: A total of 444 4D CT scans were acquired with the majority of them (342) being for lung cancer radiotherapy. Volume CT dose index (CTDIvol) as recorded over this period was fairly constant at approximately 20 mGy for adults. The CTDI for 4D CT for lung cancers of 19.6 ± 9.3 mGy (n = 168, mean ± 1SD) was found to be 63% higher than CTDIs for conventional CT scans for lung patients that were acquired in the same period (CTDIvol 12 ± 4 mGy, sample of n = 25). CTDI and dose length product (DLP) increased with increasing field of view; however, no significant difference between DLPs for different indications (breast, kidney, liver and lung) could be found. Breathing parameters such as breathing rate or pattern did not affect dose. CONCLUSION: 4D CT scans can be acquired for radiotherapy treatment planning with a dose less than twice the one required for conventional CT scanning.

Mechanism of Amine-Catalyzed Ester Formation from an Acid Chloride and Alcohol.

Stopped-flow FT-IR spectroscopy has been used to study the amine-catalyzed reactions of benzoyl chloride with either butanol or phenol in dichloromethane at 0 degrees C. There is a paucity of detailed rate information available in the literature for this process. Our goal was to determine whether amine catalysis operated by a nucleophilic-, specific-base-, or general-base-catalyzed mechanism. A large isotope effect was observed for butanol versus butanol-O-d which is consistent with a general-base-catalyzed mechanism. Some anomalous rate dependencies on reactant concentration and the relative rate of benzoyl chloride loss versus butyl benzoate formation were observed. The analogous reaction of phenol was studied in more detailed. An overall reaction order of three, and a negligible isotope effect for phenol versus phenol-d(6) are consistent with either a base- or nucleophilic-catalyzed mechanism. The most interesting result with phenol was a large sensitivity of the rate of phenyl benzoate formation on small structural changes in the amine (e.g., diethylmethylamine versus triethylamine). We observed the key intermediate (acylammonium salt) in the nucleophilic process via NMR for solutions of benzoyl chloride and amine in the absence of alcohol; however, we did not observe this intermediate in the IR during ester formation [with the exception of 4-(dimethylamino)pyridine]. While we can rule out specific-base catalysis (no evidence for phenoxide intermediates), it is difficult to completely eliminate nucleophilic catalysis.

Online kidney position verification using non-contrast radiographs on a linear accelerator with on board KV X-Ray imaging capability.

The kidneys are dose-limiting organs in abdominal radiotherapy. Kilovoltage (kV) radiographs can be acquired using on-board imager (OBI)-equipped linear accelerators with better soft tissue contrast and lower radiation doses than conventional portal imaging. A feasibility study was conducted to test the suitability of anterior-posterior (AP) non-contrast kV radiographs acquired at treatment time for online kidney position verification. Anthropomorphic phantoms were used to evaluate image quality and radiation dose. Institutional Review Board approval was given for a pilot study that enrolled 5 adults and 5 children. Customized digitally reconstructed radiographs (DRRs) were generated to provide a priori information on kidney shape and position. Radiotherapy treatment staff performed online evaluation of kidney visibility on OBI radiographs. Kidney dose measured in a pediatric anthropomorphic phantom was 0.1 cGy for kV imaging and 1.7 cGy for MV imaging. Kidneys were rated as well visualized in 60% of patients (90% confidence interval, 34-81%). The likelihood of visualization appears to be influenced by the relative AP separation of the abdomen and kidneys, the axial profile of the kidneys, and their relative contrast with surrounding structures. Online verification of kidney position using AP non-contrast kV radiographs on an OBI-equipped linear accelerator appears feasible for patients with suitable abdominal anatomy. Kidney position information provided is limited to 2-dimensional "snapshots," but this is adequate in some clinical situations and potentially advantageous in respiratory-correlated treatments. Successful clinical implementation requires customized partial DRRs, appropriate imaging parameters, and credentialing of treatment staff.

Body mass index: a marker for significant colorectal neoplasia in a screening population.

BACKGROUND AND AIMS: Although some studies suggest a positive association between increasing body mass index (BMI) and risk for colorectal neoplasia, the impact on screening has not been examined. We performed a cross-sectional study to examine the association of BMI and colorectal neoplasia in a screening population. METHODS: Data collected for 2493 patients presenting for screening colonoscopy included known risk factors for colorectal neoplasia, demographic information, and lifestyle factors. Our outcome was the endoscopic detection of significant colorectal neoplasia which included adenocarcinoma, high-grade dysplasia, villous tissue, adenomas 1 cm or greater and multiple (>2) adenomas of any size. RESULTS: Overall, we observed an increased risk and prevalence for significant colorectal neoplasia in women as BMI increased (P value for trend <0.002). This relationship was the strongest for the women with a BMI > or =40 (odds ratios=4.26; 95% confidence intervals=2.00-9.11). There was no such relationship in our male population. CONCLUSIONS: Increasing BMI, in our population, was associated with an increase risk for colorectal neoplasia in female patients. This study reinforces the importance of screening colonoscopy especially in obese women.

Perinatal HIV counseling and rapid testing in Tijuana, Baja California, Mexico: seroprevalence and correlates of HIV infection.

OBJECTIVE: To evaluate the acceptance of counseling and rapid HIV testing and to determine the associated risk factors for HIV infection in pregnant women in Baja California, Mexico. METHODS: Pregnant women attending Tijuana General Hospital who consented to participate in the study had blood drawn for a rapid HIV test (Determine HIV-1/2; Abbott Diagnostics, North Chicago, IL). A confirmatory enzyme immunoassay and Western blot were performed and demographic and risk factor data were obtained. RESULTS: From March to November 2003, 1529 (92.5%) of 1653 women who sought prenatal care and 1068 (95.2%) of 1122 women in labor consented to participate. HIV seroprevalence was significantly higher among women screened during labor (12/1068, 1.12%) compared with those seeking prenatal care (5/1529, 0.33%). HIV-infected women were significantly more likely to use injection drugs (12% vs. 1%, P = 0.02), "other" drugs, including methamphetamine, marijuana, and cocaine (65% vs. 6%, P < 0.001), to have more sex partners (3.6 vs. 2.6, P = 0.0002), to not have received prenatal care (41% vs. 13%, P = 0.03), and to have a spouse/partner who used injection drugs (36% vs. 4%, P < 0.001) or "other" drugs (73% vs. 23%, P < 0.001). In multivariate regression analysis, use of methamphetamine (adjusted odds ratio, 17.8, 95% CI, 5.6-56) was independently associated with the risk of HIV infection. CONCLUSIONS: These findings indicate a wide acceptance of HIV counseling and testing and document a higher HIV seroprevalence among pregnant women delivering at Tijuana General Hospital than current established estimates in Mexico.

Prevalence and risk of colorectal neoplasia in consumers of alcohol in a screening population.

BACKGROUND AND AIMS: Although studies suggest a positive association between alcohol consumption and risk for colorectal neoplasia, the impact on screening has not been fully examined. It is also unclear whether all types of alcohol are associated with an increased risk. We performed a cross-sectional study to examine the impact of regular alcohol consumption on the detection of significant colorectal neoplasia in a screening population. METHODS: Data collected for 2,291 patients presenting for screening colonoscopy: known risk factors for colorectal neoplasia and alcohol drinking pattern. Our outcome was the endoscopic detection of significant colorectal neoplasia, which included adenocarcinoma, high-grade dysplasia, villous tissue, adenomas 1 cm or greater and multiple (>2) adenomas of any size. RESULTS: When compared to abstainers, we found an increased risk for significant neoplasia in those patients who consumed more than eight drinks of spirits alcohol (26.3%; OR = 2.53; 95% CI = 1.10-4.28; p < 0.01) and those who drank more than eight servings of beer per week (21.7%; OR = 2.43; 95% CI = 1.11-5.32; p= 0.02). Consuming one to eight glasses of wine per week was associated with a decreased risk for significant neoplasia (OR = 0.55; 95% CI = 0.34-0.87; p < 0.01). CONCLUSIONS: While there was a more than twofold increased risk of significant colorectal neoplasia in people who drink spirits and beer, people who drank wine had a lower risk. In our sample, people who drank more than eight servings of beer or spirits per week had at least a one in five chance of having significant colorectal neoplasia detected by screening colonoscopy.

Prevalence of colorectal neoplasia in smokers.

OBJECTIVES: Smoking has been linked with colorectal neoplasia. Previous colonoscopy screening studies have omitted smoking and have examined only gender, age, and family history. Our aim was to use a screening population to measure the prevalence of neoplasia in smokers, the anatomic location of these lesions, and the strength of this association relative to other risk factors. METHODS: Data collected from the charts of 1988 screening colonoscopy patients included colonic findings, histology, risk factors for colorectal neoplasia, and smoking pattern. Current smokers were defined as those who had smoked more than 10 pack-years and were currently smoking or who had quit within the past 10 yr. Our outcomes were any adenomatous lesion and significant colonic neoplasia, which included adenocarcinoma, high grade dysplasia, villous tissue, large (>1 cm) adenomas, and multiple (more than two) adenomas. RESULTS: Multivariate analysis revealed that current smokers were more likely to have any adenomatous lesion (odds ratio [OR] = 1.89; 95% CI = 1.42-2.51; p < 0.001) as well as significant neoplasia (OR = 2.26; 95% CI = 1.56-3.27; p < 0.001) than those who had never smoked. The increased risk for smokers was predominantly for left-sided neoplasia. The risk for significant neoplasia was greater for smokers than for patients with a family history of colorectal cancer (OR = 1.20; 95% CI = 0.75-1.92; p > 0.05). CONCLUSIONS: Smoking is a significant risk factor for colorectal neoplasia in a screening population, especially for significant left-sided lesions. In our sample population, smoking posed a greater risk than family history of colorectal cancer.

Predictors of proximal neoplasia in patients without distal adenomatous pathology.

BACKGROUND: Previous colorectal cancer screening studies have observed that some patients may have advanced proximal neoplasia without distal findings. Since these studies have included only gender, age, and family history as risk factors, they are limited in their ability to identify predictors of isolated proximal neoplasia. METHODS: Data were collected from the charts of 1,988 patients who presented for colonoscopy. Information gathered included endoscopic findings, histology, known risk factors for colorectal neoplasia, and smoking pattern. Our main outcome was the presence of proximal adenomatous neoplasia in patients who had no distal adenomas. We defined significant neoplasia as adenocarcinoma, high-grade dysplasia, villous polyps, adenomas 1 cm or greater or more than two adenomas of any size. RESULTS: Fifty-five patients had isolated significant proximal neoplasia that would have been missed on a flexible sigmoidoscopy. While patients older than 60 yr had a greater risk for this neoplasia (odds ratio = 3.01: 95% CI = 1.66-4.23; p < 0.001), those who took a daily aspirin had a reduced risk (OR = 0.60; 95% CI = 0.30-0.88; p < 0.05). A family history of colorectal cancer increased the patient's risk of having any adenomas (OR = 2.01; 95% CI = 1.33-3.40; p < 0.01) or villous tissue (OR = 2.03; 95% CI = 1.27-3.51; p < 0.05) in the proximal colon without distal findings. Smoking was associated with an increased risk of large (> 1 cm) isolated proximal tubular polyps (OR = 2.71; 95% CI = 1.64-4.46; p < 0.01) as well as isolated significant proximal neoplasia (OR = 2.30; 95% CI = 1.59-3.31; p < 0.01). CONCLUSIONS: Age greater than 60 yr, a history of at least 10 pack-years of smoking, and a family history of colorectal cancer increased the risk of finding significant proximal polyps in patients without distal pathology.