AI implementation in the UK landscape: Knowledge of AI governance, perceived challenges and opportunities, and ways forward for radiographers.

INTRODUCTION: Despite the rapid increase of AI-enabled applications deployed in clinical practice, many challenges exist around AI implementation, including the clarity of governance frameworks, usability of validation of AI models, and customisation of training for radiographers. This study aimed to explore the perceptions of diagnostic and therapeutic radiographers, with existing theoretical and/or practical knowledge of AI, on issues of relevance to the field, such as AI implementation, including knowledge of AI governance and procurement, perceptions about enablers and challenges and future priorities for AI adoption. METHODS: An online survey was designed and distributed to UK-based qualified radiographers who work in medical imaging and/or radiotherapy and have some previous theoretical and/or practical knowledge of working with AI. Participants were recruited through the researchers' professional networks on social media with support from the AI advisory group of the Society and College of Radiographers. Survey questions related to AI training/education, knowledge of AI governance frameworks, data privacy procedures, AI implementation considerations, and priorities for AI adoption. Descriptive statistics were employed to analyse the data, and chi-square tests were used to explore significant relationships between variables. RESULTS: In total, 88 valid responses were received. Most radiographers (56.6 %) had not received any AI-related training. Also, although approximately 63 % of them used an evaluation framework to assess AI models' performance before implementation, many (36.9 %) were still unsure about suitable evaluation methods. Radiographers requested clearer guidance on AI governance, ample time to implement AI in their practice safely, adequate funding, effective leadership, and targeted support from AI champions. AI training, robust governance frameworks, and patient and public involvement were seen as priorities for the successful implementation of AI by radiographers. CONCLUSION: AI implementation is progressing within radiography, but without customised training, clearer governance, key stakeholder engagement and suitable new roles created, it will be hard to harness its benefits and minimise related risks. IMPLICATIONS FOR PRACTICE: The results of this study highlight some of the priorities and challenges for radiographers in relation to AI adoption, namely the need for developing robust AI governance frameworks and providing optimal AI training.

A comparison of perceived image quality between computer display monitors and augmented reality smart glasses.

INTRODUCTION: Augmented-reality (AR) smart glasses provide an alternative to standard computer display monitors (CDM). AR smart glasses may provide an opportunity to improve visualisation during fluoroscopy and interventional radiology (IR) procedures when there can be difficulty in viewing intra-procedural images on a CDM. The aim of this study was to evaluate radiographer perception of image quality (IQ) when comparing CDM and AR smart glasses. METHODS: 38 radiographers attending an international congress evaluated ten fluoroscopic-guided surgery and IR images on both a CDM (1920 × 1200 pixels) and a set of Epson Moverio BT-40 AR smart glasses (1920 × 1080 pixels). Participants provided oral responses to pre-defined IQ questions generated by study researchers. Summative IQ scores for each participant/image were compared between CDM and AR smart glasses. RESULTS: Of the 38 participants, the mean age was 39 ± 1 years. 23 (60.5%) participants required corrective glasses. In terms of generalisability, participants were from 12 different countries, the majority (n = 9, 23.7%) from the United Kingdom. For eight out of ten images, the AR smart glasses demonstrated a statistically significant increase in perceived IQ (median [IQR] 2.0 [-1.0 to 7.0] points) when compared to the CDM. CONCLUSION: AR smart glasses appear to show improvements in perceived IQ when compared to a CDM. AR smart glasses could provide an option for improving the experiences of radiographers involved in image-guided procedures and should be subject to further clinical evaluations. IMPLICATIONS FOR PRACTICE: Opportunities exist to improve perceived IQ for radiographers when reviewing fluoroscopy and IR images. AR smart glasses should be further evaluated as a potential opportunity to improve practice when visual attention is split between positioning equipment and image review.

The gendered impact of the COVID-19 pandemic on academics working in medical imaging and radiation therapy.

INTRODUCTION: Healthcare workers have been particularly impacted by the COVID-19 pandemic, as have those educating them, albeit differently. Several papers have identified a gendered difference in the impact of the pandemic. This study aims to determine impact of COVID-19 on the health and wellbeing of Medical Imaging and Radiation Therapy (MIRT) academics. METHODS: An electronic survey was designed in English on Qualtrics and distributed via email and online platforms to MIRT academics. Fifty-one questions were used; demographic (n = 9), work patterns (n = 11), general health (n = 8), mental health (n = 2), physical health (n = 10), and workload (n = 11). Overall, 46 were quantitative and five were qualitative 'open-ended' questions. The survey was open between 3rd March 2021 to 1st May 2021. Quantitative analysis was carried out using MS Excel v 16.61.1ss and SPSS v26. RESULTS: The survey reached 32 countries globally and 412 participants; 23.5% identified as men (n = 97) and 76.5% as women (n = 315). Women reported worse sleep quality than men and overwhelmingly felt they would not like to work remotely again if given a choice. A higher percentage of males, 73% versus 40.5% of females reported getting outdoors less. The CORE-10 validated questionnaire found that 10.3% of males (n = 42) and 2.7% of females (n = 11) experienced severe psychological distress the week immediately before the survey was conducted. CONCLUSION: While the study has identified some gender-related differences in the impact of COVID-19 on the mental and physical health of MIRT academics, both males and females have experienced significant deterioration in health and wellbeing due to the pandemic. IMPLICATION FOR PRACTICE: Developing mental health support for MIRT academics and defining optimum methods for raising awareness is recommended.

Identifying barriers to Irish traveller women attending breast screening.

INTRODUCTION: Breast cancer is one of the most prevalent cancers in women, however Irish Traveller women have lower breast screening rates than that of the general population. This work aims to address the gap in knowledge of Irish Traveller womens' perceptions of breast screening and the perceived barriers and enablers to attendance. METHODS: This phenomenological qualitative study involves interviews with Irish Traveller women and Health Care Professionals and discusses the incentives and barriers to attending breast screening mammography in Ireland. The work investigated attitudes and decision making amongst the Irish Traveller women across breast screening and breast health. The research investigated the participants knowledge, experience and opinions about the topic of Irish Traveller womens' attendance at BreastCheck and breast health RESULTS: Influences that create barriers to breast screening for Irish Traveller women include inequality and family/community support, fear, literacy and education, embarrassment and the health care professional, stress and appointment suitability. Findings also demonstrate inadequate data and information is available in Ireland regarding Irish Traveller women attending breast screening. CONCLUSION: Irish Traveller women face several influences when it comes to attending breast screening. The existing Irish national breast screening programme provides a health promotion service however, it is impossible to assess poor attendance at screening without the presence of an ethnic identifier. It would be very beneficial for screening promotion to record the ethnicity of attendees for statistical progress. This would benefit Irish Traveller women by recording the progress of attendance in the breast screening programme and creating a need for awareness and education within the annual reports. IMPLICATIONS FOR PRACTICE: Creating awareness and educating Irish Traveller women about the breast screening programme may remove barriers and lead to improved attendance rates.

Radiation dose tracking in computed tomography: Red alerts and feedback. Implementing a radiation dose alert system in CT.

INTRODUCTION: This study investigates instances of elevated radiation dose on a radiation tracking system to determine their aetiologies. It aimed to investigate the impact of radiographer feedback on these alerts. METHODS: Over two six-month periods 11,298 CT examinations were assessed using DoseWatch. Red alerts (dose length products twice the median) were identified and two independent reviewers established whether alerts were true (unjustifiable) or false (justifiable). During the second time period radiographers used a feedback tool to state the cause of the alert. A Chi-Square test was used to assess whether red alert incidence decreased following the implementation of radiographer feedback. RESULTS: There were 206 and 357 alerts during the first and second time periods, respectively. These occurred commonly with CT pulmonary angiography, brain, and body examinations. Procedural documentation errors and patient size accounted for 57% and 43% of false alerts, respectively. Radiographer feedback was provided for 17% of studies; this was not associated with a significant change in the number of alerts, but the number of true alerts declined (from 7 to 3) (χ2 = 4.14; p = 0.04). CONCLUSION: Procedural documentation errors as well as patient-related factors are associated with false alerts in DoseWatch. Implementation of a radiographer feedback tool reduced true alerts. IMPLICATIONS FOR PRACTICE: The implementation of a radiographer feedback tool reduced the rate of true dose alerts. Low uptake with dose alert systems is an issue; the workflow needs to be considered to address this.

Strategies for dose reduction with specific clinical indications during computed tomography.

Increasing integration of computed tomography (CT) into routine patient care has escalated concerns regarding associated radiation exposure. Specific patient cohorts, particularly those with cystic fibrosis (CF) and Crohn's disease, have repeat exposures and thus have an increased risk of high lifetime cumulative effective dose exposures. Thoracic CT is the gold standard imaging method in the diagnosis, assessment and management of pulmonary disease. In the setting of CF, CT demonstrates increased sensitivity compared with pulmonary function tests and chest radiography. Furthermore, in specific cases of Crohn's disease, CT demonstrates diagnostic superiority over magnetic resonance imaging (MRI) for radiological evaluation. Low dose CT protocols have proven beneficial in the evaluation of CF, Crohn's disease and renal calculi, and in the follow up of testicular cancer patients. For individuals with chronic conditions warranting frequent radiological follow up, the focus must continue to be the incorporation of appropriate CT use into patient care. This is of particular importance for the paediatric population who are most susceptible to potential radiation induced malignancy. CT technological developments continue to focus on radiation dose optimisation. This article aims to highlight these advancements, which prioritise the acquisition of diagnostically satisfactory images with the least amount of radiation possible.

Effective lifetime radiation risk for a number of national mammography screening programmes.

BACKGROUND AND PURPOSE: The performance of mammography screening programmes is focussed mainly on breast cancer detection rates. However, when the benefits and risks of mammography are considered, the risk of radiation-induced cancer is calculated for only the examined breast using Mean Glandular Dose (MGD). The risk from radiation during mammography is often described as low or minimal. This study aims to evaluate the effective lifetime risk from full field digital mammography (FFDM) for a number of national screening programmes. MATERIAL AND METHODS: Using an ATOM phantom, radiation doses to multiple organs were measured during standard screening mammography. Sixteen FFDM machines were used and the effective lifetime risk was calculated across the female lifespan for each machine. Once the risks were calculated using the phantom, the total effective lifetime risk across 48 national screening programmes was then calculated; this assumed that all these programmes use FFDM for screening. RESULTS: Large differences exist in effective lifetime risk, varying from 42.21 [39.12-45.30] cases/106 (mean [95% CI]) in the Maltese screening programme to 1099.67 [1019.25-1180.09] cases/106 for high breast cancer risk women in the United States of America. These differences are mainly attributed to the commencement age of screening mammography and the time interval between successive screens. CONCLUSIONS: Effective risk should be considered as an additional parameter for the assessment of screening mammography programme performance, especially for those programmes which recommend an early onset and more frequent screening mammography.

A self-directed learning intervention for radiographers rating mammographic breast density.

PURPOSE: Subjective methods of mammographic breast density (MBD) assessment are prone to inter-reader variability. This work aims to assess the impact of a short self-directed, experiential learning intervention on radiographers' reproducibility of MBD assessment. METHOD: The study used two sets of images (test and learning intervention) containing left craniocaudal and left mediolateral oblique views. The test set had MBD ratings from Volpara™ and radiologists using the fourth edition Breast Imaging and Data Systems (BI-RADS®). Seven radiographers rated the MBD of the test set before and after a self-directed learning intervention using the percentage descriptors in the fourth edition BI-RADS® Atlas. The inter-reader agreement, the agreement between radiographers and Volpara™ as well as radiologists, was assessed using a Weighted Kappa (кw). RESULTS: Overall, radiographers' inter-reader agreement (кw) was substantial (0.79; 95% CI: 0.70-0.87) before the intervention and almost perfect (0.84; 95% CI: 0.77-0.90) after the intervention. Before the intervention, radiographers demonstrated fair agreement with radiologists (0.24; 95% CI: -0.46-0.61) and Volpara™ (0.24; 95% CI: -0.41-0.59). A fair but slightly improved agreement was also observed between radiographers and radiologists (0.31; 95% CI: -0.33-0.64) as well as Volpara™ (0.28; 95% CI: -0.34-0.61) after the intervention. CONCLUSION: Findings demonstrate that a short duration self-directed, experiential learning intervention reduces inter-reader differences in MBD classification, but has a negligible impact on improving the agreement between inexperienced and expert readers.

In the digital era, architectural distortion remains a challenging radiological task.

AIM: To compare readers' performance in detecting architectural distortion (AD) compared with other breast cancer types using digital mammography. MATERIALS AND METHODS: Forty-one experienced breast screen readers (20 US and 21 Australian) were asked to read a single test set of 30 digitally acquired mammographic cases. Twenty cases had abnormal findings (10 with AD, 10 non-AD) and 10 cases were normal. Each reader was asked to locate and rate any abnormalities. Lesion and case-based performance was assessed. For each collection of readers (US; Australian; combined), jackknife free-response receiver operating characteristic (JAFROC), figure of merit (FOM), and inferred receiver operating characteristic (ROC), area under curve (Az) were calculated using JAFROC v.4.1 software. Readers' sensitivity, location sensitivity, JAFROC, FOM, ROC, Az scores were compared between cases groups using Wilcoxon's signed ranked test statistics. RESULTS: For lesion-based analysis, significantly lower location sensitivity (p=0.001) was shown on AD cases compared with non-AD cases for all reader collections. The case-based analysis demonstrated significantly lower ROC Az values (p=0.02) for the first collection of readers, and lower sensitivity for the second collection of readers (p=0.04) and all-readers collection (p=0.008), for AD compared with non-AD cases. CONCLUSIONS: The current work demonstrates that AD remains a challenging task for readers, even in the digital era.

Measurement of breast density with digital breast tomosynthesis--a systematic review.

Digital breast tomosynthesis (DBT) has gained acceptance as an adjunct to digital mammography in screening. Now that breast density reporting is mandated in several states in the USA, it is increasingly important that the methods of breast density measurement be robust, reliable and consistent. Breast density assessment with DBT needs some consideration since quantitative methods are modelled for two-dimensional (2D) mammography. A review of methods used for breast density assessment with DBT was performed. Existing evidence shows Cumulus has better reproducibility than that of the breast imaging reporting and data system (BI-RADS®) but still suffers from subjective variability; MedDensity is limited by image noise, whilst Volpara and Quantra are robust and consistent. The reported BI-RADs inter-reader breast density agreement (k) ranged from 0.65 to 0.91, with inter-reader correlation (r) ranging from 0.70 to 0.93. The correlation (r) between BI-RADS and Cumulus ranged from 0.54-0.94, whilst that of BI-RADs and MedDensity ranged from 0.48-0.78. The reported agreement (k) between BI-RADs and Volpara is 0.953. Breast density correlation between DBT and 2D mammography ranged from 0.73 to 0.97, with agreement (k) ranging from 0.56 to 0.96. To avoid variability and provide more reliable breast density information for clinicians, automated volumetric methods are preferred.

Assessing the effect of a true-positive recall case in screening mammography: does perceptual priming alter radiologists' performance?

OBJECTIVE: To measure the effect of the insertion of less-difficult malignant cases on subsequent breast cancer detection by breast imaging radiologists. METHODS: The research comprises two studies. Study 1: 8 radiologists read 2 sets of images each consisting of 40 mammographic cases. Set A contained four abnormal cases, and Set B contained six abnormal cases, including two priming cases (less difficult malignancies) placed at intervals of three and five subsequent cases before a subtle cancer. Study 2: 16 radiologists read a third condition of the same cases, known as Set C, containing six abnormal cases and two priming cases immediately preceding the subtle cancer cases. The readers were asked to localize malignancies and give confidence ratings on decisions. RESULTS: Although not significant, a decrease in performance was observed in Set B compared with in Set A. There was a significant increase in the receiver operating characteristic (ROC) area under the curve (z = -2.532; p = 0.0114) and location sensitivity (z = -2.128; p = 0.0333) between the first and second halves of Set A and a marginal improvement in jackknife free-response ROC figure of merit (z = -1.89; p = 0.0587) between the first and second halves of Set B. In Study 2, Set C yielded no significant differences between the two halves of the study. CONCLUSION: Overall findings show no evidence that priming with lower difficulty malignant cases affects the detection of higher difficulty cancers; however, performance may decrease with priming. ADVANCES IN KNOWLEDGE: This research suggests that inserting additional malignant cases in screening mammography sets as an audit tool may potentially lead to a decrease in performance of experienced breast radiologists.

Mammography test sets: reading location and prior images do not affect group performance.

AIM: To examine how the location where reading takes place and the availability of prior images can affect performance in breast test-set reading. MATERIALS AND METHODS: Under optimized viewing conditions, 10 expert screen readers each interpreted a reader-specific set of images containing 200 mammographic cases. Readers, randomly divided into two groups read images under one of two pairs of conditions: clinical read with prior images and laboratory read with prior images; laboratory read with prior images and laboratory read without prior images. Region-of-interest (ROI) figure-of-merit (FOM) was analysed using JAFROC software. Breast side-specific sensitivity and specificity were tested using Wilcoxon matched-pairs signed rank tests. Agreement between pairs of readings was measured using Kendall's coefficient of concordance. RESULTS: Group performances between test-set readings demonstrated similar ROI FOMs, sensitivity and specificity median values, and acceptable levels of agreement between pairs of readings were shown (W = 0.75-0.79, p < 0.001) for both pairs of reading conditions. On an individual reader level, two readers demonstrated significant decreases (p < 0.05) in ROI FOMs when prior images were unavailable. Reading location had an inconsistent impact on individual performance. CONCLUSION: Reading location and availability of prior images did not significantly alter group performance.

Quantifying the clinical relevance of a laboratory observer performance paradigm.

OBJECTIVE: Laboratory observer performance measurements, receiver operating characteristic (ROC) and free-response ROC (FROC) differ from actual clinical interpretations in several respects, which could compromise their clinical relevance. The objective of this study was to develop a method for quantifying the clinical relevance of a laboratory paradigm and apply it to compare the ROC and FROC paradigms in a nodule detection task. METHODS: The original prospective interpretations of 80 digital chest radiographs were classified by the truth panel as correct (C=1) or incorrect (C=0), depending on correlation with additional imaging, and the average of C was interpreted as the clinical figure of merit. FROC data were acquired for 21 radiologists and ROC data were inferred using the highest ratings. The areas under the ROC and alternative FROC curves were used as laboratory figures of merit. Bootstrap analysis was conducted to estimate conventional agreement measures between laboratory and clinical figures of merit. Also computed was a pseudovalue-based image-level correctness measure of the laboratory interpretations, whose association with C as measured by the area (rAUC) under an appropriately defined relevance ROC curve, is as a measure of the clinical relevance of a laboratory paradigm. RESULTS: Low correlations (e.g. κ=0.244) and near chance level rAUC values (e.g. 0.598), attributable to differences between the clinical and laboratory paradigms, were observed. The absolute width of the confidence interval was 0.38 for the interparadigm differences of the conventional measures and 0.14 for the difference of the rAUCs. CONCLUSION: The rAUC measure was consistent with the traditional measures but was more sensitive to the differences in clinical relevance. A new relevance ROC method for quantifying the clinical relevance of a laboratory paradigm is proposed.

Assessing reader performance in radiology, an imperfect science: lessons from breast screening.

The purpose of this article is to review the limitations associated with current methods of assessing reader accuracy in mammography screening programmes. Clinical audit is commonly used as a quality-assurance tool to monitor the performance of screen readers; however, a number of the metrics employed, such as recall rate as a surrogate for specificity, do not always accurately measure the intended clinical feature. Alternatively, standardized screening test sets, which benefit from ease of application, immediacy of results, and quicker assessment of quality improvement plans, suffer from experimental confounders, thus questioning the relevance of these laboratory-type screening test sets to clinical performance. Four key factors that impact on the external validity of screening test sets were identified: the nature and extent of scrutiny of one's action, the artificiality of the environment, the over-simplification of responses, and prevalence of abnormality. The impact of these factors on radiological and other contexts is discussed, and although it is important to acknowledge the benefit of standardized screening test sets, issues relating to the relevance of test sets to clinical activities remain. The degree of correlation between performance based on real-life clinical audit and performances at screen read test sets must be better understood and specific causal agents for any lack of correlation identified.

Review paper: Cancer chemopreventive compounds and canine cancer.

Canine cancer has become more prevalent in recent years because of increased life expectancy and greater attention to the health of pets. The range of cancers seen in dogs is as diverse as that in human patients, and despite more intensive therapeutic interventions, fatality rates remain unacceptably high in both species. Chemoprevention is therefore an important means of confronting this disease. Because domestic pets share our environment, greater cross-application and study of the protumorigenic and antitumorigenic factors in our shared environment will benefit all species, leading to the development of new families of less toxic antitumorigenic compounds based on novel and established molecular targets. Currently, the most interesting cancer preventive agents are nonsteroidal anti-inflammatory drugs, peroxisome proliferator-activated receptor-gamma ligands, and dietary compounds. This article provides an overview of what is known about how these agents affect molecular signaling in neoplastic disease, with reference to reported application and/or study in dogs where available.

Adiposity-related protection of intestinal tumorigenesis: interaction with dietary calcium.

Although high-calcium diets have been reported to reduce the risk of colorectal cancer, our preliminary data with the adenomatous polyposis coli (Apc) Min mutation (Min/+;Apc(Min/+)) mouse shows a paradoxical increase in intestinal tumor loads (> 65%) with high calcium diets. Since we previously demonstrated that increasing dietary calcium reduces adiposity, and Apc(Min/+) mice on high calcium diets exhibited profound loss of adipose tissue, we hypothesized that loss of an adipose tissue-derived tumor suppressor factor(s) resulted in increased tumor susceptibility in animals on the high calcium diet. Accordingly, tumor prone Apc(Min/+) mice were crossed with obesity prone lethal yellow agouti (A(y)/a) mice to generate obese A(y)/Apc(Min/+) mice. Low (0.2%), normal (0.5%), and high (1.2%) calcium diets were fed to both A(y)/Apc(Min/+) mice and Apc(Min/+) mice from 35-40 days until 90 days of age (n=21/strain, n=7/diet group). The high calcium diet reduced weight gain in both strains (P < 0.01) and reduced fat pad mass by 46-57% in A(y)/Apc(Min/+)(P < 0.004) and by 65-82% in Apc(Min/+)(P < 0.03).Apc(Min/+) mice on the high calcium diet exhibited an increase in tumor number (76 vs. 29, P=0.009), but this effect was not seen in the A(y)/Apc(Min/+) mice. beta-Catenin and cyclin D1 gene expression were significantly induced with high calcium diet in intestinal tumor tissue of Apc(Min/+) mice but not in A(y)/Apc(Min/+) mice. We conclude that the differential effect of dietary calcium on intestinal tumorigenesis in lean vs. obese Apc(Min/+) may result from the loss of adipose-derived protective factor(s) due to the substantial loss of body fat in Apc(Min/+) mice fed a high calcium dairy diet, increasing beta-catenin and cyclin D1 in tumors.

Dietary polyunsaturated fatty acids and colorectal neoplasia.

Epidemiology has implicated dietary fat in mortality associated with some of the most common forms of cancer, including those affecting the intestinal tract, breast and prostate. Polyunsaturated fatty acids, and arachidonate in particular, have been unequivocally linked to experimental colorectal carcinogenesis. Dietary, pharmacologic and genetic manipulation of tissue arachidonic acid and its conversion to bioactive lipids has provided insights into pathogenic mechanisms as well as compelling evidence to support rational preventative and therapeutic methods of disease intervention. While it is clear that conversion of arachidonate to prostaglandins and other bioactive lipids contributes significantly to tumorigenesis in the intestinal tract and other organs, it is also clear that no single metabolic pathway or lipid in this complex biochemical network is solely responsible for dietary or pharmacologic benefits evident in epidemiologic studies. We will review some of these data and provide a summary of our own work showing that conversion of arachidonate to prostaglandin E2 contributes significantly to tumor growth through the modulation of apoptosis and cellular proliferation.

Cyclooxygenase-2 expression in spontaneous intestinal neoplasia of domestic dogs.

Cyclooxygenase-2 (Cox-2) is commonly upregulated during human colorectal tumorigenesis, and its contribution to this process has been clearly demonstrated in genetic mouse models. The only other species that naturally develops intestinal cancer with any frequency is the domestic dog. Intestinal carcinogenesis in humans has been strongly linked to environmental factors such as diet, which may be shared by household pets. We have previously reported that beta-catenin is overexpressed in the neoplastic epithelium of canine colorectal polyps, as it is in humans and rodents. We now show that Cox-2 is also upregulated in the majority of these lesions. Thirteen out of 20 colorectal adenomas (65%) contained immunohistochemically detectable Cox-2 protein restricted to the nonneoplastic tumor stroma, including myofibroblasts and a-smooth muscle actin-negative mesenchymal cells morphologically consistent with macrophages and/or fibroblasts. In contrast to benign polyps, seven of 15 adenocarcinomas (47%) also expressed Cox-2 in the neoplastic epithelium. These changes duplicate molecular changes in human intestinal tumorigenesis and substantiate a fundamental role for both beta-catenin and Cox-2 in intestinal neoplasia.

Highly unsaturated (n-3) fatty acids, but not alpha-linolenic, conjugated linoleic or gamma-linolenic acids, reduce tumorigenesis in Apc(Min/+) mice.

We showed previously that dietary eicosapentaenoic acid [EPA, 20:5(n-3)] is antitumorigenic in the APC:(Min/+) mouse, a genetic model of intestinal tumorigenesis. Only a few studies have evaluated the effects of dietary fatty acids, including EPA and docosahexaenoic acid [DHA, 22:6(n-3)], in this animal model and none have evaluated the previously touted antitumorigenicity of alpha-linolenic acid [ALA, 18:3(n-3)], conjugated linoleic acid [CLA, 77% 18:2(n-7)], or gamma-linolenic acid [GLA, 18:3(n-6)]. Stearidonic acid [SDA, 18:4(n-3)], the Delta6-desaturase product of ALA, which is readily metabolized to EPA, has not been evaluated previously for antitumorigenic efficacy. This study was undertaken to evaluate the antitumorigenicity of these dietary fatty acids (ALA, SDA, EPA, DHA, CLA and GLA) compared with oleic acid [OA, 18:1(n-9)] at a level of 3 g/100 g in the diets of APC:(Min/+) mice and to determine whether any alterations in tumorigenesis correspond to alterations in prostaglandin biosynthesis. Tumor multiplicity was significantly lower by approximately 50% in mice fed SDA or EPA compared with controls, whereas less pronounced effects were observed in mice fed DHA (P: = 0.15). ALA, CLA and GLA were ineffective at the dose tested. Although lower tumor numbers coincided with significantly lower prostaglandin levels in SDA- and EPA-fed mice, ALA and DHA supplementation resulted in equally low prostaglandin levels, despite proving less efficacious with regard to tumor number. Prostaglandin levels did not differ significantly in the CLA and GLA groups compared with controls. These results suggest that SDA and EPA attenuate tumorigenesis in this model and that this effect may be related in part to alterations in prostaglandin biosynthesis.