Association between inflammatory bowel disease and prostate cancer: A large-scale, prospective, population-based study

Prostate and gut: Any relationship? A narrative review on the available evidence and putative mechanisms

BACKGROUND

Gut microbiome is a community of microorganisms that lives in the human intestine and exerts various functions on the host, including metabolic, immunoregulatory, and control over cell proliferation. Gut microbiome alterations have been associated with various pathological conditions, such as diabetes mellitus, obesity, and cardiovascular diseases. Gut-prostate axis is explained by the association between gut microbiome quantitative and functional alterations along with increased intestinal epithelial permeability with prostatediseases. However, the pathophysiological mechanisms and clinical importance of this association are not completely clarified yet.

METHODS

We conducted a narrative review of the most relevant articles in the Medline (US National Library of Medicine, Bethesda, MD, USA), Scopus (Elsevier, Amsterdam, The Netherlands) and Web of Science Core Collection (Thomson Reuters, Toronto, ON, Canada) databases. No chronological restrictions were applied, and the most related papers published until December 2023 were included.

RESULTS

Gut microbiota (GM) and its metabolites are capable of modifying host androgen level, as well as prostate cancer (PCa) therapy response. Moreover, patients with inflammatory bowel disease have higher rates of prostatitis-like symptoms and a potential risk of developing PCa.

CONCLUSIONS

There is evidence that interventions on the GM and its metabolites have a high potential to serve as diagnostic and therapeutic tools for prostate diseases, including PCa.

Prognostic Factors in Prostate Cancer Associated with Ulcerative Colitis

Ulcerative colitis (UC) has been associated with increased prostate cancer (PCa) risk. However, the mechanisms underlying UC and increased PCa risk remain unclear, and research on this topic is scarce in Japan. We have investigated whether UC is associated with PCa risk in the Japanese population and the risk factors related to PCa among older UC patients. This retrospective single-center cohort study was conducted between January 2010 and April 2022. A total of 68 cases were analyzed, and 9 cases of PCa were observed (13.2%). PCa occurred more frequently in the adult-onset group (8/40, 20.0%) than in the older-onset group with UC (1/28; 3.57%). No significant differences were observed between immunosuppressive therapies and PCa in patients, excluding those with pancolitis-type UC. PCa occurred more frequently in the pancolitis type, and the biologics group had no PCa cases, but the difference was not statistically significant (p = 0.07). This study suggests that pancolitis type and UC onset in middle-aged patients may be risk factors and found that biologics potentially suppress PCa development.

Two-sample Mendelian randomization study reveals no causal relationship between inflammatory bowel disease and urological cancers

Background: The relationship between inflammatory bowel disease (IBD) and urological cancers has been identified in epidemiological and observational studies, while the causality remains uncertain. We examined whether IBD is causally associated with urological cancers in a Mendelian randomization (MR) study. Methods: The causal relationship between IBD, its main subtypes, and urological cancers was investigated using genome-wide association study data. To obtain more reliable conclusions, all outcomes were divided into training and validation sets. Eligible single-nucleotide polymorphisms were selected as instrumental variables based on MR analysis assumptions. The inverse variance-weighted (IVW) method was employed as the main method along with four other complementary methods. Results: In this two-sample MR study, no genetic evidence for the causal effect of IBD on urological cancers was found in either the training or validation sets using the IVW method. Similarly, we did not observe any significant association between Crohn's disease or ulcerative colitis and urological cancers. The results of the other methods are in accordance with those obtained using the IVW method. Conclusion: In this study, we confirmed that IBD is not a causal genetic risk factor for urological cancer in a European population.

Association of ulcerative colitis and acute gastroenteritis with prostate specific antigen: results from National Health and Nutrition Examination Survey from (2009 to 2010) and Mendelian randomization analyses

Background

An increasing number of studies have demonstrated that gastrointestinal inflammation may increase prostate cancer risk and raise the prostate-specific antigen (PSA) level. However, the association between ulcerative colitis (UC) and acute gastroenteritis (AGE) with PSA remains unclear and complicated. Herein, we evaluated the relationship between UC and AGE with PSA concentration using the National Health and Nutrition Examination Survey (NHANES) database and Mendelian randomization (MR) analyses.

Materials and methods

A total of 1,234 participants fit into the study after conducting the screening based on the NHANES survey conducted from 2009 to 2010. UC and AGE were the independent variables, and PSA was the dependent variable. Weighted multiple linear regressions were utilized to estimate the association of UC and AGE with PSA concentration. To detect the causal relationship between UC and AGE with PSA, a two-sample Mendelian randomized analysis was conducted.

Results

After controlling for all covariates, PSA (log2 transform) concentrations in the UC group were increased by 0.64 (0.07, 1.21). AGE was not independently associated with PSA levels after adjusting potential confounders. In patients with coronary artery disease, AGE promotes elevated PSA (log2 transform) concentrations (β = 1.20, 95% CI: 0.21-2.20, p < 0.001). Moreover, an IVW MR analysis indicated that genetically predicted UC was associated with increased PSA, and that AGE was not associated with PSA.

Conclusion

This study indicated that a positive causal association exists between UC and the PSA level. However, there is no evidence to support the relationship between AGE and the PSA level.

Inflammatory bowel disease and prostate cancer risk: a two-sample Mendelian randomization analysis

Background

Previous epidemiological observational studies have reported an association between inflammatory bowel disease (IBD) and prostate cancer (PCa), but the causality is inconclusive. The purpose of this study was to evaluate the causality of IBD on PCa using the mendelian randomization (MR) analysis.

Methods

We performed a two-sample MR analysis with public genome-wide association studies (GWAS) data. Eligible instrumental variables (IVs) were selected according to the three assumptions of MR analysis. The inverse-variance weighted (IVW) method was the main method. Complementary methods included the MR-Egger regression, the Weighted Median, the Simple Mode, the Weighted Mode and MR pleiotropy residual sum and outlier (MR-PRESSO) methods.

Results

Genetically determined IBD did not have a causal effect on PCa (IVW P > 0.05). Additionally, there was no causal effect of Crohn's disease (CD) and ulcerative colitis (UC) on PCa in the MR analysis (IVW P > 0.05). Results of complementary methods were consistent with those of the IVW method.

Conclusions

This study does not support a causal association of IBD on PCa, which is in contrast to most observational studies.

Association between inflammatory bowel disease and risk of incident prostate cancer: a systematic review and meta-analysis of cohort studies

BACKGROUND AND OBJECTIVE

Numerous observational studies have been conducted to investigate the potential association between inflammatory bowel disease (IBD) and prostate cancer (PCa). However, a definitive conclusion has yet to be established. We therefore performed a meta-analysis to explore the relationship between these two conditions.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched to identify all relevant cohort studies that investigated the association between IBD and risk of incident PCa published from inception to February 2023. The pooled hazard ratios (HRs) with 95% confidence intervals (CI) was calculated as effect size for the outcome based on random-effects model meta-analysis.

RESULTS

A total of 18 cohort studies with 592,853 participants were included. The meta-analysis revealed that IBD was linked to an elevated risk of incident PCa (HR = 1.20, 95% CI: 1.06-1.37, P = 0.004). Further subgroup analyses revealed that ulcerative colitis (UC) was linked to an increased risk of incident PCa (HR = 1.20, 95% CI: 1.06-1.38, P = 0.006), while Crohn's disease (CD) is not significantly associated with a higher risk of PCa (HR = 1.03, 95% CI: 0.91-1.17, P = 0.65). There was a significant correlation between IBD and an elevated risk of incident PCa in the European population, but such a correlation was not observed in the Asian and North American populations. Sensitivity analyses indicated that our results were robust.

CONCLUSIONS

Our latest evidence indicates that IBD was linked to an elevated risk of incident PCa, especially in UC patients and the European population.

Inflammatory Bowel Disease Is Associated With an Increased Risk of Incident Acute Arterial Events: Analysis of the United Kingdom Biobank

BACKGROUND & AIMS

Population-based studies have suggested an increased risk of acute arterial events (AAEs) in patients with inflammatory bowel disease (IBD). We aimed to assess the risk of incident AAEs and premature AAEs, adjusted for diet, physical activity, and inflammation biomarkers, in participants with IBD in the UK Biobank (UKB) METHODS: UKB participants with IBD and without prevalent AAEs at enrollment were matched to random non-IBD controls. A Cox regression model, adjusting for baseline cardiovascular and IBD risk factors, diet, physical activity, and high-sensitivity C-reactive protein, estimated adjusted hazard ratios (aHRs) for association between IBD and AAEs or premature AAEs (age, <55 years for men and <65 years for women). Predictors of AAEs within the IBD cohort were identified in a Cox model adjusting for disease severity (IBD-related hospitalizations or surgeries).

RESULTS

Among 455,950 UKB participants, 5094 with IBD were matched to 20,376 non-IBD controls. After a median follow-up period of 12.4 years, participants with IBD had a higher incident rate of AAE (924.1 vs 730.9 per 100,000 person years; P < .001), risk of all AAEs (aHR, 1.19; 95% CI, 1.08-1.31; P < .001), and premature AAEs (aHR, 1.38; 95% CI, 1.11-1.72; P = .001). High-sensitivity C-reactive protein levels (highest quartile: aHR, 1.53; 95% CI, 1.15-2.03) and disease severity (aHR, 5.40; 95% CI, 4.03-7.22) were independent predictors of AAE in IBD.

CONCLUSIONS

In a prospective cohort, there was an increased risk of incident AAEs and premature AAEs in IBD participants. Beyond traditional AAE risk factors, quantifiable indices of IBD disease activity and severity were independent predictors of AAEs.

Inflammatory Bowel Disease and Long-term Risk of Cancer: A Prospective Cohort Study Among Half a Million Adults in UK Biobank

BACKGROUND

This study aims to examine the prospective association of inflammatory bowel disease (IBD) with long-term risk of overall, site-specific cancer and cancer-specific mortality in middle-aged and older people.

METHODS

The study included participants free of any cancer at baseline from the UK Biobank, with IBD patients as an exposure group and non-IBD patients as a reference group. Primary outcome was the incidence of overall cancer and cancer-specific mortality. Secondary outcomes included site-specific cancers and types of digestive cancers. Cox proportional hazard model was used to investigate the associated risk of incident malignancies and related mortality.

RESULTS

Among 455 927 participants, 5142 were diagnosed with IBD (3258 ulcerative colitis [UC]; 1449 Crohn's disease [CD]; others unspecified). During a median of 12.2-year follow-up, 890 cases of incident cancer were identified in IBD patients (15.74 per 1000 person years) compared with 63 675 cases in reference individuals (12.46 per 1000 person years). Of these cases, 220 and 12 838 cancer-specific deaths occurred in IBD and non-IBD groups. Compared with non-IBD participants, the adjusted hazard ratio (AHR) for overall cancer and cancer-specific mortality was 1.17 (95% CI, 1.09-1.25) and 1.26 (95% CI, 1.18-1.35) among IBD patients, with an AHR of 1.15 (95% CI, 1.02-1.31) and 1.38 (95% CI, 1.08-1.75) in UC and 1.15 (95% CI, 1.06-1.25) and 1.25 (95% CI, 1.06-1.49) in CD, respectively. Specifically, increased risk of digestive (1.33; 95% CI, 1.12-1.57), nonmelanoma (1.25; 95% CI, 1.11-1.41), and male genital (1.29; 95% CI, 1.09-1.52) cancers was observed in IBD patients.

CONCLUSIONS

Compared with non-IBD, IBD may be associated with an increased risk of overall cancer and cancer-specific mortality, particularly digestive cancers, nonmelanoma and male genital cancers.

Risk of prostate cancer in patients with inflammatory bowel disease: a nationwide cohort study in South Korea

BACKGROUND

Several studies have suggested an association between inflammatory bowel disease (IBD) and the risk of prostate cancer development. However, these findings are inconsistent, and studies based on Asian populations are limited.

OBJECTIVES

We compared the risk of prostate cancer according to IBD status using the Korean National Health Insurance Service database.

DESIGN

A population-based retrospective cohort of age-matched 59,044 non-IBD patients and 14,761 IBD patients between January 2009 and December 2011 was analyzed up to December 2017.

METHODS

The risk of prostate cancer was compared between patients with IBD and controls using the Cox proportional hazards regression model and Kaplan-Meier survival analysis.

RESULTS

During a median follow-up of 6 years, the incidence rate of prostate cancer was 264 per 100,000 person-years in non-IBD patients and 242 per 100,000 person-years in patients with IBD. IBD status was not associated with the risk of prostate cancer compared to non-IBD [adjusted hazard ratio (aHR) 0.93, 95% confidence interval (CI): 0.80-1.08, p = 0.32). The cumulative incidence of prostate cancer did not differ by IBD status (non-IBD patients versus IBD patients: log-rank p = 0.27; non-IBD patients versus ulcerative colitis versus Crohn's disease: log-rank p = 0.42). In multivariate analysis, age was an independent risk factor for the development of prostate cancer (HR 1.03, 95% CI: 1.02-1.03, p < 0.001).

CONCLUSION

In our population-based study, IBD status was not associated with the risk of prostate cancer.

Inflammatory bowel disease-associated malignancies and considerations for radiation impacting bowel: a scoping review

Background

Inflammatory bowel disease (IBD), subdivided into Crohn's disease (CD) and ulcerative colitis (UC), is an auto-inflammatory gastrointestinal condition with an established increased risk of certain malignancies. Compared to sporadic cancers in the general population, IBD-associated malignancies present unique challenges to providing quality care. Radiation therapy (RT) targeting IBD-associated malignancies may directly impact inflamed bowel, with special considerations for the risk of toxicities. Historically, patients with IBD have been less likely to receive radiotherapy in proximity to bowel due to a poor understanding of the potential for acute and chronic toxicities and unclear treatment outcomes. We present a scoping review, to more fully assess IBD-associated malignancies and their treatment. As opposed to a systematic review, this approach allows us to analyze the broadest range of literature, including experimental and non-experimental research, and reflect on current guidelines and practices.

Methods

Literature search: a systematic, scoping search of published literature was conducted using applicable PRISMA scoping review (ScR) guidelines. The literature search was conducted on PubMed and was searched systematically by screening all publications from January 1990 to June 2021. Citations from the included articles were also manually searched. Relevant National Comprehensive Cancer Network guidelines were reviewed. Final query was December 2021 in editing. Articles were selected for full text reading if the abstract reported on malignancy in IBD or bowel toxicities.

Results

The pelvic malignancies found in the IBD patient population, including colorectal carcinoma, anal carcinoma, lymphoma, small bowel adenocarcinoma (SBA), and prostate cancer (PCa) are outlined in this scoping review. Additional cancers that have a contested relationship with IBD, including cervical, bladder, and upper GI cancers, are also explored. This review provides literature guided recommendations on the eligibility of patients with IBD to receive RT, management of IBD during and after treatment, and counseling for radiation-induced toxicities.

Conclusions

After review of the literature, IBD should not be considered an absolute contraindication to radiation therapy, given the lack of evidence for increased toxicities, and the evolution of RT techniques which limit radiation dose to the bowel.

Associations between inflammatory bowel disease, social isolation, and mortality: evidence from a longitudinal cohort study

Background

Social well-being of patients with inflammatory bowel disease (IBD) is garnering increased attention; however, the impact of social isolation remained poorly understood.

Objectives

We investigated the joint association of social isolation and IBD with premature deaths to articulate the profound impact of social isolation in IBD prognosis.

Design

Longitudinal cohort study.

Methods

We leveraged data of 486,014 participants from UK Biobank (including 5791 with IBD), the mean follow-up was 11.84 years. Diagnoses of IBD and its subtypes of Crohn's disease (CD) and ulcerative colitis were confirmed with the combination of self-reporting, primary care, and hospital admission data. Social isolation was measured by the frequency of meeting family/friends, leisure and social activity, and communal/solitary living. Mortality was ascertained through data linkage with national death registries. Multivariable Cox regression models were conducted to estimate hazard ratio (HR) and 95% confidence interval (CI).

Results

Comparing non-isolated non-IBD population, the HRs of mortality in patients with IBD who were socially isolated or not were 2.06 (95% CI: 1.69, 2.51) and 1.33 (95% CI: 1.21, 1.45), respectively. The excess risk of death was observed in socially isolated patients with IBD (HR = 1.69, 95% CI: 1.36, 2.11), particularly among patients with CD (HR = 2.06, 95% CI: 1.48, 2.87) than their non-isolated counterparts. Data from subgroup and sensitivity analyses were consistent with those from the primary analysis.

Conclusion

Socially isolated patients with IBD especially CD increases the risk of premature death. Preventing social isolation might be a promising approach to improve IBD prognosis.

Plain language summary

Social isolation as a risk factor to excess mortality in patients with IBD: findings from a longitudinal cohort study Social isolation is prevalent in individuals with inflammatory bowel disease (IBD); however, its potential health impact on IBD prognosis has not been quantitatively well examined. In this study, we explored the association between social isolation and subsequent death, with the focus on patients with IBD.We leveraged data of 486,014 participants (including 5791 with IBD) from UK Biobank. We measured social isolation by the frequency of meeting family/friends, leisure and social activity, and communal/solitary living. We ascertained patients with IBD and mortality by self-report data and data linkage with primary care, hospital, and national death registry. Participants were followed up for a mean of 11.84 years.Comparing non-isolated non-IBD population, we found that patients with IBD who were deemed as socially isolated or not were associated with a 2.06-fold (1.69-2.51) and 1.33-fold (1.21-1.45) risk of death, respectively. Furthermore, we revealed that socially isolated patients with IBD and subtype Crohn's disease (CD) had 69% (36-111%) and 106% (48-187%) increased risk of premature death compared with their non-isolated counterparts, respectively.Social isolation merits attention in IBD care and management. Patients with IBD, especially CD, are more likely to be affected when socially isolated. Targeted social support strategies ought to be devised to improve IBD prognosis.

Cancer in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD), including Crohn disease and ulcerative colitis, are chronic inflammatory conditions of the gastrointestinal tract. Individuals with IBD are at increased risk for several malignancies originating in the intestine, such as colorectal cancer, small bowel adenocarcinoma, intestinal lymphoma, and anal cancer. There are also several extraintestinal malignancies associated with IBD and IBD therapies, including cholangiocarcinoma, skin cancer, hematologic malignancies, genitourinary cancer, cervical cancer, and prostate cancer. The authors summarize the risk of cancer in patients with IBD, diagnosis and management of colorectal neoplasia in IBD, and management of patients with IBD and active or recent cancer.

Sugar-sweetened beverages, artificially sweetened beverages and natural juices and risk of inflammatory bowel disease: a cohort study of 121,490 participants

BACKGROUND

Inflammatory bowel diseases (IBD) have been related to high-sugar dietary patterns, but the associations of different types of beverages with IBD risk are largely unknown.

AIMS

To examine any associations between intake of sugar-sweetened beverages, artificially sweetened beverages and natural juices and IBD risk METHODS: This cohort study included 121,490 participants in the UK Biobank who were free of IBD at recruitment. Intake of beverages was obtained from repeated 24-h diet recalls in 2009-2012. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of beverage intake with IBD risk.

RESULTS

During a mean (standard deviation) follow-up of 10.2 (1.5) years, we documented 510 incident IBD cases, (143 Crohn's disease (CD) and 367 ulcerative colitis (UC)). Compared to non-consumers, participants consuming >1 unit per day of sugar-sweetened beverages were at significantly higher risk of IBD (HR 1.51, 95% CI 1.11-2.05), but the trend was non-significant (p-trend = 0.170). This association was significant for CD (HR 2.05, 95% CI 1.22-3.46), but not for UC (HR 1.31, 95% CI 0.89-1.92). We did not observe significant associations for the consumption of artificially sweetened beverages or natural juices.

CONCLUSIONS

Our findings suggest an association between consumption of sugar-sweetened beverages, rather than artificially sweetened beverages or natural juices, and IBD risk.

Association between the visceral adiposity index and risks of all-cause and cause-specific mortalities in a large cohort: Findings from the UK biobank

BACKGROUND AND AIMS

The visceral adiposity index (VAI) has been recently established as a measure of visceral fat distribution and is shown to be associated with a wide range of adverse health events. However, the precise associations between the VAI score and all-cause and cause-specific mortalities in the general population remain undetermined.

METHODS AND RESULTS

In this large-scale prospective epidemiological study, 357,457 participants (aged 38-73 years) were selected from the UK Biobank. We used Cox competing risk regression models to estimate the association between the VAI score and all-cause, cardiovascular disease (CVD), cancer, and other mortalities. The VAI score was significantly correlated with an increased risk of all-cause mortality (hazard ratio [HR], 1.200; 95% confidence interval [CI], 1.148-1.255; P < 0.0001), cancer mortality (HR, 1.224; 95% CI, 1.150-1.303; P < 0.0001), CVD mortality (HR, 1.459; 95% CI, 1.148-1.255; P < 0.0001), and other mortalities (HR, 1.200; 95% CI, 1.148-1.255; P < 0.0001) after adjusting for a series of confounders. In addition, the subgroup analyses showed that HRs were significantly higher in participants who were male, aged below 65 years, and body mass index less than 25.

CONCLUSION

In summary, VAI was positively associated with an increased risk of all-cause and cause-specific mortalities in a nationwide, well-characterised population identified in a UK Biobank. The VAI score might be a complementary traditional predictive indicator for evaluating the risk of adverse health events in the population of Western adults aged 38 years and older.

Meat consumption and all-cause mortality in 5763 patients with inflammatory bowel disease: A retrospective cohort study

BACKGROUND

Whether meat consumption is related to risk of mortality in patients with inflammatory bowel disease (IBD) remains poorly understood.

METHODS

In the UK Biobank, 5763 patients with IBD were recruited from 2007 to 2010 and finished a brief food frequency questionnaire at baseline. We followed them until March 13, 2021 to document all-cause death events. Cox proportional hazard models were used to estimate hazard ratios (HRs) for all-cause mortality associated with consumptions of fish, unprocessed poultry, unprocessed red meat, and processed meat among the patients.

FINDINGS

During 67,095 person-years (mean follow-up 11·7 years, mean age 57·3, 52·5% female), we documented 590 death events. Higher consumption of processed meat was associated with an increased risk of all-cause mortality in patients with IBD (HR comparing >4·0 with 0-0·9 time/week=1·52, 95% confidence interval (CI) 1·05-2·19), but the P-trend for each 25 g increment was 0·075. This association remained significant in patients with Crohn's disease (HR 1·77, 95% CI 1·01-3·10) but not in patients with ulcerative colitis (HR 1·34, 95% CI 0·82-2·20). Consumptions of fish (HR 1·27, 95% CI 0·84-1·91), unprocessed poultry (HR 0·59, 95% CI 0·28-1·21), or unprocessed red meat (HR 0·87, 95% CI 0·60-1·26) were not significantly associated with the mortality of patients with IBD.

INTERPRETATION

More frequent consumption of processed meat was associated with an increased risk of mortality in patients with IBD, while no associations were observed for consumption of other types of meat. Our exploratory and speculative findings should be cautiously interpreted and need further replication in other cohorts.

FUNDING

The National Natural Science Foundation of China (81,970,494); Key Project of Research and Development Plan of Hunan Province (2019SK2041).

Somatic mutational profiles and germline polygenic risk scores in human cancer

BACKGROUND

The mutational profile of cancer reflects the activity of the mutagenic processes which have been operative throughout the lineage of the cancer cell. These processes leave characteristic profiles of somatic mutations called mutational signatures. Mutational signatures, including single-base substitution (SBS) signatures, may reflect the effects of exogenous or endogenous exposures.

METHODS

We used polygenic risk scores (PRS) to summarize common germline variation associated with cancer risk and other cancer-related traits and examined the association between somatic mutational profiles and germline PRS in 12 cancer types from The Cancer Genome Atlas. Somatic mutational profiles were constructed from whole-exome sequencing data of primary tumors. PRS were calculated for the 12 selected cancer types and 9 non-cancer traits, including cancer risk determinants, hormonal factors, and immune-mediated inflammatory diseases, using germline genetic data and published summary statistics from genome-wide association studies.

RESULTS

We found 17 statistically significant associations between somatic mutational profiles and germline PRS after Bonferroni correction (p < 3.15 × 10^-5), including positive associations between germline inflammatory bowel disease PRS and number of somatic mutations attributed to signature SBS1 in prostate cancer and APOBEC-related signatures in breast cancer. Positive associations were also found between age at menarche PRS and mutation counts of SBS1 in overall and estrogen receptor-positive breast cancer. Consistent with prior studies that found an inverse association between the pubertal development PRS and risk of prostate cancer, likely reflecting hormone-related mechanisms, we found an inverse association between age at menarche PRS and mutation counts of SBS1 in prostate cancer. Inverse associations were also found between several cancer PRS and tumor mutation counts.

CONCLUSIONS

Our analysis suggests that there are robust associations between tumor somatic mutational profiles and germline PRS. These may reflect the mechanisms through hormone regulation and immune responses that contribute to cancer etiology and drive cancer progression.

Genetic Factors Associated with Prostate Cancer Conversion from Active Surveillance to Treatment

Men diagnosed with low-risk prostate cancer (PC) are increasingly electing active surveillance (AS) as their initial management strategy. While this may reduce the side effects of treatment for prostate cancer, many men on AS eventually convert to active treatment. PC is one of the most heritable cancers, and genetic factors that predispose to aggressive tumors may help distinguish men who are more likely to discontinue AS. To investigate this, we undertook a multi-institutional genome-wide association study (GWAS) of 5,222 PC patients and 1,139 other patients from replication cohorts, all of whom initially elected AS and were followed over time for the potential outcome of conversion from AS to active treatment. In the GWAS we detected 18 variants associated with conversion, 15 of which were not previously associated with PC risk. With a transcriptome-wide association study (TWAS), we found two genes associated with conversion (MAST3, p = 6.9×10-7 and GAB2, p = 2.0×10-6). Moreover, increasing values of a previously validated 269-variant genetic risk score (GRS) for PC was positively associated with conversion (e.g., comparing the highest to the two middle deciles gave a hazard ratio [HR] = 1.13; 95% Confidence Interval [CI]= 0.94-1.36); whereas, decreasing values of a 36-variant GRS for prostate-specific antigen (PSA) levels were positively associated with conversion (e.g., comparing the lowest to the two middle deciles gave a HR = 1.25; 95% CI, 1.04-1.50). These results suggest that germline genetics may help inform and individualize the decision of AS-or the intensity of monitoring on AS-versus treatment for the initial management of patients with low-risk PC.

Habitual Fish Oil Supplementation and Risk of Incident Inflammatory Bowel Diseases: A Prospective Population-Based Study

Background

Inflammatory Bowel Diseases (IBDs) have been emerging in recent years with the advance of global industrialization and diet pattern transformation. Marine n-3 polyunsaturated fatty acids (n-3 PUFAs), enriched in fish oils, have well-known human health promotion. Evidence on the association of fish oil supplementation with the risk of developing IBDs was scarce. This study aimed to examine the association between the use of fish oil supplements and the risk of developing inflammatory bowel diseases (IBDs) among the general population.

Methods

We conducted a prospective cohort study of 447,890 participants aged 40-69 years from the UK Biobank. A touch screen questionnaire was used to get the data about fish oil intake at baseline. Incident diagnoses of IBDs were ascertained by the International Classification of Diseases (ICD-9 and ICD-10) or self-report. Cox proportional hazards model was applied to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of developing IBDs and their subtypes.

Results

We documented 1,646 incident cases of IBDs, including 533 incident cases of Crohn's disease (CD) and 1,185 incident cases of ulcerative colitis (UC) during an average of 8 years of follow-up. After multivariate adjustment, the use of fish oil was associated with a 12% lower risk of IBDs (HR: 0.88, 95% CI: 0.78-0.99, p = 0.03) compared with non-consumers. For subtypes of IBDs, fish oil supplementation was inversely associated with a 15% lower risk of UC (HR: 0.85, 95% CI: 0.75-0.99, p = 0.02) but was not correlated with the risk of CD (p = 0.22). Besides, fish oil supplementation showed a significant inverse correlation with baseline CRP levels (β = -0.021, p < 0.001) and a positive association with baseline albumin levels (β = 0.135, p < 0.001) after adjustment for multiple variates.

Conclusion

Habitual intake of fish oil supplements was associated with a lower risk of IBDs and UC. Fish oil users tended to have lower baseline C-reactive protein levels and higher baseline albumin levels compared with non-users. It was concluded that fish oil supplement use may be recommended for the prevention and control of IBDs.

Solid extraintestinal malignancies in patients with inflammatory bowel disease

Malignancies constitute the second cause of death in patients with inflammatory bowel diseases (IBD), after cardiovascular diseases. Although it has been postulated that IBD patients are at greater risk of colorectal cancer compared to the general population, lately there has been evidence supporting that this risk is diminishing over time as a result of better surveillance, while the incidence of extraintestinal cancers (EICs) is increasing. This could be attributed either to systemic inflammation caused by IBD or to long-lasting immunosuppression due to IBD treatments. It seems that the overall risk of EICs is higher for Crohn’s disease patients and it is mainly driven by skin cancers, and liver-biliary cancers in patients with IBD and primary sclerosing cholangitis. The aims of this review were first to evaluate the prevalence, characteristics, and risk factors of EICs in patients with IBD and second to raise awareness regarding a proper surveillance program resulting in early diagnosis, better prognosis and survival, especially in the era of new IBD treatments that are on the way.

Mapping Transcriptome Data to Protein-Protein Interaction Networks of Inflammatory Bowel Diseases Reveals Disease-Specific Subnetworks

Inflammatory bowel disease (IBD) is the common name for chronic disorders associated with the inflammation of the gastrointestinal tract. IBD is triggered by environmental factors in genetically susceptible individuals and has a significant number of incidences worldwide. Crohn’s disease (CD) and ulcerative colitis (UC) are the two distinct types of IBD. While involvement in ulcerative colitis is limited to the colon, Crohn’s disease may involve the whole gastrointestinal tract. Although these two disorders differ in macroscopic inflammation patterns, they share various molecular pathogenesis, yet the diagnosis can remain unclear, and it is important to reveal their molecular signatures in the network level. Improved molecular understanding may reveal disease type-specific and even individual-specific targets. To this aim, we determine the subnetworks specific to UC and CD by mapping transcriptome data to protein–protein interaction (PPI) networks using two different approaches [KeyPathwayMiner (KPM) and stringApp] and perform the functional enrichment analysis of the resulting disease type-specific subnetworks. TP63 was identified as the hub gene in the UC-specific subnet and p63 tumor protein, being in the same family as p53 and p73, has been studied in literature for the risk associated with colorectal cancer and IBD. APP was identified as the hub gene in the CD-specific subnet, and it has an important role in the pathogenesis of Alzheimer’s disease (AD). This relation suggests that some similar genetic factors may be effective in both AD and CD. Last, in order to understand the biological meaning of these disease-specific subnets, they were functionally enriched. It is important to note that chemokines—special types of cytokines—and antibacterial response are important in UC-specific subnets, whereas cytokines and antimicrobial responses as well as cancer-related pathways are important in CD-specific subnets. Overall, these findings reveal the differences between IBD subtypes at the molecular level and can facilitate diagnosis for UC and CD as well as provide potential molecular targets that are specific to disease subtypes.