PD-1 blockade induces phosphorylated STAT3 and results in an increase of Tregs with reduced suppressive function

PD-1 blockade has remarkable response rates in the treatment of melanoma; however, many patients fail to respond, and biomarkers and mechanisms of response remain unknown. We investigated the roles of Tregs, a population of immunosuppressive T-cells, in patient response to nivolumab. Tregs had a decrease in suppressive function in patients with positive outcomes (p=0.03), but not in patients with negative outcomes. Patients with no evidence of disease (NED) displayed increased percentages of Tregs post-nivolumab (p=0.04), but relapsing patients did not. RNA-seq analysis revealed genes significantly changed after treatment were distinct between Tcons and Tregs (~13% overlap) and between NED and relapsing patient Tregs (~2% overlap). Pathway analysis showed an increase in proliferation associated pathways in NED patient Tregs, but not relapsing patients. We found increased phosphoSTAT3 (pSTAT3) expression in Tregs from patients with positive outcomes (p=0.01), but not in patients with negative outcomes. Mechanistically, in vitro culturing of T-cells with αPD-1 resulted in increases in pSTAT3 expression (p=0.03) and increased percentages of Tregs (p=0.001). Culturing with αPD-1 also enhanced production of IL-10 (p=0.02), and the addition of a STAT3 inhibitor reduced the increases in IL-10 levels (p=0.01) and Treg percentages (p=0.01). The addition of an IL-10 neutralizing antibody also reduced the increased Tregs resulting from αPD-1 (p=0.01). These results support a model in which PD-1 blockade increases pSTAT3 expression leading to enhanced IL-10 production and Treg percentages, suggesting that pSTAT3 induction and reduced suppressive function are biomarkers of melanoma patient response to nivolumab.

Sex in murky waters: algal-induced turbidity increases sexual selection in pipefish

ABSTRACT

Algal-induced turbidity has been shown to alter several important aspects of reproduction and sexual selection. However, while turbidity has been shown to negatively affect reproduction and sexually selected traits in some species, it may instead enhance reproductive success in others, implying that the impact of eutrophication is far more complex than originally believed. In this study, we aimed to provide more insight into these inconsistent findings. We used molecular tools to investigate the impact of algal turbidity on reproductive success and sexual selection on males in controlled laboratory experiments, allowing mate choice, mating competition, and mate encounter rates to affect reproduction. As study species, we used the broad-nosed pipefish, Syngnathus typhle, a species practicing male pregnancy and where we have previously shown that male mate choice is impaired by turbidity. Here, turbidity instead enhanced sexual selection on male size and mating success as well as reproductive success. Effects from mating competition and mate encounter rates may thus override effects from mate choice based on visual cues, producing an overall stronger sexual selection in turbid waters. Hence, seemingly inconsistent effects of turbidity on sexual selection may depend on which mechanisms of sexual selection that have been under study.

SIGNIFICANCE STATEMENT

Algal blooms are becoming increasingly more common due to eutrophication of freshwater and marine environments. The high density of algae lowers water transparency and reduces the possibility for fish and other aquatic animals to perform behaviors dependent on vision. We have previously shown that pipefish are unable to select the best partner in mate choice trials when water transparency was reduced. However, fish might use other senses than vision to compensate for the reduction in water transparency. In this study, we found that when fish were allowed to freely interact, thereby allowing competition between partners and direct contact between the fish, the best partner was indeed chosen. Hence, the negative effects of reduced water visibility due to algal blooms may be counteracted by the use of other senses in fish.

Use of the Total Cancer Care System to Enrich Screening for CD30-Positive Solid Tumors for Patient Enrollment Into a Brentuximab Vedotin Clinical Trial: A Pilot Study to Evaluate Feasibility

Background

One approach to identify patients who meet specific eligibility criteria for target-based clinical trials is to use patient and tumor registries to prescreen patient populations.

Objective

Here we demonstrate that the Total Cancer Care (TCC) Protocol, an ongoing, observational study, may provide a solution for rapidly identifying patients with CD30-positive tumors eligible for CD30-targeted therapies such as brentuximab vedotin.

Methods

The TCC patient gene expression profiling database was retrospectively screened for CD30 gene expression determined using HuRSTA-2a520709 Affymetrix arrays (GPL15048). Banked tumor tissue samples were used to determine CD30 protein expression by semiquantitative immunohistochemistry. Statistical comparisons of Z- and H-scores were performed using R statistical software (The R Foundation), and the predictive value, accuracy, sensitivity, and specificity of CD30 gene expression versus protein expression was estimated.

Results

As of March 2015, 120,887 patients have consented to the institutional review board–approved TCC Protocol. A total of 39,157 fresh frozen tumor specimens have been collected, from which over 14,000 samples have gene expression data available. CD30 RNA was expressed in a number of solid tumors; the highest median CD30 RNA expression was observed in primary tumors from lymph node, soft tissue (many sarcomas), lung, skin, and esophagus (median Z-scores 1.011, 0.399, 0.202, 0.152, and 1.011, respectively). High level CD30 gene expression significantly enriches for CD30-positive protein expression in breast, lung, skin, and ovarian cancer; accuracy ranged from 72% to 79%, sensitivity from 75% to 100%, specificity from 70% to 76%, positive predictive value from 20% to 40%, and negative predictive value from 95% to 100%.

Conclusions

The TCC gene expression profiling database guided tissue selection that enriched for CD30 protein expression in a number of solid tumor types. Such an approach may improve screening efficiency for enrolling patients into biomarker-based clinical trials.

miRNAs associated with prostate cancer risk and progression

Prostate cancer is the most common malignancy among men in the US. Though considerable improvement in the diagnosis of prostate cancer has been achieved in the past decade, predicting disease outcome remains a major clinical challenge. Recent expression profiling studies in prostate cancer suggest microRNAs (miRNAs) may serve as potential biomarkers for prostate cancer risk and disease progression. miRNAs comprise a large family of about 22-nucleotide-long non-protein coding RNAs, regulate gene expression post-transcriptionally and participate in the regulation of numerous cellular processes. In this review, we discuss the current status of miRNA in studies evaluating the disease progression of prostate cancer. The discussion highlights key findings from previous studies, which reported the role of miRNAs in risk and progression of prostate cancer, providing an understanding of the influence of miRNA on prostate cancer. Our review indicates that somewhat consistent results exist between these studies and reports on several prostate cancer related miRNAs. Present promising candidates are miR-1, −21, 106b, 141, −145, −205, −221, and −375, which are the most frequently studied and seem to be the most promising for diagnosis and prognosis for prostate cancer. Nevertheless, the findings from previous studies suggest miRNAs may play an important role in the risk and progression of prostate cancer as promising biomarkers.

Sex differences in the presentation of stroke

Stroke affects both men and women of all ages, although the condition is more common among the elderly. Stroke occurs at an older age among women than among men; although the incidence is lower among women than among men, as women have a longer life expectancy their lifetime risk is slightly higher. Ischemic stroke is the most common type of stroke; and reperfusion treatment is possible if the patient reaches hospital early enough. Thrombolysis and thrombectomy are time-sensitive treatments - the earlier they are initiated the better is the chance of a positive outcome. It is therefore important to identify a stroke as soon as possible. Medical personnel can readily identify typical stroke symptoms but the presentation of non-traditional stroke symptoms, such as impaired consciousness and altered mental status, is often associated with a significant delay in the identification of stroke and thus delay in or inability to provide treatment. Non-traditional stroke symptoms are reported to be more common in women, who are thereby at risk of delayed recognition of stroke and treatment delay.

"Struggle to obtain redress": Women's experiences of living with symptoms attributed to dental restorative materials and/or electromagnetic fields

The aim of this study was to explore the experiences of illness and the encounters with health care professionals among women who attributed their symptoms and illness to either dental restorative materials and/or electromagnetic fields, despite the fact that research on health effects from dental fillings or electricity has failed to substantiate the reported symptoms. Thirteen women (aged 37-63 years) were invited to the study and a qualitative approach was chosen as the study design, and data were collected using semi-structured interviews. The analysis was conducted with a constant comparative method, according to Grounded Theory. The analysis of the results can be described with the core category, "Struggle to obtain redress," the two categories, "Stricken with illness" and "A blot in the protocol," and five subcategories. The core category represents the women's fight for approval and arose in the conflict between their experience of developing a severe illness and the doctors' or dentists' rejection of the symptoms as a disease, which made the women feel like malingerers. The informants experienced better support and confirmation from alternative medicine practitioners. However, sick-leave certificates from alternative medicine practitioners were not approved and this led to a continuous cycle of visits in the health care system. To avoid conflicting encounters, it is important for caregivers to listen to the patient's explanatory models and experience of illness, even if a medical answer cannot be given.

Abstract A067: PD-1 blockade enhances OX40 expression on regulatory T-cells and decreases suppressive function through induction of phospho-STAT3 signaling

Blockade of the co-inhibitory receptor PD-1 has had unprecedented success in the treatment of metastatic melanoma, with response rates of approximately 40% in previously untreated patients. However, since the majority of patients fail to respond, a better understanding of the mechanisms of action involved in response/resistance and novel approaches to overcome resistance are needed. We evaluated T-cells present in peripheral blood samples of resected stage III/IV melanoma patients treated with adjuvant nivolumab. Data from intra-patient, paired pre-treatment/post-treatment samples showed a significant (p<0.05) increase in phosphorylated STAT3 (pSTAT3) in patients without relapse, but not in patients relapsing. Increases in regulatory T-cells (Tregs) (p<0.05) in relapsers, but not in non-relapsers, and OX40 expression on Tregs (p<0.05) in both relapsers and non-relapsers were also observed. Based on these data we evaluated the ability of PD-1 blocking antibodies to induce pSTAT3 signaling in vitro. Culturing with anti-PD-1 significantly increased levels of pSTAT3 in T-cells, including Tregs, both at the basal state (p<0.05) and post-CD3/CD28 activation (p<0.01). Additionally, culturing T-cells with PD-1 blocking antibodies increased the production of the STAT3 regulated cytokine IL-10 (p<0.05), the number of Tregs (p<0.01) and Treg expression of OX40 (p<0.05). Increases in all these markers/populations were abrogated with the addition of a STAT3 inhibitor (p<0.01). Similar increases in the number of Tregs and the expression of OX40 were also found when T-cells were treated in vitro with recombinant IL-10. Addition of IL-10 neutralizing antibodies ameliorated upregulation of Treg numbers and OX40 expression resulting from PD-1 blockade. Additionally, serum levels of IL-10 were found to be significantly elevated in non-relapsing patients relative to relapsers (p<0.05). RNA-seq analysis comparing Tregs from relapsers to non-relapsers further supported the observed increase in Tregs resulting from nivolumab treatment, with pathway analyses demonstrating significantly increased cell cycle, DNA replication, mitosis and other proliferation related pathways in Tregs from non-relapsed patients. Next we evaluated changes in the function of patient Tregs in an allogenic mixed lymphocyte suppression assay. Tregs from non-relapsers had a significant reduction in suppressive capacity post-nivolumab treatment in paired analyses (p<0.05), while Tregs from relapsers had no significant change. Post-treatment samples from relapses were also found to be significantly more suppressive (p<0.01) than those of non-relapsers. Additionally, decreased percentages of CCR4+CD45RA+ Tregs, previously described as having enhanced suppressive capacity, were found in non-relapsers post-treatment, but not in relapsers. A similar decrease in CCR4+CD45RA+ Tregs was achieved in vitro using OX40 agonist antibodies. Therefore, we propose that PD-1 blockade triggers STAT3 signaling, a hereunto unknown effect. These data support a model in which STAT3 induction by PD-1 blockade results in IL-10 production, which induces proliferation of Tregs with reduced suppressive capacity and triggers OX40 expression. Based on these results and previous findings of others demonstrating that ligation of OX40 expressed on Tregs hinders suppressive capacity, combining OX40 agonist antibodies may enhance the effectiveness of PD-1 blockade by reducing Treg suppression.

Citation Format: David M. Woods, Rupal Ramakrishnan, Andressa L. Sodré, Anders Berglund, Jeffrey Weber. PD-1 blockade enhances OX40 expression on regulatory T-cells and decreases suppressive function through induction of phospho-STAT3 signaling [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A067.

Clinical presentation and predictors of survival related to extent of bone metastasis in 900 prostate cancer patients

OBJECTIVE

The aim of this study was to investigate the impact of bone metastasis on survival and quality of life (QoL) in men with hormone-naïve prostate cancer.

MATERIALS AND METHODS

The study included 900 patients from a randomized trial (No. 5) by the Scandinavian Prostate Cancer Group, comparing parenteral oestrogen with total androgen blockade. Extent of bone metastasis was categorized according to a modified Soloway score: score 1, n = 319; score 2, n = 483; and score 3, n = 98 patients. The primary outcome measurements were mean differences in QoL and overall survival.

RESULTS

QoL rating scales showed a decrease with increasing extent of bone metastasis (p < 0.001). The mean global health status decreased from 64.4 to 50.5 for Soloway score 1 and 3, respectively. Following adjustment for performance status, analgesic consumption, grade of malignancy, alkaline phosphatase, prostate-specific antigen, haemoglobin and global health status, Soloway score 2 and 3 had a 47% [hazard ratio (HR) 1.47, 95% confidence interval (CI) 1.21-1.80] and 78% (HR 1.78 95%, CI 1.32-2.42) increased mortality, respectively, compared to Soloway score 1. Independent predictive factors of mortality were assessed.

CONCLUSIONS

Patient grouping based on three categories of extent of bone metastasis related to performance status, haemoglobin and global health status at presentation, as independent predictors of mortality, may provide improved accuracy of prognosis.

BIRC3 is a novel driver of therapeutic resistance in Glioblastoma

Genome-wide analysis of glioblastoma (GBM) reveals pervasive aberrations in apoptotic signaling pathways that collectively contribute to therapeutic resistance. Inhibitors of apoptosis proteins (IAP) exert critical control on the terminal segment of apoptosis leading to apoptosis evasion. In this study, we uncover a unique role for BIRC3, as an IAP that is critical in GBM in response to therapy. Using the TCGA dataset of 524 unique samples, we identify BIRC3 is the only IAP whose differential expression is associated with long-term survival in GBM patients. Using patient tissue samples we further show that BIRC3 expression increases with recurrence. When extrapolated to a preclinical model of a human GBM cell line, we find an increase in BIRC3 expression in response to irradiation (RT) and temozolomide (TMZ) treatment. More importantly, we mechanistically implicate STAT3 and PI3K signaling pathways as drivers of RT-induced up-regulation of BIRC3 expression. Lastly, we demonstrate that both in-vivo and in-vitro BIRC3 up-regulation results in apoptosis evasion and therapeutic resistance in GBM. Collectively, our study identifies a novel translational and targetable role for BIRC3 expression as a predictor of aggressiveness and therapeutic resistance to TMZ and RT mediated by STAT3 and PI3K signaling in GBM.

Predictors of early androgen deprivation treatment failure in prostate cancer with bone metastases

Approximately 15% of men with hormone naïve metastatic prostate cancer primarily fail to respond to androgen deprivation treatment (ADT). The reason why the response to ADT differs in this subgroup of men with prostate cancer remains unclear. The aim of this study was to describe the characteristics of these men and to thereby define predictors of early ADT failure in prostate cancer patients with bone metastases. The study was based on 915 men from the prospective randomized multicenter trial (no. 5) conducted by the Scandinavian Prostate Cancer Group comparing parenteral estrogen with total androgen blockade. Early ADT failure was defined as death from metastatic prostate cancer within 12 months after the start of ADT. Multivariate logistic regression models were applied to identify clinical predictors of early ADT failure. Ninety‐four (10.3%) men were primarily nonresponders to ADT. Independent predictors of early ADT failure were poor Eastern Cooperative Oncology Group performance status (PS), analgesic consumption, low hemoglobin, and high Soloway score (extent of disease observed on the scan), in where patients with poor PS and/or high analgesic consumption had a threefold risk of early ADT failure. Not significantly factors related to early ADT failure were age, treatment, cardiovascular comorbidity, T category, grade of malignancy, serum estrogen level, and SHBG at enrolment. We analyzed characteristics of a subgroup of patients who primarily failed to respond to ADT. Four independent clinical predictors of early ADT failure could be defined, and men exhibiting these features should be considered for an alternative treatment.

Reduced cannibalism during male pregnancy

Cannibalism provides energetic benefits but is also potentially costly, especially when directed towards kin. Since fitness costs increase with time and energy invested in offspring, cannibalism should be infrequent when parental investment is high. Thus, filial cannibalism in male syngnathids, a group known for the occurrence of male pregnancy, should be rare. Using the pipefish (Syngnathus abaster) we aimed to investigate whether cannibalism does occur in both sexes and how it is affected by reproductive and nutritional states. Although rare, we witnessed cannibalism both in the wild and in the laboratory. Unlike non-pregnant males and females, pregnant and post-partum males largely refrained from cannibalising juveniles. Reproducing males decreased their feeding activity, thus rendering cannibalism, towards kin or non-kin, less likely to occur. However, if not continuously fed, all pipefish adopted a cannibal strategy, revealing that sex and life history stages influenced the ratio between the benefits and costs of cannibalism.

Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015

REASONS FOR PERFORMING STUDY

Hypoglycin A (HG) appears to cause atypical myopathy (AM), but to our knowledge, detection of HG in affected and unaffected horses and concurrently in plants that they were exposed to has not previously been reported.

OBJECTIVES

To investigate HG in samples from horses exposed to Acer pseudoplatanus (European sycamore maple) and in such plant material, at the time of clinical cases of AM in the herd.

STUDY DESIGN

Cross-sectional study.

METHODS

Blood was collected from 2 horses with AM and 22 clinically healthy co-grazing horses in 2 Swedish farms within one week of onset of signs (May 2014) and one month later, after horses were moved to other pastures. Ten healthy control horses from unaffected farms were sampled once. Samaras, seedlings, flowers and leaves from Acer pseudoplatanus and from Acer platanoides L (Norway maple) were collected from affected pastures. Hypoglycin A was analysed using chemical derivatisation with dansyl chloride (DNS) and ultra high performance liquid chromatography-tandem mass spectrometry. Hypoglycin A was detected as derivatised compound HG-DNS [M+H]+ with selected reaction monitoring.

RESULTS

Hypoglycin A was detected in the horses affected with AM, and also in 20 out of 22 co-grazing horses. One month later, a surviving case horse and 9/20 co-grazing horses were still positive for HG. Controls from other farms were negative for HG. Hypoglycin A was detected in plant material from Acer pseudoplatanus, but not from Acer platanoides L.

CONCLUSIONS

Horses grazing in pastures with HG-containing Acer pseudoplatanus were positive for HG in blood, and some showed severe signs of myopathy. Ethical animal research: Ethical consent for blood sampling was granted (C113/11) and horse owners gave their informed consent to inclusion of horses in the study.

SOURCE OF FUNDING

National Veterinary Institute, Sweden. Competing interests: None declared.

Clinical characteristics and quality-of-life in patients surviving a decade of prostate cancer with bone metastases

OBJECTIVE

To describe characteristics and quality-of-life (QoL), and to define factors associated with long-term survival in a subgroup of patients with prostate cancer with M1b disease.

PATIENTS AND METHODS

The study was based on 915 patients from a prospective randomised multicentre trial (No. 5) by the Scandinavian Prostate Cancer Group, comparing parenteral oestrogen with total androgen blockade. Long-term survival was defined as patients having an overall survival of ≥10 years, and logistic regression models were constructed to identity clinical predictors of survival. QoL during follow-up was assessed using the European Organisation for Research and Treatment of Cancer Quality-of-Life Questionnaire - C30 version 1 (EORTC-C30) ratings.

RESULTS

In all, 40 (4.4%) of the 915 men survived for >10 years. Factors significantly associated with increased likelihood of surviving for >10 years in the univariate analyses were: absence of cancer-related pain; Eastern Cooperative Oncology Group (ECOG) performance status of <2; negligible analgesic consumption; T-category of 1-2; prostate-specific antigen (PSA) level of <231 μg/L; and a Soloway score of 1. In the multivariate analyses, ECOG performance status of <2, PSA level of <231 μg/L, and Soloway score of 1, were all independent predictors of long-term survival. All subscales of the EORTC-C30 were higher in this group than for patients with short survival, but slowly declined over the decade.

CONCLUSION

A subgroup of patients with prostate cancer with M1b disease and certain characteristics showed a positive long-term response to androgen-deprivation therapy with an acceptable QoL over a decade or more. Independent predictors of long-term survival were identified as ECOG performance status of <2, limited extent of bone metastases (Soloway score of 1), and a PSA level of <231 μg/L at the time of enrolment.

Patients with Non-small Cell Lung Cancer Analyzed for EGFR: Adherence to Guidelines, Prevalence and Outcome

BACKGROUND

Epidermal growth factor receptor (EGFR) analysis is the first molecular test introduced in the routine care of patients with non-small cell lung cancer (NSCLC). In the present study, we describe the prevalence of EGFR mutations and the adherence to testing and treatment guidelines in a population-based Swedish NSCLC cohort.

MATERIALS AND METHODS

Patients with NSCLC analyzed for EGFR mutations were identified and their characteristics and survival data were retrieved. We compared the study cohort to a matched lung cancer population.

RESULTS

The EGFR mutation frequency was 10%. Mutations were enriched in women and in adenocarcinoma cases. Out of patients with advanced-stage NSCLC with non-squamous histology, only 49% were referred for EGFR analysis. Out of the patients with EGFR mutation and advanced disease, only 38% received EGFR-tyrosine kinase inhibitor (TKI) in first-line therapy.

CONCLUSION

The EGFR-mutated NSCLC population studied is similar to other Western populations. Surprisingly, a large proportion of patients were not referred for EGFR analysis. Out of the patients with EGFR mutation, fewer than 40% received EGFR-TKI as first-line treatment. Our results highlight the need for follow-up of treatment and diagnostic algorithms in routine healthcare.

[Waiting time in lung cancer care. Patient guides provided faster flow]

The work-up process for lung cancer patients consists of several steps from suspicion of malignant disease to start of treatment. Delays between these steps should be minimized. Data in the Swedish National Lung Cancer Register show that the work-up times for lung cancer patients vary greatly between different counties in central Sweden. In order to reduce delays, a trial of implementing patient guides (Sw: patientlotsar) for patients referred to the hospital was conducted. When comparing the work-up times before and after implementation of patient guides the median waiting time from suspicion of lung cancer to start of treatment in the region was reduced from 71 to 45 days. Furthermore, the duration of most of the steps in the work-up process were shortened despite more complex investigation procedures, e.g. increased use of PET/CT in the guided patient group.

Capture rate and representativity of The National Prostate Cancer Register of Sweden

BACKGROUND

Capture rate and representativity of quality registers need to be assessed in order to ensure that register data are generalizable.

MATERIAL AND METHODS

In 1998-2009, 103 047 men had been diagnosed with prostate cancer and registered in the Swedish Cancer Register to which registration is mandated by law and of these men, 100 849 men (98%) had also been registered in The National Prostate Cancer Register (NPCR) of Sweden. We compared demographics, cancer treatment, comorbidity, and mortality in men in NPCR, with those who had only been registered in the Cancer Register, by use of data from the Cause of Death Register, the In-Patient Register and the Prescribed Drug Register. In addition, we identified 1929 men who had prostate cancer as underlying cause of death in the Cause of Death Register who had neither been registered in the Cancer Register nor in NPCR.

RESULTS

Compared to men in NPCR, men only registered in the Cancer Register were slightly older, median age 72 versus 71 years, and a lower proportion underwent radical prostatectomy, 15% versus 27%. Ten year prostate cancer mortality was 23% (95% CI 20-25) for men in the Cancer Register only and 24% (95% CI 24-25) in NPCR, while mortality from competing causes was 28% (95% CI 26-31) and 30% (95% CI 30-30), respectively. Men identified with prostate cancer by a death certificate were old and had high comorbidity.

CONCLUSION

The capture rate of NPCR is very high and there are only modest differences in demographics, cancer treatment, comorbidity, and mortality between the small proportion of men only registered in the Cancer Register and men registered in NPCR, indicating that information in NPCR can be generalized to all men with prostate cancer in Sweden.

Effects of a dietary intervention on gastrointestinal symptoms after prostate cancer radiotherapy: long-term results from a randomized controlled trial

BACKGROUND AND PURPOSE

To evaluate the long-term effects of dietary intervention on gastrointestinal symptoms after highly dose-escalated radiotherapy for localized prostate cancer, using boost with protons or high-dose-rate brachytherapy.

MATERIALS AND METHODS

Patients were randomized to an intervention group (n=64) advised to reduce insoluble dietary fiber and lactose intake, or to a standard care group (n=66) advised to continue their usual diet. Gastrointestinal symptoms, other domains of health-related quality of life (HRQOL), and dietary intake were evaluated for ⩽24months post-radiotherapy with the European Organization for Research and Treatment of Cancer quality-of-life questionnaires QLQ-C30 and QLQ-PR25, Gastrointestinal Side Effects Questionnaire, and Food Frequency Questionnaire. The effect of the intervention on gastrointestinal symptoms was evaluated using generalized estimating equations.

RESULTS

Dietary intervention had no obvious effect on long-term gastrointestinal symptoms or HRQOL. The intervention group markedly reduced their dietary fiber and lactose intake during radiotherapy, but adherence tended to decline over time. The vast majority of long-term gastrointestinal symptoms were reported as 'a little', with a noticeable difference from pre-treatment only for unintentional stool leakage, limitations on daily activities, and mucus discharge.

CONCLUSION

Long-term gastrointestinal symptoms were predominantly mild, and dietary intervention was not superior to a usual diet in preventing these symptoms.