Circadian variation in radiation-induced intestinal mucositis in patients with cervical carcinoma

Impact of chrono-radiotherapy on the prognosis and treatment-related toxicity in patients with locally advanced nasopharyngeal carcinoma: A multicenter propensity-matched study

The timing of radiotherapy (RT) delivery has been reported to affect both cancer survival and treatment toxicity. However, the association among the timing of RT delivery, survival, and toxicity in locally advanced nasopharyngeal carcinoma (LA-NPC) has not been investigated. We retrospectively reviewed patients diagnosed with LA-NPC who received definitive RT at multiple institutions. The median RT delivery daytime was categorized as morning (DAY) and night (NIGHT). Seasonal variations were classified into the darker half of the year (WINTER) and brighter half (SUMMER) according to the sunshine duration. Cohorts were balanced according to baseline characteristics using propensity score matching (PSM). Survival and toxicity outcomes were evaluated using Cox regression models. A total of 355 patients were included, with 194/161 in DAY/NIGHT and 187/168 in WINTER/SUMMER groups. RT delivered during the daytime prolonged the 5-year overall survival (OS) (90.6% vs. 80.0%, p = 0.009). However, the significance of the trend was lost after PSM (p = 0.068). After PSM analysis, the DAY cohort derived a greater benefit in 5-year progression-free survival (PFS) (85.6% vs. 73.4%, p = 0.021) and distant metastasis-free survival (DMFS) (89.2% vs. 80.8%, p = 0.051) in comparison with the NIGHT subgroup. Moreover, multivariate analysis showed that daytime RT was an independent prognostic factor for OS, PFS, and DMFS. Furthermore, daytime RT delivery was associated with an increase in the incidence of leukopenia and radiation dermatitis. RT delivery in SUMMER influenced only the OS significantly (before PSM: p = 0.051; after PSM: p = 0.034). There was no association between toxicity and the timing of RT delivery by season. In LA-NPC, the daytime of radical RT served as an independent prognostic factor. Furthermore, RT administered in the morning resulted in more severe toxic side effects than that at night, which needs to be confirmed in a future study.

Circadian rhythm-based cancer therapy in randomised clinical trials

INTRODUCTION

Since the 2017 Nobel Prize awarded to J. Hall, M. Rosbash and M.W. Young for their discoveries of molecular mechanisms behind the biological clock, circadian rhythm-based therapy, also known as chronotherapy, is receiving more attention in oncology and the number of anatomical sites of interest in this field is increasing. This observation is in line with the clinical evidence provided by trials on head and neck, lung, colorectal and cervical cancers, as well as the presently ongoing chronotherapy trials for breast and brain cancers.

AREAS COVERED

The aim of this review was to collate all randomized trials conducted on chronotherapy for various tumor sites and to appraise the evidence for chrono-oncology to advance personalized therapy. Relevant literature was collected from Pubmed/Medline databases and from clinicatrials.gov.

EXPERT OPINION

Current randomized clinical trials offer a certain level of evidence for the potential of chronotherapy to personalize oncologic treatment. However, comparison of trial results is hindered by the differences in timing of radiation/chemotherapy, the absence of harmonized recommendations for treatment outcome evaluation and not ultimately, the general lack of considering gender as a matched variable in trials, which was found to be a powerful factor influencing response to treatment.

Can chronoradiotherapy offer benefits to cervical cancer patients? A scoping review

The objective of this scoping review was to synthesize the available evidence and evaluate the effectiveness of chronoradiotherapy interventions in cervical cancer patients. This scoping review was performed by searching in the PubMed, Cochrane Library, Embase, Web of Science, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINAHL), China National Knowledge Infrastructure (CNKI), Wanfang, Wenpu, and Chinese Biomedical Literature (CBM) databases. Databases were searched for studies published in English or Chinese from inception to 21 May 2021, and reference lists of relevant reports were scanned. Two investigators independently screened eligible studies in accordance with predetermined eligibility criteria and extracted data. The included studies were summarized and analyzed. Five studies including a total of 422 patients with cervical cancer were included in the scoping review; four studies were Chinese, and one was Indian. Main themes identified included the efficiency of chronoradiotherapy and relevant toxic and side effects, including diarrhea toxicity, hematologic toxicity, myelosuppression, gastrointestinal mucositis, and skin reactions. Administration of radiotherapy at different times of the day resulted in similar efficacy. However, the toxic side effects of morning radiotherapy (MR) and evening radiotherapy (ER) differed, with radiotherapy in the evening leading to more severe hematologic toxicity and myelosuppression. There were conflicting conclusions about gastrointestinal reactions with chronoradiotherapy, and further studies are needed. Radiation responses may be associated with circadian genes, through the influence of cell cycles and apoptosis.

Clock in radiation oncology clinics: cost-free modality to alleviate treatment-related toxicity

A large number of studies have reported that tumor cells are often out of sync with the surrounding healthy tissue. Exploiting this misalignment may be a way to obtain a substantial gain in the therapeutic window. Specifically, based on reports to date, we will assess whether radiotherapy outcomes differ depending on the administration time. Collectively, 24 studies met the inclusion criteria, out of which 12 at least reported that radiation therapy is less toxic when administered at a particular time, probably because there is less collateral damage to healthy cells. However, discrepancies exist across studies and urge further investigation. Mechanistic studies elucidating the relationship between radiotherapy, circadian rhythms, and cell cycle, combined with either our “digital” or “biological” chronodata, would help oncologists successfully chronotype individual patients and strategize treatment plans accordingly.

Developments on tumour site-specific chrono-oncology towards personalised treatment

Research into chronotherapy has seen notable developments over the past decades, with a clear focus on the identification of circadian clock genes as potential treatment targets. Moreover, new factors are investigated, such as gender and the role of cancer stem cells in influencing the outcome of chronomodulated treatments. These factors could add to the arsenal of parameters that assist with patient stratification and treatment personalisation. Literature analysis showed that certain anatomical sites received more attention and the associated studies reported clinically significant results, even though some findings are contradictory. The aim of this work was to review the existing studies on chrono-oncology using a tumour site-specific approach and to highlight the status of research in various cancers. Inconsistencies in data reporting, the nature of the studies and the highly heterogeneous patient characteristics, highlight the need for well-designed randomised controlled trials to elucidate the real potential of chronotherapy in oncology.

Does timing matter in radiotherapy of hepatocellular carcinoma? An experimental study in mice

This study investigates whether a chronotherapeutic treatment of hepatocellular carcinoma (HCC) may improve treatment efficacy and mitigate side effects on non-tumoral liver (NTL). HCC was induced in Per2::luc mice which were irradiated at four time points of the day. Proliferation and DNA-double strand breaks were analyzed in irradiated and nonirradiated animals by detection of Ki67 and γ-H2AX. Prior to whole animal experiments, organotypic slice cultures were investigated to determine the dosage to be used in whole animal experiments. Irradiation was most effective at the proliferation peaks in HCC at ZT02 (early inactivity phase) and ZT20 (late activity phase). Irradiation effects on NTL were minimal at ZT20. As compared with NTL, nonirradiated HCC revealed disruption in daily variation and downregulation of all investigated clock genes except Per1. Irradiation affected rhythmic clock gene expression in NTL and HCC at all ZTs except at ZT20 (late activity phase). Irradiation at ZT20 had no effect on total leukocyte numbers. Our results indicate ZT20 as the optimal time point for irradiation of HCC in mice at which the ratio between efficacy of tumor treatment and toxic side effects was maximal. Translational studies are now needed to evaluate whether the late activity phase is the optimal time point for irradiation of HCC in man.

A protective effect of morning radiotherapy on acute skin toxicity in patients with breast cancer: A prospective cohort study

The focus of this prospective cohort study was to evaluate the risk factors of severe acute skin toxicity (grade ≥2) in 100 patients with breast cancer (BC) during radiotherapy (RT).The patients were evaluated weekly during RT and 3 months after treatment. The endpoint included the occurrence of skin toxicity grade ≥2, according to Radiation Therapy Oncology Group (RTOG). Survival analysis was conducted by univariate and multivariate Cox regression analysis.In the multivariate analysis, RT in the afternoon (0-3 pm) (hazard ratios [HR] = 1.566, P = .042) was significantly associated with the early occurrence of skin toxicity, indicating a potential effect of chronotherapy related to this adverse event. In the univariate and multivariate analysis, skin phototype moderate brown (HR = 1.586, P = .042; HR = 1.706, P = .022, respectively) and dark brown or black (HR = 4.517, P < .001; HR = 5.336, P < 0.001, respectively) was significantly associated with the skin toxicity. Tangential field separation >21 cm (HR = 2.550, P = .009, HR = 2.923, P = .003), in women that were submitted to conservative surgery indicates indirectly that large breast size was also significantly associated with skin toxicity.Women with large breasts and dark brown or black skin should be followed more carefully during RT, which should be undergone in the morning, especially when submitted to conventional RT techniques, common in developing countries.

Temporal determinants of tumour response to neoadjuvant rectal radiotherapy

Introduction

In locally advanced rectal cancer, longer delay to surgery after neoadjuvant radiotherapy increases the likelihood of histopathological tumour response. Chronomodulated radiotherapy in rectal cancer has recently been reported as a factor increasing tumour response to neoadjuvant treatment in patients having earlier surgery, with patients receiving a larger proportion of afternoon treatments showing improved response. This paper aims to replicate this work by exploring the impact of these two temporal factors, independently and in combination, on histopathological tumour response in rectal cancer patients.

Methods

A retrospective review of all patients with rectal adenocarcinoma who received long course (≥24 fractions) neoadjuvant radiotherapy with or without chemotherapy at a tertiary referral centre was conducted. Delay to surgery and radiotherapy treatment time were correlated to clinicopathologic characteristics with a particular focus on tumour regression grade. A review of the literature and meta-analysis were also conducted to ascertain the impact of time to surgery from preoperative radiotherapy on tumour regression.

Results

From a cohort of 367 patients, 197 patients met the inclusion criteria. Complete pathologic response (AJCC regression grade 0) was seen in 46 (23%) patients with a further 44 patients (22%) having at most small groups of residual cells (AJCC regression grade 1). Median time to surgery was 63 days, and no statistically significant difference was seen in tumour regression between patients having early or late surgery. There was a non-significant trend towards a larger proportion of morning treatments in patients with grade 0 or 1 regression (p = 0.077). There was no difference in tumour regression when composite groups of the two temporal variables were analysed. Visualisation of data from 39 reviewed papers (describing 27379 patients) demonstrated a plateau of response to neoadjuvant radiotherapy after approximately 60 days, and a meta-analysis found improved complete pathologic response in patients having later surgery.

Conclusions

There was no observed benefit of chronomodulated radiotherapy in our cohort of rectal cancer patients. Review of the literature and meta-analysis confirms the benefit of delayed surgery, with a plateau in complete response rates at approximately 60-days between completion of radiotherapy and surgery. In our cohort, time to surgery for the majority of our patients lay along this plateau and this may be a more dominant factor in determining response to neoadjuvant therapy, obscuring any effects of chronomodulation on tumour response. We would recommend surgery be performed between 8 and 11 weeks after completion of neoadjuvant radiotherapy in patients with locally advanced rectal cancer.

The Time for Chronotherapy in Radiation Oncology

Five decades ago, Franz Halberg conceived the idea of ​​a circadian-based therapy for cancer, given the differential tolerance to treatment derived from the intrinsic host rhythms. Nowadays, different experimental models have demonstrated that both the toxicity and efficacy of several anticancer drugs vary by more than 50% as a function of dosing time. Accordingly, it has been shown that chemotherapeutic regimens optimally timed with the circadian cycle have jointly improved patient outcomes both at the preclinical and clinical levels. Along with chemotherapy, radiation therapy is widely used for cancer treatment, but its effectiveness relies mainly on its ability to damage DNA. Notably, the DNA damage response including DNA repair, DNA damage checkpoints, and apoptosis is gated by the circadian clock. Thus, the therapeutic potential of circadian-based radiotherapy against cancer is mainly dependent upon the control that the molecular clock exerts on DNA repair enzymes across the cell cycle. Unfortunately, the time of treatment administration is not usually considered in clinical practice as it varies along the daytime working hours. Currently, only a few studies have evaluated whether the timing of radiotherapy affects the treatment outcome. Several of these studies show that it is possible to reduce the toxicity of the treatment if it is applied at a specific time range, although with some inconsistencies. In this Perspective, we review the main advances in the field of chronoradiotherapy, the possible causes of the inconsistencies observed in the studies so far and provide some recommendations for future trials.

The prognostic impact of daytime and seasonality of radiotherapy on head and neck cancer

BACKGROUND

The potential impact of daytime and season of radiotherapy application on prognosis is unclear. This was analyzed in a retrospective cohort of patients who were diagnosed with non-metastatic head and neck squamous cell carcinoma (HNSCC) and treated with definitive radiotherapy with or without chemotherapy.

MATERIALS AND METHODS

Patient and tumor characteristics, treatment parameters and outcome until last follow-up or death were obtained. Median radiotherapy delivery daytime of each patient was categorized as morning (AM) and afternoon (PM). Treatment season was defined by median date of treatment course. Each year was divided into DARK and LIGHT according to equinoxes. Time-to-event endpoints were defined by first biopsy confirming the HNSCC.

RESULTS

Six hundred fifty-five cases were identified who were treated with (chemo)radiotherapy between 2002 and 2015. Median follow-up was 47 months. No significant heterogeneity in patient, tumor and treatment characteristics were observed between DARK and LIGHT or regarding median daily fraction time (X2 p > 0.05). Five-year loco-regional control (73% vs. 61%; p = 0.0108) and progression-free survival (51% vs. 43%; p = 0.0374) were superior when radiotherapy was administered in DARK. Neither the daytime nor any other treatment time-related parameter affected prognosis.

CONCLUSION

This is the first study investigating and presenting the prognostic impact of seasonality regarding the treatment course on loco-regional control and progression-free survival (DARK > LIGHT). The biological mechanism of action is unclear. These results should be interpreted with caution and our findings have to be validated externally.

The impact of delivery daytime and seasonality of radiotherapy for head and neck cancer on toxicity burden

AIM

The potential impact of the daytime and season of radiotherapy application on acute and late toxicity burden was analyzed on a cohort of curatively treated head and neck squamous cell carcinoma patients.

METHODS

Through a retrospective chart review, patient and tumor characteristics, treatment parameters and outcome were obtained. Patients treated with definitive or adjuvant radiotherapy with and without chemotherapy receiving ≥60 Gy between 2002 and 2015 were included (n = 617). Daily fraction times and dates were extracted. Median radiotherapy delivery time of each patient was categorized as morning (AM) and afternoon (PM). Treatment season was defined by the median day of the treatment course. Each year was divided into DARK and LIGHT by the March and September equinoxes. Acute (T) and late (A) toxicity were defined by TAME methodology.

RESULTS

Median follow-up was 51 months. Mean T and A scores during and after radiotherapy in DARK vs. LIGHT were 1.98 vs. 1.61 (p = 0.0127) and 0.41 vs. 0.30 (p = 0.1699), respectively. Mean T and A scores during and after AM vs. PM radiotherapy were 1.71 vs. 1.88 (p = 0.0387) and 0.31 vs. 0.41 (p = 0.2638), respectively. Multivariate analyses indicated DARK vs. LIGHT as the only independent treatment time-related factor among other factors such as tumor subsite, UICC stage, radiotherapy technique, and chemotherapy for T.

CONCLUSION

This is the first study investigating the impact of seasonality on toxicity burden, showing higher acute toxicity with radiotherapy in DARK. The daytime did not predict the toxicity. The hypothesis-generating findings of this retrospective study should be further investigated.

Clinical effects of morning and afternoon radiotherapy on high-grade gliomas

Initial clinical reports comparing the delivery of radiotherapy (RT) at distinct times of the day suggest that this strategy might affect toxicity and oncologic outcomes of radiation for multiple human tissues, but the clinical effects on high-grade gliomas (HGG) are unknown. The present study addresses the hypothesis that radiotherapy treatment time of the day (RT-TTD) influences outcome and/or toxic events in HGG. Patients treated between 2009-2018 were reviewed (n = 109). Outcomes were local control (LC), distant CNS control (DCNSC), progression-free survival (PFS), and overall survival (OS). RT-TTD was classified as morning if ≥50% of fractions were delivered before 12:00 h (n = 70) or as afternoon (n = 39) if after 12:00 h. The average age was 62.6 years (range: 14.5-86.9) and 80% were glioblastoma. The median follow-up was 10.9 months (range: 0.4-57.2). The 1y/3y LC, DCNSC, and PFS were: 61.3%/28.1%, 86.8%/65.2%, and 39.7%/10.2%, respectively. Equivalent PFS was found between morning and afternoon groups (HR 1.27; p = .3). The median OS was 16.5 months. Patients treated in the afternoon had worse survival in the univariate analysis (HR 1.72; p = .05), not confirmed after multivariate analysis (HR 0.92, p = .76). Patients with worse baseline performance status and treatment interruptions showed worse PFS and OS. The proportion of patients that developed grade 3 acute toxicity, pseudo progression, and definitive treatment interruptions were 10.1%, 9.2%, and 7.3%, respectively, and were not affected by RT-TTD. In conclusion, for patients with HGG, there was no difference in PFS and OS between patients treated in the morning or afternoon. Of note, definitive treatment interruptions adversely affected outcomes and should be avoided, especially in patients with low performance status. Based on these clinical findings, high-grade glioma cells may not be the best initial model to be irradiated in order to study the effects of chronotherapy.

Circadian Variation in Efficacy of Medications

Although much has been learned about circadian clocks and rhythms over the past few decades, translation of this foundational science underlying the temporal regulation of physiology and behavior to clinical applications has been slow. Indeed, acceptance of the modern study of circadian rhythms has been blunted because the phenomenology of cyclic changes had to counteract the 20th century dogma of homeostasis in the biological sciences and medicine. We are providing this review of clinical data to highlight the emerging awareness of circadian variation in efficacy of medications for physicians, clinicians, and pharmacists. We are suggesting that gold-standard double-blind clinical studies should be conducted to determine the best time of day for optimal effectiveness of medications; also, we suggest that time of day should be tracked and reported as an important biological variable in ongoing clinical studies hereafter. Furthermore, we emphasize that time of day is, and should be considered, a key biological variable in research design similar to sex. In common with biomedical research data that have been historically strongly skewed toward the male sex, most pharmaceutical data have been skewed toward morning dosing without strong evidence that this is the optimal time of efficacy.

Radiation-induced damage in the upper gastrointestinal tract: clinical presentation, diagnostic tests and treatment options

Radiation-induced damage of the upper gastrointestinal (GI) tract results from radiation of GI tumors or structures adjacent to the GI tract. Radiation-induced damages of the upper GI tract may be acute or delayed, and ranges from lack of appetite, mucosal inflammation (i.e. esophagitis, gastritis, duodenitis) to ulcers, which may be complicated by perforation, penetration, bleeding and stenosis. Radiation-related factors as well as individual patient predisposing factors may increase susceptibility to post-radiation damage. High quality evidence for the treatment of radiation-induced GI damage is scarce and the management is often extrapolated from studies on GI lesions of different etiology. Treatment depends on severity and localization of the radiation-induced damage, and ranges from supportive and dietary measures to endoscopic interventions or surgery. Modern radiation techniques may decrease the incidence and severity of the radiation-induced upper gastrointestinal disease.

An Optimal Time for Treatment-Predicting Circadian Time by Machine Learning and Mathematical Modelling

Tailoring medical interventions to a particular patient and pathology has been termed personalized medicine. The outcome of cancer treatments is improved when the intervention is timed in accordance with the patient's internal time. Yet, one challenge of personalized medicine is how to consider the biological time of the patient. Prerequisite for this so-called chronotherapy is an accurate characterization of the internal circadian time of the patient. As an alternative to time-consuming measurements in a sleep-laboratory, recent studies in chronobiology predict circadian time by applying machine learning approaches and mathematical modelling to easier accessible observables such as gene expression. Embedding these results into the mathematical dynamics between clock and cancer in mammals, we review the precision of predictions and the potential usage with respect to cancer treatment and discuss whether the patient's internal time and circadian observables, may provide an additional indication for individualized treatment timing. Besides the health improvement, timing treatment may imply financial advantages, by ameliorating side effects of treatments, thus reducing costs. Summarizing the advances of recent years, this review brings together the current clinical standard for measuring biological time, the general assessment of circadian rhythmicity, the usage of rhythmic variables to predict biological time and models of circadian rhythmicity.

Time-dependent changes in proliferation, DNA damage and clock gene expression in hepatocellular carcinoma and healthy liver of a transgenic mouse model

Hepatocellular carcinoma (HCC) is highly resistant to anticancer therapy and novel therapeutic strategies are needed. Chronotherapy may become a promising approach because it may improve the efficacy of antimitotic radiation and chemotherapy by considering timing of treatment. To date little is known about time-of-day dependent changes of proliferation and DNA damage in HCC. Using transgenic c-myc/transforming growth factor (TGFα) mice as HCC animal model, we immunohistochemically demonstrated Ki67 as marker for proliferation and γ-H2AX as marker for DNA damage in HCC and surrounding healthy liver (HL). Core clock genes (Per1, Per2, Cry1, Cry2, Bmal 1, Rev-erbα and Clock) were examined by qPCR. Data were obtained from samples collected ex vivo at four different time points and from organotypic slice cultures (OSC). Significant differences were found between HCC and HL. In HCC, the number of Ki67 immunoreactive cells showed two peaks (ex vivo: ZT06 middle of day and ZT18 middle of night; OSC: CT04 and CT16). In ex vivo samples, the number of γ-H2AX positive cells in HCC peaked at ZT18 (middle of the night), while in OSC their number remained high during subjective day and night. In both HCC and HL, clock gene expression showed a time-of-day dependent expression ex vivo but no changes in OSC. The expression of Per2 and Cry1 was significantly lower in HCC than in HL. Our data support the concept of chronotherapy of HCC. OSC may become useful to test novel cancer therapies.

Hypoxia, metabolism, and the circadian clock: new links to overcome radiation resistance in high-grade gliomas

Radiotherapy is the cornerstone of treatment of high-grade gliomas (HGGs). It eradicates tumor cells by inducing oxidative stress and subsequent DNA damage. Unfortunately, almost all HGGs recur locally within several months secondary to radioresistance with intricate molecular mechanisms. Therefore, unravelling specific underlying mechanisms of radioresistance is critical to elucidating novel strategies to improve the radiosensitivity of tumor cells, and enhance the efficacy of radiotherapy. This review addresses our current understanding of how hypoxia and the hypoxia-inducible factor 1 (HIF-1) signaling pathway have a profound impact on the response of HGGs to radiotherapy. In addition, intriguing links between hypoxic signaling, circadian rhythms and cell metabolism have been recently discovered, which may provide insights into our fundamental understanding of radioresistance. Cellular pathways involved in the hypoxic response, DNA repair and metabolism can fluctuate over 24-h periods due to circadian regulation. These oscillatory patterns may have consequences for tumor radioresistance. Timing radiotherapy for specific times of the day (chronoradiotherapy) could be beneficial in patients with HGGs and will be discussed.

Prediction of mucositis risk secondary to cancer therapy: a systematic review of current evidence and call to action

PURPOSE

Despite advances in personalizing the efficacy of cancer therapy, our ability to identify patients at risk of severe treatment side effects and provide individualized supportive care is limited. This is particularly the case for mucositis (oral and gastrointestinal), with no comprehensive risk evaluation strategies to identify high-risk patients. We, the Multinational Association for Supportive Care in Cancer/International Society for Oral Oncology (MASCC/ISOO) Mucositis Study Group, therefore aimed to systematically review current evidence on that factors that influence mucositis risk to provide a foundation upon which future risk prediction studies can be based.

METHODS

We identified 11,018 papers from PubMed and Web of Science, with 197 records extracted for full review and 113 meeting final eligibility criteria. Data were then synthesized into tables to highlight the level of evidence for each risk predictor.

RESULTS

The strongest level of evidence supported dosimetric parameters as key predictors of mucositis risk. Genetic variants in drug-metabolizing pathways, immune signaling, and cell injury/repair mechanisms were also identified to impact mucositis risk. Factors relating to the individual were variably linked to mucositis outcomes, although female sex and smoking status showed some association with mucositis risk.

CONCLUSION

Mucositis risk reflects the complex interplay between the host, tumor microenvironment, and treatment specifications, yet the large majority of studies rely on hypothesis-driven, single-candidate approaches. For significant advances in the provision of personalized supportive care, coordinated research efforts with robust multiplexed approaches are strongly advised.

Radiation chronotherapy-clinical impact of treatment time-of-day: a systematic review

PURPOSE

Many brain tumor patients suffer from radiation-induced toxicities. Chronotherapy is a treatment modality that utilizes circadian rhythms to optimize the effect on tumor while minimizing negative outcomes on healthy tissue. This review aims to systematically examine the literature on the application of a radiation chronotherapeutic for all cancers and determine the possible advantages of incorporating a circadian-based fixed time-of-day for radiotherapy into CNS cancers.

METHODS

A systematic review of the literature was conducted in two electronic databases from inception to February 1, 2019. Primary research manuscripts were screened for those related to adult human subjects exposed to ionizing radiation using the chronotherapy technique.

RESULTS

Nine manuscripts were included in the review from 79 eligible articles. Three were prospective randomized trails and 6 were retrospective reviews. This survey revealed that overall survival and tumor control do not have consistent effects with only 60% and 55.5% of paper which included the variables having some significance, respectively. Treatment symptoms were the primary endpoint for both the prospective trials and were examined in 3 of the retrospective reviews; effects were observed in sensitive tissue for all 5 studies including mucosal linings and skin basal layer.

CONCLUSIONS

Existing literature suggests that the application of radiation chronotherapy may reduce negative symptom outcome within highly proliferative tissues. Further examination of radiation chronotherapy in well-designed prospective trials and studies in brain tumor patients are merited.

The Circadian Clock Regulates Metabolic Phenotype Rewiring Via HKDC1 and Modulates Tumor Progression and Drug Response in Colorectal Cancer

An endogenous molecular clockwork drives various cellular pathways including metabolism and the cell cycle. Its dysregulation is able to prompt pathological phenotypes including cancer. Besides dramatic metabolic alterations, cancer cells display severe changes in the clock phenotype with likely consequences in tumor progression and treatment response. In this study, we use a comprehensive systems-driven approach to investigate the effect of clock disruption on metabolic pathways and its impact on drug response in a cellular model of colon cancer progression. We identified distinctive time-related transcriptomic and metabolic features of a primary tumor and its metastatic counterpart. A mapping of the expression data to a comprehensive genome-scale reconstruction of human metabolism allowed for the in-depth functional characterization of 24 h-oscillating transcripts and pointed to a clock-driven metabolic reprogramming in tumorigenesis. In particular, we identified a set of five clock-regulated glycolysis genes, ALDH3A2, ALDOC, HKDC1, PCK2, and PDHB with differential temporal expression patterns. These findings were validated in organoids and in primary fibroblasts isolated from normal colon and colon adenocarcinoma from the same patient. We further identified a reciprocal connection of HKDC1 to the clock in the primary tumor, which is lost in the metastatic cells. Interestingly, a disruption of the core-clock gene BMAL1 impacts on HKDC1 and leads to a time-dependent rewiring of metabolism, namely an increase in glycolytic activity, as well as changes in treatment response. This work provides novel evidence regarding the complex interplay between the circadian clock and metabolic alterations in carcinogenesis and identifies new connections between both systems with pivotal roles in cancer progression and response to therapy.

Interventions to reduce acute and late adverse gastrointestinal effects of pelvic radiotherapy for primary pelvic cancers

BACKGROUND

An increasing number of people survive cancer but a significant proportion have gastrointestinal side effects as a result of radiotherapy (RT), which impairs their quality of life (QoL).

OBJECTIVES

To determine which prophylactic interventions reduce the incidence, severity or both of adverse gastrointestinal effects among adults receiving radiotherapy to treat primary pelvic cancers.

SEARCH METHODS

We conducted searches of CENTRAL, MEDLINE, and Embase in September 2016 and updated them on 2 November 2017. We also searched clinical trial registries.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of interventions to prevent adverse gastrointestinal effects of pelvic radiotherapy among adults receiving radiotherapy to treat primary pelvic cancers, including radiotherapy techniques, other aspects of radiotherapy delivery, pharmacological interventions and non-pharmacological interventions. Studies needed a sample size of 20 or more participants and needed to evaluate gastrointestinal toxicity outcomes. We excluded studies that evaluated dosimetric parameters only. We also excluded trials of interventions to treat acute gastrointestinal symptoms, trials of altered fractionation and dose escalation schedules, and trials of pre- versus postoperative radiotherapy regimens, to restrict the vast scope of the review.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology. We used the random-effects statistical model for all meta-analyses, and the GRADE system to rate the certainty of the evidence.

MAIN RESULTS

We included 92 RCTs involving more than 10,000 men and women undergoing pelvic radiotherapy. Trials involved 44 different interventions, including radiotherapy techniques (11 trials, 4 interventions/comparisons), other aspects of radiotherapy delivery (14 trials, 10 interventions), pharmacological interventions (38 trials, 16 interventions), and non-pharmacological interventions (29 trials, 13 interventions). Most studies (79/92) had design limitations. Thirteen studies had a low risk of bias, 50 studies had an unclear risk of bias and 29 studies had a high risk of bias. Main findings include the following:Radiotherapy techniques: Intensity-modulated radiotherapy (IMRT) versus 3D conformal RT (3DCRT) may reduce acute (risk ratio (RR) 0.48, 95% confidence interval (CI) 0.26 to 0.88; participants = 444; studies = 4; I2 = 77%; low-certainty evidence) and late gastrointestinal (GI) toxicity grade 2+ (RR 0.37, 95% CI 0.21 to 0.65; participants = 332; studies = 2; I2 = 0%; low-certainty evidence). Conformal RT (3DCRT or IMRT) versus conventional RT reduces acute GI toxicity grade 2+ (RR 0.57, 95% CI 0.40 to 0.82; participants = 307; studies = 2; I2 = 0%; high-certainty evidence) and probably leads to less late GI toxicity grade 2+ (RR 0.49, 95% CI 0.22 to 1.09; participants = 517; studies = 3; I2 = 44%; moderate-certainty evidence). When brachytherapy (BT) is used instead of external beam radiotherapy (EBRT) in early endometrial cancer, evidence indicates that it reduces acute GI toxicity (grade 2+) (RR 0.02, 95% CI 0.00 to 0.18; participants = 423; studies = 1; high-certainty evidence).Other aspects of radiotherapy delivery: There is probably little or no difference in acute GI toxicity grade 2+ with reduced radiation dose volume (RR 1.21, 95% CI 0.81 to 1.81; participants = 211; studies = 1; moderate-certainty evidence) and maybe no difference in late GI toxicity grade 2+ (RR 1.02, 95% CI 0.15 to 6.97; participants = 107; studies = 1; low-certainty evidence). Evening delivery of RT may reduce acute GI toxicity (diarrhoea) grade 2+ during RT compared with morning delivery of RT (RR 0.51, 95% CI 0.34 to 0.76; participants = 294; studies = 2; I2 = 0%; low-certainty evidence). There may be no difference in acute (RR 2.22, 95% CI 0.62 to 7.93, participants = 110; studies = 1) and late GI toxicity grade 2+ (RR 0.44, 95% CI 0.12 to 1.65; participants = 81; studies = 1) between a bladder volume preparation of 1080 mls and that of 540 mls (low-certainty evidence). Low-certainty evidence on balloon and hydrogel spacers suggests that these interventions for prostate cancer RT may make little or no difference to GI outcomes.Pharmacological interventions: Evidence for any beneficial effects of aminosalicylates, sucralfate, amifostine, corticosteroid enemas, bile acid sequestrants, famotidine and selenium is of a low or very low certainty. However, evidence on certain aminosalicylates (mesalazine, olsalazine), misoprostol suppositories, oral magnesium oxide and octreotide injections suggests that these agents may worsen GI symptoms, such as diarrhoea or rectal bleeding.Non-pharmacological interventions: Low-certainty evidence suggests that protein supplements (RR 0.23, 95% CI 0.07 to 0.74; participants = 74; studies = 1), dietary counselling (RR 0.04, 95% CI 0.00 to 0.60; participants = 74; studies = 1) and probiotics (RR 0.43, 95% CI 0.22 to 0.82; participants = 923; studies = 5; I2 = 91%) may reduce acute RT-related diarrhoea (grade 2+). Dietary counselling may also reduce diarrhoeal symptoms in the long term (at five years, RR 0.05, 95% CI 0.00 to 0.78; participants = 61; studies = 1). Low-certainty evidence from one study (108 participants) suggests that a high-fibre diet may have a beneficial effect on GI symptoms (mean difference (MD) 6.10, 95% CI 1.71 to 10.49) and quality of life (MD 20.50, 95% CI 9.97 to 31.03) at one year. High-certainty evidence indicates that glutamine supplements do not prevent RT-induced diarrhoea. Evidence on various other non-pharmacological interventions, such as green tea tablets, is lacking.Quality of life was rarely and inconsistently reported across included studies, and the available data were seldom adequate for meta-analysis.

AUTHORS' CONCLUSIONS

Conformal radiotherapy techniques are an improvement on older radiotherapy techniques. IMRT may be better than 3DCRT in terms of GI toxicity, but the evidence to support this is uncertain. There is no high-quality evidence to support the use of any other prophylactic intervention evaluated. However, evidence on some potential interventions shows that they probably have no role to play in reducing RT-related GI toxicity. More RCTs are needed for interventions with limited evidence suggesting potential benefits.

The Circadian Clock Gene BMAL1 Coordinates Intestinal Regeneration

BACKGROUND & AIMS

The gastrointestinal syndrome is an illness of the intestine caused by high levels of radiation. It is characterized by extensive loss of epithelial tissue integrity, which initiates a regenerative response by intestinal stem and precursor cells. The intestine has 24-hour rhythms in many physiological functions that are believed to be outputs of the circadian clock: a molecular system that produces 24-hour rhythms in transcription/translation. Certain gastrointestinal illnesses are worsened when the circadian rhythms are disrupted, but the role of the circadian clock in gastrointestinal regeneration has not been studied.

METHODS

We tested the timing of regeneration in the mouse intestine during the gastrointestinal syndrome. The role of the circadian clock was tested genetically using the BMAL1 loss of function mouse mutant in vivo, and in vitro using intestinal organoid culture.

RESULTS

The proliferation of the intestinal epithelium follows a 24-hour rhythm during the gastrointestinal syndrome. The circadian clock runs in the intestinal epithelium during this pathologic state, and the loss of the core clock gene, BMAL1, disrupts both the circadian clock and rhythmic proliferation. Circadian activity in the intestine involves a rhythmic production of inflammatory cytokines and subsequent rhythmic activation of the JNK stress response pathway.

CONCLUSIONS

Our results show that a circadian rhythm in inflammation and regeneration occurs during the gastrointestinal syndrome. The study and treatment of radiation-induced illnesses, and other gastrointestinal illnesses, should consider 24-hour timing in physiology and pathology.

THE IMPACT OF CIRCADIAN RHYTHMS ON MEDICAL IMAGING AND RADIOTHERAPY REGIMES FOR THE PAEDIATRIC PATIENT

Daily rhythmic changes are found in cellular events in cell cycle, DNA repair, apoptosis and angiogenesis in both normal and tumour tissue, as well as in enzymatic activity and drug metabolism. In this paper, we hypothesize that circadian rhythms need to be considered in radiation protection and optimization in personalized medicine, especially for paediatric care. The sensitivity of the eye lens to ionizing radiation makes the case for limiting damage to the lens epithelium by planning medical radio-imaging procedures for the afternoon, rather than the morning. Equally, the tumour and normal tissue response to radiotherapy is also subject to diurnal variation enabling optimization of time of treatment.

Does chronomodulated radiotherapy improve pathological response in locally advanced rectal cancer?

The predominant mode of radiation-induced cell death for solid tumours is mitotic catastrophe, which is in part dependent on sublethal damage repair being complete at around 6 h. Circadian variation appears to play a role in normal cellular division, and this could influence tumour response of radiation treatment depending on the time of treatment delivery. We tested the hypothesis that radiation treatment later in the day may improve tumour response and nodal downstaging in rectal cancer patients treated neoadjuvantly with radiation therapy. Recruitment was by retrospective review of 267 rectal cancer patients treated neoadjuvantly in the Department of Radiation Oncology at the Canberra Hospital between January 2010 and November 2015. One hundred and fifty-five patients met the inclusion criteria for which demographic, pathological and imaging data were collected, as well as the time of day patients received treatment with each fraction of radiotherapy. Data analysis was performed using the Statistical Package R with nonparametric methods of significance for all tests set at p < 0.05. Of the 45 female and 110 male patients, the median age was 64. Seventy-three percent had cT3 disease and there was a mean tumour distance from the anal verge of 7 cm. Time to surgical resection following radiotherapy ranged from 4 to 162 days with a median of 50 days, with a complete pathological response seen in 21% of patients. Patients exhibiting a favourable pathological response had smaller median pre- and postradiotherapy tumour size and had a greater change in tumour size following treatment (p < 0.01). Patients who received the majority of their radiotherapy fractions after 12:00 pm were more likely to show a complete or moderate pathological response (p = 0.035) and improved nodal downstaging. There were also more favourable responses amongst patients with longer time to surgical resection postradiotherapy (p < 0.004), although no relationship was seen between response and tumour distance from the anal verge. Females were less likely to exhibit several of the above responses. Neoadjuvant radiotherapy for locally advanced rectal cancer performed later in the day coupled with a longer time period to surgical resection may improve pathological tumour response rates and nodal downstaging. A prospective study in chronomodulated radiotherapy in this disease is warranted.

The stratification of severity of acute radiation proctopathy after radiotherapy for cervical carcinoma using diffusion-weighted MRI

OBJECTIVE

To determine whether diffusion-weighted imaging (DWI) can be used for quantitatively evaluating severity of acute radiation proctopathy after radiotherapy for cervical carcinoma.

MATERIALS AND METHODS

One hundred and twenty-four patients with cervical carcinoma underwent MR examination including DWI before and after radiotherapy. Acute radiation proctopathy was classified into three groups (grade 0, grade I-II and grade III-IV) according to Toxicity Criteria of the Radiation Therapy Oncology Group (RTOG). The pretreatment ADC (ADC_pre), ADC after treatment (ADC_post) and ADC change (ΔADC) were compared among three groups. In addition, acute radiation proctopathy was classified into good-prognosis group and poor-prognosis group. ADC_pre, ADC_post and ΔADC were compared between two groups. For DWI parameter that had significant difference, discriminatory capability of the parameter was determined using receiver operating characteristics (ROC) analysis.

RESULTS

ADC_post and ΔADC were higher in grade I-II group than in grade 0 group (p<0.05), yielding a sensitivity of 79.3% and specificity of 69.4% for ADC_post, and 85.1%, 72.3% for ΔADC for discrimination between two groups. ADC_post and ΔADC were higher in grade III-IV group than in grade I-II group (p<0.05), yielding a sensitivity of 80.3% and specificity of 72.5% for ADC_post, and 84.1%, 74.5% for ΔADC for discrimination between two groups. ADC_post and ΔADC were higher in poor-prognosis group than in good-prognosis group (p<0.05), yielding a sensitivity of 79.5% and specificity of 73.4% for ADC_post, and 87.2%, 78.3% for ΔADC for discrimination between two groups.

CONCLUSION

Diffusion-weighted MRI can be used for quantitative stratification of severity of acute radiation proctopathy, which serves as an important basis for appropriate timely adjustment of radiotherapy for cervical carcinoma in order to maximally reduce the radiation injury of rectum.

Differences in toxicity and outcome associated with circadian variations between patients undergoing daytime and evening radiotherapy for prostate adenocarcinoma

This retrospective study tested the hypothesis that disease control and treatment-related toxicity in patients undergoing high-dose radiotherapy (HDRT) for prostate cancer varies in a circadian manner. Patients with localized prostate adenocarcinoma receiving HDRT (median 78 Gy) to the prostate and involved seminal vesicle(s) without elective pelvic irradiation were divided into a daytime treatment (before 5 PM) group (n = 267) and evening treatment (after 5 PM) group (n = 142). Biochemical failure (Phoenix definition), acute and late gastrointestinal (GI) and genitourinary toxicities (Common Terminology Criteria for Adverse Events version 4), biochemical failure-free survival (BFFS) and freedom from late toxicity were assessed. Analyses were performed by binary logistic regression and Cox proportional hazard regression. The median follow-up was 68 months, and 75% of patients were ≥70 years old. Evening HDRT was significantly associated with worse freedom from ≥grade 2 late GI complications (hazard ratio = 2.96; p < 0.001). The detrimental effect of evening HDRT was significant in patients older than 70 years old (p < 0.001) but not in younger patients (p = 0.63). In a subgroup of propensity score-matched cohort with T2b-T3 disease (n = 154), the 5-year BFFS was worse in the evening group than the daytime group (72% vs. 85%, hazard ratio = 1.95, p = 0.05). Our study indicates that evening HDRT may lead to more GI complications, especially in older patients, and worse BFFS in patients with T2b-T3 disease.

Application of 1H NMR spectroscopy-based metabonomics to feces of cervical cancer patients with radiation-induced acute intestinal symptoms

OBJECTIVE

Radiation-induced acute intestinal symptoms (RIAISs) are a common complication of radiotherapy for cervical cancer. The aim of this study was to use (1)H nuclear magnetic resonance ((1)H NMR) combined with chemometric analysis to develop a metabolic profile of patients with RIAISs.

METHODS

Fecal samples were collected from 66 patients with cervical cancer before and after pelvic radiotherapy. After radiotherapy, RIAISs occurred in eleven patients. We selected another 11 patients from participants without RIAISs whose age, stage, histological type and treatment methods are matched with RIAIS patients as the control group. (1)H NMR spectroscopy combined with multivariate pattern recognition analysis was used to generate metabolic profile data, as well as to establish a RIAIS-specific metabolic phenotype.

RESULTS

Orthogonal partial least-squares discriminant analysis was used to distinguish samples between the pre- and post-radiotherapy RIAIS patients and between RIAIS patients and controls. Fecal samples from RIAIS patients after pelvic radiotherapy were characterized by increased concentrations of α-ketobutyrate, valine, uracil, tyrosine, trimethylamine N-oxide, phenylalanine, lysine, isoleucine, glutamine, creatinine, creatine, bile acids, aminohippurate, and alanine, accompanied by reduced concentrations of α-glucose, n-butyrate, methylamine, and ethanol relative to samples from RIAIS patients before pelvic radiotherapy, while in RIAIS patients relative to controls, trimethylamine, n-butyrate, fumarate and acetate were down-regulated and valine, TMAO, taurine, phenylalanine, lactate, isoleucine and creatinine were up-regulated.

CONCLUSIONS

We obtained the metabolic profile of RIAIS patients from fecal samples using NMR-based metabonomics. This profile has the potential to be developed into a novel clinical tool for RIAIS diagnosis or therapeutic monitoring, and could contribute to an improved understanding of the disease mechanism. However, because of the limitations of methods, technique, bacterial contamination of feces and small sample size, further research and verification are needed.

Circadian systems biology: When time matters

The circadian clock is a powerful endogenous timing system, which allows organisms to fine-tune their physiology and behaviour to the geophysical time. The interplay of a distinct set of core-clock genes and proteins generates oscillations in expression of output target genes which temporally regulate numerous molecular and cellular processes. The study of the circadian timing at the organismal as well as at the cellular level outlines the field of chronobiology, which has been highly interdisciplinary ever since its origins. The development of high-throughput approaches enables the study of the clock at a systems level. In addition to experimental approaches, computational clock models exist which allow the analysis of rhythmic properties of the clock network. Such mathematical models aid mechanistic understanding and can be used to predict outcomes of distinct perturbations in clock components, thereby generating new hypotheses regarding the putative function of particular clock genes. Perturbations in the circadian timing system are linked to numerous molecular dysfunctions and may result in severe pathologies including cancer. A comprehensive knowledge regarding the mechanistic of the circadian system is crucial to develop new procedures to investigate pathologies associated with a deregulated clock.

In this manuscript we review the combination of experimental methodologies, bioinformatics and theoretical models that have been essential to explore this remarkable timing-system. Such an integrative and interdisciplinary approach may provide new strategies with regard to chronotherapeutic treatment and new insights concerning the restoration of the circadian timing in clock-associated diseases.

The circadian timing system in clinical oncology

The circadian timing system (CTS) controls several critical molecular pathways for cancer processes and treatment effects over the 24 hours, including drug metabolism, cell cycle, apoptosis, and DNA damage repair mechanisms. This results in the circadian time dependency of whole-body and cellular pharmacokinetics and pharmacodynamics of anticancer agents. However, CTS robustness and phase varies among cancer patients, based on circadian monitoring of rest- activity, body temperature, sleep, and/or hormonal secretion rhythms. Circadian disruption has been further found in up to 50% of patients with metastatic cancer. Such disruption was associated with poor outcomes, including fatigue, anorexia, sleep disorders, and short progression-free and overall survival. Novel, minimally invasive devices have enabled continuous CTS assessment in non-hospitalized cancer patients. They revealed up to 12-hour differences in individual circadian phase. Taken together, the data support the personalization of chronotherapy. This treatment method aims at the adjustment of cancer treatment delivery according to circadian rhythms, using programmable-in-time pumps or novel release formulations, in order to increase both efficacy and tolerability. A fixed oxaliplatin, 5-fluorouracil and leucovorin chronotherapy protocol prolonged median overall survival in men with metastatic colorectal cancer by 3.3 months as compared to conventional delivery, according to a meta-analysis (P=0.009). Further analyses revealed the need for the prevention of circadian disruption or the restoration of robust circadian function in patients on chronotherapy, in order to further optimize treatment effects. The strengthening of external synchronizers could meet such a goal, through programmed exercise, meal timing, light exposure, improved social support, sleep scheduling, and the properly timed administration of drugs that target circadian clocks. Chrono-rehabilitation warrants clinical testing for improving quality of life and survival in cancer patients.

Comparison of acute skin reaction following morning versus late afternoon radiotherapy in patients with breast cancer who have undergone curative surgical resection

We investigated the relationship between the time of radiotherapy (RT) and treatment outcomes in breast cancer. Patients with pathologic T1-2N0-1 breast cancer who received adjuvant RT in the morning (before 10:00 AM) or late afternoon (after 3:00 PM) were eligible for inclusion in this study. We retrospectively compared the clinicopathologic characteristics, acute skin reaction, and survival outcomes according to the time of RT. The median follow-up duration was 83 months (range, 10-131 months). From the 395 eligible patients, 190 (48.1%) and 205 (51.9%) patients were classified into the morning RT group and the afternoon RT group, respectively. The clinicopathologic characteristics were relatively well balanced between the treatment groups, except for pathologic N-stage (P = 0.0409). Grade 2 or higher acute skin reaction according to the Radiation Therapy Oncology Group criteria was observed in 39 (9.9%) patients, with a higher frequency in the afternoon RT group than the morning RT group (13.7% vs 5.8%, respectively; P = 0.0088). There was no difference in the failure patterns or survival outcomes between the treatment groups. RT in late afternoon was associated with increased Grade 2 or more skin reaction after RT for breast cancer patients, but treatment outcomes did not differ according to the time of RT. Individualized considerations for treatment should be taken into account to reduce the risk of skin reactions.

Radiation-induced small bowel disease: latest developments and clinical guidance

Ionizing radiation is commonly used to treat a number of malignancies. Although highly effective and now more targeted, many patients suffer side effects. The number of cancer survivors has increased and so there are more patients presenting with symptoms that have arisen as a result of radiotherapy. Radiation damage to small bowel tissue can cause acute or chronic radiation enteritis producing symptoms such as pain, bloating, nausea, faecal urgency, diarrhoea and rectal bleeding which can have a significant impact on patient's quality of life. This review outlines the pathogenesis of radiation injury to the small bowel along with the prevention of radiation damage via radiotherapy techniques plus medications such as angiotensin-converting enzyme inhibitors, statins and probiotics. It also covers the treatment of both acute and chronic radiation enteritis via a variety of medical (including hyperbaric oxygen), dietetic, endoscopic and surgical therapies.

The circadian clock gates the intestinal stem cell regenerative state

The intestine has evolved under constant environmental stresses, because an animal may ingest harmful pathogens or chemicals at any time during its lifespan. Following damage, intestinal stem cells (ISCs) regenerate the intestine by proliferating to replace dying cells. ISCs from diverse animals are remarkably similar, and the Wnt, Notch, and Hippo signaling pathways, important regulators of mammalian ISCs, are conserved from flies to humans. Unexpectedly, we identified the transcription factor period, a component of the circadian clock, to be critical for regeneration, which itself follows a circadian rhythm. We discovered hundreds of transcripts that are regulated by the clock during intestinal regeneration, including components of stress response and regeneration pathways. Disruption of clock components leads to arrhythmic ISC divisions, revealing their underappreciated role in the healing process.

Circadian rhythm disruption in cancer biology

Circadian rhythms show universally a 24-h oscillation pattern in metabolic, physiological and behavioral functions of almost all species. This pattern is due to a fundamental adaptation to the rotation of Earth around its own axis. Molecular mechanisms of generation of circadian rhythms organize a biochemical network in suprachiasmatic nucleus and peripheral tissues, building cell autonomous clock pacemakers. Rhythmicity is observed in transcriptional expression of a wide range of clock-controlled genes that regulate a variety of normal cell functions, such as cell division and proliferation. Desynchrony of this rhythmicity seems to be implicated in several pathologic conditions, including tumorigenesis and progression of cancer. In 2007, the International Agency for Research on Cancer (IARC) categorized "shiftwork that involves circadian disruption [as] probably carcinogenic to humans" (Group 2A in the IARC classification system of carcinogenic potency of an agentagent) (Painting, Firefighting, and Shiftwork; IARC; 2007). This review discusses the potential relation between disruptions of normal circadian rhythms with genetic driving machinery of cancer. Elucidation of the role of clockwork disruption, such as exposure to light at night and sleep disruption, in cancer biology could be important in developing new targeted anticancer therapies, optimizing individualized chronotherapy and modifying lighting environment in workplaces or homes.

Systematic review of agents for the management of gastrointestinal mucositis in cancer patients

PURPOSE

The aim of this study was to review the available literature and define clinical practice guidelines for the use of agents for the prevention and treatment of gastrointestinal mucositis.

METHODS

A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). The body of evidence for each intervention, in each cancer treatment setting, was assigned an evidence level. Based on the evidence level, one of the following three guideline determinations was possible: recommendation, suggestion, and no guideline possible.

RESULTS

A total of 251 clinical studies across 29 interventions were examined. Panel members were able to make one new evidence-based negative recommendation; two new evidence-based suggestions, and one evidence-based change from previous guidelines. Firstly, the panel recommends against the use of misoprostol suppositories for the prevention of acute radiation-induced proctitis. Secondly, the panel suggests probiotic treatment containing Lactobacillus spp., may be beneficial for prevention of chemotherapy and radiotherapy-induced diarrhea in patients with malignancies of the pelvic region. Thirdly, the panel suggests the use of hyperbaric oxygen as an effective means in treating radiation-induced proctitis. Finally, new evidence has emerged which is in conflict with our previous guideline surrounding the use of systemic glutamine, meaning that the panel is unable to form a guideline. No guideline was possible for any other agent, due to inadequate and/or conflicting evidence.

CONCLUSIONS

This updated review of the literature has allowed new recommendations and suggestions for clinical practice to be reached. This highlights the importance of regular updates.

Acute gastrointestinal syndrome in high-dose irradiated mice

The most detailed reports of the response of the gastrointestinal system to high dose acute radiation have focused mainly on understanding the histopathology. However, to enable medical countermeasure assessment under the animal rule criteria, it is necessary to have a robust model in which the relationship between radiation dose and intestinal radiation syndrome incidence, timing, and severity are established and correlated with histopathology. Although many mortality studies have been published, they have used a variety of mouse strains, ages, radiation sources, and husbandry conditions, all of which influence the dose response. Further, it is clear that the level of bone marrow irradiation and supportive care can influence endpoints. In order to create robust baseline data, the authors have generated dose response data in adult male mice maintained under identical conditions and exposed to either total or partial-body irradiation. Partial-body irradiation includes both extensive (40%) and minimal (5%) bone marrow sparing models, the latter designed to correlate with an established primate model and allow assessment of effects of any medical countermeasure on all three major radiation syndromes (intestinal, bone marrow, and lung) in the surviving mice. Lethal dose (LD(30), LD(50), and LD(70)) data are described in the various models, along with the impact of enteric flora and response to supportive care. Correlation with diarrhea severity and histopathology are also described. These data can be used to aid the design of good laboratory practice (GLP)-compliant Animal Rule studies that are reflective of the conditions following accidental radiation exposure.

Circadian regulation of electrolyte absorption in the rat colon

The intestinal transport of nutrients exhibits distinct diurnal rhythmicity, and the enterocytes harbor a circadian clock. However, temporal regulation of the genes involved in colonic ion transport, i.e., ion transporters and channels operating in absorption and secretion, remains poorly understood. To address this issue, we assessed the 24-h profiles of expression of genes encoding the sodium pump (subunits Atp1a1 and Atp1b1), channels (α-, β-, and γ-subunits of Enac and Cftr), transporters (Dra, Ae1, Nkcc1, Kcc1, and Nhe3), and the Na(+)/H(+) exchanger (NHE) regulatory factor (Nherf1) in rat colonic mucosa. Furthermore, we investigated temporal changes in the spatial localization of the clock genes Per1, Per2, and Bmal1 and the genes encoding ion transporters and channels along the crypt axis. In rats fed ad libitum, the expression of Atp1a1, γEnac, Dra, Ae1, Nhe3, and Nherf1 showed circadian variation with maximal expression at circadian time 12, i.e., at the beginning of the subjective night. The peak γEnac expression coincided with the rise in plasma aldosterone. Restricted feeding phase advanced the expression of Dra, Ae1, Nherf, and γEnac and decreased expression of Atp1a1. The genes Atp1b1, Cftr, αEnac, βEnac, Nkcc1, and Kcc1 did not show any diurnal variations in mRNA levels. A low-salt diet upregulated the expression of βEnac and γEnac during the subjective night but did not affect expression of αEnac. Similarly, colonic electrogenic Na(+) transport was much higher during the subjective night than the subjective day. These findings indicate that the transporters and channels operating in NaCl absorption undergo diurnal regulation and suggest a role of an intestinal clock in the coordination of colonic NaCl absorption.