Chromosome-length genome assemblies and cytogenomic analyses of pangolins reveal remarkable chromosome counts and plasticity.

We report the first chromosome-length genome assemblies for three species in the mammalian order Pholidota: the white-bellied, Chinese, and Sunda pangolins. Surprisingly, we observe extraordinary karyotypic plasticity within this order and, in female white-bellied pangolins, the largest number of chromosomes reported in a Laurasiatherian mammal: 2n = 114. We perform the first karyotype analysis of an African pangolin and report a Y-autosome fusion in white-bellied pangolins, resulting in 2n = 113 for males. We employ a novel strategy to confirm the fusion and identify the autosome involved by finding the pseudoautosomal region (PAR) in the female genome assembly and analyzing the 3D contact frequency between PAR sequences and the rest of the genome in male and female white-bellied pangolins. Analyses of genetic variability show that white-bellied pangolins have intermediate levels of genome-wide heterozygosity relative to Chinese and Sunda pangolins, consistent with two moderate declines of historical effective population size. Our results reveal a remarkable feature of pangolin genome biology and highlight the need for further studies of these unique and endangered mammals.

Anatomy of the pudendal nerve in clinically important areas: a pictorial essay and narrative review.

PURPOSE: The pudendal nerve is an anatomical structure arising from the ventral branches of the spinal roots S2-S4. Its complex course may be affected by surrounding structures. This may result in irritation or entrapment of the nerve with subsequent clinical symptoms. Aim of this study is to review the anatomy of the pudendal nerve and to provide detailed photographic documentation of the areas with most frequent clinical impact which are essential for surgical approach. METHODS: Major medical databases were searched to identify all anatomical studies investigating pudendal nerve and its variability, and possible clinical outcome of these variants. Extracted data consisted of morphometric parameters, arrangement of the pudendal nerve at the level of roots, formation of pudendal nerve, position according to sacrospinal and sacrotuberal ligaments and its terminal branches. One female cadaver hemipelvis was dissected with common variability of separate course of inferior rectal nerve. During dissection photodocumentation was made to record course of pudendal nerve with focus on areas with recorded pathologies and areas exposed to iatrogenic damage during surgical procedures. RESULTS: Narrative review was done to provide background for photodocumentation. Unique photos of course of the pudendal nerve was made in areas with great clinical significance. CONCLUSION: Knowledge of anatomical variations and course of the pudendal nerve is important for examinations and surgical interventions. Surgically exposed areas may become a site for iatrogenic damage of pudendal nerve; therefore, unique picture was made to clarify topographic relations.

Human papillomavirus infection (HPV) and pregnancy.

Human papillomavirus (HPV) is the most common sexually transmitted viral infection worldwide, which may result in the development in benign lesions or malignant tumors. The prevalence of HPV infection is twice as high in pregnancy as in non-pregnant women. Additionally, there is a risk of vertical transmission of HPV from mother to fetus during pregnancy or childbirth. Various studies have reported an increased risk of adverse pregnancy outcomes in HPV-positive women, including miscarriage, preterm birth, premature rupture of membranes, preeclampsia, fetal growth restriction, and fetal death. HPV vaccination is not currently recommended during pregnancy. On the other hand, there is no evidence linking HPV vaccination during pregnancy with adverse pregnancy outcomes and termination of pregnancy is not justified in this case.

A Degron Blocking Strategy Towards Improved CRL4CRBN Recruiting PROTAC Selectivity.

Small molecules inducing protein degradation are important pharmacological tools to interrogate complex biology and are rapidly translating into clinical agents. However, to fully realise the potential of these molecules, selectivity remains a limiting challenge. Herein, we addressed the issue of selectivity in the design of CRL4CRBN recruiting PROteolysis TArgeting Chimeras (PROTACs). Thalidomide derivatives used to generate CRL4CRBN recruiting PROTACs have well described intrinsic monovalent degradation profiles by inducing the recruitment of neo-substrates, such as GSPT1, Ikaros and Aiolos. We leveraged structural insights from known CRL4CRBN neo-substrates to attenuate and indeed remove this monovalent degradation function in well-known CRL4CRBN molecular glues degraders, namely CC-885 and Pomalidomide. We then applied these design principles on a previously published BRD9 PROTAC (dBRD9-A) and generated an analogue with improved selectivity profile. Finally, we implemented a computational modelling pipeline to show that our degron blocking design does not impact PROTAC-induced ternary complex formation. We believe that the tools and principles presented in this work will be valuable to support the development of targeted protein degradation.

Risk factors for cancer of unknown primary: a literature review.

Cancer of Unknown Primary (CUP) is metastatic cancer with an unidentifiable primary tumour origin during life. It remains difficult to study the occurrence and aetiology of CUP. Hitherto, it is unclear whether risk factors are associated with CUP, yet identifying these factors could reveal whether CUP is a specific entity or a cluster of metastasised cancers from various primary tumour origins. Epidemiological studies on possible CUP risk factors were systematically searched in PubMed and Web of Science on February 1st, 2022. Studies, published before 2022, were included if they were observational human-based, provided relative risk estimates, and investigated possible CUP risk factors. A total of 5 case-control and 14 cohort studies were included. There appears to be an increased risk for smoking in relation to CUP. However, limited suggestive evidence was found to link alcohol consumption, diabetes mellitus, and family history of cancer as increased risks for CUP. No conclusive associations could be made for anthropometry, food intake (animal or plant-based), immunity disorders, lifestyle (overall), physical activity, or socioeconomic status and CUP risk. No other CUP risk factors have been studied. This review highlights smoking, alcohol consumption, diabetes mellitus and family history of cancer as CUP risk factors. Yet, there remains insufficient epidemiological evidence to conclude that CUP has its own specific risk factor profile.

Use of oral chemotherapeutic agent, chlorambucil, as palliative treatment of thryoid adenocarcinoma in a golden-headed lion tamarin (Leontopithecus chrysomelas).

This case report describes the use of chlorambucil in a 7.5-year-old golden-headed lion tamarin (Leontopithecus chrysomelas) as palliative therapy for thyroid adenocarcinoma. Treatment was initiated at 0.1 mg/kg orally once daily. No physical abnormalities or substantial changes in complete blood cell counts and thyroid hormone levels from serial samples were detected.

Vegetable and fruit consumption and cancer of unknown primary risk: results from the Netherlands cohort study on diet and cancer.

BACKGROUND: Cancer of Unknown Primary (CUP) is a metastatic cancer for which the primary lesion remains unidentifiable during life and little is also known about the modifiable risk factors that contribute to its development. This study investigates whether vegetables and fruits are associated with CUP risk. METHODS: We used data from the prospective Netherlands Cohort Study on Diet and Cancer which includes 120,852 participants aged between 55 and 69 years in 1986. All participants completed a self-administered questionnaire on cancer risk factors at baseline. Cancer follow-up was established through record linkage to the Netherlands Cancer Registry and the Dutch Pathology Registry. As a result, 867 incident CUP cases and 4005 subcohort members were available for case-cohort analyses after 20.3 years of follow-up. Multivariable adjusted hazard ratios were calculated using proportional hazards models. RESULTS: We observed no associations between total vegetable and fruit consumption (combined or as separate groups) and CUP risk. However, there appeared to be an inverse association between the consumption of raw leafy vegetables and CUP. With respect to individual vegetable and fruit items, we found neither vegetable nor fruit items to be associated with CUP risk. CONCLUSIONS: Overall, vegetable and fruit intake were not associated with CUP incidence within this cohort.

High-resolution seismic constraints on flow dynamics in the oceanic asthenosphere.

Convective flow in the mantle and the motions of tectonic plates produce deformation of Earth's interior, and the rock fabric produced by this deformation can be discerned using the anisotropy of the seismic wave speed. This deformation is commonly inferred close to lithospheric boundaries beneath the ocean in the uppermost mantle, including near seafloor-spreading centres as new plates are formed via corner flow, and within a weak asthenosphere that lubricates large-scale plate-driven flow and accommodates smaller scale convection. Seismic models of oceanic upper mantle differ as to the relative importance of these deformation processes: seafloor spreading fabric is very strong just beneath the crust-mantle boundary (the Mohorovicic discontinuity, or Moho) at relatively local scales, but at the global and ocean-basin scales, oceanic lithosphere typically appears weakly anisotropic when compared to the asthenosphere. Here we use Rayleigh waves, recorded across an ocean-bottom seismograph array in the central Pacific Ocean (the NoMelt Experiment), to provide unique localized constraints on seismic anisotropy within the oceanic lithosphere-asthenosphere system in the middle of a plate. We find that azimuthal anisotropy is strongest within the high-seismic-velocity lid, with the fast direction coincident with seafloor spreading. A minimum in the magnitude of azimuthal anisotropy occurs within the middle of the seismic low-velocity zone, and then increases with depth below the weakest portion of the asthenosphere. At no depth does the fast direction correlate with the apparent plate motion. Our results suggest that the highest strain deformation in the shallow oceanic mantle occurs during corner flow at the ridge axis, and via pressure-driven or buoyancy-driven flow within the asthenosphere. Shear associated with motion of the plate over the underlying asthenosphere, if present, is weak compared to these other processes.

Alcohol consumption, cigarette smoking and cancer of unknown primary risk: Results from the Netherlands Cohort Study.

Cancer of unknown primary (CUP) is a metastasised malignancy with no identifiable primary tumour origin. Despite the frequent occurrence and bleak prognosis of CUP, research into its aetiology is scarce. Our study investigates alcohol consumption, tobacco smoking and CUP risk. We used data from the Netherlands Cohort Study, a cohort that includes 120 852 participants aged 55 to 69 years, who completed a self-administered questionnaire on cancer risk factors at baseline. Cancer follow-up was established through record linkage to the Netherlands Cancer Registry and Dutch Pathology Registry. After 20.3 years of follow-up, 963 CUP cases and 4288 subcohort members were available for case-cohort analyses. Multivariable-adjusted hazard ratios (HRs) were calculated using proportional hazard models. In general, CUP risk increased with higher levels of alcohol intake (Ptrend = .02). The association was more pronounced in participants who drank ≥30 g of ethanol per day (HR: 1.57, 95% confidence interval [CI]: 1.20-2.05) compared to abstainers. Current smokers were at an increased CUP risk (HR: 1.59, 95% CI: 1.29-1.97) compared to never smokers. We observed that the more the cigarettes or the longer a participant smoked, the higher the CUP risk was (Ptrend = .003 and Ptrend = .02, respectively). Interaction on additive scale was found for participants with the highest exposure categories of alcohol consumption and cigarette smoking frequency and CUP risk. Our findings demonstrate that alcohol consumption and cigarette smoking are associated with increased CUP risk. Lifestyle recommendations for cancer prevention regarding not drinking alcohol and avoiding exposure to smoking are therefore also valid for CUP.

cDC2 and plasmacytoid dendritic cells diminish from tissues of patients with non-Hodgkin orbital lymphoma and idiopathic orbital inflammation.

Non-Hodgkin orbital lymphoma (NHOL) and idiopathic orbital inflammation (IOI) are common orbital conditions with largely unknown pathophysiology. To investigate the immune cell composition of these diseases, we performed standardized 29 parameter flow cytometry phenotyping in peripheral blood mononuclear cells of 18 NHOL patients, 21 IOI patients, and 41 unaffected controls. Automatic gating by FlowSOM revealed decreased abundance of meta-clusters containing dendritic cells in patients, which we confirmed by manual gating. A decreased percentage of (HLA-DR+ CD303+ CD123+ ) plasmacytoid dendritic cells (pDC) in the circulation of IOI patients and decreased (HLA-DR+ CD11c+ CD1c+ ) conventional dendritic cells (cDC) type-2 for IOI patients were replicated in an independent cohort of patients and controls. Meta-analysis of both cohorts demonstrated that pDCs are also decreased in blood of NHOL patients and highlighted that the decrease in blood cDC type-2 was specific for IOI patients compared to NHOL or controls. Deconvolution-based estimation of immune cells in transcriptomic data of 48 orbital biopsies revealed a decrease in the abundance of pDC and cDC populations within the orbital microenvironment of IOI patients. Collectively, these data suggest a previously underappreciated role for dendritic cells in orbital disorders.

A pan-inflammatory microRNA-cluster is associated with orbital non-Hodgkin lymphoma and idiopathic orbital inflammation.

Non-Hodgkin orbital lymphoma (NHOL) and idiopathic orbital inflammation (IOI) are common orbital conditions with largely unknown pathophysiology that can be difficult to diagnose. In this study we aim to identify serum miRNAs associated with NHOL and IOI. We performed OpenArray® miRNA profiling in 33 patients and controls. Differentially expressed miRNAs were technically validated across technology platforms and replicated in an additional cohort of 32 patients and controls. We identified and independently validated a serum miRNA profile of NHOL that was remarkably similar to IOI and characterized by an increased expression of a cluster of eight miRNAs. Pathway enrichment analysis indicated that the miRNA-cluster is associated with immune-mediated pathways, which we supported by demonstrating the elevated expression of this cluster in serum of patients with other inflammatory conditions. The cluster contained miR-148a, a key driver of B-cell tolerance, and miR-365 that correlated with serum IgG and IgM concentrations. In addition, miR-29a and miR-223 were associated with blood lymphocyte and neutrophil populations, respectively. NHOL and IOI are characterized by an abnormal serum miRNA-cluster associated with immune pathway activation and linked to B cell and neutrophil dysfunction.

Meat consumption and cancer of unknown primary (CUP) risk: results from The Netherlands cohort study on diet and cancer.

PURPOSE: Cancer of unknown primary (CUP) is a metastasised cancer for which no primary lesion could be identified during life. Research into CUP aetiology with respect to dietary factors is particularly scarce. This study investigates whether meat consumption is associated with CUP risk. METHODS: Data was utilised from the prospective Netherlands cohort study that includes 1,20,852 participants aged 55-69 years. All participants completed a self-administered questionnaire on diet and other cancer risk factors at baseline. Cancer follow-up was established through record linkage to the Netherlands Cancer Registry and the Dutch Pathology Registry. A total of 899 CUP cases and 4111 subcohort members with complete and consistent dietary data were available for case-cohort analyses after 20.3 years of follow-up. Multivariable adjusted hazard ratios (HRs) were calculated using proportional hazards models. RESULTS: We found a statistically significant positive association with beef and processed meat consumption and CUP risk in women (multivariable adjusted HR Q4 vs. Q1 1.47, 95% CI 1.04-2.07, Ptrend = 0.004 and Q4 vs. Q1 1.53, 95% CI 1.08-2.16, Ptrend = 0.001, respectively), and a non-significant positive association with processed meat consumption and CUP risk in men (multivariable adjusted HR Q4 vs. Q1 1.33, 95% CI 0.99-1.79, Ptrend = 0.15). No associations were observed between red meat (overall), poultry or fish consumption and CUP risk. CONCLUSION: In this cohort, beef and processed meat consumption were positively associated with increased CUP risk in women, whereas a non-significant positive association was observed between processed meat consumption and CUP risk in men.

Family history of cancer in first degree relatives and risk of cancer of unknown primary.

OBJECTIVE: Cancer of Unknown Primary (CUP) refers to the presence of metastatic lesions, with no identifiable primary site during the patient's lifetime. Poor survival and lack of available treatment highlight the need to identify potential CUP risk factors. We investigated whether a family history of cancer is associated with increased CUP risk. METHODS: We performed a case cohort analysis using data from the Netherlands Cohort Study, which included a total of 963 CUP cases and 4,288 subcohort members. A Cox Proportional Hazards Regression was used to compare CUP risk in participants who reported to have a family member with cancer to those who did not, whilst adjusting for confounders. RESULTS: In general, we observed no increased CUP risk in those who reported a family history of cancer. CUP risk appeared slightly increased in those who reported cancer in a sibling (HR: 1.16, 95% CI: 0.97-1.38), especially in those with a sister with cancer compared with those without (HR: 1.23, 95% CI: 0.99-1.53), although these findings are not statistically significant. CONCLUSION: Having a family history of cancer is not an independent risk factor of CUP.

Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier.

Convergent margin volcanism originates with partial melting, primarily of the upper mantle, into which the subducting slab descends. Melting of this material can occur in one of two ways. The flow induced in the mantle by the slab can result in upwelling and melting through adiabatic decompression. Alternatively, fluids released from the descending slab through dehydration reactions can migrate into the hot mantle wedge, inducing melting by lowering the solidus temperature. The two mechanisms are not mutually exclusive. In either case, the buoyant melts make their way towards the surface to reside in the crust or to be extruded as lava. Here we use magnetotelluric data collected across the central state of Washington, USA, to image the complete pathway for the fluid-melt phase. By incorporating constraints from a collocated seismic study into the magnetotelluric inversion process, we obtain superior constraints on the fluids and melt in a subduction setting. Specifically, we are able to identify and connect fluid release at or near the top of the slab, migration of fluids into the overlying mantle wedge, melting in the wedge, and transport of the melt/fluid phase to a reservoir in the crust beneath Mt Rainier.

Structural and functional characterisation of human RNA helicase DHX8 provides insights into the mechanism of RNA-stimulated ADP release.

DHX8 is a crucial DEAH-box RNA helicase involved in splicing and required for the release of mature mRNA from the spliceosome. Here, we report the biochemical characterisation of full-length human DHX8 and the catalytically active helicase core DHX8Δ547, alongside crystal structures of DHX8Δ547 bound to ADP and a structure of DHX8Δ547 bound to poly(A)6 single-strand RNA. Our results reveal that DHX8 has an in vitro binding preference for adenine-rich RNA and that RNA binding triggers the release of ADP through significant conformational flexibility in the conserved DEAH-, P-loop and hook-turn motifs. We demonstrate the importance of R620 and both the hook-turn and hook-loop regions for DHX8 helicase activity and propose that the hook-turn acts as a gatekeeper to regulate the directional movement of the 3' end of RNA through the RNA-binding channel. This study provides an in-depth understanding of the activity of DHX8 and contributes insights into the RNA-unwinding mechanisms of the DEAH-box helicase family.

Bladder rupture after a fall on the ground in a patient with total uterine prolapse.

OBJECTIVE: The aim of this work is to present a case of traumatic bladder rupture in a patient with total uterine prolapse. Additionally, we provide a brief description of this issue. DESIGN: Case report. SETTING: Department of Obstetrics and Gynaecology, 3rd Faculty of Medicine, Charles University and Královské Vinohrady University Hospital, Prague; Departement of Radiology, 3rd Faculty of Medicine, Charles University and Královské Vinohrady University Hospital, Prague. RESULTS: We present a case report of a patient with a total uterine prolapse that has been examined for a lower abdominal pain, hematuria and difficulties with urination. The problems arose suddenly after the fall on the ground. These symptoms are typical for bladder rupture, but other more frequent causes have to be ruled out. CT scan showed a contrast agent leak from the bladder. The patient was indicated for surgical revision and suture of the bladder wall. CONCLUSION: Separately, rupture of the bladder occurs rarely. Most often, this injury is part of a wider trauma - especially after car crashes. However, our case report suggests that this option should be considered.

Management of patient with breast carcinoma diagnosed during pregnancy.

OBJECTIVE: To present actual complex review of diagnosis and treatment of breast cancer during pregnancy, demonstrated on particular case report. DESIGN: Case report and review article. SETTING: University Hospital Královské Vinohrady, Prague Department of Obstetrics and Gynaecology, Department of Radiotherapy and Oncology. CASE REPORT: Patient with breast cancer diagnosed in early pregnancy, her oncological treatment. Circumstantial finding was endometriosis of rectovaginal septum and dehiscence of uterotomy after C-section. DISCUSSION: On this case we demonstrate importance of all early diagnosis, prompt examination management and early therapy onset already during the pregnancy. CONCLUSION: Breast cancer therapy results are equal in pregnant and non-pregnant women, when we compare patients of same age, with same stage and same biological characteristics of tumor. The obstacle during pregnancy is often late diagnosis, which causes bigger size of tumor and more extensive affection of lymphatics in time of therapy onset.

Individualization of surgical management of cervical cancer stages IA1, IA2.

OBJECTIVE: To evaluate the risk of involvement of sentinel lymph nodes in cervical cancer stage IA1 with lymphovascular space invasion and IA2 using the detection of sentinel lymph nodes. DESIGN: Original article. SETTINGS: Department of Gynecology and Obstetrics 3rd Faculty of Medicine, Charles University, Faculty Hospital Královské Vinohrady, Prague; Oncogynecological centrum; Department of Pathology 3rd Faculty of Medicine, Charles University, Faculty Hospital Kralovské Vinohrady, Prague. METHODS: The study included women from prospective protocols LAP I and LAP II with cervical cancer stage IA1 with lymphovascular space invasion and stage IA2 from 2002 to 2018 classified according to FIGO 2014 staging, TNM 8. Detection of sentinel lymph nodes throughout this period was performed using ultra-short protocol with Tc and patent blau and also by histopathological examination. RESULTS: In the first group (28 women) with stage IA1 and lymphovascular space invasion diagnosed from cone biopsy there were two women with positive lymph nodes (7.1%). In the group stage IA2 (34 women) there were 13 women (38.2%) with positive lymphovascular space invasion and two women had positive lymph nodes (5.9%). The risk of positive lymph nodes for stage IA1 with lymphovascular space invasion and for stage IA2 is not statistically significant OR = 0.8125 (95% CI 0.1070-6.172). CONCLUSION: The detection of sentinel lymph nodes aids to individualize the therapy of early stage cervical cancer and helps to reduce the radicalization of surgery. The risk of positive lymph nodes in stage IA1 with lymphovascular space invasion and stage IA2 with/without lymphovascular space invasion is the same. The results confirm, that the detection of sentinel lymph nodes in stage IA1 with lymphovascular space invasion is fully indicated.

Histopathological and clinical features of molar pregnancy.

OBJECTIVE: To analyse own set of molar pregnancies and to develop clinically relevant procedures. TYPE OF STUDY: Review article with analysis of own data. SETTINGS: Department of Pathology 3rd Faculty of Medicine, Charles University, Faculty Hospital Královské Vinohrady, Prague; Department of Obstetrics and Gynecology 3rd Faculty of Medicine, Charles University, Faculty Hospital Královské Vinohrady, Prague. INTRODUCTION: The study monitors the decrease of laboratory values of beta-subunit of hCG gonadotropin (beta-hCG) after evacuation of partial and complete hydatidiform moles in a set of 45 partial and 46 complete moles. Two case reports of invasive moles. RESULTS: In cases of partial hydatidiform moles there was complete regression of beta-hCG in all cases, 89% regressed in six weeks, none of the women showed no subsequent elevation after reaching negativity. In cases of complete hydatidiform moles the decrease was less gradual, the negativity after six weeks was confirmed in 78%, three complete moles became malignant. CONCLUSION: The decrease of beta-hCG after molar pregnancy termination is variable. Even if in cases of complete hydatidiform moles the risk of malignization after reaching negativity is low, beta-hCG checks are recommended at monthly intervals for 6 months. Correct diagnosis of complete mole and its differentiation from partial mole can be achieved using immunohistochemistry - p57 antibody.

DPYD genotype-guided dose individualisation of fluoropyrimidine therapy in patients with cancer: a prospective safety analysis.

BACKGROUND: Fluoropyrimidine treatment can result in severe toxicity in up to 30% of patients and is often the result of reduced activity of the key metabolic enzyme dihydropyrimidine dehydrogenase (DPD), mostly caused by genetic variants in the gene encoding DPD (DPYD). We assessed the effect of prospective screening for the four most relevant DPYD variants (DPYD*2A [rs3918290, c.1905+1G>A, IVS14+1G>A], c.2846A>T [rs67376798, D949V], c.1679T>G [rs55886062, DPYD*13, I560S], and c.1236G>A [rs56038477, E412E, in haplotype B3]) on patient safety and subsequent DPYD genotype-guided dose individualisation in daily clinical care. METHODS: In this prospective, multicentre, safety analysis in 17 hospitals in the Netherlands, the study population consisted of adult patients (≥18 years) with cancer who were intended to start on a fluoropyrimidine-based anticancer therapy (capecitabine or fluorouracil as single agent or in combination with other chemotherapeutic agents or radiotherapy). Patients with all tumour types for which fluoropyrimidine-based therapy was considered in their best interest were eligible. We did prospective genotyping for DPYD*2A, c.2846A>T, c.1679T>G, and c.1236G>A. Heterozygous DPYD variant allele carriers received an initial dose reduction of 25% (c.2846A>T and c.1236G>A) or 50% (DPYD*2A and c.1679T>G), and DPYD wild-type patients were treated according to the current standard of care. The primary endpoint of the study was the frequency of severe (National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03 grade ≥3) overall fluoropyrimidine-related toxicity across the entire treatment duration. We compared toxicity incidence between DPYD variant allele carriers and DPYD wild-type patients on an intention-to-treat basis, and relative risks (RRs) for severe toxicity were compared between the current study and a historical cohort of DPYD variant allele carriers treated with full dose fluoropyrimidine-based therapy (derived from a previously published meta-analysis). This trial is registered with ClinicalTrials.gov, number NCT02324452, and is complete. FINDINGS: Between April 30, 2015, and Dec 21, 2017, we enrolled 1181 patients. 78 patients were considered non-evaluable, because they were retrospectively identified as not meeting inclusion criteria, did not start fluoropyrimidine-based treatment, or were homozygous or compound heterozygous DPYD variant allele carriers. Of 1103 evaluable patients, 85 (8%) were heterozygous DPYD variant allele carriers, and 1018 (92%) were DPYD wild-type patients. Overall, fluoropyrimidine-related severe toxicity was higher in DPYD variant carriers (33 [39%] of 85 patients) than in wild-type patients (231 [23%] of 1018 patients; p=0·0013). The RR for severe fluoropyrimidine-related toxicity was 1·31 (95% CI 0·63-2·73) for genotype-guided dosing compared with 2·87 (2·14-3·86) in the historical cohort for DPYD*2A carriers, no toxicity compared with 4·30 (2·10-8·80) in c.1679T>G carriers, 2·00 (1·19-3·34) compared with 3·11 (2·25-4·28) for c.2846A>T carriers, and 1·69 (1·18-2·42) compared with 1·72 (1·22-2·42) for c.1236G>A carriers. INTERPRETATION: Prospective DPYD genotyping was feasible in routine clinical practice, and DPYD genotype-based dose reductions improved patient safety of fluoropyrimidine treatment. For DPYD*2A and c.1679T>G carriers, a 50% initial dose reduction was adequate. For c.1236G>A and c.2846A>T carriers, a larger dose reduction of 50% (instead of 25%) requires investigation. Since fluoropyrimidines are among the most commonly used anticancer agents, these findings suggest that implementation of DPYD genotype-guided individualised dosing should be a new standard of care. FUNDING: Dutch Cancer Society.