A high black-hole-to-host mass ratio in a lensed AGN in the early Universe.

Early JWST observations have uncovered a population of red sources that might represent a previously overlooked phase of supermassive black hole growth1-3. One of the most intriguing examples is an extremely red, point-like object that was found to be triply imaged by the strong lensing cluster Abell 2744 (ref. 4). Here we present deep JWST/NIRSpec observations of this object, Abell2744-QSO1. The spectroscopy confirms that the three images are of the same object, and that it is a highly reddened (AV ≃ 3) broad emission line active galactic nucleus at a redshift of zspec = 7.0451 ± 0.0005. From the width of Hß (full width at half-maximum = 2,800 ± 250 km s-1), we derive a black hole mass of M BH = 4 - 1 + 2 × 1 0 7 M ⊙ . We infer a very high ratio of black-hole-to-galaxy mass of at least 3%, an order of magnitude more than that seen in local galaxies5 and possibly as high as 100%. The lack of strong metal lines in the spectrum together with the high bolometric luminosity (Lbol = (1.1 ± 0.3) × 1045 erg s-1) indicate that we are seeing the black hole in a phase of rapid growth, accreting at 30% of the Eddington limit. The rapid growth and high black-hole-to-galaxy mass ratio of Abell2744-QSO1 suggest that it may represent the missing link between black hole seeds6 and one of the first luminous quasars7.

Most of the photons that reionized the Universe came from dwarf galaxies.

The identification of sources driving cosmic reionization, a major phase transition from neutral hydrogen to ionized plasma around 600-800 Myr after the Big Bang1-3, has been a matter of debate4. Some models suggest that high ionizing emissivity and escape fractions (fesc) from quasars support their role in driving cosmic reionization5,6. Others propose that the high fesc values from bright galaxies generate sufficient ionizing radiation to drive this process7. Finally, a few studies suggest that the number density of faint galaxies, when combined with a stellar-mass-dependent model of ionizing efficiency and fesc, can effectively dominate cosmic reionization8,9. However, so far, comprehensive spectroscopic studies of low-mass galaxies have not been done because of their extreme faintness. Here we report an analysis of eight ultra-faint galaxies (in a very small field) during the epoch of reionization with absolute magnitudes between MUV ≈ -17 mag and -15 mag (down to 0.005L⋆ (refs. 10,11)). We find that faint galaxies during the first thousand million years of the Universe produce ionizing photons with log[ξion (Hz erg-1)] = 25.80 ± 0.14, a factor of 4 higher than commonly assumed values12. If this field is representative of the large-scale distribution of faint galaxies, the rate of ionizing photons exceeds that needed for reionization, even for escape fractions of the order of 5%.

Have we made progress in taking care of adolescents and young adults with cancer? Results of a European multi-professional survey.

BACKGROUND: It is well documented that traditional health care models do not meet the specific needs of Adolescents and Young Adults (AYA) cancer patients. METHODS: We explore a map of the development of age-specific AYA cancer care across Europe, from the perspective of healthcare professionals with an interest in AYA care, in order to understand the specific challenges and map progress over time. An on-line survey was developed by international professional cancer organisations. RESULTS: We had 377 respondents from 60 countries. The majority of respondents were physicians 298 (79%), a minority of survey respondents (39, 10.4%) work exclusively with AYA patients, most respondents declared substantial and routine clinical service collaborations to provide care and treatment to AYA with cancer. Policy for the multidisciplinary management of AYA cancer patients commonly appears in Europe now, and was reported by 234 (78.52%) respondents. Specific professional training for AYA cancer care is not uniformly available. CONCLUSION: There is considerable opportunity for many organisations to work together in raising the profile of AYA cancer related issues, in providing education and in encouraging research and collaboration.

Pre-Implementation Assessment of the Acceptability of Using Circulating microRNAs for Follow-Up of Malignant Germ-Cell Tumors.

BACKGROUND: MicroRNAs from the miR-371~373 and miR-302/367 clusters, particularly miR-371a-3p, are promising biomarkers for blood-based diagnosis and disease monitoring of malignant germ cell tumors (GCTs) and are nearing clinical implementation. These biomarkers have superior sensitivity and specificity compared with current markers alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG). We explored patient acceptability of using circulating microRNAs to replace multiple serial computed tomography (CT) scans in malignant GCT follow-up. PATIENTS AND METHODS: Two workshops involved interactive presentations and focus groups. Discussions were digitally recorded and transcribed verbatim. Qualitative thematic analysis of transcripts identified the key themes. RESULTS: Prior to the workshops, potential participants expressed concern about the adoption of new blood tests due to personal experiences of the limitations of existing (AFP/HCG) markers. Twelve males (22-57 years of age; currently, 26-59 years of age) with a malignant GCT diagnosis participated; all were in follow-up. Three had experienced recurrence. Participants had cumulative exposure of between 1 and 15 CT scans. Data saturation was reached at the second workshop; five themes emerged underpinning preference for microRNA testing versus CT scans: (1) increased sensitivity and safety, (2) reduced financial costs, (3) reduced time for testing and results, (4) practicalities, and (5) reduced anxiety. However, some participants perceived an increased diagnostic capacity of CT scans versus blood testing. CONCLUSION: This first user consultation of circulating microRNA testing for future malignant GCT follow-up suggests high acceptability with potential patient and healthcare system benefits.

Doxorubicin plus dacarbazine, doxorubicin plus ifosfamide, or doxorubicin alone as a first-line treatment for advanced leiomyosarcoma: A propensity score matching analysis from the European Organization for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group.

BACKGROUND: The optimal treatment for advanced leiomyosarcoma is still debated. Given histotype-specific prospective controlled data lacking, this study retrospectively evaluated doxorubicin plus dacarbazine, doxorubicin plus ifosfamide, and doxorubicin alone as first-line treatments for advanced/metastatic leiomyosarcoma treated at European Organization for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group (EORTC-STBSG) sites. METHODS: The inclusion criteria were a confirmed histological diagnosis, treatment between January 2010 and December 2015, measurable disease (Response Evaluation Criteria in Solid Tumors 1.1), an Eastern Cooperative Oncology Group performance status ≤2, and an age ≥ 18 years. The endpoints were progression-free survival (PFS), overall survival (OS), and overall response rate (ORR). PFS was analyzed with methods for interval-censored data. Patients were matched according to their propensity scores, which were estimated with a logistic regression model accounting for histology, grade, age, sex, performance status, tumor site, and tumor extent. RESULTS: Three hundred three patients from 18 EORTC-STBSG sites were identified. One hundred seventeen (39%) received doxorubicin plus dacarbazine, 71 (23%) received doxorubicin plus ifosfamide, and 115 (38%) received doxorubicin. In the 2:1:2 propensity score-matched population (205 patients), the estimated median PFS was 9.2 months (95% confidence interval [CI], 5.2-9.7 months), 8.2 months (95% CI, 5.2-10.1 months), and 4.8 months (95% CI, 2.3-6.0 months) with ORRs of 30.9%, 19.5%, and 25.6% for doxorubicin plus dacarbazine, doxorubicin plus ifosfamide, and doxorubicin alone, respectively. PFS was significantly longer with doxorubicin plus dacarbazine versus doxorubicin (hazard ratio [HR], 0.72; 95% CI, 0.52-0.99). Doxorubicin plus dacarbazine was associated with longer OS (median, 36.8 months; 95% CI, 27.9-47.2 months) in comparison with both doxorubicin plus ifosfamide (median, 21.9 months; 95% CI, 16.7-33.4 months; HR, 0.65; 95% CI, 0.40-1.06) and doxorubicin (median, 30.3 months; 95% CI, 21.0-36.3 months; HR, 0.66; 95% CI, 0.43-0.99). Adjusted analyses retained an effect for PFS but not for OS. None of the factors selected for multivariate analysis had a significant interaction with the received treatment for both PFS and OS. CONCLUSIONS: This is the largest retrospective study of first-line treatment for advanced leiomyosarcoma. In the propensity score-matched population, doxorubicin and dacarbazine showed favorable activity in terms of both ORR and PFS and warrants further evaluation in prospective trials.

Care of adolescents and young adults with cancer in Asia: results of an ESMO/SIOPE/SIOP Asia survey.

BACKGROUND: Adolescents and young adults (AYAs) with cancer require dedicated management encompassing both adult and paediatric cancer services. Following a European survey, the European Society for Medical Oncology, the European Society for Paediatric Oncology and the Asian continental branch of International Society of Paediatric Oncology undertook a similar survey to assess AYA cancer care across Asia. METHODS: A link to the online survey was sent to healthcare professionals (HCPs) in Asia interested in AYA cancer care. Questions covered the demographics and training of HCPs, their understanding of AYA definition, availability and access to specialised AYA services, the support and advice offered during and after treatment, and factors of treatment non-compliance. RESULTS: We received 268 responses from 22 Asian countries. There was a striking variation in the definition of AYA (median lower age 15 years, median higher age 29 years). The majority of the respondents (78%) did not have access to specialised cancer services and 73% were not aware of any research initiatives for AYA. Over two-thirds (69%) had the option to refer their patients for psychological and/or nutritional support and most advised their patients on a healthy lifestyle. Even so, 46% did not ask about smokeless tobacco habits and only half referred smokers to a smoking cessation service. Furthermore, 29% did not promote human papillomavirus vaccination for girls and 17% did not promote hepatitis B virus vaccination for high-risk individuals. In terms of funding, 69% reported governmental insurance coverage, although 65% reported that patients self-paid, at least partially. Almost half (47%) reported treatment non-compliance or abandonment as an issue, attributed to financial and family problems (72%), loss of follow-up (74%) and seeking of alternative treatments (77%). CONCLUSIONS: Lack of access to and suboptimal delivery of AYA-specialised cancer care services across Asia pose major challenges and require specific interventions.

Risk of subsequent primary neoplasms in survivors of adolescent and young adult cancer (Teenage and Young Adult Cancer Survivor Study): a population-based, cohort study.

BACKGROUND: Few studies have investigated the risks of subsequent primary neoplasms after adolescent and young adult (AYA) cancer. We investigated the risks of specific subsequent primary neoplasms after each of 16 types of AYA cancer. METHODS: The Teenage and Young Adult Cancer Survivor Study is a population-based cohort of 200 945 survivors of cancer diagnosed when aged 15-39 years in England and Wales from Jan 1, 1971, to Dec 31, 2006. The cohort was established using cancer registrations from the Office for National Statistics and the Welsh Cancer registry. Follow-up was from 5-year survival until the first occurrence of death, emigration, or study end date (Dec 31, 2012). In this analysis, we focus on the risk of specific subsequent primary neoplasms after 16 types of AYA cancer: breast; cervical; testicular; Hodgkin lymphoma (female); Hodgkin lymphoma (male); melanoma; CNS (intracranial); colorectal; non-Hodgkin lymphoma; thyroid; soft-tissue sarcoma; ovarian; bladder; other female genital; leukaemia; and head and neck cancer. We report absolute excess risks (AERs; per 10 000 person-years) and cumulative incidence of specific types of subsequent primary neoplasm after each type of AYA cancer. FINDINGS: During the 2 631 326 person-years of follow-up (median follow-up 16·8 years, IQR 10·5-25·2), 12 321 subsequent primary neoplasms were diagnosed in 11 565 survivors, most frequently among survivors of breast cancer, cervical cancer, testicular cancer, and Hodgkin lymphoma. AERs of any subsequent primary neoplasms were 19·5 per 10 000 person-years (95% CI 17·4-21·5) in survivors of breast cancer, 10·2 (8·0-12·4) in survivors of cervical cancer, 18·9 (16·6-21·1) in survivors of testicular cancer, 55·7 (50·4-61·1) in female survivors of Hodgkin lymphoma, and 29·9 (26·3-33·6) in male survivors of Hodgkin lymphoma. The cumulative incidence of all subsequent primary neoplasms 35 years after diagnosis was 11·9% (95% CI 11·3-12·6) in survivors of breast cancer, 15·8% (14·8-16·7) in survivors of cervical cancer, 20·2% (18·9-21·5) in survivors of testicular cancer, 26·6% (24·7-28·6) in female survivors of Hodgkin lymphoma, and 16·5% (15·2-18·0) in male survivors of Hodgkin lymphoma. In patients who had survived at least 30 years from diagnosis of cervical cancer, testicular cancer, Hodgkin lymphoma in women, breast cancer, and Hodgkin lymphoma in men, we identified a small number of specific subsequent primary neoplasms that account for 82%, 61%, 58%, 45%, and 41% of the total excess number of neoplasms, respectively. Lung cancer accounted for a notable proportion of the excess number of neoplasms across all AYA groups investigated. INTERPRETATION: Our finding that a small number of specific subsequent primary neoplasms account for a large percentage of the total excess number of neoplasms in long-term survivors of cervical, breast, and testicular cancer, and Hodgkin lymphoma provides an evidence base to inform priorities for clinical long-term follow-up. The prominence of lung cancer after each of these AYA cancers indicates the need for further work aimed at preventing and reducing the burden of this cancer in future survivors of AYA cancer. FUNDING: Cancer Research UK, National Institute for Health Research, Academy of Medical Sciences, and Children with Cancer UK.

The care of adolescents and young adults with cancer: results of the ESMO/SIOPE survey.

INTRODUCTION: Adolescents and young adults (AYA) with cancer require dedicated clinical management and care. Little is known about the training and practice of European healthcare providers in regard to AYA and the availability of specialised services. METHODS: A link to an online survey was sent to members of the European Society for Medical Oncology (ESMO) and the European Society for Paediatric Oncology (SIOPE). The link was also sent to ESMO National Representatives and circulated to other European oncology groups. Questions covered the demographics and clinical training of respondents, their definition of AYA, education about AYA cancer, access to specialised clinical and supportive care, research and further education. Data from Europe were analysed by region. RESULTS: Three hundred tweenty two questionnaires were submitted and we focused on data from the 266 European healthcare professionals. Responses revealed considerable variation both within and between countries in the definition of AYA. Over two-thirds of respondents did not have access to specialised centres for AYA (67%), were not aware of research initiatives focusing on AYA with cancer (69%) and had no access to specialist services for managing the late effects of treatment (67%). The majority of the respondents were able to refer AYA patients to professional psychological support and specialised social workers. However, more than half had no access to an age-specialised nurse or specialised AYA education. Overall, 38% of respondents reported that their AYA patients did not have access to fertility specialists. This figure was 76% in Eastern Europe. Lack of specialised AYA care was particularly evident in Eastern and South-Eastern Europe. CONCLUSION: There is important underprovision and inequity of AYA cancer care across Europe. Improving education and research focused on AYA cancer care should be a priority.

Access to principal treatment centres and survival rates for children and young people with cancer in Yorkshire, UK.

BACKGROUND: Principal Treatment Centres (PTC) were established to provide age-appropriate care as well as clinical expertise for children and young people with cancer. However, little is known about the effects of specialist treatment centres on survival outcomes especially for teenagers and young adults. This population-based study aimed to describe access to PTC and the associated trends in survival for 0-24 year olds accounting for stage of disease at presentation and treatment. METHODS: Patients diagnosed from 1998-2009 aged 0-24 years were extracted from the Yorkshire Specialist Register of Cancer in Children and Young People, including information on all treating hospitals, followed-up until 31st December 2014. The six commonest cancer types were included: leukaemia (n = 684), lymphoma (n = 558), CNS tumours (n = 547), germ cell tumours (n = 364), soft tissue sarcomas (n = 171) and bone tumours (n = 163). Treatment was categorised into three groups: 'all', 'some' or 'no' treatment received at a PTC. Treatment at PTC was examined by diagnostic group and patient characteristics. Overall survival was modelled using Cox regression adjusting for case-mix including stage, treatment and other socio-demographic and clinical characteristics. RESULTS: Overall 72% of patients received all their treatment at PTC whilst 13% had no treatment at PTC. This differed by diagnostic group and age at diagnosis. Leukaemia patients who received no treatment at PTC had an increased risk of death which was partially explained by differences in patient case-mix (adjusted Hazard Ratio (HR) = 1.73 (95%CI 0.98-3.04)). Soft tissue sarcoma patients who had some or no treatment at PTC had better survival outcomes, which remained after adjustment for patient case-mix (adjusted HR = 0.48 (95%CI 0.23-0.99)). There were no significant differences in outcomes for other diagnostic groups (lymphoma, CNS tumours, bone tumours and germ cell tumours). For leukaemia patients survival outcomes for low risk patients receiving no treatment at PTC were similar to high risk patients who received all treatment at PTC, implying a benefit for care at the PTC. CONCLUSION: This study demonstrates that for leukaemia patients receiving treatment at a PTC is associated with improved survival that may compensate for a poorer prognosis presentation. However, further information on risk factors is needed for all diagnostic groups in order to fully account for differences in patient case-mix.

Epidemiology of Adolescents and Young Adults with Cancer in Europe.

To design the services for adolescents and young adults (AYAs) with cancer, we need to understand the patterns of disease and the other clinical and managerial challenges of the patient group. Cancer occurring between the ages of 15 and 39 years is 4 times less rare than cancer occurring during the first 15 years of life and consists of 2% of all invasive cancer in Europe, about 66,000 patients in Europe each year. AYAs have a unique distribution of cancer types, including the peak in incidence of Hodgkin lymphoma (HL) or germ cell tumors. The relative improvement in the survival rate in AYAs has not kept pace with that achieved in younger children, especially for acute leukemia, non-HLs, Ewing tumors and rhabdomyosarcoma. Etiological factors are under-researched and remain largely hypothetical. In this unique group of illnesses, improving AYA cancer management involves bridging interfaces. Since this has begun, outcomes have also begun to improve. The local nature of these interfaces determines the age group considered as AYA. Specific skills are necessary in the clinical, biological and psychosocial domains. Services need support from policy, clinical and administrative professionals. National policy and supranational groups such as SIOPE and ESMO are in constructive collaboration to develop this further.

Adult Cancers in Adolescents and Young Adults.

The pattern of cancer seen in young people changes with increasing age, transitioning from childhood- to adult-type cancer in adolescence and the third decade. The risk factors, presentation and biology of cancer in young adults differ from those in the older adult population. Factors of particular significance in adolescents and young adults (AYAs) include genetic predisposition to adult-type cancer, diagnostic uncertainty, long-term morbidity and considerations of fertility. New systemic therapies are being introduced that can prolong life and even increase the chance of cure, but the impact on AYAs is uncertain, as these patients are often under-represented in clinical trials. Here, we discuss the management of AYAs with 3 of the most common cancers affecting adults, when they emerge in the AYA populations, and therefore are currently met by medical oncologists - breast cancer, colorectal cancer and melanoma.

Critical Review of Clinical Practice Guidelines for Fertility Preservation in Teenagers and Young Adults with Cancer.

Purpose: The 5-year survival of teenagers and young adults (TYAs; 13-24 years old) with cancer has continued to rise, but as a result more patients experience late effects of treatment, such as infertility. Advice regarding fertility preservation in relation to cancer is provided in numerous clinical practice guidelines, but the rigor of their development is unclear. Methods: A systematic search was undertaken for clinical practice guidelines regarding fertility preservation in TYAs with cancer. All guidelines were reviewed according to the Appraisal of Guidelines for Research and Evaluation (AGREE-II) criteria. Five out of 13 identified guidelines scored over 75% in the "rigor of development" section and were further appraised. Content, scope, and consistencies between recommendations were also examined. Results: All five of the reviewed guidelines encouraged oncologists to have discussions with their patients about potential fertility issues associated with treatment and available fertility preservation methods. The cryopreservation of sperm, oocytes, and embryos were all recommended as first-line interventions in postpubertal patients. Recommendations surrounding pre- or peripubescent adolescents were few, with many techniques only recommended as part of a clinical trial. The risk of subfertility associated with different treatment regimens was poorly described. Conclusions: The methodology and development of guidelines describing fertility preservation in TYA cancer patients varied greatly. Methodological quality did not clearly influence key recommendations. Those involved with the development of guidelines are encouraged to clearly define their development methods to allow users to be confident of the quality.

Population mixing for leukaemia, lymphoma and CNS tumours in teenagers and young adults in England, 1996-2005.

BACKGROUND: Little aetiological epidemiological research has been undertaken for major cancers occurring in teenagers and young adults (TYA). Population mixing, as a possible proxy for infectious exposure, has been well researched for childhood malignancies. We aimed to investigate effects of population mixing in this older age group using an English national cancer dataset. METHODS: Cases of leukaemia, lymphoma and central nervous system (CNS) tumours amongst 15-24 year olds in England (diagnosed 1996-2005) were included in the study. Data were obtained by ward of diagnosis and linked to 1991 census variables including population mixing (Shannon index); data on person-weighted population density and deprivation (Townsend score) were also used and considered as explanatory variables. Associations between TYA cancer incidence and census variables were investigated using negative binomial regression, and results presented as incidence rate ratios (IRR) with 95% confidence intervals (CI). RESULTS: A total of 6251 cases of leukaemia (21%), lymphoma (49%) and CNS tumours (30%) were analysed. Higher levels of population mixing were associated with a significant decrease in the incidence of CNS tumours (IRR=0.83, 95% CI=0.75-0.91), accounted for by astrocytomas and 'other CNS tumours'; however, there was no association with leukaemia or lymphoma. Incidence of CNS tumours and lymphoma was 3% lower in more deprived areas (IRR=0.97, 95% CI=0.96-0.99 and IRR=0.97, 95% CI=.96-0.98 respectively). Population density was not associated with the incidence of leukaemia, lymphoma or CNS tumours. CONCLUSIONS: Our results suggest a possible role for environmental risk factors with population correlates in the aetiology of CNS tumours amongst TYAs. Unlike studies of childhood cancer, associations between population mixing and the incidence of leukaemia and lymphoma were not observed.

Treatment and survival patterns for germ cell tumors among 13- to 24-year olds in Yorkshire, UK.

BACKGROUND: Teenage and young adult (TYA) patient care can fall into gaps between adult and children's services. Increasingly UK TYA multi-disciplinary teams manage germ cell tumors (GCT) in locally agreed collaborations and age ranges. Patterns of care are changing rapidly. However, between disciplines protocols define different assessment and management in GCT. We aimed to document changes in incidence, treatment, and survival since 1990, to record the baseline to which future trends can be compared. PROCEDURE: Details were extracted from the UK population-based Yorkshire Specialist Cancer Register on 237 TYA aged 13-24 years diagnosed with a GCT between 1990 and 2004, followed-up until 2009. Incidence and survival patterns were assessed using Poisson and Cox regression. RESULTS: Testicular (n = 190; 80%) and ovarian (n = 22; 9%) GCT were the most common malignancies, and 90% of GCT occurred aged 17-24 years. The overall incidence rate was 26.9 per million person years. Rates increased significantly by 4.0% (95% CI: 1.0-7.1%) per year on average. The most common treatment modality was surgery combined with chemotherapy (49%). Initial treatment changed significantly over time (P = 0.003) and by age (P = 0.005). There were significant differences in the management of stage 1 testicular tumors by age. Among 13- to 16-year olds, 56% were treated exclusively in adult departments. Five-year survival rates were 93-95% for gonadal GCT, and 70-75% for other sites. Survival did not differ by age (P = 0.65) or period (P = 0.41). CONCLUSIONS: The age-related differences observed in the approach to GCT treatment suggest a collaborative approach to the models of care among TYA is required.

Early star-forming galaxies and the reionization of the Universe.

Star-forming galaxies trace cosmic history. Recent observational progress with the NASA Hubble Space Telescope has led to the discovery and study of the earliest known galaxies, which correspond to a period when the Universe was only ∼800 million years old. Intense ultraviolet radiation from these early galaxies probably induced a major event in cosmic history: the reionization of intergalactic hydrogen.

Epidemiology of leukaemia and lymphoma in children and young adults from the north of England, 1990-2002.

AIM: We aimed to describe and contrast the epidemiology of haematological malignancies among 0-14 and 15-24-year-olds in northern England from 1990 to 2002 and compare clinical trial entry by age group. PATIENTS AND METHODS: Incidence rates were examined by age, sex and period of diagnosis and differences were tested using Poisson regression. Differences and trends in survival were assessed using Cox regression. RESULTS: 1680 subjects were included comprising 948 leukaemias and 732 lymphomas. Incidence rates for acute lymphoblastic leukaemia were significantly higher for 0-14 compared to 15-24-year-olds, whilst Hodgkin lymphoma showed the reverse. No significant changes in incidence were observed. 60% of leukaemia patients aged 15-24 years entered trials compared to 92% of 0-14-year-olds. Survival rates were significantly lower and improved less markedly over time for 15-24 compared to 0-14-year-olds, particularly for leukaemia. CONCLUSIONS: Trial accrual rates need to be improved amongst 15-24-year-olds and a more structured follow-up approach adopted for this unique population.

The formation and assembly of a typical star-forming galaxy at redshift z approximately 3.

Recent studies of galaxies approximately 2-3 Gyr after the Big Bang have revealed large, rotating disks, similar to those of galaxies today. The existence of well-ordered rotation in galaxies during this peak epoch of cosmic star formation indicates that gas accretion is likely to be the dominant mode by which galaxies grow, because major mergers of galaxies would completely disrupt the observed velocity fields. But poor spatial resolution and sensitivity have hampered this interpretation; such studies have been limited to the largest and most luminous galaxies, which may have fundamentally different modes of assembly from those of more typical galaxies (which are thought to grow into the spheroidal components at the centres of galaxies similar to the Milky Way). Here we report observations of a typical star-forming galaxy at z = 3.07, with a linear resolution of approximately 100 parsecs. We find a well-ordered compact source in which molecular gas is being converted efficiently into stars, likely to be assembling a spheroidal bulge similar to those seen in spiral galaxies at the present day. The presence of undisrupted rotation may indicate that galaxies such as the Milky Way gain much of their mass by accretion rather than major mergers.