Diagnosis and treatment outcomes from prebronchodilator spirometry performed alongside lung cancer screening in a Lung Health Check programme.

INTRODUCTION: Incorporating spirometry into low-dose CT (LDCT) screening for lung cancer may help identify people with undiagnosed chronic obstructive pulmonary disease (COPD), although the downstream impacts are not well described. METHODS: Participants attending a Lung Health Check (LHC) as part of the Yorkshire Lung Screening Trial were offered spirometry alongside LDCT screening. Results were communicated to the general practitioner (GP), and those with unexplained symptomatic airflow obstruction (AO) fulfilling agreed criteria were referred to the Leeds Community Respiratory Team (CRT) for assessment and treatment. Primary care records were reviewed to determine changes to diagnostic coding and pharmacotherapy. RESULTS: Of 2391 LHC participants undergoing prebronchodilator spirometry, 201 (8.4%) fulfilled the CRT referral criteria of which 151 were invited for further assessment. Ninety seven participants were subsequently reviewed by the CRT, 46 declined assessment and 8 had already been seen by their GP at the time of CRT contact. Overall 70 participants had postbronchodilator spirometry checked, of whom 20 (29%) did not have AO. Considering the whole cohort referred to the CRT (but excluding those without AO postbronchodilation), 59 had a new GP COPD code, 56 commenced new pharmacotherapy and 5 were underwent pulmonary rehabilitation (comprising 2.5%, 2.3% and 0.2% of the 2391 participants undergoing LHC spirometry). CONCLUSIONS: Delivering spirometry alongside lung cancer screening may facilitate earlier diagnosis of COPD. However, this study highlights the importance of confirming AO by postbronchodilator spirometry prior to diagnosing and treating patients with COPD and illustrates some downstream challenges in acting on spirometry collected during an LHC.

Participation in community-based lung cancer screening: the Yorkshire Lung Screening Trial.

BACKGROUND: Screening with low-dose computed tomography (LDCT) reduces lung cancer mortality; however, the most effective strategy for optimising participation is unknown. Here we present data from the Yorkshire Lung Screening Trial, including response to invitation, screening eligibility and uptake of community-based LDCT screening. METHODS: Individuals aged 55-80 years, identified from primary care records as having ever smoked, were randomised prior to consent to invitation to telephone lung cancer risk assessment or usual care. The invitation strategy included general practitioner endorsement, pre-invitation and two reminder invitations. After telephone triage, those at higher risk were invited to a Lung Health Check (LHC) with immediate access to a mobile CT scanner. RESULTS: Of 44 943 individuals invited, 50.8% (n=22 815) responded and underwent telephone-based risk assessment (16.7% and 7.3% following first and second reminders, respectively). A lower response rate was associated with current smoking status (adjusted OR 0.44, 95% CI 0.42-0.46) and socioeconomic deprivation (adjusted OR 0.58, 95% CI 0.54-0.62 for the most versus the least deprived quintile). Of those responding, 34.4% (n=7853) were potentially eligible for screening and offered a LHC, of whom 86.8% (n=6819) attended. Lower uptake was associated with current smoking status (adjusted OR 0.73, 95% CI 0.62-0.87) and socioeconomic deprivation (adjusted OR 0.78, 95% CI 0.62-0.98). In total, 6650 individuals had a baseline LDCT scan, representing 99.7% of eligible LHC attendees. CONCLUSIONS: Telephone risk assessment followed by a community-based LHC is an effective strategy for lung cancer screening implementation. However, lower participation associated with current smoking status and socioeconomic deprivation underlines the importance of research to ensure equitable access to screening.

SABRTooth: a randomised controlled feasibility study of stereotactic ablative radiotherapy (SABR) with surgery in patients with peripheral stage I nonsmall cell lung cancer considered to be at higher risk of complications from surgical resection.

OBJECTIVES: Stereotactic ablative radiotherapy (SABR) is a well-established treatment for medically inoperable peripheral stage I nonsmall cell lung cancer (NSCLC). Previous nonrandomised evidence supports SABR as an alternative to surgery, but high-quality randomised controlled trial (RCT) evidence is lacking. The SABRTooth study aimed to establish whether a UK phase III RCT was feasible. DESIGN AND METHODS: SABRTooth was a UK multicentre randomised controlled feasibility study targeting patients with peripheral stage I NSCLC considered to be at higher risk of surgical complications. 54 patients were planned to be randomised 1:1 to SABR or surgery. The primary outcome was monthly average recruitment rates. RESULTS: Between July 2015 and January 2017, 318 patients were considered for the study and 205 (64.5%) were deemed ineligible. Out of 106 (33.3%) assessed as eligible, 24 (22.6%) patients were randomised to SABR (n=14) or surgery (n=10). A key theme for nonparticipation was treatment preference, with 43 (41%) preferring nonsurgical treatment and 19 (18%) preferring surgery. The average monthly recruitment rate was 1.7 patients against a target of three. 15 patients underwent their allocated treatment: SABR n=12, surgery n=3. CONCLUSIONS: We conclude that a phase III RCT randomising higher risk patients between SABR and surgery is not feasible in the National Health Service. Patients have pre-existing treatment preferences, which was a barrier to recruitment. A significant proportion of patients randomised to the surgical group declined and chose SABR. SABR remains an alternative to surgery and novel study approaches are needed to define which patients benefit from a nonsurgical approach.

Surgery or radiotherapy for stage I lung cancer? An intention-to-treat analysis.

INTRODUCTION: Surgery is the standard of care for early-stage lung cancer, with stereotactic ablative body radiotherapy (SABR) a lower morbidity alternative for patients with limited physiological reserve. Comparisons of outcomes between these treatment options are limited by competing comorbidities and differences in pre-treatment pathological information. This study aims to address these issues by assessing both overall and cancer-specific survival for presumed stage I lung cancer on an intention-to-treat basis. METHODS: This retrospective intention-to-treat analysis identified all patients treated for presumed stage I lung cancer within a single large UK centre. Overall survival, cancer-specific survival, and combined cancer and treatment-related survival were assessed with adjustment for confounding variables using Cox proportional hazards and Fine-Gray competing risks analyses. RESULTS: 468 patients (including 316 surgery and 99 SABR) were included in the study population. Compared with surgery, SABR was associated with inferior overall survival on multivariable Cox modelling (SABR HR 1.84 (95% CI 1.32-2.57)), but there was no difference in cancer-specific survival (SABR HR 1.47 (95% CI 0.80-2.69)) or combined cancer and treatment-related survival (SABR HR 1.27 (95% CI 0.74-2.17)). Combined cancer and treatment-related death was no different between SABR and surgery on Fine-Gray competing risks multivariable modelling (subdistribution hazard 1.03 (95% CI 0.59-1.81)). Non-cancer-related death was significantly higher in SABR than surgery (subdistribution hazard 2.16 (95% CI 1.41-3.32)). CONCLUSION: In this analysis, no difference in cancer-specific survival was observed between SABR and surgery. Further work is needed to define predictors of outcome and help inform treatment decisions.

The phylogenetic placement of the enigmatic Indian Cormorant, Phalacrocorax fuscicollis (Phalacrocoracidae).

The Indian Cormorant (Phalacrocorax fuscicollis) is a common avian piscivore that occurs throughout the Indian subcontinent and east to southern Vietnam. Its evolutionary relationships, however, have remained obscure, largely because of a lack of material available for either osteological or genetic analysis. Here we show using DNA-sequence data from both nuclear and mitochondrial genes that this species is sister to the allopatric Little Black Cormorant (P. sulcirostris), which occurs from Java in the west through southern Indonesia and New Guinea to Australia and New Zealand in the south. We estimate this split to have happened 2.5-3.2 million years ago, during the late Pliocene. We also report on genetic variation within the mitochondrial control region, which suggests that this part of the genome may be useful in investigating if there is genetic structure across the geographical range of the Indian Cormorant.

Lung cancer stage-shift following a symptom awareness campaign.

BACKGROUND: Lung cancer outcomes in the UK are worse than in many other developed nations. Symptom awareness campaigns aim to diagnose patients at an earlier stage to improve cancer outcomes. METHODS: An early diagnosis campaign for lung cancer commenced in Leeds, UK in 2011 comprising public and primary-care facing components. Rates of community referral for chest X-ray and lung cancer stage (TNM seventh edition) at presentation were collected from 2008 to 2015. Linear trends were assessed by χ2 test for trend in proportions. Headline figures are presented for the 3 years pre-campaign (2008-2010) and the three most recent years for which data are available during the campaign (2013-2015). FINDINGS: Community-ordered chest X-ray rates per year increased from 18 909 in 2008-2010 to 34 194 in 2013-2015 (80.8% increase). A significant stage shift towards earlier stage lung cancer was seen (χ2(1)=32.2, p<0.0001). There was an 8.8 percentage point increase in the proportion of patients diagnosed with stage I/II lung cancer (26.5% pre-campaign vs 35.3% during campaign) and a 9.3% reduction in the absolute number of patients diagnosed with stage III/IV disease (1254 pre-campaign vs 1137 during campaign). INTERPRETATION: This is the largest described lung cancer stage-shift in association with a symptom awareness campaign. A causal link between the campaign and stage-shift cannot be proven but appears plausible. Limitations of the analysis include a lack of contemporary control population.

Secondary-care costs associated with lung cancer diagnosed at emergency hospitalisation in the United Kingdom.

Lung cancer diagnosis during emergency hospital admission has been associated with higher early secondary-care costs and lower longer-term costs than outpatient diagnoses. This retrospective cohort study analyses the secondary-care costs of 3274 consecutive patients with lung cancer. Patients diagnosed during emergency admissions incurred greater costs during the first month and had a worse prognosis compared with outpatient diagnoses. In patients who remained alive, costs after the first month were comparable between diagnostic routes. In addition to improving patient experience and outcome, strategies to increase earlier diagnosis may reduce the additional healthcare costs associated with this route to diagnosis.

Speciation, range contraction and extinction in the endemic New Zealand King Shag complex.

New Zealand's endemic King Shag (Leucocarbo carunculatus) has occupied only a narrow portion of the northeastern South Island for at least the past 240years. However, pre-human Holocene fossil and archaeological remains have suggested a far more widespread distribution of the three Leucocarbo species (King, Otago, Foveaux) on mainland New Zealand at the time of Polynesian settlement in the late 13th Century CE. We use modern and ancient DNA, and morphometric and osteological analyses, of modern King Shags and Holocene fossil Leucocarbo remains to assess the pre-human distribution and taxonomic status of the King Shag on mainland New Zealand, and the resultant conservation implications. Our analyses show that the King Shag was formerly widespread around southern coasts of the North Island and the northern parts of the South Island but experienced population and lineage extinctions, and range contraction, probably after Polynesian arrival. This history parallels range contractions of other New Zealand seabirds. Conservation management of the King Shag should take into account this species narrow distribution and probable reduced genetic diversity. Moreover, combined genetic, morphometric and osteological analyses of prehistoric material from mainland New Zealand suggest that the now extinct northern New Zealand Leucocarbo populations comprised a unique lineage. Although these distinctive populations were previously assigned to the King Shag (based on morphological similarities and geographic proximity to modern Leucocarbo populations), we herein describe them as a new species, the Kohatu Shag (Leucocarbo septentrionalis). The extinction of this species further highlights the dramatic impacts Polynesians and introduced predators had on New Zealand's coastal and marine biodiversity. The prehistoric presence of at least four species of Leucocarbo shag on mainland NZ further highlights its status as a biodiversity hotspot for Phalacrocoracidae.

Geographically contrasting biodiversity reductions in a widespread New Zealand seabird.

Unravelling prehistoric anthropogenic impacts on biodiversity represents a key challenge for biologists and archaeologists. New Zealand's endemic Stewart Island Shag (Leucocarbo chalconotus) comprises two distinct phylogeographic lineages, currently restricted to the country's south and southeast. However, fossil and archaeological remains suggest a far more widespread distribution at the time of Polynesian settlement ca. 1280 AD, encompassing much of coastal South Island. We used modern and ancient DNA, radiocarbon dating, and Bayesian modelling, to assess the impacts of human arrival on this taxon. Our analyses show that the southeast South Island (Otago) lineage was formerly widespread across coastal South Island, but experienced dramatic population extinctions, range retraction and lineage loss soon after human arrival. By comparison, the southernmost (Foveaux Strait) lineage has experienced a relatively stable demographic and biogeographic history since human arrival, retaining much of its mitochondrial diversity. Archaeological data suggest that these contrasting demographic histories (retraction vs. stability) reflect differential human impacts in mainland South Island vs. Foveaux Strait, highlighting the importance of testing for temporal and spatial variation in human-driven faunal declines.

Classification of the cormorants of the world.

Relationships among the 40 or so extant species of cormorants (family Phalacrocoracidae) have been obscured by their morphological similarities, many of which have recently been shown to be the result of convergent evolution. Previous attempts to derive an evolutionarily justifiable classification for this group of birds using osteological and behavioral data have been hampered by these similarities. We present a well-resolved evolutionary tree for some 40 cormorant taxa based on the results of extensive genetic work that produced over 8000 bases of mitochondrial and nuclear DNA sequence. This tree implies a novel classification for the cormorants, which reflects their evolutionary history and can be implemented using some 7 genera. Some of the relationships among the species are well-known but many are previously unrecognized. Nevertheless, much of the classification makes sense in terms of biogeography.

Behavioural evolution in penguins does not reflect phylogeny.

Over the past two decades, behavioural biologists and ecologists have made effective use of the comparative method, but have often stopped short of adopting an explicitly phylogenetic approach. We examined 68 behaviour and life history (BLH) traits of 15 penguin species to: (i) infer penguin phylogeny, (ii) assess homology of behavioural characters, and (iii) evaluate hypotheses about character evolution and ancestral states. Parsimony analysis of the BLH dataset found either two shortest trees (characters coded as unordered) or a single shortest tree (characters coded as a combination of unordered and Dollo). The BLH data had significant structure. Kishino-Hasegawa tests indicated that BLH trees were significantly different from most previous estimates of penguin phylogeny. The BLH phylogeny generated from Dollo characters appeared to be less accurate than the tree derived from the completely unordered dataset. Dividing BLH data into display and non-display traits resulted in no significant differences in level of homoplasy and no difference in the accuracy of phylogeny. Tests for homology of BLH traits were performed by mapping the characters onto a molecular tree. Assuming that independent gains are less likely than losses of character states, 65 of the 68 characters were likely to be homologous across taxa, and at least several characters appeared to have been stable since the origin of modern penguins around 30 Myr. Finally, the likely BLH traits of the most recent common ancestor of extant penguins were reconstructed from character states along the internal branch leading to the penguins. This analysis suggested that the "proto-penguin" probably had a similar life history to current temperate penguins but few ritualized behaviours. A southern, cool-temperate origin of penguins is suggested.

Determining the impact of an artificial intelligence tool on the management of pulmonary nodules detected incidentally on CT (DOLCE) study protocol: a prospective, non-interventional multicentre UK study.

INTRODUCTION: In a small percentage of patients, pulmonary nodules found on CT scans are early lung cancers. Lung cancer detected at an early stage has a much better prognosis. The British Thoracic Society guideline on managing pulmonary nodules recommends using multivariable malignancy risk prediction models to assist in management. While these guidelines seem to be effective in clinical practice, recent data suggest that artificial intelligence (AI)-based malignant-nodule prediction solutions might outperform existing models. METHODS AND ANALYSIS: This study is a prospective, observational multicentre study to assess the clinical utility of an AI-assisted CT-based lung cancer prediction tool (LCP) for managing incidental solid and part solid pulmonary nodule patients vs standard care. Two thousand patients will be recruited from 12 different UK hospitals. The primary outcome is the difference between standard care and LCP-guided care in terms of the rate of benign nodules and patients with cancer discharged straight after the assessment of the baseline CT scan. Secondary outcomes investigate adherence to clinical guidelines, other measures of changes to clinical management, patient outcomes and cost-effectiveness. ETHICS AND DISSEMINATION: This study has been reviewed and given a favourable opinion by the South Central-Oxford C Research Ethics Committee in UK (REC reference number: 22/SC/0142).Study results will be available publicly following peer-reviewed publication in open-access journals. A patient and public involvement group workshop is planned before the study results are available to discuss best methods to disseminate the results. Study results will also be fed back to participating organisations to inform training and procurement activities. TRIAL REGISTRATION NUMBER: NCT05389774.

Beyond phylogeny: pelecaniform and ciconiiform birds, and long-term niche stability.

Phylogenetic trees are a starting point for the study of further evolutionary and ecological questions. We show that for avian evolutionary relationships, improved taxon sampling, longer sequences and additional data sets are giving stability to the prediction of the grouping of pelecaniforms and ciconiiforms, thus allowing inferences to be made about long-term niche occupancy. Here we report the phylogeny of the pelecaniform birds and their water-carnivore allies using complete mitochondrial genomes, and show that the basic groupings agree with nuclear sequence phylogenies, even though many short branches are not yet fully resolved. In detail, we show that the Pelecaniformes (minus the tropicbird) and the Ciconiiformes (storks, herons and ibises) form a natural group within a seabird water-carnivore clade. We find pelicans are the closest relatives of the shoebill (in a clade with the hammerkop), and we confirm that tropicbirds are not pelecaniforms. In general, the group appears to be an adaptive radiation into an 'aquatic carnivore' niche that it has occupied for 60-70 million years. From an ecological and life history perspective, the combined pelecaniform-ciconiform group is more informative than focusing on differences in morphology. These findings allow a start to integrating molecular evolution and macroecology.

The phylogenetic relationships of the extant pelicans inferred from DNA sequence data.

The pelicans are a charismatic group of large water birds, whose evolutionary relationships have been long debated. Here we use DNA sequence data from both mitochondrial and nuclear genes to derive a robust phylogeny of all the extant species. Our data rejects the widespread notion that pelicans can be divided into white- and brown-plumaged groups. Instead, we find that, in contrast to all previous evolutionary hypotheses, the species fall into three well-supported clades: an Old World clade of the Dalmatian, Spot-billed, Pink-backed and Australian Pelicans, a New World clade of the American White, Brown and Peruvian Pelicans, and monospecific clade consisting solely of the Great White Pelican, weakly grouped with the Old World clade. We discuss possible evolutionary scenarios giving rise to this diversity.

The radiology quality assurance process in the Yorkshire Lung Screening Trial, and findings from the baseline round of low dose CT screening for lung cancer.

OBJECTIVE: As lung cancer screening is rolled-out, there is a need to develop an effective quality assurance (QA) framework around radiology reporting to ensure optimal implementation. Here, we report a structured QA process for low-dose CT (LDCT) scans performed in the Yorkshire Lung Screening Trial. METHODS: Negative LDCT scans were single read after using computer-aided detection software. The radiology QA process included reviewing 5% of negative scans selected at random, and all cases with a subsequent diagnosis of extrapulmonary cancer or interval lung cancer not detected on the baseline scan. Radiologists were not informed of the reason for review and original radiology reports were scored as either "satisfactory", "satisfactory with learning points", or "unsatisfactory". RESULTS: From 6650 participants undergoing LDCT screening, 208 negative scans were reviewed alongside 11 cases with subsequent extrapulmonary cancer and 10 cases with interval lung cancer. Overall, only three reports were ultimately judged "unsatisfactory", 1% of randomly selected negative scans (n = 2/208) and one interval lung cancer scan (n = 1/10). Four out of a total of five cases judged "satisfactory with learning points" were related to oesophageal abnormalities where the participant was subsequently diagnosed with oesophageal cancer. CONCLUSION: The described process attempts to minimise bias in retrospective review of screening scans, and may represent a framework for future QA of national screening programmes. ADVANCES IN KNOWLEDGE: This study describes a structured QA process for a lung cancer screening programme, involving blinded second-read of LDCT screening scans to ensure fair, constructive audit of clinical performance.

Measuring spirometry in a lung cancer screening cohort highlights possible underdiagnosis and misdiagnosis of COPD.

Introduction: COPD is underdiagnosed, and measurement of spirometry alongside low-dose computed tomography (LDCT) screening for lung cancer is one strategy to increase earlier diagnosis of this disease. Methods: Ever-smokers at high risk of lung cancer were invited to the Yorkshire Lung Screening Trial for a lung health check (LHC) comprising LDCT screening, pre-bronchodilator spirometry and a smoking cessation service. In this cross-sectional study we present data on participant demographics, respiratory symptoms, lung function, emphysema on imaging and both self-reported and primary care diagnoses of COPD. Multivariable logistic regression analysis identified factors associated with possible underdiagnosis and misdiagnosis of COPD in this population, with airflow obstruction defined as forced expiratory volume in 1 s/forced vital capacity ratio <0.70. Results: Out of 3920 LHC attendees undergoing spirometry, 17% had undiagnosed airflow obstruction with respiratory symptoms, representing potentially undiagnosed COPD. Compared to those with a primary care COPD code, this population had milder symptoms, better lung function and were more likely to be current smokers (p≤0.001 for all comparisons). Out of 836 attendees with a primary care COPD code who underwent spirometry, 19% did not have airflow obstruction, potentially representing misdiagnosed COPD, although symptom burden was high. Discussion: Spirometry offered alongside LDCT screening can potentially identify cases of undiagnosed and misdiagnosed COPD. Future research should assess the downstream impact of these findings to determine whether any meaningful changes to treatment and outcomes occur, and to assess the impact on co-delivering spirometry on other parameters of LDCT screening performance such as participation and adherence. Additionally, work is needed to better understand the aetiology of respiratory symptoms in those with misdiagnosed COPD, to ensure that this highly symptomatic group receive evidence-based interventions.

Diagnoses and treatments for participants with interstitial lung abnormalities detected in the Yorkshire Lung Screening Trial.

INTRODUCTION: Interstitial lung abnormalities (ILA) are relatively common incidental findings in participants undergoing low-dose CT screening for lung cancer. Some ILA are transient and inconsequential, but others represent interstitial lung disease (ILD). Lung cancer screening therefore offers the opportunity of earlier diagnosis and treatment of ILD for some screening participants. METHODS: The prevalence of ILA in participants in the baseline screening round of the Yorkshire Lung Screening Trial is reported, along with the proportion referred to a regional ILD service, eventual diagnoses, outcomes and treatments. RESULTS: Of 6650 participants undergoing screening, ILA were reported in 169 (2.5%) participants. Following review in a screening review meeting, 56 participants were referred to the ILD service for further evaluation (0.8% of all screening participants). 2 participants declined referral, 1 is currently awaiting review and the remaining 53 were confirmed as having ILD. Eventual diagnoses were idiopathic pulmonary fibrosis (n=14), respiratory bronchiolitis ILD (n=4), chronic hypersensitivity pneumonitis (n=2), connective tissue disease/rheumatoid arthritis-related ILD (n=4), asbestosis (n=1), idiopathic non-specific interstitial pneumonia (n=1), sarcoidosis (n=1) and pleuroparenchymal fibroelastosis (n=1). Twenty five patients had unclassifiable idiopathic interstitial pneumonia. Overall, 10 people received pharmacotherapy (7 antifibrotics and 3 prednisolone) representing 18% of those referred to the ILD service and 0.15% of those undergoing screening. 32 people remain under surveillance in the ILD service, some of whom may require treatment in future. DISCUSSION: Lung cancer screening detects clinically significant cases of ILD allowing early commencement of disease-modifying treatment in a proportion of participants. This is the largest screening cohort to report eventual diagnoses and treatments and provides an estimate of the level of clinical activity to be expected by ILD services as lung cancer screening is implemented. Further research is needed to clarify the optimal management of screen-detected ILD. TRIAL REGISTRATION NUMBER: ISRCTN42704678.

Early-stage lung cancer associated with higher frequency of chest x-ray up to three years prior to diagnosis.

OBJECTIVES: Symptom awareness campaigns have contributed to improved early detection of lung cancer. Previous research suggests that this may have been achieved partly by diagnosing lung cancer in those who were not experiencing symptoms of their cancer. This study aimed to explore the relationship between frequency of chest x-ray in the three years prior to diagnosis and stage at diagnosis. SETTINGS: Lung cancer service in a UK teaching hospital. PARTICIPANTS: Patients diagnosed with lung cancer between 2010 and 2013 were identified. The number of chest x-rays for each patient in the three years prior to diagnosis was recorded. Statistical analysis of chest x-ray frequency comparing patients with early- and late-stage disease was performed. RESULTS: One-thousand seven-hundred fifty patients were included - 589 (33.7%) with stage I/II and 1,161 (66.3%) with stage III/IV disease. All patients had at least one chest x-ray in the six months prior to diagnosis. Those with early-stage disease had more chest x-rays in this period (1.32 vs 1.15 radiographs per patient, P = 0.009). In the period 36 months to six months prior to lung cancer diagnosis, this disparity was even greater (1.70 vs 0.92, radiographs per patient, P < 0.001). CONCLUSIONS: Increased rates of chest x-ray are likely to contribute to earlier detection. Given the known symptom lead time many patients diagnosed through chest x-ray may not have been experiencing symptoms caused by their cancer. The number of chest x-rays performed could reflect patient and/or clinician behaviours in response to symptoms.

Identifying cliques of convergent characters: concerted evolution in the cormorants and shags.

A phylogenetic tree comprising clades with high bootstrap values or other strong measures of statistical support is usually interpreted as providing a good estimate of the true phylogeny. Convergent evolution acting on groups of characters in concert, however, can lead to highly supported but erroneous phylogenies. Identifying such groups of phylogenetically misleading characters is obviously desirable. Here we present a procedure that uses an independent data source to identify sets of characters that have undergone concerted convergent evolution. We examine the problematic case of the cormorants and shags, for which trees constructed using osteological and molecular characters both have strong statistical support and yet are fundamentally incongruent. We find that the osteological characters can be separated into those that fit the phylogenetic history implied by the molecular data set and those that do not. Moreover, these latter nonfitting osteological characters are internally consistent and form groups of mutually compatible characters or "cliques," which are significantly larger than cliques of shuffled characters. We suggest, therefore, that these cliques of characters are the result of similar selective pressures and are a signature of concerted convergence.