Datasets for the reporting of primary tumour in bone: recommendations from the International Collaboration on Cancer Reporting (ICCR).

BACKGROUND AND OBJECTIVES: Bone tumours are relatively rare and, as a consequence, treatment in a centre with expertise is required. Current treatment guidelines also recommend review by a specialised pathologist. Here we report on international consensus-based datasets for the pathology reporting of biopsy and resection specimens of bone sarcomas. The datasets were produced under the auspices of the International Collaboration on Cancer Reporting (ICCR), a global alliance of major (inter-)national pathology and cancer organisations. METHODS AND RESULTS: According to the ICCR's process for dataset development, an international expert panel consisting of pathologists, an oncologic orthopaedic surgeon, a medical oncologist, and a radiologist produced a set of core and noncore data items for biopsy and resection specimens based on a critical review and discussion of current evidence. All professionals involved were bone tumour experts affiliated with tertiary referral centres. Commentary was provided for each data item to explain the rationale for selecting it as a core or noncore element, its clinical relevance, and to highlight potential areas of disagreement or lack of evidence, in which case a consensus position was formulated. Following international public consultation, the documents were finalised and ratified, and the datasets, including a synoptic reporting guide, were published on the ICCR website. CONCLUSION: These first international datasets for bone sarcomas are intended to promote high-quality, standardised pathology reporting. Their widespread adoption will improve the consistency of reporting, facilitate multidisciplinary communication, and enhance comparability of data, all of which will help to improve management of bone sarcoma patients.

Deep Learning-based Outcome Prediction in Progressive Fibrotic Lung Disease Using High-Resolution Computed Tomography.

Rationale: Reliable outcome prediction in patients with fibrotic lung disease using baseline high-resolution computed tomography (HRCT) data remains challenging. Objectives: To evaluate the prognostic accuracy of a deep learning algorithm (SOFIA [Systematic Objective Fibrotic Imaging Analysis Algorithm]), trained and validated in the identification of usual interstitial pneumonia (UIP)-like features on HRCT (UIP probability), in a large cohort of well-characterized patients with progressive fibrotic lung disease drawn from a national registry. Methods: SOFIA and radiologist UIP probabilities were converted to Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED)-based UIP probability categories (UIP not included in the differential, 0-4%; low probability of UIP, 5-29%; intermediate probability of UIP, 30-69%; high probability of UIP, 70-94%; and pathognomonic for UIP, 95-100%), and their prognostic utility was assessed using Cox proportional hazards modeling. Measurements and Main Results: In multivariable analysis adjusting for age, sex, guideline-based radiologic diagnosis, anddisease severity (using total interstitial lung disease [ILD] extent on HRCT, percent predicted FVC, DlCO, or the composite physiologic index), only SOFIA UIP probability PIOPED categories predicted survival. SOFIA-PIOPED UIP probability categories remained prognostically significant in patients considered indeterminate (n = 83) by expert radiologist consensus (hazard ratio, 1.73; P < 0.0001; 95% confidence interval, 1.40-2.14). In patients undergoing surgical lung biopsy (n = 86), after adjusting for guideline-based histologic pattern and total ILD extent on HRCT, only SOFIA-PIOPED probabilities were predictive of mortality (hazard ratio, 1.75; P < 0.0001; 95% confidence interval, 1.37-2.25). Conclusions: Deep learning-based UIP probability on HRCT provides enhanced outcome prediction in patients with progressive fibrotic lung disease when compared with expert radiologist evaluation or guideline-based histologic pattern. In principle, this tool may be useful in multidisciplinary characterization of fibrotic lung disease. The utility of this technology as a decision support system when ILD expertise is unavailable requires further investigation.

Biomarker signatures for progressive idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease in which circulatory biomarkers have the potential for guiding management in clinical practice. We assessed the prognostic role of serum biomarkers in three independent IPF cohorts: Australian Idiopathic Pulmonary Fibrosis Registry (AIPFR), Trent Lung Fibrosis (TLF) and Prospective Observation of Fibrosis in the Lung Clinical Endpoints (PROFILE). METHODS: In the AIPFR cohort, candidate proteins were assessed by ELISA as well as in an unbiased proteomic approach. LASSO (least absolute shrinkage and selection operator) regression was used to restrict the selection of markers that best accounted for the progressor phenotype at 1 year in the AIPFR cohort, and subsequently prospectively selected for replication in the validation TLF cohort and assessed retrospectively in the PROFILE cohort. Four significantly replicating biomarkers were aggregated into a progression index model based on tertiles of circulating concentrations. RESULTS: 189 participants were included in the AIPFR cohort, 205 participants from the TLF cohort and 122 participants from the PROFILE cohort. Differential biomarker expression was observed by ELISA and replicated for osteopontin, matrix metallopeptidase-7, intercellular adhesion molecule-1 and periostin for those with a progressor phenotype at 1 year. Proteomic data did not replicate. The progression index in the AIPFR, TLF and PROFILE cohorts predicted risk of progression, mortality and progression-free survival. A statistical model incorporating the progression index demonstrated the capacity to distinguish disease progression at 12 months, which was increased beyond the clinical GAP (gender, age and physiology) score model alone in all cohorts, and significantly so within the incidence-based TLF and PROFILE cohorts. CONCLUSION: A panel of circulatory biomarkers can provide potentially valuable clinical assistance in the prognosis of IPF patients.

Cryobiopsy for Identification of Usual Interstitial Pneumonia and Other Interstitial Lung Disease Features. Further Lessons from COLDICE, a Prospective Multicenter Clinical Trial.

Rationale: Transbronchial lung cryobiopsy (TBLC) is an emerging technique for interstitial lung disease diagnosis. Good histopathologic agreement between TBLC and surgical lung biopsy (SLB) was demonstrated in the COLDICE (Cryobiopsy versus Open Lung Biopsy in the Diagnosis of Interstitial Lung Disease Alliance) study; however, diagnostic confidence was frequently lower for TBLC than SLB. Objectives: To characterize specific features of TBLC predictive of usual interstitial pneumonia (UIP) in corresponding SLB and to identify clinical indices predictive of biopsy concordance. Methods: The COLDICE study was a prospective, multicenter study investigating diagnostic agreement between TBLC and SLB. The participants underwent both procedures with blinded pathologist analysis of specimens, applying international guideline criteria. The TBLC features predictive of UIP in the paired SLB and predictive features of overall concordance were analyzed. Measurements and Main Results: A total of 65 patients (66.1 ± 9.3 yr; FVC, 84.7 ± 14.2%; DlCO, 63.4 ± 13.8%) participated in the COLDICE study. UIP was identified in 33/65 (50.8%) SLB, and 81.5% were concordant with corresponding TBLC (κ, 0.61; 95% confidence interval [CI], 0.38-0.77). The UIP guideline criteria of "predominantly subpleural or paraseptal fibrosis" was infrequently reported in TBLC (8/33, 24.2%), whereas "patchy fibrosis," "fibroblast foci," and the "absence of alternative diagnostic features" were frequently observed in TBLC. The combination of these three features strongly predicted UIP in paired SLB (odds ratio [OR], 23.4; 95% CI, 6.36-86.1; P < 0.0001). Increased numbers of TBLC samples predicted histopathologic concordance with SLB (OR, 1.8; 95% CI, 1.08-3.01; P = 0.03). The predictors of discordance included older age, family history, and radiologic asymmetry. Conclusions: Subpleural and/or paraseptal fibrosis were not essential for diagnosing UIP in TBLC, provided that other guideline criteria features were present. The diagnostic accuracy of TBLC was strengthened when increased numbers of samples were taken. Clinical trial registered with www.anzctr.org.au (ACTRN12615000718549).

Updates in the molecular pathology of non-small cell lung cancer.

An understanding of the molecular pathology of non-small cell lung cancer (NSCLC) is important for pathologists as molecular characterization is now required for treatment decisions in advanced stage disease. While assessment for EGFR mutations, ALK and ROS1 fusions, and in some countries BRAF mutations, is now standard practice, other oncogenic mutations are also emerging that may impact routine clinical practice including alterations involving KRAS, NTRK, RET, MET and HER2. In addition, molecular pathology alterations of NSCLC are associated with responses to immune checkpoint therapy and are being increasingly investigated. Finally, specific molecular pathological alterations define some rarer subtypes of NSCLC such as salivary gland tumours, NUT carcinoma and SMARCA4-deficient undifferentiated tumour, and an understanding of the molecular pathology is important for their accurate diagnosis. In this review, the molecular pathology of NSCLC is discussed with a focus on clinically relevant molecular alterations.

Implications of the diagnostic criteria of idiopathic pulmonary fibrosis in clinical practice: Analysis from the Australian Idiopathic Pulmonary Fibrosis Registry.

BACKGROUND AND OBJECTIVE: Current guidelines for the diagnosis of idiopathic pulmonary fibrosis (IPF) provide specific criteria for diagnosis in the setting of multidisciplinary discussion (MDD). We evaluate the utility and reproducibility of these diagnostic guidelines, using clinical data from the Australian IPF Registry. METHODS: All patients enrolled in the registry undergo a diagnostic review whereby international IPF guidelines are applied via a registry MDD. We investigated the clinical applicability of these guidelines with regard to: (i) adherence to guidelines, (ii) Natural history of IPF diagnostic categories and (iii) Concordance for diagnostic features. RESULTS: A total of 417 participants (69% male, 70.6 ± 8.0 years) with a clinical diagnosis of IPF underwent MDD. The 23% of participants who did not meet IPF diagnostic criteria displayed identical disease behaviour to those with confirmed IPF. Honeycombing on radiology was associated with a worse prognosis and this translated into poorer prognosis in the 'definite' IPF group. While there was moderate agreement for IPF diagnostic categories, agreement for specific radiological features, other than honeycombing, was poor. CONCLUSION: In clinical practice, physicians do not always follow IPF diagnostic guidelines. We demonstrate a cohort of IPF patients who do not meet IPF diagnostic guideline criteria, based largely on their radiology and lack of lung biopsy, but who have outcomes identical to those with IPF.

Gastroesophageal reflux and antacid therapy in IPF: analysis from the Australia IPF Registry.

BACKGROUND AND OBJECTIVE: Gastroesophageal reflux disease (GORD) is highly prevalent in idiopathic pulmonary fibrosis (IPF) and may play a role in its pathogenesis. Recent IPF treatment guidelines suggest that all patients with IPF be considered for antacid therapy. However, emerging evidence suggests that antacid therapy does not improve IPF patient outcomes and may increase the risk of pulmonary infection. METHODS: Using prospectively collected data from the Australian IPF Registry including use of antacid therapy, GORD diagnosis and GORD symptoms, the relationship of these GORD variables to survival and disease progression was assessed. The severity of GORD symptoms using the frequency scale for symptoms of GORD (FSSG) and its relationships to outcomes was also assessed for the first time in an IPF cohort. RESULTS: Five hundred eighty-seven (86%) of the 684 patients in the Australian IPF Registry were eligible for inclusion. Patients were mostly male (69%), aged 71.0 ± 8.5 years with moderate disease (FVC 81.7 ± 21.5%; DLco 48.5 ± 16.4%). Most patients were taking antacids (n = 384; 65%), though fewer had a diagnosis of GORD (n = 243, 41.4%) and typical GORD symptoms were even less common (n = 171, 29.1%). The mean FSSG score was 8.39 ± 7.45 with 43% (n = 251) having a score > 8. Overall, there was no difference in survival or disease progression, regardless of antacid treatment, GORD diagnosis or GORD symptoms. CONCLUSIONS: Neither the use of antacid therapy nor the presence of GORD symptoms affects longer term outcomes in IPF patients. This contributes to the increasing evidence that antacid therapy may not be beneficial in IPF patients and that GORD directed therapy should be considered on an individual basis to treat the symptoms of reflux.

Fluorescent In Situ Hybridization in Surgical Pathology Practice.

There have been rapid and significant advances in diagnostic and predictive molecular techniques in recent years with profound impact on patient care. In situ hybridization (ISH) studies have become well entrenched in surgical pathology practice and their role in the evaluation of HER2 in breast carcinoma and their diagnostic utility in soft tissue pathology are well known. Fluorescent ISH is being increasingly used in other sites such as the head and neck and the gynecologic tract. Like most tests in surgical pathology, ISH studies require good quality tissue, correlation with clinical and histopathologic findings, and adherence to guidelines for optimal assay performance and interpretation. Although ISH studies are largely performed in tertiary centers, the tissue is often processed by a variety of laboratories and the referring pathologists are required to discuss the need, relevance, and significance of these tests and the results with their clinical colleagues. Here we review the predictive and diagnostic utility of fluorescent ISH studies in a variety of organ systems, the preanalytical factors that may affect the results, and the pitfalls in the interpretation that all practicing surgical pathologists should be aware of.

Diagnosis and management of idiopathic pulmonary fibrosis: Thoracic Society of Australia and New Zealand and Lung Foundation Australia position statements summary.

INTRODUCTION: Idiopathic pulmonary fibrosis (IPF) is a fibrosing interstitial lung disease associated with debilitating symptoms of dyspnoea and cough, resulting in respiratory failure, impaired quality of life and ultimately death. Diagnosing IPF can be challenging, as it often shares many features with other interstitial lung diseases. In this article, we summarise recent joint position statements on the diagnosis and management of IPF from the Thoracic Society of Australia and New Zealand and Lung Foundation Australia, specifically tailored for physicians across Australia and New Zealand. Main suggestions: A comprehensive multidisciplinary team meeting is suggested to establish a prompt and precise IPF diagnosis. Antifibrotic therapies should be considered to slow disease progression. However, enthusiasm should be tempered by the lack of evidence in many IPF subgroups, particularly the broader disease severity spectrum. Non-pharmacological interventions including pulmonary rehabilitation, supplemental oxygen, appropriate treatment of comorbidities and disease-related symptoms remain crucial to optimal management. Despite recent advances, IPF remains a fatal disease and suitable patients should be referred for lung transplantation assessment.

Disease progression in idiopathic pulmonary fibrosis with mild physiological impairment: analysis from the Australian IPF registry.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal fibrosing lung disease of unknown cause. The advent of anti-fibrotic medications known to slow disease progression has revolutionised IPF management in recent years. However, little is known about the natural history of IPF patients with mild physiological impairment. We aimed to assess the natural history of these patients using data from the Australian IPF Registry (AIPFR). METHODS: Using our cohort of real-world IPF patients, we compared FVC criteria for mild physiological impairment (FVC ≥ 80%) against other proposed criteria: DLco ≥ 55%; CPI ≤40 and GAP stage 1 with regards agreement in classification and relationship with disease outcomes. Within the mild cohort (FVC ≥ 80%), we also explored markers associated with poorer prognosis at 12 months. RESULTS: Of the 416 AIPFR patients (mean age 70.4 years, 70% male), 216 (52%) were classified as 'mild' using FVC ≥ 80%. There was only modest agreement between FVC and DLco (k = 0.30), with better agreement with GAP (k = 0.50) and CPI (k = 0.48). Patients who were mild had longer survival, regardless of how mild physiologic impairment was defined. There was, however, no difference in the annual decline in FVC% predicted between mild and moderate-severe groups (for all proposed criteria). For patients with mild impairment (n = 216, FVC ≥ 80%), the strongest predictor of outcomes at 12 months was oxygen desaturation on a 6 min walk test. CONCLUSION: IPF patients with mild physiological impairment have better survival than patients with moderate-severe disease. Their overall rate of disease progression however, is comparable, suggesting that they are simply at different points in the natural history of IPF disease.

Baseline characteristics of idiopathic pulmonary fibrosis: analysis from the Australian Idiopathic Pulmonary Fibrosis Registry.

7The prevalence of idiopathic pulmonary fibrosis (IPF), a fatal and progressive lung disease, is estimated at 1.25-63 out of 100 000, making large population studies difficult. Recently, the need for large longitudinal registries to study IPF has been recognised.The Australian IPF Registry (AIPFR) is a national registry collating comprehensive longitudinal data of IPF patients across Australia. We explored the characteristics of this IPF cohort and the effect of demographic and physiological parameters and specific management on mortality.Participants in the AIPFR (n=647, mean age 70.9±8.5 years, 67.7% male, median follow up 2 years, range 6 months-4.5 years) displayed a wide range of age, disease severity and co-morbidities that is not present in clinical trial cohorts. The cumulative mortality rate in year one, two, three and four was 5%, 24%, 37% and 44% respectively. Baseline lung function (forced vital capacity, diffusing capacity of the lung for carbon monoxide, composite physiological index) and GAP (gender, age, physiology) stage (hazard ratio 4.64, 95% CI 3.33-6.47, p<0.001) were strong predictors of mortality. Patients receiving anti-fibrotic medications had better survival (hazard ratio 0.56, 95% CI 0.34-0.92, p=0.022) than those not on anti-fibrotic medications, independent of underlying disease severity.The AIPFR provides important insights into the understanding of the natural history and clinical management of IPF.

The interstitial lung disease multidisciplinary meeting: A position statement from the Thoracic Society of Australia and New Zealand and the Lung Foundation Australia.

Interstitial lung diseases (ILD) are a diverse group of pulmonary diseases for which accurate diagnosis is critical for optimal treatment outcomes. Diagnosis of ILD can be challenging and a multidisciplinary approach is recommended in international guidelines. The purpose of this position paper is to review the evidence for the use of the multidisciplinary meeting (MDM) in ILD and suggest an approach to its governance and constitution, in an attempt to provide a standard methodology that could be applied across Australia and New Zealand. This position paper is endorsed by the Thoracic Society of Australia and New Zealand (TSANZ) and the Lung Foundation Australia (LFA).

Health-related quality of life in idiopathic pulmonary fibrosis: Data from the Australian IPF Registry.

BACKGROUND AND OBJECTIVE: Studies analysing the effect of worsening pulmonary physiological impairment in idiopathic pulmonary fibrosis (IPF) with respect to quality of life have been limited to single centres or highly selected trial populations. The aim of this study was to determine the principal determinants of baseline and longitudinal health-related quality of life (HRQoL) in a large unselected IPF population. METHODS: We used the Australian IPF Registry to examine the relationship between HRQoL, measured using the St George Respiratory Questionnaire (SGRQ), and demographic features, physiological features, co-morbidities and symptoms. Linear regression analysis was performed to identify predictors of baseline HRQoL, linear mixed model analysis to determine the effect of time and forced vital capacity (FVC) on SGRQ and Cox proportional hazards regression to examine the relationship between HRQoL and all-cause mortality. RESULTS: Baseline data from 516 patients were available (347 males; mean (SD) age: 71.3 ± 8.6 years). Univariate analysis showed significant associations between HRQoL and demographic, clinical and physiological features. However, multivariate analysis demonstrated independent associations only between SGRQ and dyspnoea (University of California San Diego Shortness of Breathlessness Questionnaire (UCSD-SOBQ); R2 = 0.71, P < 0.0001), cough severity (visual analogue scale; R2 = 0.06, P < 0.0001) and depression (Hospital Anxiety and Depression Scale; R2 = 0.04, P < 0.0001). Linear mixed-effects modelling of combined baseline and longitudinal data confirmed these associations, as well as for FVC% predicted (P = 0.005). Multivariate Cox proportionate-proportional hazards regression analysis demonstrated no association between HRQoL and risk of mortality. CONCLUSION: Cough, dyspnoea and depression are major symptomatic determinants of HRQoL in IPF. FVC decline is associated with worsening HRQoL.

Atypical Ewing sarcoma breakpoint region 1 fluorescence in-situ hybridization signal patterns in bone and soft tissue tumours: diagnostic experience with 135 cases.

AIMS: Recurrent Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangements characterize a select group of bone and soft tissue tumours. In our routine diagnostic practice with fluorescence in-situ hybridization (FISH), we have occasionally observed EWSR1 gene rearrangements in tumours not associated classically with EWSR1 translocations. This study aimed to review our institutional experience of this phenomenon and also to highlight the occurrence of unusual EWSR1 FISH signals (i.e. 5' centromeric region or 3' telomeric region signals) that do not fulfil the published diagnostic criteria for rearrangements. METHODS AND RESULTS: Using an EWSR1 break-apart probe, we performed FISH assays on formalin-fixed paraffin-embedded tissue sections from 135 bone and soft tissue specimens as part of their routine diagnostic work-up. EWSR1 gene rearrangements were identified in 51% of cases, 56% of which also showed an abnormal FISH signal pattern (in addition to classically rearranged signals). However, atypical FISH signals were present in 45% of the non-rearranged cases. In addition, we observed tumours unrelated to those described classically as EWSR1-associated that were technically EWSR1-rearranged in 6% of cases. Borderline levels of rearrangement (affecting 10-30% of lesional cells) were present in an additional 17% of these cases. CONCLUSIONS: While our study confirmed that FISH is a sensitive and specific tool in the diagnosis of EWSR1-associated tumours, atypical FISH signals and classical rearrangement in entities other than EWSR1-associated tumours can occur. Therefore, it is essential that the FISH result not be used as an isolated test, but must be evaluated in the context of clinical features, imaging, pathological and immunohistochemical findings.

Clinical impact of the interstitial lung disease multidisciplinary service.

BACKGROUND AND OBJECTIVE: Multidisciplinary discussions (MDDs) have been shown to improve diagnostic accuracy in interstitial lung disease (ILD) diagnosis. However, their clinical impact on patient care has never been clearly demonstrated. We describe the effect that an ILD multidisciplinary service has upon the diagnosis and management of patients with suspected ILD. METHODS: Patients at two specialized centres with suspected ILD underwent ILD multidisciplinary team review (ILD-MDT) (standard ILD clinic visit and diagnostic review at ILD-MDD). We compared changes in ILD diagnosis and management at referral to those following the ILD-MDT. RESULTS: Ninety patients, 60% males (54/90), aged 67.3 years (SD = 11.4) were reviewed for suspected ILD. Overall, the ILD-MDT resulted in a change in specific ILD diagnosis in 48/90 (53%) patients. Of the 27 patients referred with a diagnosis of idiopathic pulmonary fibrosis (IPF), the diagnosis was changed at MDD in 10 patients. In contrast, seven patients had their diagnosis changed to IPF. There was also a significant reduction in 'unclassifiable' diseases and disease behaviour classifications provided additional information beyond ILD diagnosis. CONCLUSION: Dedicated tertiary ILD-MDT service has an important clinical impact on the care of the ILD patient, with frequent changes in ILD diagnosis and subsequent management. Further research to investigate long-term clinical outcomes of ILD-MDT is required.

Australian Idiopathic Pulmonary Fibrosis Registry: vital lessons from a national prospective collaborative project.

There is little Australian epidemiologic data on idiopathic pulmonary fibrosis (IPF), a relatively uncommon but devastating disease. The vast geographic distances in Australia have been a major impediment for collaborative research into IPF. A collaborative national effort, the Australian IPF Registry, has been formed, launched and is recruiting successfully (n = 359, January 2014). Our experience provides unique insights for others wishing to set up IPF registries and in time for a global IPF registry.

Disease Behaviour Classification: A pragmatic model for predicting outcomes in Interstitial Lung Disease.

BACKGROUND AND OBJECTIVE: The interstitial lung diseases (ILD) are a heterogenous group of disorders with similar clinical presentation, but widely varying prognoses. The use of a pragmatic disease behaviour classification (DBC), first proposed in international guidelines in 2013, categorises diseases into five behavioural classes based on their predicted clinical course. This study aimed to determine the prognostic utility of the DBC in an ILD cohort. METHODS: Consecutive patients presented at the weekly multidisciplinary meeting (MDM) of a specialist ILD centre were included. MDM consensus was obtained for diagnosis and DBC category (1-5). Baseline and serial clinical and physiological data were collected over the study period (median 3.9 years, range 0-5.4 years). The relationship between DBC and prognostic outcomes was explored. RESULTS: 137 ILD patients, [64 (47%) female] were included with mean age 67.0 ± 1.1 years, baseline FVC% 72.7 ± 1.7, and baseline DLco% 57.8 ± 1.6%. Patients were stratified into DBC by consensus at MDM: DBC1 n = 0 (0%), DBC2 n = 16 (12%), DBC3 n = 10 (7.3%), DBC4 n = 55 (40%), and DBC5 n = 56 (41%). On univariable Cox regression, increasing DBC class was associated with poorer progression-free survival (HR 1.6, 95% CI 1.2-2.0, p < 0.001). On multivariable Cox regression, DBC remained predictive of PFS when combined with age and gender (HR 1.4, 95% CI 1.1-1.9, p = 0.011), baseline FVC% (HR 1.5, 95% CI 1.1-1.8, p = 0.003) and ILD diagnosis (HR 1.6, 95% CI 1.2-2.2, p < 0.0001). CONCLUSION: DBC as determined at ILD multidisciplinary meeting may be a useful prognostic tool for the management of ILD patients.

ROS1 rearrangements in lung adenocarcinomas are defined by diffuse strong immunohistochemical expression of ROS1.

A small subset of lung adenocarcinomas harbour ROS1 gene arrangements and are amenable to tyrosine kinase inhibitor therapy. Current practice in Australia involves screening for ROS1 rearrangements in adenocarcinomas using ROS1 immunohistochemistry (IHC) followed by confirmatory molecular testing such as fluorescence in situ hybridisation (FISH), if other known genetic driver alterations are absent. The best threshold to determine ROS1 IHC positivity is not well defined, however, and this study aims to determine the optimal threshold for ROS1 IHC screening to identify ROS1-rearranged lung adenocarcinomas. A total of 177 lung adenocarcinomas tested for a ROS1 rearrangement by FISH at our institution between 2017 and 2020 due to presence of ROS1 IHC staining were included in the study. ROS1 IHC staining was assessed by scoring the staining intensity (0, 1, 2, or 3+) and multiplying by the percentage of positive cells to generate an H-score. IHC H-scores were compared with FISH. Of 177 cases, 32 (18%) were ROS1 FISH-positive and 145 (82%) were negative. FISH-positive cases had a median H-score of 300 (range 200-300; mean 290.3) and negative cases had a median H-score of 40 (range 0-300; mean 63). All FISH-positive cases showed strong and diffuse IHC positivity. Using a threshold H-score of 200, the sensitivity of identifying ROS1 rearrangements was 100% and the specificity was 95% amongst cases referred with ROS1 IHC positivity. Adenocarcinomas with a FISH-confirmed ROS1 rearrangement demonstrate diffuse, strong (2-3+) IHC staining. Cases with weak, patchy ROS1 IHC staining are not associated with ROS1 rearrangements and in these cases FISH testing is of little to no utility.