Early prehabilitation reduces admissions and time in hospital in patients with newly diagnosed lung cancer.

OBJECTIVES: Lung cancer is the leading cause of cancer death in the UK. Prehabilitation aims to maximise patient fitness and minimise the negative impact of anticancer treatment. What constitutes prehabilitation before non-surgical anticancer treatment is not well established. We present data from a pilot project of Early prehabilitation In lung Cancer. METHODS: All new patients with likely advanced lung cancer were offered prehabilitation at respiratory clinic, if fit for further investigation. Prehabilitation included assessment and appropriate intervention from a consultant in palliative medicine, registered dietitian and rehabilitation physiotherapist. Four objective endpoints were identified, namely admissions to hospital, time spent in the hospital, treatment rates and overall survival. Outcomes were to be compared with 178 prehab eligible historical controls diagnosed from 2019 to 2021. RESULTS: From July 2021 to June 2023, 65 patients underwent prehabilitation and 72% of patients underwent all 3 interventions. 54 patients had a stage 3 or 4 lung cancer. In the prehab group, fewer patients attended Accident and Emergency (31.5 vs 37.4 attendances per 100 patients) and fewer were admitted (51.9 vs 67.9) when compared with historical controls. Those receiving prehab spent a lot less time in the hospital (129.7 vs 543.5 days per 100 patients) with shorter admissions (2.5 vs 8 days). Systemic anticancer treatment rates increased in the short term but were broadly similar overall. Median survival was higher in the prehabilitation group (0.73 vs 0.41 years, p=0.046). CONCLUSIONS: Early prehabilitation appears to reduce time spent in the hospital. It may improve survival. Further work is required to understand its full effect on treatment rates.

Early prehabilitation in suspected locally advanced and metastatic lung cancer.

OBJECTIVES: The most common treatment for locally advanced and metastatic lung cancer is best supportive care. Patients with lung cancer are often comorbid with a high symptom burden. We wanted to assess whether early prehabilitation was feasible in patients with likely lung cancer. METHODS: Patients were offered prehabilitation if they were attending the new patient respiratory clinic, had a CT scan suggesting stage III or IV lung cancer and undergoing further investigations. Patients receiving palliative care were ineligible. All prehabilitation patients were referred to a palliative medicine physician, registered dietitian and rehabilitation physiotherapist. RESULTS: 50 patients underwent prehabilitation between June 2021 and August 2022. The median age was 72 years (range 54-89 years). 48 patients had lung cancer. 84% of patients attended all three interventions.Half of the palliative care consultations focused on pain. Half of the patients seen had a change in medication. 25% of patients' weights were stable, 32% required a food-first strategy and 33% required oral nutritional supplements. 57% of patients discussed managing breathlessness with the physiotherapist. CONCLUSIONS: Early prehabilitation is feasible alongside the investigation of locally advanced and metastatic lung cancer. Further work will aim to assess its impact on admission to the hospital, survival and treatment rates.

A multi-center prospective study of plant-based nutritional support in adult community-based patients at risk of disease-related malnutrition.

Introduction: There is an emerging need for plant-based, vegan options for patients requiring nutritional support. Methods: Twenty-four adults at risk of malnutrition (age: 59 years (SD 18); Sex: 18 female, 6 male; BMI: 19.0 kg/m2 (SD 3.3); multiple diagnoses) requiring plant-based nutritional support participated in a multi-center, prospective study of a (vegan suitable) multi-nutrient, ready-to-drink, oral nutritional supplement (ONS) [1.5 kcal/mL; 300 kcal, 12 g protein/200 mL bottle, mean prescription 275 mL/day (SD 115)] alongside dietary advice for 28 days. Compliance, anthropometry, malnutrition risk, dietary intake, appetite, acceptability, gastrointestinal (GI) tolerance, nutritional goal(s), and safety were assessed. Results: Patients required a plant-based ONS due to personal preference/variety (33%), religious/cultural reasons (28%), veganism/reduce animal-derived consumption (17%), environmental/sustainability reasons (17%), and health reasons (5%). Compliance was 94% (SD 16). High risk of malnutrition ('MUST' score ≥ 2) reduced from 20 to 16 patients (p = 0.046). Body weight (+0.6 kg (SD 1.2), p = 0.02), BMI (+0.2 kg/m2 (SD 0.5), p = 0.03), total mean energy (+387 kcal/day (SD 416), p < 0.0001) and protein intake (+14 g/day (SD 39), p = 0.03), and the number of micronutrients meeting the UK reference nutrient intake (RNI) (7 vs. 14, p = 0.008) significantly increased. Appetite (Simplified Nutritional Appetite Questionnaire (SNAQ) score; p = 0.13) was maintained. Most GI symptoms were stable throughout the study (p > 0.06) with no serious adverse events related. Discussion: This study highlights that plant-based nutrition support using a vegan-suitable plant-based ONS is highly complied with, improving the nutritional outcomes of patients at risk of malnutrition.

A bifunctional kinase-phosphatase module balances mitotic checkpoint strength and kinetochore-microtubule attachment stability.

Two major mechanisms safeguard genome stability during mitosis: the mitotic checkpoint delays mitosis until all chromosomes have attached to microtubules, and the kinetochore-microtubule error-correction pathway keeps this attachment process free from errors. We demonstrate here that the optimal strength and dynamics of these processes are set by a kinase-phosphatase pair (PLK1-PP2A) that engage in negative feedback from adjacent phospho-binding motifs on the BUB complex. Uncoupling this feedback to skew the balance towards PLK1 produces a strong checkpoint, hypostable microtubule attachments and mitotic delays. Conversely, skewing the balance towards PP2A causes a weak checkpoint, hyperstable microtubule attachments and chromosome segregation errors. These phenotypes are associated with altered BUB complex recruitment to KNL1-MELT motifs, implicating PLK1-PP2A in controlling auto-amplification of MELT phosphorylation. In support, KNL1-BUB disassembly becomes contingent on PLK1 inhibition when KNL1 is engineered to contain excess MELT motifs. This elevates BUB-PLK1/PP2A complex levels on metaphase kinetochores, stabilises kinetochore-microtubule attachments, induces chromosome segregation defects and prevents KNL1-BUB disassembly at anaphase. Together, these data demonstrate how a bifunctional PLK1/PP2A module has evolved together with the MELT motifs to optimise BUB complex dynamics and ensure accurate chromosome segregation.

Nutritional status and symptom burden in advanced non-small cell lung cancer: results of the dietetic assessment and intervention in lung cancer (DAIL) trial.

INTRODUCTION: European Society for Clinical Nutrition and Metabolism guidelines recommend that patients with cancer should be screened for malnutrition at diagnosis. The dietetic assessment and intervention in lung cancer study investigated the nutritional status of patients with non-small cell lung cancer (NSCLC) and the need for dietetic intervention. METHODS: In this observational cohort pilot study, patients with stage 3b and 4 NSCLC were assessed prior to starting first line systemic anticancer therapy (SACT) with a range of measurements and questionnaires. We report the outcomes related to the Patient Generated Subjective Global Assessment tool (PG-SGA), RESULTS: 96 patients were consented between April 2017 and August 2019. The PG-SGA identified that 78% of patients required specialist nutritional advice; with 52% patients having a critical need for dietetic input and symptom management. Results were dominated by symptom scores. As a screening test, one or more symptoms or recent weight loss history had a sensitivity of 88% (95% CI 78.44% to 94.36%) and specificity of 95.24% (95% CI 76.18% to 99.88%) for need for dietetic intervention. CONCLUSION: A large proportion of patients with NSCLC have a high symptom burden and are at risk of malnutrition prior to starting SACT and would benefit from dietetic review. It is imperative that oncologists and healthcare professionals discuss weight loss history and symptoms with lung cancer patients to correct nutritional deficiencies and resolve symptoms prior to starting treatment.

Early dietitian referral in lung cancer: use of machine learning.

OBJECTIVES: The Dietetic Assessment and Intervention in Lung Cancer (DAIL) study was an observational cohort study. It triaged the need for dietetic input in patients with lung cancer, using questionnaires with 137 responses. This substudy tested if machine learning could predict need to see a dietitian (NTSD) using 5 or 10 measures. METHODS: 76 cases from DAIL were included (Royal Surrey NHS Foundation Trust; RSH: 56, Frimley Park Hospital; FPH 20). Univariate analysis was used to find the strongest correlates with NTSD and 'critical need to see a dietitian' CNTSD. Those with a Spearman correlation above ±0.4 were selected to train a support vector machine (SVM) to predict NTSD and CNTSD. The 10 and 5 best correlates were evaluated. RESULTS: 18 and 13 measures had a correlation above ±0.4 for NTSD and CNTSD, respectively, producing SVMs with 3% and 7% misclassification error. 10 measures yielded errors of 7% (NTSD) and 9% (CNTSD). 5 measures yielded between 7% and 11% errors. SVM trained on the RSH data and tested on the FPH data resulted in errors of 20%. CONCLUSIONS: Machine learning can predict NTSD producing misclassification errors <10%. With further work, this methodology allows integrated early referral to a dietitian independently of a healthcare professional.

Multinational Association of Supportive Care in Cancer (MASCC) expert opinion/guidance on the use of clinically assisted nutrition in patients with advanced cancer.

PURPOSE: The pro vision of clinically assisted nutrition (CAN) in patients with advanced cancer is controversial, and there is a paucity of specific guidance, and so a diversity in clinical practice. Consequently, the Palliative Care Study Group of the Multinational Association of Supportive Care in Cancer (MASCC) formed a Subgroup to develop evidence-based guidance on the use CAN in patients with advanced cancer. METHODS: This guidance was developed in accordance with the MASCC Guidelines Policy. A search strategy for Medline was developed, and the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials were explored for relevant reviews/trials respectively. The outcomes of the review were categorised by the level of evidence, and a "category of guideline" based on the level of evidence (i.e. "recommendation", "suggestion", or "no guideline possible"). RESULTS: The Subgroup produced 11 suggestions, and 1 recommendation (due to the paucity of evidence). These outcomes relate to assessment of patients, indications for CAN, contraindications for CAN, procedures for initiating CAN, and re-assessment of patients. CONCLUSIONS: This guidance provides a framework for the use of CAN in advanced cancer, although every patient needs individualised management.

Reference Ranges for Pulsed-Wave Doppler of the Fetal Cardiac Inflow and Outflow Tracts from 13 to 36 Weeks' Gestation.

BACKGROUND: Doppler assessment of ventricular filling and outflow tract velocities is an integral part of fetal echocardiography, to assess diastolic function, systolic function, and outflow tract obstruction. There is a paucity of prospective data from a large sample of normal fetuses in the published literature. The authors report reference ranges for pulsed-wave Doppler flow of the mitral valve, tricuspid valve, aortic valve, and pulmonary valve, as well as heart rate, in a large number of fetuses prospectively examined at a single tertiary fetal cardiology center. METHODS: The study population comprised 7,885 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective pulsed-wave Doppler blood flow measurements were taken of the mitral, tricuspid, aortic, and pulmonary valves. The fetal heart rate was recorded at the time of each assessment. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age. RESULTS: The measurement for each cardiac Doppler measurement was expressed as a Z score (difference between observed and expected values divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac inflow and outflow tracts. CONCLUSIONS: This study establishes reference ranges for fetal cardiac Doppler measurements and heart rate between 13 to 36 weeks' gestation that may be useful in clinical practice.

Cyclin B1 scaffolds MAD1 at the kinetochore corona to activate the mitotic checkpoint.

Cyclin B:CDK1 is the master kinase regulator of mitosis. We show here that, in addition to its kinase functions, mammalian Cyclin B also scaffolds a localised signalling pathway to help preserve genome stability. Cyclin B1 localises to an expanded region of the outer kinetochore, known as the corona, where it scaffolds the spindle assembly checkpoint (SAC) machinery by binding directly to MAD1. In vitro reconstitutions map the key binding interface to a few acidic residues in the N-terminal region of MAD1, and point mutations in this sequence abolish MAD1 corona localisation and weaken the SAC. Therefore, Cyclin B1 is the long-sought-after scaffold that links MAD1 to the corona, and this specific pool of MAD1 is needed to generate a robust SAC response. Robustness arises because Cyclin B1:MAD1 localisation loses dependence on MPS1 kinase after the corona has been established, ensuring that corona-localised MAD1 can still be phosphorylated when MPS1 activity is low. Therefore, this study explains how corona-MAD1 generates a robust SAC signal, and it reveals a scaffolding role for the key mitotic kinase, Cyclin B1:CDK1, which ultimately helps to inhibit its own degradation.

Dietetic assessment and intervention in lung cancer.

PURPOSE OF REVIEW: Systemic therapy for lung cancer is increasing in intensity and duration. European nutrition guidelines suggest screening for weight loss and malnutrition, however acknowledges there is a lack of evidence. We discuss current data round this issue and identify opportunities for further research. RECENT FINDINGS: International guidelines now exist to aid the definition of weight loss in cancer, including cachexia, sarcopenia and malnutrition. These allow consistent definition of overlapping, but distinct clinical syndromes. Nutritional status can be assessed in a range of ways including questionnaires, functional assessments, blood markers, physical activity, weight and BMI. Weight loss is commonly associated with a proinflammatory state. Future treatment is likely to be a combination of dietetic support and pharmacological treatment of cachexia. SUMMARY: There is a paucity of data on dietetic intervention. It is potentially quick, inexpensive and patient specific, using a holistic approach to aid patients who are malnourished or at risk of malnutrition. Lung cancer-related weight loss is common, further strategies are needed to effectively assess and intervene. Dietetic intervention has the potential to improve patients' quality of life and outcomes.

Division of labour between PP2A-B56 isoforms at the centromere and kinetochore.

PP2A-B56 is a serine/threonine phosphatase complex that regulates several major mitotic processes, including sister chromatid cohesion, kinetochore-microtubule attachment and the spindle assembly checkpoint. We show here that these key functions are divided between different B56 isoforms that localise to either the centromere or kinetochore. The centromeric isoforms rely on a specific interaction with Sgo2, whereas the kinetochore isoforms bind preferentially to BubR1 and other proteins containing an LxxIxE motif. In addition to these selective binding partners, Sgo1 helps to anchor PP2A-B56 at both locations: it collaborates with BubR1 to maintain B56 at the kinetochore and it helps to preserve the Sgo2/B56 complex at the centromere. A series of chimaeras were generated to map the critical region in B56 down to a small C-terminal loop that regulates the key interactions and defines B56 localisation. Together, this study describes how different PP2A-B56 complexes utilise isoform-specific interactions to control distinct processes during mitosis.

Timed degradation of Mcl-1 controls mitotic cell death.

Mitotic arrest can result in cell death through the process of apoptosis. We have shown by live-cell imaging that the ubiquitin-proteasome dependent proteolysis of the apoptotic regulator Mcl-1 under the control of the anaphase-promoting complex or cyclosome (APC/C) provides a timing mechanism that distinguishes prolonged mitotic arrest from normal mitosis.

Prenatal diagnosis and clinical implications of an apparently isolated right aortic arch.

OBJECTIVE: To define the associations of a prenatally diagnosed, apparently isolated right aortic arch (RAA) with chromosomal or genetic abnormalities and tracheal compression. METHODS: This was a retrospective study of apparently isolated RAA assessed by fetal cardiologists and fetal medicine specialists at Kings College Hospital, London between 2000 and 2017. RESULTS: The search identified 138 cases of apparently isolated RAA. Invasive testing was performed in 75, and chromosomal or genetic anomalies were identified in 16 (22%), and the most common was 22q11 microdeletion. An aberrant left subclavian artery was seen in 51% of cases. Symptoms of a vascular ring were present in 24 of 97 (25%) children who were reviewed after birth. Bronchoscopy was performed in 33 children, and significant tracheal compression was diagnosed in 28, including 18 of 19 symptomatic and 10 of 14 asymptomatic children. CONCLUSIONS: An apparently isolated RAA is associated with a high incidence of chromosomal or genetic abnormalities and a high incidence of tracheal compression in symptomatic and asymptomatic patients. Prenatal counselling for genetic associations and postnatal airway assessment in the context of the vascular anatomy is recommended.

Reference Ranges for the Size of the Fetal Cardiac Outflow Tracts From 13 to 36 Weeks Gestation: A Single-Center Study of Over 7000 Cases.

BACKGROUND: Assessment of the outflow tract views is an integral part of routine fetal cardiac scanning. For some congenital heart defects, notably coarctation of the aorta, pulmonary valve stenosis, and aortic valve stenosis, the size of vessels is important both for diagnosis and prognosis. Existing reference ranges of fetal outflow tracts are derived from a small number of cases. METHODS AND RESULTS: The study population comprised 7945 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective measurements were taken of (1) the aortic and pulmonary valves in diastole at the largest diameter with the valve closed, (2) the distal transverse aortic arch on the 3 vessel and trachea view beyond the trachea at the distal point at its widest systolic diameter, and (3) the arterial duct on the 3 vessel and trachea view at its widest systolic diameter. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age. The measurement for each cardiac diameter was expressed as a z score (difference between observed and expected value divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac outflow tracts and for the distal transverse aortic arch:arterial duct ratio. CONCLUSIONS: The study established reference ranges for fetal outflow tract measurements at 13 to 36 weeks' gestation that are useful in clinical practice.

Atypical APC/C-dependent degradation of Mcl-1 provides an apoptotic timer during mitotic arrest.

The initiation of apoptosis in response to the disruption of mitosis provides surveillance against chromosome instability. Here, we show that proteolytic destruction of the key regulator Mcl-1 during an extended mitosis requires the anaphase-promoting complex or cyclosome (APC/C) and is independent of another ubiquitin E3 ligase, SCFFbw7 Using live-cell imaging, we show that the loss of Mcl-1 during mitosis is dependent on a D box motif found in other APC/C substrates, while an isoleucine-arginine (IR) C-terminal tail regulates the manner in which Mcl-1 engages with the APC/C, converting Mcl-1 from a Cdc20-dependent and checkpoint-controlled substrate to one that is degraded independently of checkpoint strength. This mechanism ensures a relatively slow but steady rate of Mcl-1 degradation during mitosis and avoids its catastrophic destruction when the mitotic checkpoint is satisfied, providing an apoptotic timer that can distinguish a prolonged mitotic delay from normal mitosis. Importantly, we also show that inhibition of Cdc20 promotes mitotic cell death more effectively than loss of APC/C activity through differential effects on Mcl-1 degradation, providing an improved strategy to kill cancer cells.

USP9X Limits Mitotic Checkpoint Complex Turnover to Strengthen the Spindle Assembly Checkpoint and Guard against Chromosomal Instability.

Faithful chromosome segregation during mitosis depends on the spindle assembly checkpoint (SAC), which delays progression through mitosis until every chromosome has stably attached to spindle microtubules via the kinetochore. We show here that the deubiquitinase USP9X strengthens the SAC by antagonizing the turnover of the mitotic checkpoint complex produced at unattached kinetochores. USP9X thereby opposes activation of anaphase-promoting complex/cyclosome (APC/C) and specifically inhibits the mitotic degradation of SAC-controlled APC/C substrates. We demonstrate that depletion or loss of USP9X reduces the effectiveness of the SAC, elevates chromosome segregation defects, and enhances chromosomal instability (CIN). These findings provide a rationale to explain why loss of USP9X could be either pro- or anti-tumorigenic depending on the existing level of CIN.

Persistently elevated nuchal translucency and the fetal heart.

OBJECTIVE: To describe the outcome of fifteen cases with an elevated nuchal translucency (NT) which persisted into the second trimester as nuchal edema (NE) >6 mm whom underwent fetal echocardiography. MATERIALS AND METHODS: Cases were identified following retrospective review of cardiac and genetic findings in fetuses with NE. RESULTS: Minor congenital heart disease was identified in 3/15 by the second trimester. Agenesis of the ductus venosus was evident in four. Pulmonary valve stenosis was diagnosed in one fetus at the 20-week scan and hypertrophic cardiomyopathy in one. However, hypertrophic cardiomyopathy or pulmonary valve stenosis was present after birth in all surviving cases by 3 months of age. On the basis of intention to treat, 11/12 survived to delivery and 9/12 survived to 28 days. There were 6 deaths before 14 months of age as a result of severe hypertrophic cardiomyopathy. Noonan syndrome was confirmed with genetic testing in 11/15 cases. CONCLUSIONS: All fetuses with NT and NE had evidence of congenital heart disease at birth, and therefore, late gestation and postnatal review is recommended even when second trimester echocardiogram is considered normal. There is a high prevalence of Noonan syndrome and targeted genetic analysis should be considered. The outcome in these cases is poor.

Randomized controlled trial of dietary fiber for the prevention of radiation-induced gastrointestinal toxicity during pelvic radiotherapy.

Background: Therapeutic radiotherapy is an important treatment of pelvic cancers. Historically, low-fiber diets have been recommended despite a lack of evidence and potentially beneficial mechanisms of fiber.Objective: This randomized controlled trial compared low-, habitual-, and high-fiber diets for the prevention of gastrointestinal toxicity in patients undergoing pelvic radiotherapy.Design: Patients were randomly assigned to low-fiber [≤10 g nonstarch polysaccharide (NSP)/d], habitual-fiber (control), or high-fiber (≥18 g NSP/d) diets and received individualized counseling at the start of radiotherapy to achieve these targets. The primary endpoint was the difference between groups in the change in the Inflammatory Bowel Disease Questionnaire-Bowel Subset (IBDQ-B) score between the starting and nadir (worst) score during treatment. Other measures included macronutrient intake, stool diaries, and fecal short-chain fatty acid concentrations.Results: Patients were randomly assigned to low-fiber (n = 55), habitual-fiber (n = 55), or high-fiber (n = 56) dietary advice. Fiber intakes were significantly different between groups (P < 0.001). The difference between groups in the change in IBDQ-B scores between the start and nadir was not significant (P = 0.093). However, the change in score between the start and end of radiotherapy was smaller in the high-fiber group (mean ± SD: -3.7 ± 12.8) than in the habitual-fiber group (-10.8 ± 13.5; P = 0.011). At 1-y postradiotherapy (n = 126) the difference in IBDQ-B scores between the high-fiber (+0.1 ± 14.5) and the habitual-fiber (-8.4 ± 13.3) groups was significant (P = 0.004). No significant differences were observed in stool frequency or form or in short-chain fatty acid concentrations. Significant reductions in energy, protein, and fat intake occurred in the low- and habitual-fiber groups only.Conclusions: Dietary advice to follow a high-fiber diet during pelvic radiotherapy resulted in reduced gastrointestinal toxicity both acutely and at 1 y compared with habitual-fiber intake. Restrictive, non-evidence-based advice to reduce fiber intake in this setting should be abandoned. This trial was registered at clinicaltrials.gov as NCT 01170299.

Phosphorylation of XIAP by CDK1-cyclin-B1 controls mitotic cell death.

Regulation of cell death is crucial for the response of cancer cells to drug treatments that cause arrest in mitosis, and is likely to be important for protection against chromosome instability in normal cells. Prolonged mitotic arrest can result in cell death by activation of caspases and the induction of apoptosis. Here, we show that X-linked inhibitor of apoptosis (XIAP) plays a key role in the control of mitotic cell death. Ablation of XIAP expression sensitises cells to prolonged mitotic arrest caused by a microtubule poison. XIAP is stable during mitotic arrest, but its function is controlled through phosphorylation by the mitotic kinase CDK1-cyclin-B1 at S40. Mutation of S40 to a phosphomimetic residue (S40D) inhibits binding to activated effector caspases and abolishes the anti-apoptotic function of XIAP, whereas a non-phosphorylatable mutant (S40A) blocks apoptosis. By performing live-cell imaging, we show that phosphorylation of XIAP reduces the threshold for the onset of cell death in mitosis. This work illustrates that mitotic cell death is a form of apoptosis linked to the progression of mitosis through control by CDK1-cyclin-B1.

Prolonged mitotic arrest induces a caspase-dependent DNA damage response at telomeres that determines cell survival.

A delay in the completion of metaphase induces a stress response that inhibits further cell proliferation or induces apoptosis. This response is thought to protect against genomic instability and is important for the effects of anti-mitotic cancer drugs. Here, we show that mitotic arrest induces a caspase-dependent DNA damage response (DDR) at telomeres in non-apoptotic cells. This pathway is under the control of Mcl-1 and other Bcl-2 family proteins and requires caspase-9, caspase-3/7 and the endonuclease CAD/DFF40. The gradual caspase-dependent loss of the shelterin complex protein TRF2 from telomeres promotes a DDR that involves DNA-dependent protein kinase (DNA-PK). Suppression of mitotic telomere damage by enhanced expression of TRF2, or the inhibition of either caspase-3/7 or DNA-PK during mitotic arrest, promotes subsequent cell survival. Thus, we demonstrate that mitotic stress is characterised by the sub-apoptotic activation of a classical caspase pathway, which promotes telomere deprotection, activates DNA damage signalling, and determines cell fate in response to a prolonged delay in mitosis.