BACKGROUND AND PURPOSE:FAST-Forward showed that 26 Gray (Gy) in 5 fractions (Fr) over one week adjuvant radiotherapy to breast or chest wall was as safe and effective as a three-week schedule (40 Gy/15Fr) for early breast cancer. The nodal sub-study investigated whether a one-week schedule is safe for adjuvant axillary radiotherapy. MATERIALS AND METHODS:In this randomised, non-inferiority, non-blinded sub-study (ISRCTN19906132), patients with invasive breast cancer (pT1-3, pN1-3a, M0) following surgery requiring axillary radiotherapy (any or all levels 1-4) were randomised to 40 Gy/15Fr (three weeks, control), 26 Gy/5Fr or 27 Gy/5Fr (one week) atlas-based radiotherapy planning, including quality assurance. The 27 Gy/5Fr group closed early due to three-year main trial normal tissue effects suggesting 26 Gy/5Fr would be optimal; this analysis focusses on comparison between 26 Gy/5Fr and control. Primary endpoint was five-year patient-reported moderate or marked arm or hand swelling, aiming to exclude a 10 % increase (assuming 10 % incidence with control; 90 % power, one-sided α = 0.05, n = 172 per group). RESULTS:469 patients were randomised from 50 UK centres (182 40 Gy/15Fr, 183 26 Gy/5Fr, 104 27 Gy/5Fr). Median age 61 years; 250 (54 %) and 182 (39 %) had grade 2 and 3 tumours respectively; 261 (56 %) had axillary dissection. Of those who completed a five-year questionnaire, 11/107 (10 %) 40 Gy/15Fr and 13/116 (11 %) 26 Gy/5Fr reported moderate or marked arm or hand swelling, difference 1 % (90 % confidence interval -6%, 8 %, p = 0.49). Other arm and shoulder symptoms were similar between groups with no cases of brachial plexopathy. CONCLUSION:Five-year patient-reported normal tissue effects suggest 26 Gy/5Fr/1-week hypofractionation is safe for breast cancer patients requiring adjuvant axillary radiotherapy.

BACKGROUND:The IMPORT LOW trial evaluated partial-breast radiotherapy with intensity-modulated radiotherapy in women with early-stage breast cancer at below average risk of ipsilateral breast tumour recurrence (IBTR). 5-year results concluded non-inferiority of IBTR for reduced-dose and partial-breast radiotherapy, with similar or lower frequency of adverse effects compared with whole-breast radiotherapy. We report outcomes after 10 years. METHODS:IMPORT LOW was a randomised, open-label, multicentre, non-inferiority, phase 3 trial. Women were eligible if they were aged 50 years or older and had had breast conservation surgery for unifocal invasive ductal adenocarcinoma, pT1-2 (tumour size of ≤3 cm), N0-1 (none to three positive axillary nodes), grades 1-3, with microscopic margins of non-cancerous tissue of 2 mm or more. Patients were ineligible if they had a previous malignancy of any kind (except non-melanomatous skin cancer), had undergone mastectomy, or had received neoadjuvant or concurrent adjuvant chemotherapy. Patients were randomly assigned (1:1:1) by randomly permuted blocks to radiotherapy regimens of 40 Gy in 15 fractions to the whole breast (whole-breast group), 36 Gy in 15 fractions to the whole breast plus 40 Gy in 15 fractions to the partial breast (reduced-dose group), or 40 Gy in 15 fractions to the partial breast (partial-breast group). Participants were stratified by treatment centre, without masking. The primary endpoint was IBTR. 10-year outcomes were analysed in the intention-to-treat population. Clinician-reported late adverse effects were evaluated in all participants with available data analysed according to allocated treatment. The study is registered in the ISRCTN registry (ISRCTN12852634) and is now complete. FINDINGS:2018 patients were recruited between May 3, 2007, and Oct 5, 2010, from 30 radiotherapy centres in the UK and randomly assigned to the whole-breast group (n=675), reduced-dose group (n=674), or partial-breast group (n=669). Two participants subsequently withdrew consent. Median age was 63 years (IQR 58-68). 854 (42%) of 2016 patients had grade 1 tumours, 959 (48%) had grade 2 tumours, and 200 (10%) had grade 3 tumours (three tumours were ungradable); 59 (3%) had node-positive disease. Median follow-up was 120 months (IQR 119-122) for the whole-breast group, 121 months (IQR 120-122) for the reduced-dose group, and 120 months (IQR 119-122) for the partial-breast group. By 10 years, IBTR events were reported for 45 of 2016 participants: 17 of 674 in the whole-breast group, 11 of 673 in the reduced-dose group, and 17 of 669 in the partial-breast group, with cumulative incidence of 2·8% (95% CI 1·8-4·5), 1·9% (1·1-3·5), and 3·0% (1·9-4·8), respectively. The estimated absolute difference in 10-year IBTR incidence was -1·02% (95% CI -1·98 to 0·99) for the reduced-dose group and 0·16% (-1·28 to 2·89) for the partial-breast group compared with the whole-breast group. Similar low levels of moderate or marked adverse effects were recorded for participants in all three groups in 10-year clinical assessments. Breast shrinkage had the highest incidence (30 [9%] of 321 in the whole-breast group, 28 [9%] of 322 in the reduced-dose group, and 22 [7%] of 333 in the partial-breast group). INTERPRETATION:Long-term follow-up provides further evidence that partial-breast and reduced-dose radiotherapy are as safe and effective as whole-breast radiotherapy in patients with low-risk early breast cancer. These results reaffirm the use of partial-breast radiotherapy delivered with intensity-modulated radiotherapy in this population as standard of care. FUNDING:Cancer Research UK.

Male sex is associated with worse outcome in acute myeloid leukemia (AML) in many studies. We analyzed the survival of 4281 patients treated with intensive chemotherapy in the AML17 and AML19 trials based on sex. Men had a significantly lower remission rate than women. Men had a higher incidence of adverse cytogenetic features and a lower incidence of the relatively favorable NPM1 mutation. However, male sex was an independent risk factor for survival in multi-variate analysis. We hypothesized that androgen signaling in men could worsen outcomes by protecting AML cells from chemotherapy. We demonstrated high levels of androgen receptor (AR) expression in AML across cytogenetic risk groups. We showed the AR expression was induced by IL-6 signaling in vitro and correlates with poor overall survival. Androgens had no effect on survival of primary AML cells in vitro, nor did they impact gene expression. Androgens did not protect AML cells against chemotherapy either in vitro or in vivo. Similar results were observed with estrogen signaling through estrogen receptor in vitro in AML cells. In conclusion, targeting the androgen pathway may not be a promising clinical strategy and sex hormone signaling in AML cells does not explain the poorer outcomes of men.

BACKGROUND AND OBJECTIVE:Some metastatic castration-resistant prostate cancers (mCRPCs) present mismatch repair deficiency (MMRd) and other molecular subtypes potentially sensitive to immune checkpoint inhibitors (ICIs). The PERSEUS1 trial evaluated the response to pembrolizumab in these subtypes. METHODS:This open-label, investigator-initiated, single-arm, phase 2 trial used a two-stage Simon minimax design. Results from stage 1 are presented here. Tumour biopsies from patients with mCRPC progressing on standard therapies were analysed via targeted next-generation sequencing and immunohistochemistry. Patients with MMRd and/or other molecular subtypes associated with ICI sensitivity were treated with pembrolizumab until disease progression or unacceptable toxicity. The primary outcome was response by 24 wk using a composite of radiological objective response; confirmed decrease in prostate-specific antigen ≥50%; or conversion of circulating tumour cell count. The hypothesised desirable response rate was 40%, with 20% deemed unacceptable; >5/24 responses were required for progression to stage 2. KEY FINDINGS AND LIMITATIONS:In total, 25 patients from two centres received a median of 6 cycles (range 2-13) of pembrolizumab, with a response observed in seven (28.0%, 95% confidence interval 12.1-49.4%). Median progression-free survival was 2.8 mo and median overall survival was 16.0 mo. Nineteen patients (76%) experienced treatment-related adverse events, including three (12%) grade 3-4 events. There were no treatment-related deaths. While the prespecified threshold for futility was not met, slow accrual meant the study did not progress to stage 2. CONCLUSIONS AND CLINICAL IMPLICATIONS:Pembrolizumab showed antitumour activity against MMRd and/or other mCRPC molecular subtypes, with a manageable toxicity profile. Genomic and molecular stratification and further translational research are needed to refine patient selection for this therapy in the mCRPC setting.

AimsTo resolve the ongoing controversy surrounding the impact of teratoma (TER) in the primary among patients with metastatic testicular non-seminomatous germ-cell tumours (NSGCT).Patients and methodsUsing the International Germ Cell Cancer Collaborative Group (IGCCCG) Update Consortium database, we compared the survival probabilities of patients with metastatic testicular GCT with TER (TER) or without TER (NTER) in their primaries corrected for known prognostic factors. Progression-free survival (5y-PFS) and overall survival at 5 years (5y-OS) were estimated by the Kaplan-Meier method.ResultsAmong 6792 patients with metastatic testicular NSGCT, 3224 (47%) had TER in their primary, and 3568 (53%) did not. In the IGCCCG good prognosis group, the 5y-PFS was 87.8% in TER versus 92.0% in NTER patients (p = 0.0001), the respective 5y-OS were 94.5% versus 96.5% (p = 0.0032). The corresponding figures in the intermediate prognosis group were 5y-PFS 76.9% versus 81.6% (p = 0.0432) in TER and NTER and 5y-OS 90.4% versus 90.9% (p = 0.8514), respectively. In the poor prognosis group, there was no difference, neither in 5y-PFS [54.3% in TER patients versus 55.4% (p = 0.7472) in NTER], nor in 5y-OS [69.4% versus 67.7% (p = 0.3841)]. NSGCT patients with TER had more residual masses (65.3% versus 51.7%, p < 0.0001), and therefore received post-chemotherapy surgery more frequently than NTER patients (46.8% versus 32.0%, p < 0.0001).ConclusionTeratoma in the primary tumour of patients with metastatic NSGCT negatively impacts on survival in the good and intermediate, but not in the poor IGCCCG prognostic groups.

138 Background: Immunotherapy is an ineffective approach in molecularly unselected mCRPC, and improving patient selection for targeted treatment in this setting is an unmet medical need. We evaluated the antitumour activity of pembrolizumab in a subset of molecularly selected mCRPC with putative phenotypes associated with immunotherapy sensitivity. Methods: PERSEUS1 (NCT03506997) is a multicentre, open-label, single arm, phase II trial in patients suffering from mCRPC progressive on at least one approved treatment for mCRPC, and who had at least one of the following molecular profiles: mismatch repair deficiency (MMRd); bi-allelic CDK12 loss; high microsatellite instability with either MMRd, a high CD3 count, or high mutational load (HIMUT); HIMUT with high CD3 or a deleterious mutation in a DNA repair gene; or DNA repair defects with high CD3. Patients were treated with pembrolizumab 200mg intravenously every 3 weeks until progression, unacceptable toxicity, or 2 years. The primary endpoint was composite response rate by 24-weeks based on either: iRECIST, circulating tumour cell (CTC) count conversion from ≥5 to <5/7.5ml, or PSA decline ≥50%. The trial used a two-stage Simon Minimax design; H a =40%, H 0 =20%. We report stage 1, with target n=24 participants and >5 responses required to warrant progression to stage 2. Progression-free survival (PFS), overall survival (OS) and safety using CTCAE v4.0 were secondary endpoints. Results: From Nov-2018 to May-2023, 25 participants were enrolled, with 24 reaching response-evaluability. Median follow-up was 28.4 months. Median age of evaluable patients was 69 years, and patients had received 1-4 previous lines of treatment. Participants received a median of 6 cycles of pembrolizumab (range 2–13). Seven out of 24 patients (29.2%) had a composite response by 24 weeks (95% CI 12.6%-51.1%). Responses according to iRECIST, CTC and PSA criteria were 3/24 (12.5%), 3/24 (12.5%) and 4/24 (16.7%) respectively. Median PFS was 4.2 months (95% CI 3.0–8.3). Median OS was 14.5 months (95% CI 9.9–18.4). Of the 3 radiological responses, 2 patients were MMRd, including one with complete metabolic response (iRECIST partial response (PR); 49 months, ongoing) and another with PR (8.3 months PFS). Eight patients (33.3%) experienced grade 3-4 toxicity. This led to discontinuation in two patients: one (patient with complete metabolic response) with immunotherapy-induced colitis, and another with immune-related myocarditis and pneumonitis. Conclusions: Pembrolizumab showed prolonged antitumour activity against a subset of molecularly selected mCRPC. Although the analysis met the pre-specified threshold of composite response criteria, due to slow accrual and modest clinical relevance in most responders, it was decided not to continue to stage 2 of the trial. Clinical trial information: NCT03506997 .

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.POUT was a phase III, randomized, open-label trial, including 261 patients with muscle-invasive or lymph node-positive, nonmetastatic upper tract urothelial cancer (UTUC) randomly assigned after radical nephroureterectomy to platinum-based chemotherapy (132) or surveillance (129). Primary outcome analysis demonstrated that chemotherapy improved disease-free survival (DFS). At that time, the planned secondary outcome analysis of overall survival (OS) was immature. By February 2022, 50 and 67 DFS events had occurred in the chemotherapy and surveillance groups, respectively, at a median follow-up of 65 months. The 5-year DFS was 62% versus 45%, univariable hazard ratio (HR), 0.55 (95% CI, 0.38 to 0.80, P = .001). The restricted mean survival time (RMST) was 18 months longer (95% CI, 6 to 30) in the chemotherapy arm. There were 46 and 60 deaths in the chemotherapy and control arms, respectively. The 5-year OS was 66% versus 57%, with univariable HR, 0.68 (95% CI, 0.46 to 1.00, P = .049) and RMST difference 11 months (95% CI, 1 to 21). Treatment effects were consistent across chemotherapy regimens (carboplatin or cisplatin) and disease stage. Toxicities were similar to those previously reported, and there were no clinically relevant differences in quality of life between arms. In summary, although OS was not the primary outcome measure, the updated results add further support for the use of adjuvant chemotherapy in patients with UTUC, suggesting long-term benefits.

The management of axillary lymph nodes in breast cancer is continually evolving. Recent data now support omitting axillary lymph node dissection (ALND) in most patients with metastases in up to two sentinel lymph nodes (SLNs) during upfront surgery and those with residual isolated tumor cells after neoadjuvant chemotherapy (NACT). In the upfront surgery setting, ALND is still indicated, however, in patients with clinically node-positive breast cancer or more than two positive SLNs and, after NACT, in case of residual micrometastases and macrometastases. Omission of the sentinel lymph node biopsy (SLNB) can be considered in many postmenopausal patients with small luminal breast cancer, particularly when axillary ultrasound is negative. Several randomized controlled trials (RCTs) are currently aiming at eliminating the remaining indications for ALND and also establishing omission of SLNB in a broader patient population. The movement to deescalate axillary staging is in part because of the association between ALND and lymphedema, which is swelling of an extremity because of lymphatic damage and obstructed lymphatic drainage. To reduce the risk of developing this condition, patients undergoing ALND can undergo reverse mapping of the axilla and immediate reconstruction or bypass of the lymphatics from the involved extremity. Decongestion and compression are the foundation of conservative treatment for established lymphedema, while lymphovenous bypass and lymph node transfer are surgical procedures to address the physiologic dysfunction. Radiotherapy is an essential component of breast locoregional therapy: more than three decades of radiation research has optimized treatment according to patient's risk of local recurrence while substantially reducing the number of treatment visits. High-quality RCTs have shown the efficacy and safety of hypofractionation-more than 2Gy radiation dose per treatment (fraction)-significantly reducing the burden of radiotherapy treatment for many patients with breast cancer. In 2024, guidelines recommend no more than 15-16 fractions for whole-breast and nodal radiotherapy, with some recommending five fractions for whole-breast radiotherapy. In addition, simultaneous integrated boost (SIB) has been shown to be noninferior to sequential boost with regards to ipsilateral breast tumor recurrence with similar or reduced long-term side effects, also reducing overall treatment length. Further RCTs are underway investigating other indications for five fractions, including SIB and regional node irradiation, such that, in future, it may be possible for the majority of breast radiotherapy patients to be treated with a 1-week course. This manuscript serves to outline the latest updates on axillary surgical staging, lymphatic surgery, and evidence-based radiotherapy in the treatment of breast cancer.

Background The presence of germline mutations plays an increasingly important role in risk assessment and treatment of prostate cancer (PrCa). Screening for high-risk mutations in subsets of patients is becoming routine. We explore the prevalence of germline genetic mutations in men with metastatic castration-resistant prostate cancer (mCRPC) recruited to the BARCODE2 trial. Methods The BARCODE2 trial is a two-part study investigating the response to carboplatin chemotherapy in mCRPC patients carrying a germline variant in a DNA repair gene (DRG). We report interim data from Part 1, in which participants are recruited for germline genetic testing using a customised next-generation sequencing panel consisting of 115 genes. Results These interim results ( N = 220) demonstrate a similar frequency of germline DRG variants in mCRPC patients compared with previously published data (15% detection rate). No significant clinical differences were identified between all carriers and non-carriers, though BRCA2/ATM carriers were found to have a shorter time to mCRPC diagnosis. Conclusions Germline pathogenic/likely pathogenic (P/LP) variants in BRCA2 and ATM genes are associated with a shorter time to progression and rarer P/LP variants in other DRG genes may play a role in mCRPC. This justifies the use of routine screening of men with advanced PrCa for germline variants and supports the need for an expanded panel test.

501 Background: Prognosis in stage I seminoma is excellent. Most patients are cured by orchiectomy and, for the 15%-20% that relapse, salvage treatment is generally successful (survival approaching 100%). Relapse risk is reduced with adjuvant carboplatin but may unnecessarily expose young patients to long-term health risks. Effective and reliable risk stratification could guide use of adjuvant treatment and potentially reduce intensity of surveillance for the lowest risk patients. We used data from a UK multicentre, phase III trial to evaluate prognostic factors for relapse in stage I seminoma, including validation of a recently proposed model from the European Association of Urology (EAU)(1). Methods: TRISST used a randomised, factorial design to evaluate imaging schedules (3 vs 7 scans) and modality (MRI vs CT) in surveillance for men who had undergone orchidectomy for stage I seminoma (n=669). In this secondary analysis, model selection was used to fit a multivariable Cox regression to TRISST data to investigate factors predicting time to relapse, including: age, tumour mass size, rete testis invasion (RTI), T stage, lymphovascular invasion (LVI), side of tumour, and tumour markers (LDH, β-HCG). The final model was used to divide the cohort into risk groups. Relapse risk was also estimated according to EAU prognostic groups. Harrell’s C-index was used to measure model fit. Results: Based on TRISST data, tumour size ≥4cm and pT3 disease were associated with the highest risk (multivariable hazard ratio for ≥4cm vs <2cm: HR=4.00, 95% confidence interval 2.00-8.01; pT3 vs pT1: HR=3.89, 1.77-8.57). Patients with one or both of these features (24% of the cohort) had 5-year relapse rate of 22.0%. Medium risk (age<30 years and/or 2-4cm and/or pT2) and low risk (age≥30 years, <2cm and pT1) groups had 5-year relapse rates 12.0% and 2.3% respectively. The EAU model was a good fit to the TRISST data (C-index=0.62); 66%, 33% and 2% fell into the very low, low and high-risk EAU groups respectively with 5-year relapse rates of 10.1%, 16.1% and 45.5%. Conclusions: In stage I seminoma, relapse risk in patients managed with surveillance following orchiectomy is low for the majority of patients. Tumour size is consistently shown to be the best predictor of relapse. The EAU prognostic model, validated here, identifies a small group (>5cm, with RTI and LVI) with particularly high risk who may benefit from adjuvant therapy. Reference: 1. Boormans J, et al. Journal of Clinical Oncology 2023; 41 (6_suppl): 410. Clinical trial information: ISRCTN65987321 .

408 Background: Risk of radiation exposure from standard computed tomography (CT) surveillance is a major concern in the management of stage I seminoma testis patients. The TRISST randomized trial (NCT00589537) demonstrated that effective monitoring could be achieved with a reduced scan schedule or using Magnetic Resonance Imaging (MRI) instead of CT. Here, TRISST data is used to evaluate the economic consequences and health outcomes of different surveillance schedules in seminoma patients in the UK. Methods: 669 men were randomized to 4 surveillance groups undergoing 7 CTs over 5 years, 3 CTs over 3 years, 7 MRIs, or 3 MRIs of the retroperitoneum. Resource use (including investigations, scans, hospitalisations and treatment for relapse) and health outcomes data (EQ-5D 3L) on each patient were collected at baseline and over a period of 6 years after randomization. Health resources were costed using publicly available national unit costs. Within-trial mean total costs and quality-adjusted life years (QALYs) were estimated for each alternative schedule. Under the perspective of the UK health system, cost-effectiveness was evaluated using a cost per QALY gained framework. Probabilistic sensitivity analysis was used to reflect parameter uncertainty and evaluate results robustness. Results: Since only 82 men (12%) relapsed, most health resource consumption (76%) happened during the disease-free period. Patients undergoing 7 MRIs yielded, on average, slightly higher health benefits (5.20 QALYs) but at higher costs (GBP £6,632, see table). Compared to 7 CTs, 7 MRIs was estimated to have 63% probability of being cost-effective at a system willingness to pay threshold of £20k/QALY. 3 MRIs had similar costs and benefit to 7 CTs, whereas 3CTs was more expensive than 7 CTs and 3 MRIs, providing marginal additional benefits. Conclusions: Overall, small differences exist in total costs and total QALYs between different strategies. A 7 scan MRI schedule yielded more health benefits than other strategies, but at higher costs. Considering possible capacity constraints with MRI, the reduced radiation exposure relative to CT, and non-inferiority for clinical outcomes in the primary analysis, a 3 scan MRI schedule may be the best option to replace current CT-based longer surveillance practice. Clinical trial information: NCT00589537 . [Table: see text]

Background Pre-clinical models demonstrate that platelet activation is involved in the spread of malignancy. Ongoing clinical trials are assessing whether aspirin, which inhibits platelet activation, can prevent or delay metastases. Methods Urinary 11-dehydro-thromboxane B 2 (U-TXM), a biomarker of in vivo platelet activation, was measured after radical cancer therapy and correlated with patient demographics, tumour type, recent treatment, and aspirin use (100 mg, 300 mg or placebo daily) using multivariable linear regression models with log-transformed values. Results In total, 716 patients (breast 260, colorectal 192, gastro-oesophageal 53, prostate 211) median age 61 years, 50% male were studied. Baseline median U-TXM were breast 782; colorectal 1060; gastro-oesophageal 1675 and prostate 826 pg/mg creatinine; higher than healthy individuals (~500 pg/mg creatinine). Higher levels were associated with raised body mass index, inflammatory markers, and in the colorectal and gastro-oesophageal participants compared to breast participants ( P < 0.001) independent of other baseline characteristics. Aspirin 100 mg daily decreased U-TXM similarly across all tumour types (median reductions: 77–82%). Aspirin 300 mg daily provided no additional suppression of U-TXM compared with 100 mg. Conclusions Persistently increased thromboxane biosynthesis was detected after radical cancer therapy, particularly in colorectal and gastro-oesophageal patients. Thromboxane biosynthesis should be explored further as a biomarker of active malignancy and may identify patients likely to benefit from aspirin.

PURPOSE Survival in stage I seminoma is almost 100%. Computed tomography (CT) surveillance is an international standard of care, avoiding adjuvant therapy. In this young population, minimizing irradiation is vital. The Trial of Imaging and Surveillance in Seminoma Testis (TRISST) assessed whether magnetic resonance images (MRIs) or a reduced scan schedule could be used without an unacceptable increase in advanced relapses. METHODS A phase III, noninferiority, factorial trial. Eligible participants had undergone orchiectomy for stage I seminoma with no adjuvant therapy planned. Random assignment was to seven CTs (6, 12, 18, 24, 36, 48, and 60 months); seven MRIs (same schedule); three CTs (6, 18, and 36 months); or three MRIs. The primary outcome was 6-year incidence of Royal Marsden Hospital stage ≥ IIC relapse (> 5 cm), aiming to exclude increases ≥ 5.7% (from 5.7% to 11.4%) with MRI ( v CT) or three scans ( v 7); target N = 660, all contributing to both comparisons. Secondary outcomes include relapse ≥ 3 cm, disease-free survival, and overall survival. Intention-to-treat and per-protocol analyses were performed. RESULTS Six hundred sixty-nine patients enrolled (35 UK centers, 2008-2014); mean tumor size was 2.9 cm, and 358 (54%) were low risk (< 4 cm, no rete testis invasion). With a median follow-up of 72 months, 82 (12%) relapsed. Stage ≥ IIC relapse was rare (10 events). Although statistically noninferior, more events occurred with three scans (nine, 2.8%) versus seven scans (one, 0.3%): 2.5% absolute increase, 90% CI (1.0 to 4.1). Only 4/9 could have potentially been detected earlier with seven scans. Noninferiority of MRI versus CT was also shown; fewer events occurred with MRI (two [0.6%] v eight [2.6%]), 1.9% decrease (–3.5 to –0.3). Per-protocol analyses confirmed noninferiority. Five-year survival was 99%, with no tumor-related deaths. CONCLUSION Surveillance is a safe management approach—advanced relapse is rare, salvage treatment successful, and outcomes excellent, regardless of imaging frequency or modality. MRI can be recommended to reduce irradiation; and no adverse impact on long-term outcomes was seen with a reduced schedule.

Background Late-phase platform protocols (including basket, umbrella, multi-arm multi-stage (MAMS), and master protocols) are generally agreed to be more efficient than traditional two-arm clinical trial designs but are not extensively used. We have gathered the experience of running a number of successful platform protocols together to present some operational recommendations. Methods Representatives of six UK clinical trials units with experience in running late-phase platform protocols attended a 1-day meeting structured to discuss various practical aspects of running these trials. We report and give guidance on operational aspects which are either harder to implement compared to a traditional late-phase trial or are specific to platform protocols. Results We present a list of practical recommendations for trialists intending to design and conduct late-phase platform protocols. Our recommendations cover the entire life cycle of a platform trial: from protocol development, obtaining funding, and trial set-up, to a wide range of operational and regulatory aspects such as staffing, oversight, data handling, and data management, to the reporting of results, with a particular focus on communication with trial participants and stakeholders as well as public and patient involvement. Discussion Platform protocols enable many questions to be answered efficiently to the benefit of patients. Our practical lessons from running platform trials will support trial teams in learning how to run these trials more effectively and efficiently.

Monitoring with regular computed tomography (CT) is an effective means of identifying relapse in patients treated for stage I seminoma testis; however, risks of radiation exposure are a major concern in these young patients, many of whom won't relapse. The TRISST randomized trial assessed whether a reduced CT or Magnetic Resonance Imaging (MRI) schedule could be effective alternatives to standard CT-based surveillance. It found that fewer CTs or MRIs were non-inferior in terms of clinical outcomes. This study used the TRISST trial data to evaluate the health care resource consequences and health-related quality-of-life of different surveillance strategies in patients with seminoma testicular cancer in the UK.