Perspectives and Concerns on Late Effects Regarding Sexuality among Adolescents and Young Adults Treated for Testicular Germ Cell Tumor: The PRICELESS-Study-A Qualitative Study.

This study aimed to explore perspectives and concerns regarding sexuality among adolescents and young adults (AYAs) possibly experiencing late effects after testicular germ cell tumor (TGCT) treatment. A qualitative study was performed in which semi-structured interviews were held with thirteen AYAs from a center of expertise for TGCT in the Netherlands. Data were analyzed using Braun and Clark's thematic analysis method. Seven interacting and interconnected themes were found: desire to have children, rediscovering sexuality, insecurity about sexual performance, acceptance of physical change, loss of masculinity, burden on relationship, and openness in discussing sexuality. Concerns about the desire to have children seem to play a significant role. In conclusion, TGCT patients face multiple changes (physical, emotional, relational, and sexual), followed by a difficult period of acceptance, after which a new phase of rediscovering sexuality appeared. These findings can help to make healthcare professionals aware of the underlying mechanisms and concerns about sexuality. Furthermore, insights can help to develop sexuality-themed items for a broader monitoring tool to structurally assess the late effects to support discussing sexuality.

Treatment Patterns and Use of Immune Checkpoint Inhibitors Among Patients with Metastatic Bladder Cancer in a Dutch Nationwide Cohort.

Since 2017, two immune checkpoint inhibitors (ICIs) have become the standard of care for the treatment of metastatic urothelial carcinoma in Europe: pembrolizumab as second-line therapy and avelumab as maintenance therapy. Our aim was to describe the use of ICIs as first and later lines of treatment in patients with metastatic bladder cancer (mBC) in the Netherlands. We identified all patients diagnosed with primary mBC between 2018 and 2021 in the Netherlands from the Netherlands Cancer Registry (NCR). NCR data were supplemented with data from the Dutch nationwide Prospective Bladder Cancer Infrastructure (ProBCI) collected from medical files, with follow-up until death or end of data collection on January 1, 2023. A total of 1525 patients were diagnosed with primary mBC between 2018 and 2021 in the Netherlands. Of these, 34.7% received at least one line of systemic treatment with chemotherapy or ICI. After first-line platinum-based chemotherapy, 34.1% received second-line ICI and 3.9% received maintenance ICI. Among patients who completed or discontinued first-line cisplatin- or carboplatin-based chemotherapy after approval of maintenance ICI in the Netherlands, 40.7% and 19.7% received second-line ICI, and 9.3% and 14.1% received maintenance ICI, respectively. ICI use for mBC treatment has not increased considerably since their introduction in 2017. Future research should assess whether the introduction of maintenance avelumab (available since April 2021 in the Netherlands) has led to increases in the proportion of patients with mBC patients receiving systemic treatment and the proportion receiving ICI. Patient summary: We assessed the rate of immunotherapy use for patients with metastatic bladder cancer in the Netherlands. Since its introduction, immunotherapy has been used in a minority of patients, mostly as second-line treatment after platinum-based chemotherapy.

Prevalence of neoplasia at colonoscopy among testicular cancer survivors treated with platinum-based chemotherapy.

Testicular cancer survivors (TCS) treated with platinum-based chemotherapy have an increased risk of colorectal cancer (CRC). We determined the yield of colonoscopy in TCS to assess its potential in reducing CRC incidence and mortality. We conducted a colonoscopy screening study among TCS in four Dutch hospitals to assess the yield of colorectal neoplasia. Neoplasia was defined as adenomas, serrated polyps (SPs), advanced adenomas (AAs: ≥10 mm diameter, high-grade dysplasia or ≥25% villous component), advanced serrated polyps (ASPs: ≥10 mm diameter or dysplasia) or CRC. Advanced neoplasia (AN) was defined as AA, ASP or CRC. Colonoscopy yield was compared to average-risk American males who underwent screening colonoscopy (n = 24,193) using a propensity score matched analysis, adjusted for age, smoking status, alcohol consumption and body mass index. A total of 137 TCS underwent colonoscopy. Median age was 50 years among TCS (IQR 43-57) vs 55 years (IQR 51-62) among American controls. A total of 126 TCS were matched to 602 controls. The prevalence of AN was higher in TCS than in controls (8.7% vs 1.7%; P = .0002). Nonadvanced adenomas and SPs were detected in 45.2% of TCS vs 5.5% of controls (P < .0001). No lesions were detected in 46.0% of TCS vs 92.9% of controls (P < .0001). TCS treated with platinum-based chemotherapy have a higher prevalence of neoplasia and AN than matched controls. These results support our hypothesis that platinum-based chemotherapy increases the risk of colorectal neoplasia in TCS. Cost-effectiveness studies are warranted to ascertain the threshold of AN prevalence that justifies the recommendation of colonoscopy for TCS.

[Breast cancer during pregnancy and the postpartum period: challenging diagnosis of an aggressive disease]. / Borstkanker tijdens en na de zwangerschap.

Breast cancer is the most common malignancy diagnosed during pregnancy. Breast cancer during pregnancy or within the first postpartum year is commonly described as Pregnancy-Associated Breast Cancer (PABC). PABC often exhibits poorer histopathologic features and has a worse prognosis when compared to young breast cancer patients without a current or recent pregnancy. Here, we describe two cases of PABC in which the presenting symptoms of the patients were interpreted as pregnancy-related changes, causing a diagnostic delay. Therefore, we argue that every pregnant or postpartum woman with changes in the breast must be thoroughly evaluated to exclude the possibility of a malignancy. In case of any suspicion, patients must be referred to a breast cancer center for further evaluation.

From Surviving Cancer to Getting on With Life: Adult Testicular Germ Cell Tumor Survivors' Perspectives on Transition From Follow-Up Care to Long-Term Survivorship.

With an increasing incidence and a high cure rate, a growing number of testicular germ cell tumor (TGCT) survivors require specialized follow-up care. However, knowledge of these patients' needs is lacking, leaving TGCT survivors with unmet care needs at risk of symptom burden when transitioning to long-term survivorship. This grounded theory study aimed to understand the perspectives of TGCT survivors' transition from follow-up care to long-term survivorship. A total of 12 adult TGCT survivors in follow-up care or completion less than a year were in-depth semi-structured interviewed. Interviews were audiotaped and transcribed verbatim. Transcripts were analyzed by constant comparison, and the core category "Dealing with back-and-forth forces" emerged in the integrated concepts. Two comparative processes in dealing with those forces were identified: the process of Living beyond the sword of Damocles involved the transition from feeling threatened by cancer to overcoming those threats; the process of Getting on with one's life can be described as transitioning from a period where cancer overruled their lives to carrying on with everyday life. The processes toward long-term survivorship follow general characteristics; the transition itself is an individual journey that depends on (life) experiences. The constructed model can guide healthcare professionals and researchers involved in TGCT survivorship to understand TGCT survivors' individual and ensuing needs. When TGCT survivors receive individualized and tailored follow-up care, it can assist in preventing and reducing long-term and late effects on long-term survivorship.

The prevalence and intensity of late effects in patients with testicular germ cell tumors: A first step of instrument development using a stepwise approach.

PURPOSE: Patients with Testicular Germ Cell Tumors (TGCT) may suffer from several late effects due to their diagnosis or treatment. Follow-up care aims to identify the recurrence of cancer and support patients with TGCT in their experienced late effects. In the Netherlands, the validated Dutch version of the Edmonton Symptom Assessment System, Utrecht Symptom Diary (USD) is used to assess and monitor patient reported symptoms. As a first step to develop a specific USD module for TGCT-patients, it was necessary to identify the prevalence and intensity of late effects in patients with TGCT, covering the physical, social, psychical and existential domains of care. METHODS: A cross-sectional study was conducted. First, literature was systematically assessed to create a comprehensive list of symptoms. This generated list was reviewed by expert healthcare professionals and the research group. Lastly, a survey was distributed amongst patients with TGCT in follow-up care in the University Medical Center Utrecht (UMCU) outpatient clinic. RESULTS: In total, 65 TGCT-patients completed the survey. All described late effects were recognized by TGCT-patients, with 'fatigue', 'disturbed overall well-being', 'concentration problems' and 'neuropathy', indicated as most prevalent and scored with highest intensity. When prioritizing these late effects, patients assigned 'neuropathy' as most important. CONCLUSIONS: This study provided insight into prevalence and intensity of late effects, as indicated by TGCT-patients. In clinical practice, follow-up care can improve by empowering patients to discuss important items in daily life with their health-care professionals.

High- or low-dose preoperative ipilimumab plus nivolumab in stage III urothelial cancer: the phase 1B NABUCCO trial.

Cohort 1 of the phase 1B NABUCCO trial showed high pathological complete response (pCR) rates with preoperative ipilimumab plus nivolumab in stage III urothelial cancer (UC). In cohort 2, the aim was dose adjustment to optimize responses. Additionally, we report secondary endpoints, including efficacy and tolerability, in cohort 2 and the association of presurgical absence of circulating tumor DNA (ctDNA) in urine and plasma with clinical outcome in both cohorts. Thirty patients received two cycles of either ipilimumab 3 mg kg-1 plus nivolumab 1 mg kg-1 (cohort 2A) or ipilimumab 1 mg kg-1 plus nivolumab 3 mg kg-1 (cohort 2B), both followed by nivolumab 3 mg kg-1. We observed a pCR in six (43%) patients in cohort 2A and a pCR in one (7%) patient in cohort 2B. Absence of urinary ctDNA correlated with pCR in the bladder (ypT0Nx) but not with progression-free survival (PFS). Absence of plasma ctDNA correlated with pCR (odds ratio: 45.0; 95% confidence interval (CI): 4.9-416.5) and PFS (hazard ratio: 10.4; 95% CI: 2.9-37.5). Our data suggest that high-dose ipilimumab plus nivolumab is required in stage III UC and that absence of ctDNA in plasma can predict PFS. ClinicalTrials.gov registration: NCT03387761 .

Comparison between de novo and metachronous metastatic breast cancer: the presence of a primary tumour is not the only difference-a Dutch population-based study from 2008 to 2018.

PURPOSE: The aim of this study was to compare characteristics and survival of patients with de novo and metachronous metastatic breast cancer. METHODS: Data of patients with metastatic breast cancer were obtained from the Netherlands Cancer Registry. Patients were categorized as having de novo metastatic breast cancer (n = 8656) if they had distant metastases at initial presentation, or metachronous metastatic disease (n = 2374) in case they developed metastases within 5 or 10 years after initial breast cancer diagnosis. Clinicopathological characteristics and treatments of these two groups were compared, after which multiple imputation was performed to account for missing data. Overall survival was compared for patients treated with systemic therapy in the metastatic setting, using Kaplan Meier curves and multivariable Cox proportional hazards models. The hazard ratio for overall survival of de novo versus metachronous metastases was assessed accounting for time-varying effects. RESULTS: Compared to metachronous patients, patients with de novo metastatic breast cancer were more likely to be ≥ 70 years, to have invasive lobular carcinoma, clinical T3 or T4 tumours, loco-regional lymph node metastases, HER2 positivity, bone only disease and to have received systemic therapy in the metastatic setting. They were less likely to have triple negative tumours and liver or brain metastases. Patients with de novo metastases survived longer (median 34.7 months) than patients with metachronous metastases (median 24.3 months) and the hazard ratio (0.75) varied over time. CONCLUSIONS: Differences in clinicopathological characteristics and survival between de novo and metachronous metastatic breast cancer highlight that these are distinct patients groups.

Hematologic malignancies following immune checkpoint inhibition for solid tumors.

Immune checkpoint inhibition (ICI) can induce durable responses in patients with advanced malignancies. Three cases of hematological neoplasia following ICI for solid tumors have been reported to date. We present five patients treated at our tertiary referral center between 2017 and 2021 who developed chronic myeloid leukemia (two patients), acute myeloid leukemia, myelodysplastic syndrome and chronic eosinophilic leukemia during or after anti-PD-1-based treatment. Molecular analyses were performed on pre-ICI samples to identify baseline variants in myeloid genes. We hypothesize that PD-1 blockade might accelerate progression to overt myeloid malignancies and discuss potential underlying mechanisms.

Interlaboratory Gleason grading variation affects treatment: a Dutch historic cohort study in 30 509 patients with prostate cancer.

AIM: Substantial variation in Gleason grading (GG) of prostate cancer (PCa) exists between Dutch pathology laboratories. This study investigates its impact on treatment strategies. METHODS: Pathology reports of prostate needle biopsies and clinical data of patients with PCa diagnosed between 2017 and 2019 were retrieved from the Dutch nationwide network and registry of histopathology and cytopathology and The Netherlands Cancer Registry. We investigated the impact of grading variation on treatment strategy for patients whose grade was decisive in treatment choice. First, we evaluated the effect of grading practice (low, average or high grading) on active treatment (AT) versus active surveillance in patients with prostate-specific antigen (PSA) <10 ng/mL and cT1c/cT2a disease. Second, we assessed the association of grading practice with performance of pelvic lymph node dissection (PLND) in patients with PSA 10-20 ng/mL or cT2b disease. We used multivariable logistic regression to analyse the relation between laboratories' grading practices and AT or PLND. RESULTS: We included 30 509 patients. GG was decisive in treatment strategy for 11 925 patients (39%). AT was performed significantly less often in patients diagnosed by laboratories that graded lower than average (OR=0.77, 95% CI 0.68 to 0.88). Conversely, patients received AT significantly more often when diagnosed in high-grading laboratories versus average-grading laboratories (OR=1.21, 95% CI 1.03 to1.43). PLND was performed significantly less often in patients diagnosed by low-grading versus average-grading laboratories (OR=0.66, 95% CI 0.48 to 0.90). CONCLUSION: Our study shows that the odds that a patient undergoes AT or PLND, depends on laboratories' grading practices in a substantial number of patients. This likely influences patient prognosis and outcome, necessitating standardisation of GG to prevent suboptimal patient outcome.

Use of the ISUP e-learning module improves interrater reliability in prostate cancer grading.

AIMS: Prostate cancer (PCa) grading is an important prognostic parameter, but is subject to considerable observer variation. Previous studies have shown that interobserver variability decreases after participants were trained using an e-learning module. However, since the publication of these studies, grading of PCa has been enhanced by adopting the International Society of Urological Pathology (ISUP) 2014 grading classification. This study investigates the effect of training on interobserver variability of PCa grading, using the ISUP Education web e-learning on Gleason grading. METHODS: The ISUP Education Prostate Test B Module was distributed among Dutch pathologists. The module uses images graded by the ISUP consensus panel consisting of 24 expert uropathologists. Participants graded the same 10 images before and after e-learning. We included those who completed the tests before and after training. We evaluated variation in PCa grading in a fully crossed study design, using linearly weighted kappa values for each pathologist, comparing them to other pathologists and to the ISUP consensus panel. We analysed the improvement in median weighted kappas before and after training, using Wilcoxon's signed rank-test. RESULTS: We included 42 pathologists. Inter-rater reliability between pathologists improved from 0.70 before training to 0.74 after training (p=0.01). When compared with the ISUP consensus panel, five pathologists improved significantly, whereas the kappa of one pathologist was significantly lower after training. All pathologists who improved significantly, graded with less than substantial agreement before training. CONCLUSIONS: ISUP Prostate Test B e-learning reduces variability in PCa grading. E-learning is a cost-effective method for standardisation of pathology.

Improving prediction of response to neoadjuvant treatment in patients with breast cancer by combining liquid biopsies with multiparametric MRI: protocol of the LIMA study - a multicentre prospective observational cohort study.

INTRODUCTION: The response to neoadjuvant chemotherapy (NAC) in breast cancer has important prognostic implications. Dynamic prediction of tumour regression by NAC may allow for adaption of the treatment plan before completion, or even before the start of treatment. Such predictions may help prevent overtreatment and related toxicity and correct for undertreatment with ineffective regimens. Current imaging methods are not able to fully predict the efficacy of NAC. To successfully improve response prediction, tumour biology and heterogeneity as well as treatment-induced changes have to be considered. In the LIMA study, multiparametric MRI will be combined with liquid biopsies. In addition to conventional clinical and pathological information, these methods may give complementary information at multiple time points during treatment. AIM: To combine multiparametric MRI and liquid biopsies in patients with breast cancer to predict residual cancer burden (RCB) after NAC, in adjunct to standard clinico-pathological information. Predictions will be made before the start of NAC, approximately halfway during treatment and after completion of NAC. METHODS: In this multicentre prospective observational study we aim to enrol 100 patients. Multiparametric MRI will be performed prior to NAC, approximately halfway and after completion of NAC. Liquid biopsies will be obtained immediately prior to every cycle of chemotherapy and after completion of NAC. The primary endpoint is RCB in the surgical resection specimen following NAC. Collected data will primarily be analysed using multivariable techniques such as penalised regression techniques. ETHICS AND DISSEMINATION: Medical Research Ethics Committee Utrecht has approved this study (NL67308.041.19). Informed consent will be obtained from each participant. All data are anonymised before publication. The findings of this study will be submitted to international peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT04223492.

Pregnancy-associated breast cancer: the influence of gestational age.

Whether pregnancy-associated breast cancer (PABC) arise before or during pregnancy and whether this histopathology is affected by gestational age are currently unclear. The present study assesses the influence of gestational age and lactation on the histopathologic profile of PABC. We identified 744 patients with PABC (defined as breast cancer during pregnancy or 6 months following delivery). Histopathologic features were compared between pregnant and postpartum patients. We found that age at diagnosis was 34.2 years, and a majority of cancers were diagnosed during pregnancy (71.3%). Within pregnant patients, tumors were significantly more often estrogen receptor (ER)-negative in second and third trimesters (57.4%), as compared to first trimesters (41.9%) (P = 0.036). Similarly, a progesterone receptor (PR)-negative status was reported significantly less often within first trimesters (38.0%) compared to second and third trimesters (57.1%) (P = 0.032). For human EGF receptor 2 status, no significant differences were observed between gestational trimesters or lactating vs non-lactating patients. In postpartum patients, grade III tumors were found in over 80%, with high percentages of ER-negative tumors reaching 63% in those lactating vs 49% in non-lactating patients. This study demonstrates the varying histopathologic profile of PABC by gestational age and lactation status. Second- and third-trimester cancers display most typically the common ER/PR-negative phenotype, which is commonly reported in the literature. The increased ER-negative status and percentage grade III tumors in lactating vs non-lactating patients also suggest the presence of additional factors further diversifying histology. This indicates the need for clear definitions of PABC and the role of potential subgroups, which may provide a stepping stone for further in-depth research into PABC-carcinogenesis.

Significant Inter- and Intralaboratory Variation in Gleason Grading of Prostate Cancer: A Nationwide Study of 35,258 Patients in The Netherlands.

PURPOSE: Our aim was to analyze grading variation between pathology laboratories and between pathologists within individual laboratories using nationwide real-life data. METHODS: We retrieved synoptic (n = 13,397) and narrative (n = 29,377) needle biopsy reports from the Dutch Pathology Registry and prostate-specific antigen values from The Netherlands Cancer Registration for prostate cancer patients diagnosed between January 2017 and December 2019. We determined laboratory-specific proportions per histologic grade and unadjusted odds ratios (ORs) for International Society of Urological Pathologists Grades 1 vs. 2-5 for 40 laboratories due to treatment implications for higher grades. Pathologist-specific proportions were determined for 21 laboratories that consented to this part of analysis. The synoptic reports of 21 laboratories were used for analysis of case-mix correction for PSA, age, year of diagnosis, number of biopsies and positive cores. RESULTS: A total of 38,321 reports of 35,258 patients were included. Grade 1 ranged between 19.7% and 44.3% per laboratory (national mean = 34.1%). Out of 40 laboratories, 22 (55%) reported a significantly deviant OR, ranging from 0.48 (95% confidence interval (CI) 0.39-0.59) to 1.54 (CI 1.22-1.93). Case-mix correction was performed for 10,294 reports, altering the status of 3/21 (14%) laboratories, but increasing the observed variation (20.8% vs. 17.7%). Within 15/21 (71%) of laboratories, significant inter-pathologist variation existed. CONCLUSION: Substantial variation in prostate cancer grading was observed between and within Dutch pathology laboratories. Case-mix correction did not explain the variation. Better standardization of prostate cancer grading is warranted to optimize and harmonize treatment.

Receptor status of breast cancer diagnosed during pregnancy: A literature review.

The definition of PABC is inconsistently given as either breast cancer diagnosed exclusively during pregnancy, or combined with breast cancer diagnosed within six months to five years after delivery, and sometimes even longer. The longer away from the delivery date breast cancer is diagnosed, the less clear this association with pregnancy may become. Therefore, breast cancer diagnosed during pregnancy (BCdP) may not necessarily be the same disease entity as PABC. This review aims to provide an overview of BCdP receptor status, as this has not been assessed before. BCdP tumors were predominantly ER negative (56.6 %), PR negative (57.2 %) or both ER and PR negative (47.9 %). Moreover, HER2-overexpression was seen in 33.2 % of BCdP patients and 27.6 % had triple negative disease. This predominantly ER and PR negative profile with more often HER2 overexpression is aggressive and distinct from non-pregnant similar-aged patients, warranting future comparative research.

Immune checkpoint inhibitor-associated acute kidney injury and mortality: An observational study.

BACKGROUND: Immune checkpoint inhibitors, approved for the treatment of various types of cancer, are known to cause a unique spectrum of side effects, including acute kidney injury (AKI). The aim of this study was to describe the incidence, risk factors, renal outcomes, and mortality of AKI in patients receiving checkpoint inhibitors. METHODS: Patients receiving checkpoint inhibitors between January 2013 and May 2020 at the University Medical Center Utrecht, the Netherlands, were identified using the Utrecht Patient Oriented Database. AKI was defined as an increase in serum creatinine of ≥1.5 times the baseline value, based on the Kidney Disease: Improving Global Outcomes criteria. Cox proportional hazard regression analysis was used to assess risk factors for AKI and to evaluate the relationship between AKI and mortality. Persistent renal dysfunction was diagnosed in AKI patients with a final serum creatinine measurement of >1.3 times the baseline value. RESULTS: Among 676 patients receiving checkpoint inhibitors, the overall incidence of AKI was 14.2%. Baseline variables independently associated with AKI were a gynecologic malignancy, monotherapy with ipilimumab, and the use of a diuretic, angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker, or proton pump inhibitor at baseline. AKI was checkpoint inhibitor-associated in one third of all patients with AKI. Checkpoint inhibitor-associated AKI was mostly low-grade, occurred a median of 15 weeks after checkpoint inhibitor initiation, and resulted in persistent renal dysfunction in approximately 40% of the patients. Patients with all-cause AKI had a twofold increased mortality risk, but checkpoint inhibitor-associated AKI was not associated with increased mortality. CONCLUSIONS: In this study, patients receiving checkpoint inhibitors frequently developed AKI due to various etiologies. AKI directly related to the effect of checkpoint inhibitor toxicity did not increase mortality. However, AKI not related to the effect of checkpoint inhibitor toxicity was associated with increased mortality.

Phase I feasibility study of Magnetic Resonance guided High Intensity Focused Ultrasound-induced hyperthermia, Lyso-Thermosensitive Liposomal Doxorubicin and cyclophosphamide in de novo stage IV breast cancer patients: study protocol of the i-GO study.

INTRODUCTION: In breast cancer, local tumour control is thought to be optimised by administering higher local levels of cytotoxic chemotherapy, in particular doxorubicin. However, systemic administration of higher dosages of doxorubicin is hampered by its toxic side effects. In this study, we aim to increase doxorubicin deposition in the primary breast tumour without changing systemic doxorubicin concentration and thus without interfering with systemic efficacy and toxicity. This is to be achieved by combining Lyso-Thermosensitive Liposomal Doxorubicin (LTLD, ThermoDox, Celsion Corporation, Lawrenceville, NJ, USA) with mild local hyperthermia, induced by Magnetic Resonance guided High Intensity Focused Ultrasound (MR-HIFU). When heated above 39.5°C, LTLD releases a high concentration of doxorubicin intravascularly within seconds. In the absence of hyperthermia, LTLD leads to a similar biodistribution and antitumour efficacy compared with conventional doxorubicin. METHODS AND ANALYSIS: This is a single-arm phase I study in 12 chemotherapy-naïve patients with de novo stage IV HER2-negative breast cancer. Previous endocrine treatment is allowed. Study treatment consists of up to six cycles of LTLD at 21-day intervals, administered during MR-HIFU-induced hyperthermia to the primary tumour. We will aim for 60 min of hyperthermia at 40°C-42°C using a dedicated MR-HIFU breast system (Profound Medical, Mississauga, Canada). Afterwards, intravenous cyclophosphamide will be administered. Primary endpoints are safety, tolerability and feasibility. The secondary endpoint is efficacy, assessed by radiological response.This approach could lead to optimal loco-regional control with less extensive or even no surgery, in de novo stage IV patients and in stage II/III patients allocated to receive neoadjuvant chemotherapy. ETHICS AND DISSEMINATION: This study has obtained ethical approval by the Medical Research Ethics Committee Utrecht (Protocol NL67422.041.18, METC number 18-702). Informed consent will be obtained from all patients before study participation. Results will be published in an academic peer-reviewed journal. TRIAL REGISTRATION NUMBERS: NCT03749850, EudraCT 2015-005582-23.