Discontinuation of imatinib in patients with oligometastatic gastrointestinal stromal tumour who are in complete radiological remission: a prospective multicentre phase II study.

INTRODUCTION: Metastatic gastrointestinal stromal tumour (GIST) is considered incurable, and life-long treatment with tyrosine kinase inhibitors is recommended. We investigated whether selected patients with metastatic GIST may remain in durable remission despite imatinib discontinuation. PATIENTS: In this 1-group, prospective, multicentre phase II trial selected patients with oligometastatic (≤3 metastases) GIST discontinued imatinib treatment. Eligible patients had been treated with imatinib >5 years without progression and had no radiologically detectable metastases after metastasectomy, radiofrequency ablation (RFA) or complete response to imatinib. The primary endpoint was progression-free survival (PFS) 3-years after stopping imatinib. Overall survival (OS) and quality of life (QoL) were secondary endpoints. RESULTS: The trial closed prematurely due to slow accrual. Between January 5, 2017, and June 5, 2019, 13 patients were enrolled, of whom 12 discontinued imatinib. The median follow-up time was 55 months (range, 36 to 69) after study entry. Five (42%) of the 12 eligible patients remained progression free, and seven (58%) progressed with a median time to progression 10 months. Median PFS was 23 months and the estimated 3-year PFS 41%. Six of the seven patients who progressed restarted imatinib, and all six responded. Three-year OS was 100%, and all patients were alive at the time of the study analysis. QoL measured 5 and 11 months after discontinuation of imatinib demonstrated improvement compared to the baseline. INTERPRETATION: A substantial proportion of selected patients with oligometastatic GIST treated with imatinib and metastasis surgery/RFA may remain disease-free for ≥3 years with improved QoL after stopping of imatinib.

Survival prediction in patients with gynecological cancer irradiated for brain metastases.

BACKGROUND AND PURPOSE: This large population-based, retrospective, single-center study aimed to identify prognostic factors in patients with brain metastases (BM) from gynecological cancers. MATERIAL AND METHODS: One hundred and forty four patients with BM from gynecological cancer treated with radiotherapy (RT) were identified. Primary cancer diagnosis, age, performance status, number of BM, presence of extracranial disease, and type of BM treatment were assessed. Overall survival (OS) was calculated using the Kaplan-Meier method and the Cox proportional hazards regression model was used for multivariable analysis. A prognostic index (PI) was developed based on scores from independent predictors of OS. RESULTS: Median OS for the entire study population was 6.2 months. Forty per cent of patients died within 3 months after start of RT. Primary cancer with the origin in cervix or vulva (p = 0.001),  Eastern Cooperative Oncology Group (ECOG) 3-4 (p < 0.001), and the presence of extracranial disease (p = 0.001) were associated with significantly shorter OS. The developed PI based on these factors, categorized patients into three risk groups with a median OS of 13.5, 4.0, and 2.4 months for the good, intermediate, and poor prognosis group, respectively. INTERPRETATION: Patients with BM from gynecological cancers carry a poor prognosis. We identified prognostic factors and developed a scoring tool to select patients with better or worse prognosis. Patients in the high-risk group have a particular poor prognosis, and omission of RT could be considered.

Ewing sarcoma of the temporal bone with aneurysmal bone cyst-like changes: A rare case report with an unusual radiological presentation.

Ewing sarcoma (ES) is a malignant small round cell tumor, accounting for 10-15% of all primary bone tumors and approximately 3% of all pediatric cancers. Primary ES of the cranial bone is unusual with reported incidence from 1% to 6% of all ES cases. This report shows a rare case of primary ES of the squamous temporal bone in a 12-year-old boy with a history of swelling of the right temporal region and symptoms of increased intracranial pressure. We illustrate the extremely unusual radiological presentation of this primary ES of temporal bone associated with large aneurysmal bone cyst-like (ABC-like) changes. The boy was successfully treated according to Euro Ewing 2012 protocol. He is alive with no evidence of recurrence and metastasis after 16 months of completed treatment.

Genomic Complexity as a Biomarker to De-Escalate Adjuvant Imatinib Treatment in High-Risk Gastrointestinal Stromal Tumor.

PURPOSE: Adjuvant imatinib treatment is recommended for patients with localized gastrointestinal stromal tumor (GIST) at high risk of recurrence. Almost half of high-risk patients are cured by surgery alone, indicating a need for improved selection of patients for adjuvant therapy. The aim of this study was to investigate if genomic tumor complexity could be used as a prognostic biomarker. METHODS: The discovery cohort consisted of patients who underwent resection of primary GIST at Oslo University Hospital between 1998 and 2020. Karyotypes were categorized as simple if they had ≤ 5 chromosomal changes and complex if there were > 5 chromosomal aberrations. Validation was performed in an independent patient cohort where chromosomal imbalances were mapped using comparative genomic hybridization. RESULTS: Chromosomal aberrations were detected in 206 tumors, of which 76 had a complex karyotype. The most frequently observed changes were losses at 14q, 22q, 1p, and 15q. The 5-year recurrence-free survival (RFS) in patients classified as very low, low, or intermediate risk was 99%. High-risk patients with a simple tumor karyotype had an estimated 5-year RFS of 94%, and patients with a complex karyotype had an estimated 5-year RFS of 51%. A complex karyotype was associated with poor RFS in patients with and without adjuvant imatinib treatment and in multivariable analysis adjusted for tumor site, size, mitotic count, and rupture. The prognostic impact of genomic complexity was confirmed in the validation cohort. In both cohorts, the 5-year disease-specific survival was > 90% for high-risk patients with genomically simple tumors. CONCLUSION: Genomic tumor complexity is an independent prognostic biomarker in localized, high-risk GIST. Recurrences were infrequent for tumors with simple karyotypes. De-escalation of adjuvant imatinib treatment should be explored in patients with cytogenetically simple GISTs.

Inoperable or incompletely resected craniofacial osteosarcoma treated by particle radiotherapy.

Background: To report survival of craniofacial osteosarcoma patients treated by particle radiotherapy. Methods: Between January 2010 and December 2021, 51 patients with primary (N = 35) or recurrent (N = 16) inoperable or incompletely resected craniofacial osteosarcoma were treated. In most cases, intracranial infiltration (59%) and macroscopic tumor on MRI/CT (75%) were present. Thirteen had a secondary osteosarcoma (25%). Treatment concepts included combined ion beam radiotherapy (CIBRT, N = 18), protons only (N = 3), carbon ions only (N = 12), IMRT with a carbon ion boost (N = 5), and carbon ion re-irradiation (N = 13). Eighty percent (N = 41) received additionally chemotherapy, most frequently EURAMOS-1 (47%) or EURO-B.O.S.S. (18%). Results: The median age was 38, and all patients finished treatment predominantly as outpatients (N = 44). Information on overall survival was available for N = 49 patients. The median follow-up of the survivors was 55 months. For the whole cohort 1-, 2-, 3-, and 5-year overall survival (OS) was 82.8%, 60.4%, 55.2%, and 51.7%, respectively. Those treated by CIBRT (N = 17) demonstrated a superior OS with 92.9% after 1 and 2 years and 83.6% after 3 and 5 years. The median clinical target volume (CTV) was 192.7 and 95.2 cc for the primary and boost plan, respectively. CIBRT, primary diagnosis, age ≤40a, and no macroscopic residual tumor were associated with improved survival in univariate analysis (p = 0.006, p = 0.004, p = 0.002, p = 0.026, respectively), while any foregoing resection compared to biopsy was not identified as a prognostic factor. CIBRT and no macroscopic residual tumor were confirmed as independent predictors of OS on multivariate analysis (HR = 0.107, 95% CI = [0.014, 0.797], p = 0.029 and HR = 0.130, 95% CI = [0.023, 0.724], p = 0.020, respectively). No acute toxicity > grade III was observed. Conclusion: CIBRT shows promising results for patients with inoperable or incompletely resected craniofacial osteosarcoma.

Real-world evidence on perioperative chemotherapy in localized soft tissue sarcoma of the extremities and trunk wall; a population-based study.

BACKGROUND: Data from the real-world setting on perioperative chemotherapy in high-risk, localized soft tissue sarcoma (STS) is limited. Real-world data (RWD) includes data derived from patients treated outside clinical trials and often captures long-term follow-up not recorded in clinical trials. The aim of this study was to provide population-based, real-world evidence on perioperative chemotherapy in localized STS. MATERIAL AND METHODS: Adult patients with localized STS in the extremities or trunk wall treated at Oslo University Hospital, Oslo, Norway from 1998 to 2017 were included in the study. Data were extracted from a prospectively maintained database, supplemented by retrospective review of medical records. RESULTS: The total study cohort included 806 patients, of whom 154 (19%) received perioperative chemotherapy. A regimen with anthracycline and ifosfamide was given in 141 of 154 cases (92%). During long-term follow-up two patients developed secondary malignancies, cardiac toxicity was registered in 11 patients (7%) and renal toxicity in 12 patients (8%). Seventy-one of 154 patients (46%) were treated outside of clinical trials and constituted the RWD cohort. The median age at surgery was slightly lower and there were more synovial sarcomas and fewer myxofibrosarcomas in the RWD cohort. No difference in chemotherapy dose intensity was observed. The estimated 5-year metastasis-free survival (MFS) in all patients receiving perioperative chemotherapy was 58%. In the RWD cohort 5-year MFS was 53% and in the clinical study cohort 61% (HR 1.24; 95% CI 0.77-2.00). CONCLUSION: Long-term outcome after perioperative chemotherapy was comparable for patients treated in routine clinical practice to those in clinical trials. Secondary malignancy and cardiac toxicity were observed. The risk of serious late side effects should be included in the decision process on perioperative chemotherapy.

Cytogenetic and molecular analyses of 291 gastrointestinal stromal tumors: site-specific cytogenetic evolution as evidence of pathogenetic heterogeneity.

Gastrointestinal stromal tumor (GIST) is a mesenchymal neoplasm with variable behavior. An increased understanding of the tumor pathogenesis may improve clinical decision-making. Our aim was to obtain more data about the overall chromosome aberrations and intratumor cytogenetic heterogeneity in GIST. We analyzed 306 GIST samples from 291 patients using G-banding, direct sequencing, and statistics. Clonal chromosome aberrations were found in 81% of samples, with 34% of 226 primary tumors demonstrating extensive cytogenetic heterogeneity. 135 tumors had simple (≤5 changes) and 91 had complex (>5 changes) karyotypes. The karyotypically complex tumors more often were non-gastric (P < 0.001), larger (P < 0.001), more mitotically active (P = 0.009) and had a higher risk of rupture (P < 0.001) and recurrence (P < 0.001). Significant differences between gastric and non-gastric tumors were found also in the frequency of main chromosome losses: of 14q (79% vs. 63%), 22q (38% vs. 67%), 1p (23% vs. 88%), and 15q (18% vs. 77%). Gastric PDGFRA-mutated tumors, compared with gastric KIT-mutated, had a lower incidence of 22q losses (18% vs. 43%) but a higher rate of 1p losses (42% vs. 22%). The present, largest by far karyotypic study of GISTs provides further evidence for the existence of variable pathogenetic pathways operating in these tumors' development.

Hope as a Lifeline: Imatinib Discontinuation in Patients With Oligometastatic Gastrointestinal Stromal Tumours.

BACKGROUND/AIM: This study explored how highly selected oligometastatic gastrointestinal stromal tumour (GIST) patients subjectively experienced the discontinuation of imatinib (IM) treatment. PATIENTS AND METHODS: Being an exploratory qualitative study, we applied a phenomenological and hermeneutical approach. We conducted in-depth semi-structured interviews with nine oligometastatic GIST patients who were in long-term clinical remission. The gathered data were interpreted using a thematic analysis. RESULTS: The analysis of the interview data revealed four main themes; getting one's life back, fear of recurrence, hope as a lifeline and the pros/cons of participating in this clinical trial. The participants disclosed that hope of being cancer free and without the side-effects of IM was essential for both participating in this study and enduring the uncertainty of drug discontinuation. CONCLUSION: Use of a qualitative approach in clinical trials can result in a better understanding of patients' perspectives and therefore lead to improved clinical practice.

Exploring Mentorship as a Novel Approach to Improving Quality of Life in Sarcoma Survivors: A Qualitative Pilot Study.

BACKGROUNDS: To investigate whether a formal mentoring program involving mentors from the business community could improve the quality of life (QoL) of sarcoma survivors struggling with the late effects of treatment. METHODS: Seven former sarcoma patients participated in an eight-month formal mentoring program. The program was assessed through a qualitative study involving a phenomenological approach that utilized a hermeneutical design. In-depth, semistructured interviews were conducted with the mentees after the intervention and six months later. The mentors were interviewed after the program was over. The gathered data were interpreted using a thematic analysis. RESULTS: The program facilitated dialogue between the mentors and mentees as well as between the mentees. Afterwards, the mentees were more willing to accept the challenges they faced following cancer treatment. During the program, the mentees were pushed out of their comfort zone, which led to mastery and personal growth in them all. However, the program also revealed some additional challenges, including unfulfilled expectations in two mentor-mentee relationships. CONCLUSIONS: The mentoring program facilitated the mentees' reorientation and enhanced their QoL. Its eight-month duration appeared important in terms of allowing the mentees to go through a long-lasting process with continued support. The program could serve as the basis for larger studies involving other cancer survivors.

Outcome in dedifferentiated chondrosarcoma for patients treated with multimodal therapy: Results from the EUROpean Bone Over 40 Sarcoma Study.

INTRODUCTION: The role of chemotherapy for patients with dedifferentiated chondrosarcoma (DDCS) is still under discussion. Here, we present the outcome in patients with DDCS treated with intensive chemotherapy from the EUROpean Bone Over 40 Sarcoma Study. MATERIALS AND METHODS: The chemotherapy regimen included doxorubicin, ifosfamide and cisplatin. Postoperative methotrexate was added in case of poor histological response. Toxicity was graded based on the National Cancer Institute expanded common toxicity criteria, version 2.0, and survival was analysed using Kaplan-Meier curves, log-rank tests and univariate Cox regression models. RESULTS: Fifty-seven patients with DDCS (localised, 34 [60%]; metastatic, 23 [40%]) aged 42-65 years were included. Surgical complete remission (SCR) was achieved in 36 (63%) patients. The median overall survival (OS) was 24 months (95% confidence interval, 22-25), and the 5-year OS was 39%. Patients with extremity localisation had a 5-year OS of 49% compared with 29% in patients with a central tumour (P = 0.08). Patients with localised disease had a 5-year OS of 46%, whereas patients with metastatic disease had a 5-year OS of 29% (P = 0.12). Patients in SCR had a 5-year OS of 49%, whereas patients not in SCR had a 5-year OS of 23% (P = 0.004). Chemotherapy toxicity was considerable but manageable. There was no treatment-related death, and 39 (70%) patients received ≥6 cycles of the planned nine chemotherapy cycles. CONCLUSIONS: Adding intensive chemotherapy to surgery for treatment of DDCS is feasible and shows favourable survival data compared with previous reports. With the limitations of data from a non-controlled trial, we conclude that chemotherapy could be considered in the management of patients aged >40 years.

Integrating Anatomical, Molecular and Clinical Risk Factors in Gastrointestinal Stromal Tumor of the Stomach.

BACKGROUND: Adjuvant imatinib for 3 years is recommended to patients with high-risk gastrointestinal stromal tumor (GIST). Risk stratification is inaccurate, and risk assessments are further complicated by the increased use of neoadjuvant treatment. Anatomical criteria for prognostication have not been investigated. METHODS: Clinical, molecular, and anatomical variables were retrospectively studied in a population-based cohort of 295 patients with gastric GIST resected between 2000 and 2018. Gastric subsite was divided into the upper, middle, and lower thirds. Growth pattern was classified as luminal, exophytic, or transmural based on imaging and surgical reports. RESULTS: Of 113 tumors in the upper third of the stomach, 103 (91.2%) were KIT mutated, 7 (6.2%) were PDGFRA mutated, and 104 (92.0%) harbored genotypes sensitive to imatinib. Transmural tumors were strongly associated with a high mitotic index. Five-year recurrence-free survival (RFS) was 71% for patients with transmural tumors versus 96% with luminal or exophytic tumors (hazard ratio [HR] 8.45, 95% confidence interval [CI] 3.69-19.36; p < 0.001), and, in high-risk patients, 5-year RFS was 46% for patients with transmural tumors versus 83% with luminal or exophytic tumors (HR 4.47, 95% CI 1.71-11.66; p = 0.001). Among 134 patients with tumors > 5 cm, there were 29 recurrences. Only five patients with exophytic or luminal tumors had recurrent disease, of whom four had tumor rupture. Five-year RFS for patients with exophytic/luminal tumors >5 cm without rupture was 98%. CONCLUSIONS: In the upper third, over 90% of tumors were sensitive to imatinib. Patients with exophytic or luminal tumors without rupture, irrespective of size, had an excellent prognosis and may not benefit from adjuvant therapy.

Pembrolizumab in advanced osteosarcoma: results of a single-arm, open-label, phase 2 trial.

AIM: To evaluate the activity and safety of the PD-1 antibody pembrolizumab in adult patients with advanced osteosarcoma. MATERIAL AND METHODS: The study was a single-arm, open-label, phase 2 trial in patients with unresectable, relapsed osteosarcoma. The primary endpoint was clinical benefit rate (CBR) at 18 weeks of treatment, defined as complete response, partial response, or stable disease using RECIST v1.1. The trial had a Simon´s two-stage design, and ≥ 3 of 12 patients with clinical benefit in stage 1 were required to proceed to stage 2. The trial is registered with ClinicalTrials.gov, number NCT03013127. NanoString analysis was performed to explore tumor gene expression signatures and pathways. RESULTS: Twelve patients were enrolled and received study treatment. No patients had clinical benefit at 18 weeks of treatment, and patient enrollment was stopped after completion of stage 1. Estimated median progression-free survival was 1.7 months (95% CI 1.2-2.2). At time of data cut-off, 11 patients were deceased due to osteosarcoma. Median overall survival was 6.6 months (95% CI 3.8-9.3). No treatment-related deaths or drug-related grade 3 or 4 adverse events were observed. PD-L1 expression was positive in one of 11 evaluable tumor samples, and the positive sample was from a patient with a mixed treatment response. CONCLUSION: In this phase 2 study in advanced osteosarcoma, pembrolizumab was well-tolerated but did not show clinically significant antitumor activity. Future trials with immunomodulatory agents in osteosarcoma should explore combination strategies in patients selected based on molecular profiles associated with response.

Striving towards Normality in Daily Life: A Qualitative Study of Patients Living with Metastatic Gastrointestinal Stromal Tumour in Long-Term Clinical Remission.

BACKGROUND: This study explored how patients with metastatic gastrointestinal stromal tumour (GIST) experience the psychosocial challenges associated with their disease and its treatment, as well as how that experience influenced their practical, relational, vocational, and existential life. METHODS: This qualitative study has an explorative design and applied a phenomenological and hermeneutical approach. We conducted in-depth, semistructured interviews with 20 patients with metastatic GIST in long-term clinical remission. The gathered data were interpreted using a thematic analysis. RESULTS: Living with metastatic GIST, as well as the side effects of the required medication, led to changes that limited the participants' daily life. They expressed how tiredness, impaired memory, and physical challenges were among the detrimental impacts of the disease on their family life, vocational life, social life, and leisure time. Adjustments were necessary to ensure they had sufficient energy to cope with the practical and relational aspects of everyday life. Feelings of uncertainty stemming from drug resistance, disease progression, and the possibility of early death were also experienced as challenging. Half the participants stated that it was difficult to keep negative mental health issues at bay, and all of them considered the time spent waiting for their scheduled follow-up scan to be burdensome. CONCLUSIONS: It is important to focus increased attention on how the daily practical and psychosocial life of patients with chronic cancer, including metastatic GIST, is affected by their disease. Doing so might provide health-care workers with clues regarding how best to guide and support such patients throughout their emotional journey and, therefore, to improve their quality of life. As new medical treatments can also prolong survival and induce long-term clinical remission in relation to several other forms of metastatic cancer, the findings concerning GIST reported in this study might have widespread implications.

Cardiac sarcoma. / Sarkom i hjertet.

BACKGROUND: Although very rare, cardiac sarcoma is the most common malignant cardiac tumour. Cardiac tumours may present with constitutional symptoms and this can lead to delayed diagnosis. CASE PRESENTATION: A woman in her late twenties was admitted to the acute psychiatric ward with suspected depressive psychosis. Although she presented with insomnia, auditory hallucinosis and paranoid delusions, her main symptoms were dyspnoea, tachycardia and exhaustion. She was discharged after 17 days and admitted directly to the medical ward for further examination. A thorough somatic examination, including diagnostic imaging, revealed a tumour in the left atrium obstructing the mitral ostium in the diastole, resulting in orthopnoea. She had urgent cardiac surgery and the histology was consistent with an intimal sarcoma. INTERPRETATION: This case illustrates a rare disease presenting with atypical symptoms. Her psychiatric symptoms resolved after surgery and oncologic treatment of her cardiac tumour.

Use of a simple form to facilitate communication on long-term consequences of treatment in sarcoma survivors.

BACKGROUND: To report on our experience using a simple optional form to facilitate communication on late effects between the patients and the oncologists during outpatient follow-up and to detail on the spectrum of challenges reported by sarcoma survivors. METHODS: The form was presented for the patients to complete before their consultation and covered topics related to late effects and unmet needs that the patient wished to discuss with the medical personnel. Logistic regression analysis examined how the distribution of the topics varied with age, gender, diagnosis and type of treatment received. RESULTS: The form was manageable in a busy outpatient clinic. Of the 265 patients that received the form, 236 (89%) returned it. Patients in a palliative setting and those with other diagnosis than bone sarcoma (BS) and soft-tissue sarcoma (STS) were excluded for subsequent analyses. The final study-cohort comprised 160 patients, 54 (34%) with BS and 106 (66%) with STS. Among these, 140 (88%) had late-effect topics they wanted to discuss with their oncologist. Fatigue was raised by 39% of the patients, pain by 29% and impaired mobility by 23%. BS patients raised fatigue more often (P < 0.005) than those with STS. Patients who had undergone multimodal treatment with chemotherapy raised fatigue more frequently (P < 0.001) than those who had only undergone surgery, radiotherapy or both. CONCLUSIONS: A simple form on the long-term consequences of sarcoma treatment achieved a high response rate, was feasible to use in an outpatient clinic and facilitated communication on these issues. Fatigue was the most frequent topic raised and it was raised significantly more often in patients who had undergone chemotherapy.

Perspectives on treatment side effects in patients with metastatic gastrointestinal stromal tumour: a qualitative study.

BACKGROUND: This study aims to explore how patients with metastatic gastrointestinal stromal tumour (GIST) experience the adverse effects of treatment, as expressed by the individuals themselves. METHODS: A qualitative, phenomenological and hermeneutic design was applied. Twenty patients with metastatic GIST participated in the study. In-depth and semi-structured interviews were conducted and then analysed by means of an inductive thematic analysis. RESULTS: The majority of participants reported experiencing a changed life after being diagnosed with metastatic GIST and commencing systemic medical treatment. More than half of them described partially debilitating self-reported side effects and complaints that had a detrimental impact on their lives. The life-prolonging tyrosine kinase inhibitor treatment prompted the participants to adapt to 'a new normal'. Several participants also emphasised having an ambivalent relationship with the pill, although most looked upon it as 'a friend' because it kept them alive. Paradoxically, while the participants struggled with the side effects of treatment as well as the consequences of living with a chronic cancer, half of them considered themselves to be healthy and, thus, to not actually be cancer patients. CONCLUSIONS: We observed a gap between the biomedical perspective on disease that health professionals typically adopt and the individual experiences of patients living with metastatic GIST. For those patients who are living in limbo between having metastatic cancer and offered an effective treatment, a holistic view of health on the part of their healthcare providers seems crucial. A vital goal should hence be to improve communication between healthcare professionals and GIST patients so as to secure an individualised follow-up with guidance on coping with, and adapting to, their new normal.Trial registration The study was approved by the data protection officer of the Oslo University Hospital (Approval Number 2016/15358).

Multimodal kreftbehandling av gastrointestinal stromal tumor.

Gastrointestinal stromal tumour (GIST) is a subtype of sarcoma that may occur in any part of the gastrointestinal system, most frequently in the stomach and small intestine. The most common symptoms are bleeding and abdominal pain. In this clinical review, we summarise the progress made with this condition and discuss the recommended diagnostics and treatment of GIST.

Recurrence-Free Survival After Resection of Gastric Gastrointestinal Stromal Tumors Classified According to a Strict Definition of Tumor Rupture: A Population-Based Study.

BACKGROUND: In gastrointestinal stromal tumors (GISTs), rupture is a high-risk feature and an indication for adjuvant treatment; however, the independent impact of rupture on prognosis is uncertain and the term is inconsistently defined. In the present study, a previously proposed definition of 'tumor rupture' was applied on a population-based cohort of gastric GISTs. METHODS: Patients undergoing surgery for non-metastatic gastric GISTs from 2000 to 2015 were identified in the regional sarcoma database of Oslo University Hospital. Tumor rupture included spillage or fracture, piecemeal resection, incisional biopsy, blood-tinged ascites, gastric perforation, and microscopic adjacent infiltration. Minor defects of tumor integrity were not considered rupture, i.e. core needle biopsy, peritoneal tumor penetration, superficial peritoneal rupture, and R1 resection. Risk was assessed according to the modified National Institutes of Health consensus criteria. RESULTS: Among 242 patients, tumor rupture occurred in 22 patients and minor defects of tumor integrity occurred in 81 patients. Five-year recurrence-free survival (RFS) for patients with tumor rupture, minor defects of tumor integrity, and no defect was 37, 91, and 96%, respectively (p < 0.001). In the high-risk group, 5 year RFS for patients with rupture was 37%, versus 77% without rupture (hazard ratio 3.56, 95% confidence interval 1.57-8.08, p = 0.001). On multivariable analysis, tumor rupture and mitotic index were independently associated with recurrence. Of 13 patients who received adjuvant imatinib after tumor rupture, 11 relapsed. CONCLUSIONS: Tumor rupture according to the present definition was independently associated with recurrence. With tumor rupture, patients relapsed despite adjuvant treatment. Without rupture, prognosis was good, even in the high-risk group.

Prediction of long-term survival in patients with metastatic gastrointestinal stromal tumor: analysis of a large, single-institution cohort.

BACKGROUND: A subset of patients with metastatic GIST become long-term survivors, and a more precise prediction of outcome could improve clinical decision-making. MATERIAL AND METHODS: One-hundred and thirty-three patients diagnosed with metastatic GIST from 1995 to 2013 were identified from the sarcoma database at Oslo University Hospital. Clinical data prospectively registered in the database were supplemented with retrospective review of medical records. Factors associated with survival were analyzed using Kaplan-Meier curves, log-rank test, univariate and multivariate Cox regression analyses. RESULTS: One-hundred and fifteen patients with metastatic GIST were included in the final study cohort. Median overall survival (OS) was 6.9 years (95% CI 5.6-8.3). Factors associated with long-term survival in univariate analysis were good baseline performance status (ECOG ≤1; p < .001), young age (p = .022), oligometastatic disease (OMD) (≤3 metastases; p < .001), maximum tumor diameter <5 cm (p < .001), surgery for metastatic disease (p = .005), surgery of the primary tumor (p < .001), normal baseline hemoglobin level (p = .05), normal baseline albumin level (p = .001) and normal baseline neutrophil count (p = .03). On multivariate analysis, good performance status, small tumor diameter and, OMD were the factors associated with long-term survival. Five and 10-year OS for patients with OMD were 89% and 71%, respectively, compared to 38% and 20% for patients with polymetastatic disease (p < .001). CONCLUSIONS: In this single-institution cohort of patients, OMD was as a strong prognostic factor in patients with metastatic GIST. Patients with OMD had an outcome similar to patients with high-risk localized disease, and should be regarded as a separate category among patients with metastatic GIST.