Clinical and biological landscape of constitutional mismatch-repair deficiency syndrome: an International Replication Repair Deficiency Consortium cohort study

BACKGROUND

Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare and aggressive cancer predisposition syndrome. Because a scarcity of data on this condition contributes to management challenges and poor outcomes, we aimed to describe the clinical spectrum, cancer biology, and impact of genetics on patient survival in CMMRD.

METHODS

In this cohort study, we collected cross-sectional and longitudinal data on all patients with CMMRD, with no age limits, registered with the International Replication Repair Deficiency Consortium (IRRDC) across more than 50 countries. Clinical data were extracted from the IRRDC database, medical records, and physician-completed case record forms. The primary objective was to describe the clinical features, cancer spectrum, and biology of the condition. Secondary objectives included estimations of cancer incidence and of the impact of the specific mismatch-repair gene and genotype on cancer onset and survival, including after cancer surveillance and immunotherapy interventions.

FINDINGS

We analysed data from 201 patients (103 males, 98 females) enrolled between June 5, 2007 and Sept 9, 2022. Median age at diagnosis of CMMRD or a related cancer was 8·9 years (IQR 5·9-12·6), and median follow-up from diagnosis was 7·2 years (3·6-14·8). Endogamy among minorities and closed communities contributed to high homozygosity within countries with low consanguinity. Frequent dermatological manifestations (117 [93%] of 126 patients with complete data) led to a clinical overlap with neurofibromatosis type 1 (35 [28%] of 126). 339 cancers were reported in 194 (97%) of 201 patients. The cumulative cancer incidence by age 18 years was 90% (95% CI 80-99). Median time between cancer diagnoses for patients with more than one cancer was 1·9 years (IQR 0·8-3·9). Neoplasms developed in 15 organs and included early-onset adult cancers. CNS tumours were the most frequent (173 [51%] cancers), followed by gastrointestinal (75 [22%]), haematological (61 [18%]), and other cancer types (30 [9%]). Patients with CNS tumours had the poorest overall survival rates (39% [95% CI 30-52] at 10 years from diagnosis; log-rank p<0·0001 across four cancer types), followed by those with haematological cancers (67% [55-82]), gastrointestinal cancers (89% [81-97]), and other solid tumours (96% [88-100]). All cancers showed high mutation and microsatellite indel burdens, and pathognomonic mutational signatures. MLH1 or MSH2 variants caused earlier cancer onset than PMS2 or MSH6 variants, and inferior survival (overall survival at age 15 years 63% [95% CI 55-73] for PMS2, 49% [35-68] for MSH6, 19% [6-66] for MLH1, and 0% for MSH2; p<0·0001). Frameshift or truncating variants within the same gene caused earlier cancers and inferior outcomes compared with missense variants (p<0·0001). The greater deleterious effects of MLH1 and MSH2 variants as compared with PMS2 and MSH6 variants persisted despite overall improvements in survival after surveillance or immune checkpoint inhibitor interventions.

INTERPRETATION

The very high cancer burden and unique genomic landscape of CMMRD highlight the benefit of comprehensive assays in timely diagnosis and precision approaches toward surveillance and immunotherapy. These data will guide the clinical management of children and patients who survive into adulthood with CMMRD.

FUNDING

The Canadian Institutes for Health Research, Stand Up to Cancer, Children's Oncology Group National Cancer Institute Community Oncology Research Program, Canadian Cancer Society, Brain Canada, The V Foundation for Cancer Research, BioCanRx, Harry and Agnieszka Hall, Meagan's Walk, BRAINchild Canada, The LivWise Foundation, St Baldrick Foundation, Hold'em for Life, and Garron Family Cancer Center.

Challenges in Treating Childhood Infratentorial Ependymoma: A Low- and Middle-Income Country Experience

PURPOSE

Patients and physicians in low- and middle-income countries (LMICs) face challenges owing to limited expertise and suboptimal access to appropriate diagnostic and treatment modalities. We report our experience in treating posterior fossa ependymoma (PFE) at MAHAK, a charity organization in Iran whose radiation oncology department is the only one exclusively dedicated to childhood cancer in the whole country.

METHODS AND MATERIALS

Pediatric patients with PFE referred to MAHAK between November 2008 and January 2016 were identified. Details on investigations and management done before referral were collected. Management at MAHAK and patient outcomes were analyzed.

RESULTS

Of 80 patients diagnosed as having ependymoma, 54 with PFE were identified. Forty-three patients received adjuvant radiation therapy, and 11 were irradiated initially after recurrence. At a median follow-up of 5.1 years (range, 0.3-9.7 years), the latter group had the worst outcome, with a 5-year overall survival (OS) rate of 27% (95% CI, 7%-54%). Patients who started radiation therapy within 77 days after initial surgery had a better outcome compared with those who started later (5-year OS: 74% vs 32%; P = .05). Compliance with follow-up recommendations was poor. Only 22% of the patients had at least 2 IQ test assessments, and 50% showed some decline over time. Three cases of growth hormone deficiency were detected, but none of the patients received replacement therapy.

CONCLUSIONS

Access to pediatric neurosurgery, anesthesia, and timely radiation therapy are among the most challenging obstacles to be overcome in LMICs. Our series confirmed that chemotherapy is not an appropriate option for delaying radiation therapy, especially in young children. The importance of long-term follow-up should be acknowledged by the parents and medical team.

Impact of COVID-19 pandemic on delivery of pediatric radiotherapy: A critical review

The COVID-19 pandemic has prevented the timely diagnosis and treatment of many diseases, including pediatric cancer. Its impact on pediatric oncologic treatments warrants investigation. As radiotherapy is an integral component of cancer care, we reviewed the published data regarding the impact of COVID-19 on the delivery of pediatric radiotherapy to inform actions for future global events. We found that disruptions in radiotherapy were reported amongst interruptions in other therapies. Disruptions were more common in low-income countries (78%) and low middle-income countries (68%) compared with upper middle-income countries (46%) and high-income countries (10%). Several papers included recommendations for mitigation strategies. Altered treatment regimens were common, including increasing the use of active surveillance and systemic therapy to delay local therapies, and accelerated/hypofractionated dose delivery. Our findings suggest that COVID-19 has impacted radiotherapy delivery in the pediatric population globally. Countries with limited resources may be more affected. Various mitigation strategies have been developed. The efficacy of mitigation measures warrants further investigation.

Survival Benefit for Individuals With Constitutional Mismatch Repair Deficiency Undergoing Surveillance

Constitutional mismatch repair deficiency syndrome (CMMRD) is a lethal cancer predisposition syndrome characterized by early-onset synchronous and metachronous multiorgan tumors. We designed a surveillance protocol for early tumor detection in these individuals.

Survivor and parent engagement in childhood cancer treatment in Iran

In Iran (with a population of 83 million), 19,973 children were diagnosed with cancer from 2009 to 2019 (MAHAK Charity). This study was part of the International Society of Paediatric Oncology, Paediatric Oncology in Developing Countries Committee, ‘Patient, Family and Stakeholder Engagement Task Force’ engagement study in ten low- and middle-income countries in 2019. We documented childhood cancer survivors and parents’ experiences and quality of engagement, including perceptions and expectations, during their cancer treatment journey in Iran. Fourteen in-depth interviews and three focus group discussions were conducted by three Iranian qualitative researchers with 29 participants: recent adolescent/young adult survivors (12–20 years), long-term survivors (21–30 years) and parents [36–61 years (six mothers and four fathers)] from diverse socio-economic and ethnic backgrounds. Data were recorded, transcribed and analysed, and then translated from Farsi into English. Participants’ expectations included inter alia improved communication and information flow among the key stakeholders including doctors, nurses, parents and patients. A need for improved patterns of doctor–patient relationships and communication, more effective psychosocial support and the importance of peer support groups (for survivors and parents) were reported. Participants identified areas of satisfaction and dissatisfaction regarding their actual engagement and decision-making. The dominance of a medical-only approach instead of multidisciplinary approach in care, the shortage of psychosocial support, the lack of an integrated system for providing information and delivering a package of printed material about the treatment journey and the absence of patient navigator in childhood cancer care systems were among obstacles for successful engagement of patients and parents throughout their cancer journey.

MBRS-54. POOR SURVIVAL IN REPLICATION REPAIR DEFICIENT HYPERMUTANT MEDULLOBLASTOMA AND CNS EMBRYONAL TUMORS: A REPORT FROM THE INTERNATIONAL RRD CONSORTIUM

BACKGROUND

Mutations in mismatch repair (MMR) and DNA-polymerase (POL) genes lead to DNA replication repair deficiency (RRD), resulting in a growing group of previously under-recognized childhood brain tumors. Medulloblastoma and embryonal tumors are rarely reported in RRD. Their biological and clinical significance is unknown.

METHODS

We analyzed the clinical and genomic data of embryonal tumors registered in the International RRD Consortium.

RESULTS

Twenty-six tumors were centrally reviewed to confirm medulloblastoma (n=18), embryonal-tumor, NOS (n=5), and three glioblastoma (excluded). Embryonal tumors were observed at a young age (median: 7-years, IQR: 5;11), and all but one exhibited clinical cues (café-au-lait macules/ family history) of germline RRD. Medulloblastomas with RRD exhibited high-risk features, including anaplastic histology (50%), and SHH-subgroup with TP53-mutation (50%). Importantly, 68% harbored POLE/POLD1 mutations, resulting in median tumor mutation burden of 164 mut/mb. POL-mutated tumors were significantly ultra-hypermutated (&gt;100 mut/mb) than tumors with MMR-deficiency alone (p=0.015). Synchronous and metachronous tumors were observed in 40%. However 90% of the deaths were related to the diagnosis of embryonal CNS tumor. Median survival for the entire cohort was 17-months (95% CI: 10 to 23). Predicted 3-year survival was 37% for medulloblastoma, with no survivors among other embryonal tumors.

CONCLUSIONS

This is the largest cohort of replication repair deficient medulloblastoma reported till date. The tumors are hypermutated, harbor somatic mutations in TP53 and/or POLE/POLD1, and have very poor survival with current chemo-irradiation based approaches. These biologically unique tumors expand the spectrum of high-risk TP53-mutant SHH-medulloblastoma, and need novel strategies for treatment.

Recommendations for the treatment of children with radiotherapy in low- and middle-income countries (LMIC): A position paper from the Pediatric Radiation Oncology Society (PROS-LMIC) and Pediatric Oncology in Developing Countries (PODC) working groups of the International Society of Pediatric Oncology (SIOP)

Pediatric radiotherapy is a critical part of pediatric oncology protocols and the quality of the radiotherapy may determine the future quality of life for long-term survivors. Multidisciplinary team decision making provides the basis for high-quality care. However, delivery of high-quality radiotherapy is dependent on resources. This article provides guidelines for delivery of good quality radiation therapy in resource-limited countries based on rational procurement and maintenance planning, protocol development, three-dimensional planning, quality assurance, and adequate staff numbers and training.

Prospective coronary heart disease screening in asymptomatic Hodgkin lymphoma patients using coronary computed tomography angiography: results and risk factor analysis

PURPOSE

To prospectively investigate the coronary artery status using coronary CT angiography (CCTA) in patients with Hodgkin lymphoma treated with combined modalities and mediastinal irradiation.

METHODS AND MATERIALS

All consecutive asymptomatic patients with Hodgkin lymphoma entered the study during follow-up, from August 2007 to May 2012. Coronary CT angiography was performed, and risk factors were recorded along with leukocyte telomere length (LTL) measurements.

RESULTS

One hundred seventy-nine patients entered the 5-year study. The median follow-up was 11.6 years (range, 2.1-40.2 years), and the median interval between treatment and the CCTA was 9.5 years (range, 0.5-40 years). Coronary artery abnormalities were demonstrated in 46 patients (26%). Coronary CT angiography abnormalities were detected in nearly 15% of the patients within the first 5 years after treatment. A significant increase (34%) occurred 10 years after treatment (P=.05). Stenoses were mostly nonostial. Severe stenoses were observed in 12 (6.7%) of the patients, entailing surgery with either angioplasty with stent placement or bypass grafting in 10 of them (5.5%). A multivariate analysis demonstrated that age at treatment, hypertension, and hypercholesterolemia, as well as radiation dose to the coronary artery origins, were prognostic factors. In the group of patients with LTL measurements, hypertension and LTL were the only independent risk factors.

CONCLUSIONS

The findings suggest that CCTA can identify asymptomatic individuals at risk of acute coronary artery disease who might require either preventive or curative measures. Conventional risk factors and the radiation dose to coronary artery origins were independent prognostic factors. The prognostic value of LTL needs further investigation.

Low-dose radiation treatment in pulmonary mucosa-associated lymphoid tissue lymphoma: a plausible approach? A single-institution experience in 10 patients

PURPOSE

To propose an alternative approach for treatment of pulmonary marginal zone lymphoma, using a very small radiation dose (2 × 2 Gy) delivered exclusively to tumor sites.

METHODS AND MATERIALS

Patients had localized pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma according to the World Health Organization classification. The 6-MV radiation treatments were delivered using tumor-limited fields, except in cases of diffuse bilateral involvement. Two daily fractions of 2 Gy were delivered to tumor-limited fields using a 6-MV linear accelerator.

RESULTS

Ten patients with pulmonary MALT lymphoma entered the study. All but 1 had localized tumor masses. The median follow-up was 56 months (range, 2-103 months). Complete remission or an unconfirmed complete remission was obtained in 60% of patients within the first 2 months, and two additional partial responses were converted into a long-term unconfirmed complete remission. All patients are well and alive, no local progression was observed, and the 5-year progression-free survival rate was 87.5% (95% confidence interval 49%-97%).

CONCLUSIONS

Our results suggest that extremely low radiation doses delivered exclusively to tumor sites might be a treatment option in pulmonary MALT lymphoma.

[Intensity-modulated radiotherapy and involved-node concept in patients with Hodgkin lymphoma: experience of the Gustave-Roussy Institute]

PURPOSE

To assess the clinical outcome of the involved-node radiotherapy concept with the use of intensity modulated radiotherapy (IMRT) in patients with localized supradiaphragmatic Hodgkin lymphoma.

PATIENTS AND METHODS

Patients with early-stage supradiaphragmatic Hodgkin lymphoma were treated with chemotherapy prior to irradiation. Radiation treatments were delivered using the involved-node radiotherapy (INRT) concept according to the EORTC guidelines. Intensity modulated radiotherapy was performed free-breathing.

RESULTS

Forty-seven patients with Hodgkin lymphoma (44 patients with primary Hodgkin lymphoma and three patients with recurrent disease) entered the study from January 2003 to December 2010. The median age was 31 years (range 17 to 62). Thirty patients had stage I-IIA, 14 had stage I-IIB disease and three had relapse. Forty-two patients received three to six cycles of adriamycin, bleomycin, vinblastine and dacarbazine (ABVD). The median radiation dose to patients was 36 Gy (range: 20-40). Protection of various organs at risk was satisfactory. The median follow-up was 57.4 months (range: 5.4-94.3). For patients with primary Hodgkin lymphoma, the 5-year survival and 5-year progression-free survival rates were 96% (95% confidence interval: 80-99) and 92% (95% confidence interval: 78-97), respectively. None of the three patients with recurrent disease has relapsed. Recurrences occurred in three patients: one was in-field relapse and two were visceral recurrences. Grade 3 acute lung toxicity (transient pneumonitis) occurred in one case.

CONCLUSION

Our results suggest that patients with localized Hodgkin lymphoma can be safely and efficiently treated using the involved node irradiation concept and intensity modulated irradiation.

The efficacy and toxicity of EGFR in the settings of radiotherapy: Focus on published clinical trials

Basic research in solid malignant tumours has led to a wealth of knowledge about this disease process and about novel ways to more effectively target our therapies. Laboratory research continues to identify novel therapeutic targets and moreover, clinical research is identifying effective new treatment regimens. Many preclinical studies in this area have targeted the epidermal growth factor receptor (EGFR) signalling pathway to increase radiosensitivity. The in vitro rationale for targeting EGFR and concurrent ionising radiation is well established, but to date, rare clinical data could provide proof-of-principle. Here we report all the different published clinical trials focusing on efficacy and toxicity in order to clarify and to summarise the present state-of-the-art of this particularly promising combination in solid tumour management.

Is FDG-PET scan in patients with early stage Hodgkin lymphoma of any value in the implementation of the involved-node radiotherapy concept and dose painting?

BACKGROUND AND PURPOSE

To evaluate the input of FDG-PET data in the implementation of the involved-node radiotherapy concept and dose painting.

MATERIALS AND METHODS

Patients with early-stage Hodgkin lymphoma treated with combined modality treatments. First, patients underwent a PET/CT before chemotherapy in the treatment position using a head and shoulder immobilization mask. Second, all patients had a CT simulation for treatment planning. The CT simulation was coregistered with the prechemotherapy CT and FDG-PET scan. All prechemotherapy volumes were superimposed on the CT simulation. The initially involved lymph node areas to be irradiated were delineated on the CT simulation scan. Chemotherapy-induced shrinkage rates of the tumor masses visible on CT scan and on FDG-PET were determined and compared.

RESULTS

Before chemotherapy, FDG-PET-avid areas represented 25% of the total volume on CT. After chemotherapy, the influence of initial FDG-PET data on the delineation of involved-node radiotherapy fields was significant and was due to the fact that in 36% of the patients, FDG-PET helped pinpoint lymph nodes that were undetected on CT. After chemotherapy, the rates of tumor volume shrinkage on CT and FDG-PET were similar. This finding suggests similar chemosensitivity for FDG-PET-avid and non-avid areas. There was no correlation between initial FDG-PET-avid volumes and the clinical outcome.

CONCLUSION

Prechemotherapy FDG-PET data are essential for correctly implementing the involved-node radiotherapy concept but seem to be of minimal value for applying the concept of dose painting.

Radiotherapy of hodgkin lymphoma: indications, new fields, and techniques

In recent years, radiotherapy in patients with Hodgkin lymphoma has evolved considerably because of sophisticated imaging technologies and radiation delivery techniques. Even more recently, a new radiation field concept has emerged to ensure better normal tissue protection while preserving an excellent clinical outcome. The role of radiation therapy is also rapidly changing because the concept of a risk-adapted treatment strategy, in which combined-modality treatments were the order of the day, is now expanding into a concept of response-adapted treatments.

Involved-node radiotherapy (INRT) in patients with early Hodgkin lymphoma: Concepts and guidelines

BACKGROUND AND PURPOSE

To describe new concepts for radiation fields in patients with early stage Hodgkin lymphoma treated with a combined modality.

PATIENTS AND MATERIALS

Patients receiving combined modality therapy with at least 2 or 3 cycles of chemotherapy prior to radiotherapy. Pre- and postchemotherapy cervical and thoracic CT scans are mandatory and should be performed, whenever possible, in the treatment position with the use of image fusion capabilities. A pre-chemotherapy PET scan is strongly recommended to increase the detection of involved lymph nodes.

RESULTS

Radiation fields are designed to irradiate the initially involved lymph nodes exclusively and to encompass their initial volume. In some cases, radiation fields are slightly modified to avoid unnecessary irradiation of muscles or organs at risk.

CONCLUSIONS

The concept of involved-node radiotherapy (INRT) described here is the first attempt to reduce the size of radiation fields compared to the classic involved fields used in adult patients. Proper implementation of INRT requires adequate training and an efficient prospective or early retrospective quality assurance program.

Les traitements par les radiations ionisantes dans les lymphomes. Indications actuelles et futures

Presently, radiotherapy is rarely an upfront treatment in patients with lymphomas. The modern evolution of radiation treatment calls for the development of therapeutic niches in which radiotherapy remains absolutely necessary. The development of new imaging techniques and their use in radiation planning systems along with new sophisticated radiation delivery techniques such as IMRT and respiratory gating should permit an increased accuracy an increased accuracy in the treatment of tumor masses and a decrease in late normal tissue complications.

Is intensity-modulated radiotherapy better than conventional radiation treatment and three-dimensional conformal radiotherapy for mediastinal masses in patients with Hodgkin's disease, and is there a role for beam orientation optimization and dose constraints assigned to virtual volumes?

PURPOSE

To evaluate the role of beam orientation optimization and the role of virtual volumes (VVs) aimed at protecting adjacent organs at risk (OARs), and to compare various intensity-modulated radiotherapy (IMRT) setups with conventional treatment with anterior and posterior fields and three-dimensional conformal radiotherapy (3D-CRT).

METHODS AND MATERIALS

Patients with mediastinal masses in Hodgkin's disease were treated with combined modality therapy (three to six cycles of adriamycin, bleomycin, vinblastine, and dacarbazine [ABVD] before radiation treatment). Contouring and treatment planning were performed with Somavision and CadPlan Helios (Varian Systems, Palo Alto, CA). The gross tumor volume was determined according to the prechemotherapy length and the postchemotherapy width of the mediastinal tumor mass. A 10-mm isotropic margin was added for the planning target volume (PTV). Because dose constraints assigned to OARs led to unsatisfactory PTV coverage, VVs were designed for each patient to protect adjacent OARs. The prescribed dose was 40 Gy to the PTV, delivered according to guidelines from International Commission on Radiation Units and Measurements Report No. 50. Five different IMRT treatment plans were compared with conventional treatment and 3D-CRT.

RESULTS

Beam orientation was important with respect to the amount of irradiated normal tissues. The best compromise in terms of PTV coverage and protection of normal tissues was obtained with five equally spaced beams (5FEQ IMRT plan) using dose constraints assigned to VVs. When IMRT treatment plans were compared with conventional treatment and 3D-CRT, dose conformation with IMRT was significantly better, with greater protection of the heart, coronary arteries, esophagus, and spinal cord. The lungs and breasts in women received a slightly higher radiation dose with IMRT compared with conventional treatments. The greater volume of normal tissue receiving low radiation doses could be a cause for concern.

CONCLUSIONS

The 5FEQ IMRT plan with dose constraints assigned to the PTV and VV allows better dose conformation than conventional treatment and 3D-CRT, notably with better protection of the heart and coronary arteries. Of concern is the "spreading out" of low doses to the rest of the patient's body.

Das plexiforme Schwannom des Hodens

In this report we describe the case of a testicular schwannoma in a human. Histologically, the tumor presented as a plexiform schwannoma. This rare benign peripheral nerve sheath tumor is an uncommon nodular variant of schwannoma, which mimics plexiform neurofibroma by its multinodular growth.

Haemangiopericytoma of the thyroid gland in combination with Hashimoto?s disease

We present a hitherto unique case of haemangiopericytoma (HP) of the thyroid gland in a 15-year-old female patient suffering from Hashimoto's disease for several months. Since angiogenesis has been discussed to play a major role in both diseases, we examined the expression of vascular endothelial growth factor (VEGF), VEGF receptors (VEGFRs) and platelet-derived growth factor receptors (PDGFRs). Most interestingly, strong expression of PDGFR alpha and beta was found in spindle-shaped tumour cells and tumour vessels in HP, while VEGF and VEGFR type I and -II were negative in these regions. In contrast, VEGF was expressed in the lymphoid infiltrate of Hashimoto's disease. Since PDGFR-beta is commonly expressed in pericytes, we suggest that the strong expression discovered in this study further supports the view that HP is derived from pericytes. The combination of HP and Hashimoto's disease is most probably a coincidental event. However, this case confirms previous reports demonstrating that in patients with Hashimoto's disease different neoplasias can occur.

Multiplex polymerase chain reaction for rapid detection of atypical mycobacteria and Mycobacterium tuberculosis complex

A three-step polymerase chain reaction (PCR) method was developed for the detection and typing of mycobacterial DNA in clinical samples and fixed tissue specimens. The first step was to rule out or prove the presence of DNA of Mycobacterium tuberculosis complex. An amplified fragment from the insertion sequence (IS) 6110 was used for this purpose. Patients negative for IS 6110 were evaluated for a fragment of the 65 kDa-antigen, present in all mycobacteria. In positive patients, a multiplex PCR was performed for M. gordonae, M. avium, M. kansasii, M. fortuitum, and M. malmoense, combined in one PCR run. As another control, to prove mycobacterial DNA, PCR was used for the gene coding for the 16S ribosomal RNA also found in all mycobacteria. Appropriate negative controls were included. Different clinical samples were compared for an efficient amplification of these different mycobacterial DNA fragments. Different mycobacteria can be identified within one day in either unfixed cytologic and bacteriologic samples, or formalin-fixed paraffin-embedded tissue samples. Therefore, this method is a quick, cost efficient, and reliable tool to identify mycobacteria other than the tuberculosis complex.