Radiation-induced meningiomas after high-dose cranial irradiation

Increased risk of subsequent neoplasm after hematopoietic stem cell transplantation in 5-year survivors of childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) survivors are at risk for developing subsequent neoplasms, but there is limited information on long-term risks and risk factors for both subsequent malignant neoplasms (SMNs) and subsequent non-malignant neoplasms (SNMNs). We analyzed long-term risk and risk factors for SMNs and SNMNs among 3291 5-year ALL survivors from the Dutch Childhood Cancer Survivor Study-LATER cohort (1963-2014). We calculated standardized incidence ratios (SIRs) and cumulative incidences and used multivariable Cox proportional hazard regression analyses for analyzing risk factors. A total of 97 survivors developed SMNs and 266 SNMNs. The 30-year cumulative incidence was 4.1% (95%CI: 3.5-5.3) for SMNs and 10.4%(95%CI: 8.9-12.1) for SNMNs. Risk of SMNs was elevated compared to the general population (SIR: 2.6, 95%CI: 2.1-3.1). Survivors treated with hematopoietic stem cell transplantation (HSCT) with total body irradiation (TBI) (HR:4.2, 95%CI: 2.3-7.9), and without TBI (HR:4.0,95%CI: 1.2-13.7) showed increased SMN risk versus non-transplanted survivors. Cranial radiotherapy (CRT) was also a risk factor for SMNs (HR:2.1, 95%CI: 1.4-4.0). In conclusion, childhood ALL survivors have an increased SMN risk, especially after HSCT and CRT. A key finding is that even HSCT-treated survivors without TBI treatment showed an increased SMN risk, possibly due to accompanied chemotherapy treatment. This emphasizes the need for careful follow-up of HSCT and/or CRT-treated survivors.

Case report: Low-dose radiation-induced meningioma with a short latency period

Patients with radiation-induced meningioma (RIM), most of whom had received head radiation therapy or had been exposed to ionizing radiation during childhood or adolescence, are at risk of developing cranial meningiomas throughout their lifetimes because of the long latency period. Although intermediate-to-high-dose ionizing radiation exposure is an established risk factor for RIM, risk factors for low-dose RIM remain incompletely defined. This study presents the case of a 56-year-old woman diagnosed with radiation-induced giant meningioma 2.5 years after undergoing an interventional embolization procedure for a brain aneurysm. This is the first report of RIM attributable to a brain intervention with an extremely short latency period. The total radiation dose received by the patient during the operation was 1367.3 mGy, representing a low dose. Our case report strengthens the evidence that even low radiation doses can increase the risk of RIM. These findings provide a realistic basis for the theoretical study of RIM and suggest some new ideas for RIM treatment. The need for caution in the use of radioactive treatments and optimization of interventional procedures is highlighted.

Favourable outcomes with an initial active surveillance strategy for asymptomatic radiation-induced meningiomas in long-term survivors of paediatric and young adult malignancies

PURPOSE

Radiation-induced meningiomas (RIM) are the most common secondary neoplasm post cranial radiotherapy, yet optimal surveillance and treatment strategies remain contentious. Herein, we report the clinical outcomes and radiological growth rate of RIM, diagnosed in a cohort of survivors undergoing MRI screening, with the objective of informing clinical guidelines and practice.

MATERIALS AND METHODS

Long-term survivors of paediatric or young-adult malignancies, diagnosed with RIM between 1990 and 2015, were identified. Absolute (AGR) and relative (RGR) volumetric growth rates were calculated. Rapid growth was defined as AGR > 2 cm3/year or AGR > 1 cm3/year and RGR ≥ 30% RESULTS: Fifty-two patients (87 RIM) were included. Median age at first RIM diagnosis was 33.9 (range,13.8-54.1) years. Seventy-seven (88%) RIM were asymptomatic at detection. Median follow-up time from first RIM detection was 11 (range, 0.6-28) years. Median absolute and relative volumetric growth rates were 0.05 (IQR 0.01-0.11) cm3 and 26 (IQR 7-79) % per year, respectively. Two (3.3%) RIM demonstrated rapid growth. Active surveillance was adopted for 67 (77%) RIM in 40 patients. Neurological sequelae due to RIM progression were reported in 5% of patients on active surveillance. Surgery was performed for 33 RIM (30 patients): 18 (54.5%) at diagnosis and 15 (45.5%) after active surveillance. Histopathology was WHO Grade 1 (85.2%), 2 (11.1%), 3 (3.7%). Following resection, 10-year local recurrence rate was 12%. During follow-up, 19 (37%) survivors developed multiple RIM.

CONCLUSIONS

Asymptomatic RIM are typically low-grade tumours which exhibit slow growth. Active surveillance appears to be a safe initial strategy for asymptomatic RIM, associated with a low rate of neurological morbidity.

Radiation-induced meningiomas (RIM) in adults: A single-centre retrospective experience

Introduction

Radiotherapy of central nervous system (CNS) is treatment against many paediatric cancers, even if it is a well-recognized risk factor for meningioma formation. An increased risk of developing secondary brain tumors like radiation-induced meningiomas (RIM) is related to irradiated patients.

Research question

This retrospective study aims to present RIM cases treated in a single tertiary-hospital in Greece and compare the results with international literature and cases of sporadic meningiomas.

Materials and methods

A single-centre retrospective study of all patients diagnosed between January 2012 and September 2022 with RIM after having been irradiated in CNS for paediatric cancer was undertaken through hospital's electronic record and clinical notes, identifying baseline demographics and latency period.

Results

Thirteen patients were identified with RIM diagnosis after receiving irradiation for Acute Lymphoblastic Leukaemia (69.2%), Premature Neuro-Ectodermal Tumour (23.1%), and Astrocytoma (7.7%). Median age at irradiation was 5 years old and 32 years old at RIM's presentation. The latent period from irradiation to meningioma diagnosis was 26.23 ​± ​5.96 years. After surgical excision, histopathologic results showed grade I meningiomas in 12 out of thirteen cases, while only one atypical meningioma was diagnosed.

Conclusion

Patients who underwent CNS-radiotherapy in childhood for any condition have an increased risk of developing secondary brain tumors such as radiation-induced meningiomas. RIMs resemble sporadic meningiomas in symptomatology, location, treatment, and histologic grade. However, long-term follow-up and regular check-ups are recommended in irradiated patients due to short latency period from irradiation to RIM development, which means younger age patients than those with sporadic meningiomas cases.

Radiation-Induced Meningiomas

While the majority of meningiomas encountered clinically are sporadic, there is a rare subset that arises due to early life or childhood irradiation. Sources of this radiation exposure may be due to treatment of other cancers such as acute childhood leukemia, other central nervous system tumors such as medulloblastoma, the treatment of tinea capitis (rarely and historically), or environmental exposures, as seen in some of the Hiroshima and Nagasaki atomic bomb survivors. Regardless of their etiology, however, radiation-induced meningiomas (RIMs) tend to be highly biologically aggressive irrespective of WHO grade and are usually refractory to the conventional treatment modalities of surgery and/or radiotherapy. In this chapter, we will discuss these RIMs in their historical context, their clinical presentation, their genomic features and ongoing efforts to better understand these tumors from a biological standpoint in order to develop better, more efficacious therapies for these patients.

Evaluation of the growth rates and related prognostic factors in radiation-induced meningiomas

PURPOSE

Literature dedicated to growth patterns and growth rate influencing factors of radiation-induced meningiomas (RIMs) is limited. To deliver new insights into the topic, a volumetric growth analysis of RIMs was performed.

METHODS

This single-center, retrospective cohort study included patients diagnosed with intracranial meningioma who received radiation treatment at least > 5 years before the RIM diagnosis. Volumetric analysis of individual RIMs was performed using 3D volumetry at the time of RIM diagnosis and during follow-up. RIM growth was determined by calculating absolute (AGR), and relative (RGR) growth rates. Prognostic factors associated with RIM growth were evaluated.

RESULTS

A total of 26 patients with 33 meningiomas were enrolled in the study and radiologically/clinically followed up during a median duration of 5.6 years (IQR 3.9-8.8 years). Median AGR was 0.19 cm³ per year and the median RGR was 34.5% per year. Surgically managed RIMs were more likely fast-growing compared to observed ones based on the AGR (p < 0.002). The recurrence rate after total resection was 14.3%. Younger age at RIM diagnosis was associated with higher tumor growth (RGR ≥ 30%, p = 0.040). A significant correlation was found between the length of latency period and the RGR (p = 0.005).

CONCLUSION

To diagnose RIM as early as possible comprehensive MRI surveillance is required. Younger patients with shorter latency periods may profit from shortened MRI intervals, with further management being dependent on the growth rate and eventual symptomatology.

Glioblastoma Following Treated Medulloblastoma After 29 Years in the Posterior Fossa: Case Report and Review of Literature

Glioblastoma multiforme (GBM) is a high-grade glioma that may be a rare complication of radiotherapy. We report a case of a patient who was treated for medulloblastoma (MB) of the posterior fossa at the age of 27 years. Twenty-nine years later, at the age of 56 years, he presented with a double-location tumor: supratentorial and in the posterior fossa. Imaging features of the supratentorial location were very suggestive of a meningioma. We operated on the posterior fossa location, which revealed a glioblastoma. Histologically, the tumor cells exhibited characteristics of both GBM and rhabdoid tumor cells. Literature reports of cases of GBM following MB at the same place are very rare, and presenting rhabdoid characteristics is even rarer. This is the first case of MB and GBM at ages 27 and 56 years, respectively. The double-location supratentorial probable meningioma and GBM of the posterior fossa 32 years after MB is the only case reported in the literature. What to do in this case remains a topic of debate, and there are no clear recommendations in the literature.

Natural history of meningiomas: a serial volumetric analysis of 240 tumors

OBJECTIVE

The management of asymptomatic intracranial meningiomas is controversial. Through the assessment of growth predictors, the authors aimed to create the basis for practicable clinical pathways for the management of these tumors.

METHODS

The authors volumetrically analyzed meningiomas radiologically diagnosed at their institution between 2003 and 2015. The primary endpoint was growth of tumor volume. The authors used significant variables from the multivariable regression model to construct a decision tree based on the exhaustive Chi-Square Automatic Interaction Detection (CHAID) algorithm.

RESULTS

Of 240 meningiomas, 159 (66.3%) demonstrated growth during a mean observation period of 46.9 months. On multivariable logistic regression analysis, older age (OR 0.979 [95% CI 0.958-1.000], p = 0.048) and presence of calcification (OR 0.442 [95% CI 0.224-0.872], p = 0.019) had a negative predictive value for tumor growth, while T2-signal iso-/hyperintensity (OR 4.415 [95% CI 2.056-9.479], p < 0.001) had a positive predictive value. A decision tree model yielded three growth risk groups based on T2 signal intensity and presence of calcifications. The median tumor volume doubling time (Td) was 185.7 months in the low-risk, 100.1 months in the intermediate-risk, and 51.7 months in the high-risk group (p < 0.001). Whereas 0% of meningiomas in the low- and intermediate-risk groups had a Td of ≤ 12 months, the percentage was 8.9% in the high-risk group (p = 0.021).

CONCLUSIONS

Most meningiomas demonstrated growth during follow-up. The absence of calcifications and iso-/hyperintensity on T2-weighted imaging offer a practical way of stratifying meningiomas as low, intermediate, or high risk. Small tumors in the low- or intermediate-risk categories can be monitored with longer follow-up intervals.

The growth rate and clinical outcomes of radiation induced meningioma undergoing treatment or active monitoring

INTRODUCTION

Radiation induced meningioma (RIM) incidence is increasing in line with improved childhood cancer survival. No optimal management strategy consensus exists. This study aimed to delineate meningioma growth rates from tumor discovery and correlate with clinical outcomes.

METHODS

Retrospective study of patients with a RIM, managed at a specialist tertiary neuroscience center (2007-2019). Tumor volume was measured from diagnosis and at subsequent interval scans. Meningioma growth rate was determined using a linear mixed-effects model. Clinical outcomes were correlated with growth rates accounting for imaging and clinical prognostic factors.

RESULTS

Fifty-four patients (110 meningiomas) were included. Median duration of follow-up was 74 months (interquartile range [IQR], 41-102 months). Mean radiation dose was 41 Gy (standard deviation [SD] = 14.9) with a latency period of 34.4 years (SD = 13.7). Median absolute growth rate was 0.62 cm³/year and the median relative growth rate was 72%/year. Forty meningiomas (between 27 patients) underwent surgical intervention after a median follow-up duration of 4 months (IQR 2-35). Operated RIMs were clinically aggressive, likely to be WHO grade 2 at first resection (43.6%) and to progress after surgery (41%). Median time to progression was 28 months (IQR 13-60.5). A larger meningioma at discovery was associated with growth (HR 1.2 [95% CI 1.0-1.5], P = 0.039) but not progression after surgery (HR 2.2 [95% CI 0.7-6.6], P = 0.181). Twenty-seven (50%) patients had multiple meningiomas by the end of the study.

CONCLUSION

RIMs exhibit high absolute and relative growth rates after discovery. Surgery is recommended for symptomatic or rapidly growing meningiomas only. Recurrence risk after surgery is high.

Radiation-induced meningiomas

Radiation-induced meningiomas (RIMs) became more common as the use of ionizing radiation was adopted in the treatment of medical conditions, both benign and malignant. Currently, RIMs represent the most common radiation-induced tumors. They are heterogeneous in terms of patient characteristics, radiographic appearance, genetics, pathology, symptoms, and management strategies. They tend to occur in a younger population and are generally more aggressive in nature than their spontaneous counterparts. Their characteristics also vary based on the dose of radiation received, which is most commonly separated into low dose (<10Gy) and high dose (>10Gy). The importance of the dosing classification is that it can provide insight into the nature and biologic behavior of the tumor. Given their heterogeneity, RIMs pose significant challenges in management. While surgical resection remains the preferred treatment when feasible, recent data supports stereotactic radiosurgery (SRS) as a comparable alternative. Although there is more knowledge about the molecular pathways leading to RIMs, targeted drug therapy is still limited and is the focus of current research.

Primary and Secondary Optic Nerve Sheath Meningioma

Objective  This study was aimed to review issues relating to the recognition, radiographic diagnosis, monitoring, and management of primary and secondary optic nerve sheath meningioma (ONSM). Design  This study is a review of peer-reviewed literature combined with illustrative case studies. Participants and Methods  A literature search was conducted via the PubMed database using pertinent search terms. Selected articles were limited to those written or translated into English. Additional works cited within articles were also included. Individual cases were drawn from the experience of a tertiary academic neuroophthalmic and orbital practice. Tables summarize radiotherapeutic and surgical studies, excluding single case reports and studies focusing on meningioma of intracranial origin. Main Outcome Measurements  Review of reported surgical and radiotherapeutic series is the primary measurement. Results  The natural history of optic nerve sheath meningiomas is primarily characterized by progressive ipsilateral vision loss. Diagnosis is typically based on radiographic imaging findings, with biopsy remaining indicated in some patients. Management strategies may include observation, radiation, and/or surgical intervention, or a combination of these approaches. The role of surgery, especially with respect to primary ONSM (pONSM), remains controversial. Advancement of radiotherapy techniques has shifted modern treatment paradigms in pONSM toward radiation as primary treatment, as surgical outcomes are inferior in major studies. Although radiation remains the treatment of choice in many cases, selected patients may benefit from surgery, especially in the setting of secondary ONSM (sONSM). Conclusion  A wide variety of radiotherapeutic and surgical treatment modalities for ONSM exist. The specific indications for each management strategy continue to be redefined.

Molecular and translational advances in meningiomas

Meningiomas are the most common primary intracranial neoplasm. The current World Health Organization (WHO) classification categorizes meningiomas based on histopathological features, but emerging molecular data demonstrate the importance of genomic and epigenomic factors in the clinical behavior of these tumors. Treatment options for symptomatic meningiomas are limited to surgical resection where possible and adjuvant radiation therapy for tumors with concerning histopathological features or recurrent disease. At present, alternative adjuvant treatment options are not available in part due to limited historical biological analysis and clinical trial investigation on meningiomas. With advances in molecular and genomic techniques in the last decade, we have witnessed a surge of interest in understanding the genomic and epigenomic landscape of meningiomas. The field is now at the stage to adopt this molecular knowledge to refine meningioma classification and introduce molecular algorithms that can guide prediction and therapeutics for this tumor type. Animal models that recapitulate meningiomas faithfully are in critical need to test new therapeutics to facilitate rapid-cycle translation to clinical trials. Here we review the most up-to-date knowledge of molecular alterations that provide insight into meningioma behavior and are ready for application to clinical trial investigation, and highlight the landscape of available preclinical models in meningiomas.

Radiation-Induced Meningiomas After Childhood Brain Tumor: A Magnetic Resonance Imaging Screening Study

Purpose: Childhood brain tumors (CBTs) and their treatment increase the risk of secondary neoplasms (SNs). We studied the incidence of secondary craniospinal tumors with magnetic resonance imaging (MRI) screening in a national cohort of survivors of CBT treated with radiotherapy, and we analyzed the Finnish Cancer Registry (FCR) data on SNs in survivors of CBT with radiotherapy registered as a part of the primary tumor treatment. Methods: A total of 73 survivors of CBT participated in the MRI study (mean follow-up of 19 ± 6.2 years). The incidence of SNs in a cohort of CBT patients (N = 569) was retrieved from the FCR (mean follow-up of 11 ± 12.9 years). Brain tumors were diagnosed at age ≤16 years between the years 1970 and 2008 in the clinical study and the years 1963 and 2010 in the FCR population. Results: Secondary brain tumors, meningiomas in all and schwannoma in one, were found in 6 of the 73 (8.2%) survivors with a mean of 23 ± 4.3 years after the diagnosis of the primary tumor. The cumulative incidence was 10.2% (95% confidence interval [CI] 3.9-25.1) in 25 years of follow-up. In the FCR data, the 25-year cumulative incidence of SNs was 2.4% (95% CI 1.3-4.1); only two brain tumors, no meningiomas, were registered. Conclusion: Survivors of CBT treated with radiotherapy have a high incidence of meningiomas, which are rarely registered in the FCR.

Radiation-induced meningiomas: A case-control study at single center institution

BACKGROUND

Our understanding of radiation induced meningiomas (RIM) is limited. It has been suggested that RIM harbor more aggressive cellular pathology and must be observed vigilantly. However, the actual recurrence rates of RIM compared to the sporadic meningiomas has yet to be defined.

OBJECTIVE

We employ a single center case-control study to retrospectively assess recurrence rates between RIM (n = 12) and sporadic meningiomas (n = 118).

METHODS

The criteria for the RIM group included the following: 1) History of intracranial clinical-dose radiation 2) Initial pathology other than meningioma, 3) Radiation administered greater than 5 years prior to meningioma onset. Recurrence rates, extent of resection and outcomes were analyzed.

RESULTS

There was a significant difference in recurrence rates between the RIM group and sporadic meningioma: 50% vs. 5% respectively, p = 0.004. There was no significant difference in race, preoperative tumor volume, extent of resection, Ki67, or age between the two groups. Multivariate analysis demonstrated that size (OR 0.95 95%CI (0.92-0.99)), extent of resection (OR 1.08 95%CI (1.01-1.14)), WHO grade (OR 160.24 95% CI (6.32-74509)) and history of previous radiation (OR 1.28 95%CI (1.01-1.62)) were independent risk factors for recurrence. RIM patients had significantly higher proportion of atypical or malignant histology compared to sporadic patients (p < 0.0001).

CONCLUSION

RIM patients may have a higher predisposition for tumor recurrence than patients with sporadic RIM. The use of Ki67 indices may help identify patients with a higher risk of tumor recurrence. Prospective studies focusing on newly diagnosed patients with RIM may help identify an optimal surveillance and treatment plan.

Therapeutic radiation for childhood cancer drives structural aberrations of NF2 in meningiomas

Cranial radiotherapy improves survival of the most common childhood cancers, including brain tumors and leukemia. Unfortunately, long-term survivors are faced with consequences of secondary neoplasia, including radiation-induced meningiomas (RIMs). We characterized 31 RIMs with exome/NF2 intronic sequencing, RNA sequencing and methylation profiling, and found NF2 gene rearrangements in 12/31 of RIMs, an observation previously unreported in sporadic meningioma (SM). Additionally, known recurrent mutations characteristic of SM, including AKT1, KLF4, TRAF7 and SMO, were not observed in RIMs. Combined losses of chromosomes 1p and 22q were common in RIMs (16/18 cases) and overall, chromosomal aberrations were more complex than that observed in SM. Patterns of DNA methylation profiling supported similar cell of origin between RIMs and SMs. The findings indicate that the mutational landscape of RIMs is distinct from SMs, and have significant therapeutic implications for survivors of childhood cranial radiation and the elucidation of the molecular pathogenesis of meningiomas.

Radiation-induced meningiomas are often more aggressive than sporadic ones. In this study, the authors perform an exome, methylation and RNA-seq analysis of 31 cases of radiation-induced meningioma and show NF2 rearrangement, an observation previously unreported in the sporadic tumors.

An Overview of Anterior Skull Base Meningiomas and the Endoscopic Endonasal Approach

Meningiomas represent 30% of all primary brain tumors. Anterior skull base meningiomas represent 8.8% of all meningiomas. Surgical resection is a main treatment option for tumors that are symptomatic and/or growing. Recurrence is directly related to the extent of resection of the tumor, the dural attachment, and pathologic bone. Endoscopic endonasal approaches represent an important addition to the treatment armamentarium for skull base meningiomas. This article provides an overview of meningiomas, with a focus on those of the anterior skull base and their management.

Multiple meningiomas in a woman irradiated in utero

Meningiomas are a common central nervous system tumour and radiation is a known risk factor for their development. In utero radiation exposure correlates to developmental abnormalities and carcinogenesis in a dose- and gestational age-related manner. Radiation induced meningioma has been reported in detail in the literature in patients who had been irradiated earlier in life. At the time of publication, there was no data on radiation exposure whilst in utero and meningioma. We report on a 42-year-old woman with multiple intracranial meningiomas and no other risk factors except a history of in utero exposure to low dose X-ray radiation at 12weeks gestational age.

Radiotherapy for benign disease; assessing the risk of radiation-induced cancer following exposure to intermediate dose radiation

Most radiotherapy (RT) involves the use of high doses (>50 Gy) to treat malignant disease. However, low to intermediate doses (approximately 3-50 Gy) can provide effective control of a number of benign conditions, ranging from inflammatory/proliferative disorders (e.g. Dupuytren's disease, heterotopic ossification, keloid scarring, pigmented villonodular synovitis) to benign tumours (e.g. glomus tumours or juvenile nasopharyngeal angiofibromas). Current use in UK RT departments is very variable. This review identifies those benign diseases for which RT provides good control of symptoms with, for the most part, minimal side effects. However, exposure to radiation has the potential to cause a radiation-induced cancer (RIC) many years after treatment. The evidence for the magnitude of this risk comes from many disparate sources and is constrained by the small number of long-term studies in relevant clinical cohorts. This review considers the types of evidence available, i.e. theoretical models, phantom studies, epidemiological studies, long-term follow-up of cancer patients and those treated for benign disease, although many of the latter data pertain to treatments that are no longer used. Informative studies are summarized and considered in relation to the potential for development of a RIC in a range of key tissues (skin, brain etc.). Overall, the evidence suggests that the risks of cancer following RT for benign disease for currently advised protocols are small, especially in older patients. However, the balance of risk vs benefit needs to be considered in younger adults and especially if RT is being considered in adolescents or children.

Pathology and molecular genetics of meningioma: recent advances

Meningiomas are the most common intracranial primary neoplasm in adults. Although the spectrum of clinical and molecular genetic issues regarding meningiomas remains undefined, novel genetic alterations that are associated with tumor morphology, malignancy, or location have recently been discovered. This review focuses on recent advances in understanding of the heterogenous pathology of meningiomas, particularly on associations between the clinical, histological, etiological, epidemiological, and molecular genetical aspects of the neoplasm.

The evolving role of radiosurgery in the management of radiation-induced meningiomas: a review of current advances and future directions

Meningiomas are among the most common primary adult brain tumors, which arise either spontaneously or secondary to environmental factors such as ionizing radiation. The latter are referred to as radiation-induced meningiomas (RIMs) which, while much less common than their spontaneous counterparts, are challenging from a management point of view. Similar to spontaneous meningiomas, the optimal management of RIMs is complete surgical resection. However, given their high grade, multiplicity, tendency to invade bone and venous sinuses, and high recurrence rate, this cannot always be accomplished safely. Therefore, other therapeutic modalities, such as stereotactic radiosurgery, have emerged. In the current review, we provide an overview of the historical outcomes achieved for RIMs through radiosurgery and microsurgical resection. Furthermore, we provide a discussion of clinical and radiological parameters that affect the decision-making process with regard to the management of RIMs. We also provide an outline of recent changes in our understanding of RIMs, based on molecular and genetic markers, and how these will change our management perspective. We conclude the review by summarizing some of the current obstacles in the management of RIMs with SRS and how current and future research can address these challenges.