Rectal cancer, which accounts for approximately 40% of colorectal cancers, remains a major clinical concern. Recent advances in diagnostic imaging, surgical techniques, radiotherapy, and systemic treatment have steadily improved rectal cancer outcomes. Considering this, the Korean Rectal Cancer Multidisciplinary (KRCM) Committee has aimed to provide clinicians and policymakers with up-to-date, evidence-based clinical practice guidelines to support optimal decision-making, reflecting current evidence, the Korean healthcare context, and patient values and preferences. The Clinical Practice Guidelines for Rectal Cancer version 2.0 were developed through multidisciplinary collaboration with related academic societies, building upon and updating the KRCM Clinical Practice Guidelines version 1.0 (titled “Multidisciplinary guidelines for the management of rectal cancer”). These consensus guidelines of the KRCM were established based on a comprehensive literature review, evidence synthesis, with recommendation development guided by the GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology, and consideration of applicability in real-world clinical practice under the national health insurance system. Each recommendation has been presented with its strength and level of evidence.

Purpose: Pediatric papillary thyroid cancer (PTC) is recommended to perform aggressive surgery to reduce the risk of recurrence.This study was designed to evaluate the concurrent association between multifocality, bilaterality, and the risk of recurrence in pediatric PTC. Materials and Methods: This retrospective cohort study included pediatric patients (age <19 years) who underwent total thyroidectomy for PTC between 1996 and 2014 in a single tertiary center. Clinicopathological parameters were analyzed to evaluate the prevalence of multifocality, bilaterality, recurrence, and their association. Results: We analyzed 58 pediatric patients with PTC. There was no factor related to the presence of multifocality or bilaterality in multivariate analysis. Also, in univariate analysis, multifocality and bilaterality were not independent risk factors of each other’s presentation (p=0.061 and p=0.061, respectively). Recurrence was observed in 19 (32.8%) patients. In multivariate analysis of recurrence, clear cell subtype, multifocality, and gross extrathyroidal extension (ETE) were independent risk factors (p=0.027, p=0.035, and p=0.038, respectively). Most recurrences (68.4%) happened during the first 4 years of follow-up after the initial thyroidectomy. Conclusion Multifocality and bilaterality were not independent risk factors of each other’s presentation; however, multifocality was the risk factor for recurrence in pediatric PTC. For pediatric PTC, close monitoring for recurrence within the initial 4 years is recommended, particularly in patients with clear cell subtype, multifocality, and gross ETE.

Background: While the clinical course of radiation-induced meningioma (RIM) is considered to be more aggressive than that of sporadic meningioma (SM), the genetic predisposition for RIM is not established well. The present study aimed to analyze the clinical and genetic characteristics of RIMs to increase understanding of the tumorigenesis and prognosis of RIMs. Methods: We investigated a database of 24 patients who met the RIM criteria between January 2000 and April 2023. Genetic analysis through next-generation sequencing with a targeted gene panel was performed on 10 RIM samples. Clinical, radiological, and pathological parameters were evaluated with genetic analyses. Results: The median ages for receiving radiotherapy (RT) and RIM diagnosis were 8.0 and 27.5 years, respectively, with an interval of 17.5 years between RT and RIM diagnosis. RIMs tended to develop in non-skull bases and multifocal locations. Most primary pathologies included germ cell tumors and medulloblastoma. The tumor growth rate was 3.83 cm 3 per year, and the median doubling time was 0.8 years. All patients underwent surgical resection of RIMs. The histological grade of RIMs was World Health Organization grade 1 (64%) or 2 (36%). RIMs showed higher incidences in young-age (63%), high-dose (75%), and extendedfield (79%) RT groups. The recurrence rate was 21%. Genetic analysis revealed NF2 one copy loss in 90% of the patients, with truncating NF2 mutations and additional copy number aberrations in grade 2 RIMs. TERT promoter mutation and CDKN2A/B deletion were not identified. Notably, loss of H3K27me3 was identified in 26% of RIMs. H3K27me3 loss was associated with a higher prevalence of grade 2 RIMs (67%) and high recurrence rates (33%). Conclusion The study reveals a higher prevalence of high-grade tumors among RIMs with more rapid growth and higher recurrences than SMs. Genetically, RIMs are primarily associated with NF-2 alterations with chromosomal abnormalities in grade 2 tumors, along with a higher proportion of H3K27me3 loss.

Background: While the clinical course of radiation-induced meningioma (RIM) is considered to be more aggressive than that of sporadic meningioma (SM), the genetic predisposition for RIM is not established well. The present study aimed to analyze the clinical and genetic characteristics of RIMs to increase understanding of the tumorigenesis and prognosis of RIMs. Methods: We investigated a database of 24 patients who met the RIM criteria between January 2000 and April 2023. Genetic analysis through next-generation sequencing with a targeted gene panel was performed on 10 RIM samples. Clinical, radiological, and pathological parameters were evaluated with genetic analyses. Results: The median ages for receiving radiotherapy (RT) and RIM diagnosis were 8.0 and 27.5 years, respectively, with an interval of 17.5 years between RT and RIM diagnosis. RIMs tended to develop in non-skull bases and multifocal locations. Most primary pathologies included germ cell tumors and medulloblastoma. The tumor growth rate was 3.83 cm 3 per year, and the median doubling time was 0.8 years. All patients underwent surgical resection of RIMs. The histological grade of RIMs was World Health Organization grade 1 (64%) or 2 (36%). RIMs showed higher incidences in young-age (63%), high-dose (75%), and extendedfield (79%) RT groups. The recurrence rate was 21%. Genetic analysis revealed NF2 one copy loss in 90% of the patients, with truncating NF2 mutations and additional copy number aberrations in grade 2 RIMs. TERT promoter mutation and CDKN2A/B deletion were not identified. Notably, loss of H3K27me3 was identified in 26% of RIMs. H3K27me3 loss was associated with a higher prevalence of grade 2 RIMs (67%) and high recurrence rates (33%). Conclusion The study reveals a higher prevalence of high-grade tumors among RIMs with more rapid growth and higher recurrences than SMs. Genetically, RIMs are primarily associated with NF-2 alterations with chromosomal abnormalities in grade 2 tumors, along with a higher proportion of H3K27me3 loss.

Background: While the clinical course of radiation-induced meningioma (RIM) is considered to be more aggressive than that of sporadic meningioma (SM), the genetic predisposition for RIM is not established well. The present study aimed to analyze the clinical and genetic characteristics of RIMs to increase understanding of the tumorigenesis and prognosis of RIMs. Methods: We investigated a database of 24 patients who met the RIM criteria between January 2000 and April 2023. Genetic analysis through next-generation sequencing with a targeted gene panel was performed on 10 RIM samples. Clinical, radiological, and pathological parameters were evaluated with genetic analyses. Results: The median ages for receiving radiotherapy (RT) and RIM diagnosis were 8.0 and 27.5 years, respectively, with an interval of 17.5 years between RT and RIM diagnosis. RIMs tended to develop in non-skull bases and multifocal locations. Most primary pathologies included germ cell tumors and medulloblastoma. The tumor growth rate was 3.83 cm 3 per year, and the median doubling time was 0.8 years. All patients underwent surgical resection of RIMs. The histological grade of RIMs was World Health Organization grade 1 (64%) or 2 (36%). RIMs showed higher incidences in young-age (63%), high-dose (75%), and extendedfield (79%) RT groups. The recurrence rate was 21%. Genetic analysis revealed NF2 one copy loss in 90% of the patients, with truncating NF2 mutations and additional copy number aberrations in grade 2 RIMs. TERT promoter mutation and CDKN2A/B deletion were not identified. Notably, loss of H3K27me3 was identified in 26% of RIMs. H3K27me3 loss was associated with a higher prevalence of grade 2 RIMs (67%) and high recurrence rates (33%). Conclusion The study reveals a higher prevalence of high-grade tumors among RIMs with more rapid growth and higher recurrences than SMs. Genetically, RIMs are primarily associated with NF-2 alterations with chromosomal abnormalities in grade 2 tumors, along with a higher proportion of H3K27me3 loss.

Background: While the clinical course of radiation-induced meningioma (RIM) is considered to be more aggressive than that of sporadic meningioma (SM), the genetic predisposition for RIM is not established well. The present study aimed to analyze the clinical and genetic characteristics of RIMs to increase understanding of the tumorigenesis and prognosis of RIMs. Methods: We investigated a database of 24 patients who met the RIM criteria between January 2000 and April 2023. Genetic analysis through next-generation sequencing with a targeted gene panel was performed on 10 RIM samples. Clinical, radiological, and pathological parameters were evaluated with genetic analyses. Results: The median ages for receiving radiotherapy (RT) and RIM diagnosis were 8.0 and 27.5 years, respectively, with an interval of 17.5 years between RT and RIM diagnosis. RIMs tended to develop in non-skull bases and multifocal locations. Most primary pathologies included germ cell tumors and medulloblastoma. The tumor growth rate was 3.83 cm 3 per year, and the median doubling time was 0.8 years. All patients underwent surgical resection of RIMs. The histological grade of RIMs was World Health Organization grade 1 (64%) or 2 (36%). RIMs showed higher incidences in young-age (63%), high-dose (75%), and extendedfield (79%) RT groups. The recurrence rate was 21%. Genetic analysis revealed NF2 one copy loss in 90% of the patients, with truncating NF2 mutations and additional copy number aberrations in grade 2 RIMs. TERT promoter mutation and CDKN2A/B deletion were not identified. Notably, loss of H3K27me3 was identified in 26% of RIMs. H3K27me3 loss was associated with a higher prevalence of grade 2 RIMs (67%) and high recurrence rates (33%). Conclusion The study reveals a higher prevalence of high-grade tumors among RIMs with more rapid growth and higher recurrences than SMs. Genetically, RIMs are primarily associated with NF-2 alterations with chromosomal abnormalities in grade 2 tumors, along with a higher proportion of H3K27me3 loss.

Purpose: Pediatric papillary thyroid cancer (PTC) is recommended to perform aggressive surgery to reduce the risk of recurrence.This study was designed to evaluate the concurrent association between multifocality, bilaterality, and the risk of recurrence in pediatric PTC. Materials and Methods: This retrospective cohort study included pediatric patients (age <19 years) who underwent total thyroidectomy for PTC between 1996 and 2014 in a single tertiary center. Clinicopathological parameters were analyzed to evaluate the prevalence of multifocality, bilaterality, recurrence, and their association. Results: We analyzed 58 pediatric patients with PTC. There was no factor related to the presence of multifocality or bilaterality in multivariate analysis. Also, in univariate analysis, multifocality and bilaterality were not independent risk factors of each other’s presentation (p=0.061 and p=0.061, respectively). Recurrence was observed in 19 (32.8%) patients. In multivariate analysis of recurrence, clear cell subtype, multifocality, and gross extrathyroidal extension (ETE) were independent risk factors (p=0.027, p=0.035, and p=0.038, respectively). Most recurrences (68.4%) happened during the first 4 years of follow-up after the initial thyroidectomy. Conclusion Multifocality and bilaterality were not independent risk factors of each other’s presentation; however, multifocality was the risk factor for recurrence in pediatric PTC. For pediatric PTC, close monitoring for recurrence within the initial 4 years is recommended, particularly in patients with clear cell subtype, multifocality, and gross ETE.

Purpose: Pediatric papillary thyroid cancer (PTC) is recommended to perform aggressive surgery to reduce the risk of recurrence.This study was designed to evaluate the concurrent association between multifocality, bilaterality, and the risk of recurrence in pediatric PTC. Materials and Methods: This retrospective cohort study included pediatric patients (age <19 years) who underwent total thyroidectomy for PTC between 1996 and 2014 in a single tertiary center. Clinicopathological parameters were analyzed to evaluate the prevalence of multifocality, bilaterality, recurrence, and their association. Results: We analyzed 58 pediatric patients with PTC. There was no factor related to the presence of multifocality or bilaterality in multivariate analysis. Also, in univariate analysis, multifocality and bilaterality were not independent risk factors of each other’s presentation (p=0.061 and p=0.061, respectively). Recurrence was observed in 19 (32.8%) patients. In multivariate analysis of recurrence, clear cell subtype, multifocality, and gross extrathyroidal extension (ETE) were independent risk factors (p=0.027, p=0.035, and p=0.038, respectively). Most recurrences (68.4%) happened during the first 4 years of follow-up after the initial thyroidectomy. Conclusion Multifocality and bilaterality were not independent risk factors of each other’s presentation; however, multifocality was the risk factor for recurrence in pediatric PTC. For pediatric PTC, close monitoring for recurrence within the initial 4 years is recommended, particularly in patients with clear cell subtype, multifocality, and gross ETE.

Purpose: Pediatric papillary thyroid cancer (PTC) is recommended to perform aggressive surgery to reduce the risk of recurrence.This study was designed to evaluate the concurrent association between multifocality, bilaterality, and the risk of recurrence in pediatric PTC. Materials and Methods: This retrospective cohort study included pediatric patients (age <19 years) who underwent total thyroidectomy for PTC between 1996 and 2014 in a single tertiary center. Clinicopathological parameters were analyzed to evaluate the prevalence of multifocality, bilaterality, recurrence, and their association. Results: We analyzed 58 pediatric patients with PTC. There was no factor related to the presence of multifocality or bilaterality in multivariate analysis. Also, in univariate analysis, multifocality and bilaterality were not independent risk factors of each other’s presentation (p=0.061 and p=0.061, respectively). Recurrence was observed in 19 (32.8%) patients. In multivariate analysis of recurrence, clear cell subtype, multifocality, and gross extrathyroidal extension (ETE) were independent risk factors (p=0.027, p=0.035, and p=0.038, respectively). Most recurrences (68.4%) happened during the first 4 years of follow-up after the initial thyroidectomy. Conclusion Multifocality and bilaterality were not independent risk factors of each other’s presentation; however, multifocality was the risk factor for recurrence in pediatric PTC. For pediatric PTC, close monitoring for recurrence within the initial 4 years is recommended, particularly in patients with clear cell subtype, multifocality, and gross ETE.

Purpose: Pediatric papillary thyroid cancer (PTC) is recommended to perform aggressive surgery to reduce the risk of recurrence.This study was designed to evaluate the concurrent association between multifocality, bilaterality, and the risk of recurrence in pediatric PTC. Materials and Methods: This retrospective cohort study included pediatric patients (age <19 years) who underwent total thyroidectomy for PTC between 1996 and 2014 in a single tertiary center. Clinicopathological parameters were analyzed to evaluate the prevalence of multifocality, bilaterality, recurrence, and their association. Results: We analyzed 58 pediatric patients with PTC. There was no factor related to the presence of multifocality or bilaterality in multivariate analysis. Also, in univariate analysis, multifocality and bilaterality were not independent risk factors of each other’s presentation (p=0.061 and p=0.061, respectively). Recurrence was observed in 19 (32.8%) patients. In multivariate analysis of recurrence, clear cell subtype, multifocality, and gross extrathyroidal extension (ETE) were independent risk factors (p=0.027, p=0.035, and p=0.038, respectively). Most recurrences (68.4%) happened during the first 4 years of follow-up after the initial thyroidectomy. Conclusion Multifocality and bilaterality were not independent risk factors of each other’s presentation; however, multifocality was the risk factor for recurrence in pediatric PTC. For pediatric PTC, close monitoring for recurrence within the initial 4 years is recommended, particularly in patients with clear cell subtype, multifocality, and gross ETE.