Extension Margins Research Articles

The geology of the Shyok suture zone: evidence for Cretaceous extension of the southern Eurasian margin and Eocene India-Eurasia collision

The geology of the Shyok suture zone: evidence for Cretaceous extension of the southern Eurasian margin and Eocene India-Eurasia collision

TERT mutations and aggressive histopathologic characteristics of radioiodine-refractory papillary thyroid cancer.

Radioiodine (RI) ablation following thyroid-stimulating hormone suppression is an effective treatment for papillary thyroid cancer (PTC), typically leading to favorable outcomes. However, RI-refractory tumors exhibit aggressive behavior and poor prognoses. Recent studies highlight the role of genetic abnormalities in PTC signaling pathways, including the activation of telomerase reverse transcriptase (TERT), and the correlation of mutations with adverse outcomes. This study analyzed mutations in BRAF V600E and the TERT-promoter genes, comparing clinicopathological features between RI-refractory and RI-responsive PTCs. Among 82 RI-refractory patients, formalin-fixed, paraffin-embedded tissues from initial surgeries were available for 26. Another 89 without distant metastasis over 5 years formed a matched RI-responsive control group. Histopathologically, RI-refractory PTCs showed increased frequencies of small tumor clusters without fibrovascular cores, hobnail features, and a high height-to-width ratio of tumor cells. These tumors were more likely to exhibit necrosis, mitosis, lymph node metastasis, extrathyroidal extension, and involvement of resection margins. TERT-promoter mutations were statistically significantly associated with these aggressive clinicopathologic features. Immunohistochemically, decreased expression of sodium iodide symporter and thyroglobulin stimulating hormone receptor proteins was common in RI-refractory PTCs, along with lower levels of oncogenic proteins such as vascular endothelial cell growth factor, vascular endothelial cell growth factor receptor 2, and nuclear factor kappa-light-chain-enhancer of activated B cells. Total loss of PTEN expression was occasionally observed. In contrast, all cases tested positive for cytoplasmic β-catenin. RI-refractory PTCs are linked to TERT mutations and exhibit specific aggressive histopathologic features, particularly in tumor centers.

A comparison of whole-mount and conventional sections for pathological mesorectal extension and circumferential resection margin assessment after total mesorectal excision

IntroductionThe objective of the study is to compare 2 techniques for histological handling of rectal cancer specimens, namely whole-mount in a large block vs conventional sampling using small blocks, for mesorectal pathological assessment of circumferential resection margin status and depth of tumor invasion into the mesorectal fat. MethodsThis is a prospective study including 27 total mesorectal excision specimens of rectal cancer from patients treated for primary rectal carcinoma between 2020 and 2022 in a specialized multidisciplinary Colorectal Unit. For each total mesorectal excision specimen, 2 contiguous representative tumoral slices were selected and comparatively analyzed with whole-mount and small blocks macroscopic dissection techniques, enabling comparison between them in the same surgical specimen. The agreement between the 2 techniques to assess the distance of the tumor from the circumferential resection margin as well as the depth of tumor invasion was evaluated with the Student’s t-test for paired samples, Pearson’s correlation coefficient, and the Bland-Altman method comparison analysis. ResultsComplete mesorectal excision was observed in 8% of cases. Circumferential resection margin involvement was observed in only one case (4 %). The whole-mount and small block techniques obtained similar results when we assessed the distance to the circumferential resection margin (t-test P = 0.8, r = 0.92) and the depth of mesorectal infiltration (t-test P = 0.6, r = 0.95). ConclusionsBoth gross dissection techniques (whole-mount vs multiple small cassettes) are equivalent and reliable to assess the distance to circumferential resection margin and the depth of mesorectal infiltration in the mesorectal fat in rectal cancer staging.

"Inverted flap rhexis" - Salvation of intumescence.

Intumescent cataract can be a challenge even for an experienced surgeon, particularly for creating a continuous curvilinear capsulorhexis (CCC) because of increased endolenticular pressure. CCC in white intumescent cataract is associated with increased risk of extension of rhexis margin leading to radial tear or biradial extension causing "Argentinian flag sign" and associated complications. We describe a novel technique for CCC, in which we manipulate the vector forces acting in creating a capsulorhexis. After making a mini CCC, a flap is raised and then inverted under the rhexis margin and CCC is done by keeping the flap inverted using shearing and tearing forces, keeping the direction of force down and toward the center in a curvilinear fashion. It is a new surgical technique to perform a successful and safer CCC in intumescent cataract with consistent outcome.

The Sex and Age-Associated Infiltration of B Cells May Result in the Dimorphic Behaviors Observed in Papillary Thyroid Carcinomas.

Sex and age show a dimorphism role in the pathogenesis, lymph node metastasis, and prognostic outcomes of papillary thyroid carcinoma. This investigation endeavors to elucidate the mechanisms underlying these disparities. The clinicopathological characteristics and risk factors of lymph node metastasis were explored by analyzing the 2261 patients. The gene expression information of 497 samples from The Cancer Genome Atlas Thyroid Cancer database was used to explore the differentially expressed genes in different phenotypes. What's more, the single-cell RNA sequencing data obtained from the Gene Expression Omnibus database was used to explore the gene expression in specific cells. Multivariate logistic regression analysis showed that in male patients, a larger tumor size, extrathyroidal extension, younger age, and the presence of calcification emerged as significant predictors for lymph node metastasis (LNM)(p < 0.05). Conversely, female patients exhibited a different profile, with larger tumor size, extrathyroidal extension, younger age, calcification, and bilateral tumors being identified as key risk factors (p < 0.05). Further stratification by age demonstrated distinct patterns: among the younger cohort, a larger tumor size, extrathyroidal extension, male gender, calcification, multifocality, and the presence of Hashimoto's thyroiditis held statistical significance (p < 0.05). In contrast, the older subgroup was characterized by a larger tumor size, extrathyroidal extension, male gender, calcification, bilateral tumors, and unclear margins as salient indicators of risk (p < 0.05). In the bulk gene analysis, there were two sex-age-related differentially expressed genes with a contrary trend in tissue sources and LNM status: TCL1A and CR2. The analysis of single-cell RNA sequencing showed that the infiltration of TCL1A- and CR2-related B cells varied in different clinical subtypes. Lymph node metastasis of papillary thyroid carcinoma in different sexes and ages may have distinct patterns, and the ages-sex-related B cell infiltration might explain the dimorphism biological behavior.

Predictive Factors for Early Biochemical Recurrence Following Robot-assisted Radical Prostatectomy.

The primary objective of this study was to identify predictors for biochemical recurrence (BCR) within 2 years following robot-assisted radical prostatectomy (RARP). Identifying predictors will enable insights that enhance personalized patient management and facilitate the ongoing refinement of postoperative therapy strategies. This retrospective study included patients undergoing RARP from September 2014 to January 2021. Exclusion criteria were preoperative endocrine therapy, BCR beyond 2 years post-surgery, and incomplete postoperative data. Multivariate analyses were conducted to evaluate predictors of BCR, focusing on preoperative prostate-specific antigen (PSA) level, pathological tumor (pT) stage, Gleason score (GS), extraprostatic extension (EPE), and surgical margin status. Among 374 patients, 40 experienced BCR within 2 years. Significant predictors of early BCR included initial PSA level ≥10 ng/ml, pT3 or greater, GS ≥8, EPE, and positive surgical margins (RM1). Multivariate analysis identified pT3 or higher, GS ≥8, and RM1 as independent risk factors for early BCR. Early BCR after RARP is significantly associated with advanced pathological stage, high GS, and positive surgical margins. These findings emphasize the need for tailored postoperative management strategies and highlight the importance of precision in surgical technique to improve patient outcomes.

Middle triassic magmatism in the Afyon Zone of the Anatolides/Eastern Mediterranean: Implications for the extension of the Northern margin of Gondwana and opening of the Inner-Tauride Ocean

The northward subduction of the Paleo-Tethys beneath the southern margin of Laurasia during the Triassic caused the development of an extensional tectonic regime on the northern Gondwana by pull-forces. The Middle Triassic volcanic activity on the passive continental margin of Gondwana can be attributed to this rifting stage. The Afyon Zone represents the deeply buried northern margin of the Anatolide-Tauride Block (ATB), which was rifted from Gondwana in the Triassic by the opening of the southern Neo-Tethys. It is characterized by the existence of widespread Middle Triassic volcanic activity, which unconformably cover deeply eroded pre-Triassic basement. Early Middle Triassic rhyolites and andesites (245.2 ± 2.0 Ma) represent the first stage of the magmatic activity and exhibit a subduction signature, attributed to the former short-lived southward subduction of the Paleo-Tethys beneath northern Gondwana during the Carboniferous. The second stage of magmatic activity is dominated by trachyandesitic volcanic rocks (243.1 ± 1.9–239.2 ± 1.2 Ma) and rhyolites (243.0 ± 2.9–238.2 ± 1.2 Ma), which were generated in a rift setting. The final stage of magmatic activity at the northern margin of the ATB is characterized by extensional anorogenic alkaline rhyolitic volcanism (237.2 ± 2.3–229.4 ± 2.7 Ma), following the earlier stages described. During Middle to Late Triassic, this rifting on the northern Gondwana led to the synchronous opening of the Inner Tauride Ocean in the north and the southern branch of the Neo-Tethys in the south. The generation of these two oceans and the separation of the ATB and Kırşehir blocks from the northern margin of Gondwana should have resulted in the failure of the northern branch of the Neo-Tethys to open as a new oceanic basin.

Geochemistry of Pelites at Chengmen Area: Implications for Sediments Resource and Tectonic Environment.

The pelite samples were collected from drillholes from the Chengmen area of the Fuzhou Basin of Fujian, China to reveal the sediments resource and tectonic environment of these pelites via an analysis of its lithology and geochemistry. The rare earth element distribution pattern of the pelites exhibited a high degree of fractionation between light and heavy rare earth elements, moderate negative Eu anomalies, and positive Ce anomalies, which are consistent with the rare earth element distribution pattern of Minjiang sediments and Fujian soils. Moreover, the variations in trace elements are also generally consistent, indicating a common provenance. The extremely high chemical index of alteration (CIA) and index of chemical variability (ICV) values of the pelites suggest that the source area experienced intense weathering, indicating a subtropical hot and humid climate environment in the source area and the Fuzhou Basin at that time. The source rock attribute discrimination diagrams show that the main source of pelites is felsic igneous rocks. The ratios of REDOX parameters show that during the sedimentary period, the water body in the study area was predominantly in an oxidizing environment. Furthermore, the tectonic background diagrams reveal that the source area underwent geological tectonic evolution processes of active and passive continental margins, marking the transition from the continental margin above the subduction of the ancient Pacific plate to the continental margin extension after subduction cessation.

A phase I/II study evaluating the feasibility and safety of delivering adjuvant hypofractionated radiotherapy in resected oral cavity cancers (HYPO-ART study)

Background and purposeTo evaluate the tolerability and efficacy of adjuvant Hypofractionated radiotherapy in resected oral cavity cancer patients. Materials and methodsPost-operative oral cavity cancer patients with indications for adjuvant (chemo) radiotherapy were enrolled. T3/T4 disease, positive lymph nodes(s), lympho-vascular invasion, and/or perineural invasion were considered intermediate risk factors for which a radiation dose of 50Gy over four weeks was delivered. Extra-nodal extension and/or positive margins were considered high-risk factors for which a radiation dose of 62.5Gy over five weeks was delivered. The primary end-point was the incidence of acute radiation-induced toxicities. Secondary endpoints were locoregional control and overall survival. Results38 patients were enrolled in the trial and completed planned radiotherapy treatment. No grade 4 toxicity was observed. Acute grade 3 toxicity included oral mucositis in 60.5 % of patients and dysphagia in 18.3 % of patients. 71 % of patients required nasogastric tube placement and 50 % needed day-care support. At a median follow-up of 20.35 months, 57.9 % were alive with no evidence of disease, and 31.6 % of patients had a loco-regional recurrence. Loco-regional control and overall survival at one year were 68 % and 84 %; at two years, they were 59 % and 59 %, respectively. ConclusionsModerately hypofractionated radiotherapy is well tolerated and can safely be delivered for resected oral cavity tumors with optimal supportive care while maintaining similar oncological outcomes compared to conventional fractionation.

Oncological outcomes post transoral robotic surgery (TORS) for HPV-associated oropharyngeal squamous cell carcinoma, a single-centre retrospective Australian study

We present a cohort review of TORS resection for HPV-associated oropharyngeal squamous cell carcinoma (OPSCC) and its associated oncological outcomes spanning a 10-year period. A retrospective case series review was performed of patients undergoing primary surgical treatment for HPV-associated OPSCC through the St. Vincent’s Head and Neck Cancer service from 2011 to 2022. The primary outcomes were to investigate complete resection of the primary tumour, rates of recurrence, and survival analysis. Secondary outcomes included complications, rates of adjuvant therapy, sites of recurrence and rates of percutaneous endoscopic gastrostomy (PEG). 184 patients underwent TORS-based therapy with neck dissection, and guideline-directed adjuvant therapy for HPV-associated OPSCC. Our median follow-up was 46 months. The positive margin rate on final histopathology analysis was 10.9%. Adjuvant therapy was indicated in 85 patients (46%). The local recurrence rate was 10.9% with the majority (80%) of patients recurring in the first 3 years since treatment. The disease-specific survival at 3 years was 98.6% and at 5 years was 94.4%. The 3-year and 5-year OS for the cohort was 96.7% and 92.5%, respectively. The presence of extranodal extension and positive margins were associated with increased risk of recurrence, whereas adjuvant therapy was found to be a protective factor for both overall recurrence and survival. Major complications occurred in 12 patients (6.5%), resulting in one death. This study has demonstrated that primary surgical therapy for HPV-associated OPSCC is a safe and effective treatment modality with low local recurrence and complication rates, and overall survival benefits.

Consequences of Continental Core Complexes on Rifting Patterns: Insights From Multichannel Seismic Data From the Northern Margin of the South China Sea

AbstractCore complex type structures are common in continental margins. Recent studies have proposed exhumation of deeper crustal and mantle levels during extension of the continental margin along the Northern South China Sea (NSCS) in a core complex mode. Here, we present high‐resolution seismic profiles across different sections of the NSCS that allow us to observe two types of core complex systems. The Kaiping Rift and eastern Baiyun Rift are characterized by a sub‐horizontal Moho and exhumation of ductile deeper crust beneath an extremely thinned brittle upper crust. The central Baiyun Rift in contrast is marked by homogeneous thinning of the entire crust that is floored by mantle unroofing with a concave‐down Moho geometry. While the former type, referred to as crustal core complexes, coincides with relatively intense syn‐rift magmatism, the latter, referred to as mantle core complexes, is marked by limited magmatism. Consistently, basin subsidence rates are lower over crustal core complexes than mantle core complexes. Compared to mantle core complexes at the magma‐poor Iberian margin, the widely distributed crustal core complexes in the NSCS indicate higher geotherms and more intense magmatism during extension of the continental lithosphere. We propose that the continental core complexes observed at the NSCS represent a typical outcome of extension of a gravitationally unstable lithosphere.

The impact of nodule size on malignancy risk in indeterminate thyroid nodules.

The association between malignancy risk and nodule size in indeterminate thyroid nodules (ITNs) remains controversial. Thus, we aimed to explore the impact of nodule size as a predictor of cancer in patients with ITNs. This cross-sectional study assessed 113 patients who underwent surgical intervention for ITNs, comparing two groups based on nodule size (≥4 or <4 cm). The correlation between nodule size and malignancy risk was examined. Other variables of interest included demographics, thyroid-stimulating hormone (TSH) levels, type of surgery, and ultrasound features. Of the 113 patients, 88.5% were aged <55 years, 76.1% were women, and 65.5% had nodules <4 cm. Mean nodule size was 3.4±2.3 cm. There was no significant correlation between malignancy risk and nodule size (P=0.55). An association was observed between <4 cm nodules and elevated TSH levels (P=0.03) and between ≥4 cm nodules and the presence of hypervascularity (P=0.04). Nodules <4 cm were more likely to have extrathyroidal extension, lymphovascular invasion, and positive margins than those ≥4 cm; however, this was not significant. Our findings showed no association between nodule size and malignancy risk, suggesting that size alone is not a predictor of cancer development. Further prospective studies are required to confirm these results.

Rate of residual tumor after repeat surgery for positive margins in ductal carcinoma in Situ, and predictive factors

AimsTo evaluate the rate of residual tumor in re-excision specimen of patients with positive margins in ductal carcinoma in situ (DCIS) following breast-conservative surgery, and to identify predictive factors of residual tumor. Material and methodsWe conducted a monocentric, retrospective study, from January 2010 to December 2020. All 103 patients who underwent re-excision for positive margins in DCIS following breast-conservative surgery for in situ or invasive breast carcinoma were included. Positive margins were defined as inferior to 2 mm from the DCIS component. Two groups were defined, depending on the presence of residual tumor or not, and were compared on their clinical and histopathological characteristics to identify predictive factors of residual tumor. ResultsResidual tumor was found in re-excision specimen of 46 patients (44.7 %). The risk of residual tumor was increased in patients with more than 2 tumor foci (aOR: 12.4; 95 % CI: 1.2 -124.1; p = 0.032) and in those with extensive margin involvement (aOR: 3.2; 95 % CI: 1.3–8.2; p = 0.013). Finally, surgery performed after 2013 was associated with a lower risk of residual tumor (aOR: 0.23; 95 % CI: 0.09–0.058; p = 0.002). ConclusionThe rate of residual tumor in re-excision specimen of patients with positive margins in DCIS is high. Both the number of tumor foci and the extension of positive margins were identified as risk factors. Finally, the surgical learning curve for this procedure seems to be significantly correlated with the risk of residual tumor and needs to be considered.

A comparison of whole-mount and conventional sections for pathological mesorectal extension and circumferential resection margin assessment after total mesorectal excision

IntroductionThe objective of the study is to compare 2 techniques for histological handling of rectal cancer specimens, namely whole-mount in a large block vs conventional sampling using small blocks, for mesorectal pathological assessment of circumferential resection margin status and depth of tumor invasion into the mesorectal fat. MethodsThis is a prospective study including 27 total mesorectal excision specimens of rectal cancer from patients treated for primary rectal carcinoma between 2020 and 2022 in a specialized multidisciplinary Colorectal Unit. For each total mesorectal excision specimen, 2 contiguous representative tumoral slices were selected and comparatively analyzed with whole-mount and small blocks macroscopic dissection techniques, enabling comparison between them in the same surgical specimen. The agreement between the 2 techniques to assess the distance of the tumor from the circumferential resection margin as well as the depth of tumor invasion was evaluated with the Student’s t-test for paired samples, Pearson’s correlation coefficient, and the Bland-Altman method comparison analysis. ResultsComplete mesorectal excision was observed in 8% of cases. Circumferential resection margin involvement was observed in only one case (4 %). The whole-mount and small block techniques obtained similar results when we assessed the distance to the circumferential resection margin (t-test P = 0.8, r = 0.92) and the depth of mesorectal infiltration (t-test P = 0.6, r = 0.95). ConclusionsBoth gross dissection techniques (whole-mount vs multiple small cassettes) are equivalent and reliable to assess the distance to circumferential resection margin and the depth of mesorectal infiltration in the mesorectal fat in rectal cancer staging.

Late Paleozoic magmatism from northern Sibumasu terrane: Constraints on separation of Cimmeria from Gondwana

The Cimmerian is one of several continental terranes that separated from northern Gondwana during the Carboniferous-Permian period. Magmatic evidence for the rifting of the fragments from Gondwana is preserved in the Baoshan area of eastern Cimmeria. These magmatic rocks outcrop over an area of more than 10,000 km2 and are mainly composed of basalts and dolerites, with limited occurrences of picrites. Our new results show that the basalts are tholeiitic and exhibit enriched trends in light rare earth elements (LREE), negative anomalies in Nb-Ta-Ti, and enriched isotopic signatures in Sr-Nd-Pb. They underwent fractional crystallization of clinopyroxene and olivine, with insignificant crustal contamination. Suppositional primary melt compositions and REE modeling results suggest that they were mainly formed by 2–5 % degrees of melting of spinel lherzolites with minor garnet (<1%) in a shallow enriched EMII lithospheric mantle, with minor components from the depleted mantle. Lack of plume-related ocean island basalts, a narrow south-north distribution, and a relatively low melting temperature may contradict the plume model. The Woniusi basalts could have originated in a back-arc environment, but further research is required to gather a more complete spectrum of volcanic rocks associated with the arc. In contrast, we propose that they were formed on the lower-plate passive Gondwana margin after the northward subduction of the Paleo-Tethys Ocean since the Late Devonian. This subduction may result in a longer-lasting extension of the passive Gondwana margin. The Woniusi basalts are roughly coeval with the subduction of the mid-ocean ridge during the Latest Carboniferous. After the active ridge has subducted, the slab pull is strong enough to separate a terrane, because the ridge spreading no longer absorbs the strain caused by subduction. If this is the case, subduction of the Paleo-Tethys ocean-ridge would enhance slab-pull forces and finally trigger Woniusi magmatism.

Effects of Cystic Duct Margin Involvement on the Survival Rates of Patients With Gallbladder Cancer: A Propensity Score-Matched Case-Control Study.

Background In gallbladder cancer (GBC), extrahepatic bile duct (EHBD) resection is selectively performed if gross direct extension or microscopic involvement of the cystic duct margin (CDM) is detected. Although CDMis usually sent for frozen biopsy intraoperatively in most centers, there are no studies regarding the routine use of CDM frozen biopsy irrespective of the tumor location and paucity of literature regarding the impact ofCDM status on recurrence-free and overall survival inGBC. The presence of obstructive jaundice in GBC usually indicates the involvement of EHBD or cystic duct-bile duct junction. The present study aimed to analyze the necessity of routineCDM frozen biopsy inpatients with resectable GBC withoutjaundice, regardless of the tumor location. The impact of positive CDM on survival was also evaluated. Methods This retrospective observational case-control study was conducted from May 2009 to March 2021 and included 105 patients with resectable GBC without macroscopic EHBD infiltration andjaundice. Patients were divided into CDM-negative (n=91) and CDM-positive (n=14) groups. Propensity score matchingwas performed for variables such asperformance status, tumor size, tumor-node-metastasis (TNM) stage, and adjuvant chemotherapy. After propensity score matching, 27 patients (CDM-negative=13, CDM-positive=14) were included. The primary outcome was to analyze the role of routine CDM frozen biopsy regardless of tumor location, and secondary outcomes were to study the impact of positive CDM status on survival andevaluate predictive factors for CDM positivity. A subgroup analysis was conducted to assess clinicopathologic characteristics and outcomes of the anatomical location of the tumor. Results Of 105 patients, 91 had negative CDM, and 14 had positive CDM. Among 14 patients with positive CDM, only one patient had a tumor in the fundus/body, and the remaining had a tumor involving the neck. All CDM-positive patients underwent bile duct excision with hepaticojejunostomy. Common bile duct (CBD) involvement was present in 50% of patients with positive CDM in the final histopathological examination. In the matched population, patients with positive CDM had a significantly higher rate of neck tumors (p=0.001). Recurrence-free survival (24 vs. 12 months, p=0.30) and overall survival (24.5 vs. 20 months, p=0.417) were comparable between CDM-negative and CDM-positive groups, respectively. On multivariate analysis, preoperative and intraoperative tumor location were independent predictive factors for CDM positivity. On subgroup analysis, 30 patients had tumor involving the neck of the gallbladder, and the remaining 75 had at the fundus and body of the gallbladder. Neck tumors had inferior recurrence-free survival (17 vs. 30 months, p=0.012) and overall survival (24 vs. 36 months, p=0.048) compared to non-neck tumors. Conclusions Routine use of CDM frozen analysis in patients with resectable GBC without jaundice, regardless of tumor location, can be avoided. Itcan be selectively preferred in patients with GBC involving the neck since tumor location is found to be an independent predictive factorfor CDM positivity. Positive CDM has comparable survival outcomes to negative CDM, providing a similarR0 resection rate and tumor stage.However, neck tumors have aworse prognosis than non-neck tumors.

Mode of extension and final architecture of the south Angolan margins controlled by Precambrian lithospheric heterogeneity

We use offshore 2-3D seismic reflection and potential field data coupled with field work to investigate the control of lithospheric heterogeneity and shear zone rejuvenation on the mode of extension and the architectural segmentation of the southern Angola margins. The pre-rift basement is inherited from several Precambrian deformation events ended by the Pan-African/Brasiliano orogen that accreted four different age-dependent lithospheric domains with contrasted thickness, fabrics, thermal structure, and chemical composition. From north to south, the continental crust is composed of Neoproterozoic metapelites, Paleoproterozoic gneisses and migmatites and Archean greenstone belts pervasively intruded by TTG granitoids. The latter are compartmentalized by lithospheric-scale Archean – Paleoproterozoic shear zones with a general sub-vertical fabric. Upon extension, these pre-existing shear zones nucleated extensional deformation, focalized magmatism and accommodated different rates of extension and width of offshore rift domains. In the north, younger Neoproterozoic lithospheric domain deformed with a ductile behavior and multiple crustal detachments promoting lithospheric decoupling and a distributed extension, with late continental break-up. It favored the formation of a wide magma-poor margin where extension was accommodated by low-angle, seaward-dipping extensional faults and mantle-exhumation. To the south, Archean and Paleoproterozoic lithospheric domain with stronger and brittle strength profile promoted a more localized extensional deformation and favored an early lithospheric coupling and continental break-up. This ultimately led to the formation of a short margin with increased magmatic budget, where extension was accommodated by high-angle, landward-dipping extensional faults and mantle-exhumation. We demonstrate that the pre-rift heterogeneity of the lithosphere controlled the mode of extension during the rift and the along-strike variation of margin geometry. Moreover, the rejuvenation of Precambrian shear zones as extensional transverse fault zones also promoted the activation of lithospheric-scale thermal drains facilitating the emplacement of mantle-related melts into the upper crust.

Lateral changes of crustal extension and passive margin type along the Brazilian southeastern margin

For the last half century, studies based on an increasing, diverse data set, have focused on passive continental margin evolution, as a result of a sequence of tectonic processes that occur in crustal scale and in the geological time. Where extensive subsurface data exists, two distinct endmembers of continental margin architectures were first described along specific margins of the North Atlantic: 1) wide continent-ocean transitions or hyper-extended; 2) narrow continent-ocean transitions or hypo-extended. The lateral transition between these endmember margins, which can occur laterally in short distances, is still not fully understood. The same two endmember margin types are observed across passive margins around the world and notably along the South Atlantic margin. In an area known for controversial interpretations about the crustal nature and the limits of thinned continental crust, this investigation integrates crustal thickness, seismic interpretation, and facies analyses across ∼150,000 km of seismic data along the Brazilian southeastern margin. This study has implications for those investigating the crustal geometry variations for basin analysis and results impact hydrocarbon assessments for the southeastern margin of Brazil. We resume continental margin analyses, in a critical moment as hydrocarbon exploration advances from the continental slope to ultra-deep waters. Results indicate a marked change from a narrow, hypo-extended, sub-aerial, Iceland-like, plume-related volcanic crust in the Pelotas Basin, to a hyper-extended, Iberia-like, magma-rich crust in the Santos Basin, which is separated by a pronounced oceanic transform-fault zone. Dextral movement along this NW-oriented fault zone accommodated differential extensional rates between the hypo- and the hyper-extended margins. Lateral variations in magmatic content within these margin types are interpreted as result from the interaction with mantellic plumes. Margin architecture can locally be affected by pre-existing fault zones and be later modified by oceanic transform faults. The interactions between crustal extensional rates, crustal rheology, mantle underplating, and volcanic material exhumed through mantle-derived plumes, are the key controls for the evolution of continental margins. Tectonic framework classification proposed in this study presents an alternative, original model for continental passive margins evolution.

Deglaciation of the north American ice sheet complex in calendar years based on a comprehensive database of chronological data: NADI-1

The most recent deglaciation of the North American Ice Sheet Complex (NAISC: comprising the Innuitian, Cordilleran, and Laurentide ice sheets) offers a broad perspective from which to analyze the timing and rate of ice retreat, deglacial sea-level rise, and abrupt climate change events. Previous efforts to portray the retreat of the NAISC have been focused largely on minimum-limiting radiocarbon ages and ice margin location(s) tied to deglacial landforms that were not, for the most part, chronologically constrained. Here, we present the first version of North American Deglaciation Isochrones (NADI-1) spanning 25 to 1 ka in calendar years before present. Key new features of this work are (i) the incorporation of cosmogenic nuclide data, which offer a direct constraint on the timing of ice recession; (ii) presentation of all data and time-steps in calendar years; (iii) optimal, minimum, and maximum ice extents for each time-step that are designed to capture uncertainties in the ice margin position, and; (iv) extensive documentation and justification for the placement of each ice margin. Our data compilation includes 2229 measurements of 10Be, 459 measurements of 26Al and 35 measurements of 36Cl from a variety of settings, including boulders, bedrock surfaces, cobbles, pebbles, and sediments. We also updated a previous radiocarbon dataset (n = 4947), assembled luminescence ages (n = 397) and gathered uranium-series data (n = 2). After scrutiny of the geochronological dataset, we consider >90% of data to be reliable or likely reliable. Key findings include (i) a highly asynchronous maximum glacial extent in North America, occurring as early as 27 ka to as late as 17 ka, within and between ice sheets. In most marine realms, extension of the ice margin to the continental shelf break at 25 ka is somewhat speculative because it is based on undated and spatially scattered ice stream and geomorphic evidence; (ii) detachment of the Laurentide and Cordilleran ice sheets took place gradually via southerly and northerly ‘unzipping’ of the ice masses, starting at 17.5 ka and ending around 14 ka; (iii) the final deglaciation of Hudson Bay began at 8.5 ka, with the collapse completed by 8 ka. The maximum extent of ice during the last glaciation occurred at 22 ka and covered 15,470,000 km2. All North American ice sheets merged at 22 ka for the first time in the Quaternary. The highly asynchronous Last Glacial Maximum in North America means that our isochrones (starting at 25 ka) capture ice advance across some areas, which is based on limited evidence and is therefore somewhat speculative. In the Supplementary Data, the complete NADI-1 chronology is available in PDF, GIF and shapefile format, together with additional visualizations and spreadsheets of geochronological data. The NADI-1 shapefiles are also available at https://doi.org/10.5281/zenodo.8161764.

Adjuvant External Beam Radiotherapy and Histopathologic Prognostic Factors in Tall Cell Papillary Thyroid Carcinoma

Differentiated thyroid cancer is a diverse disease, with histopathologic characteristics contributing to prognosis and treatment decisions. Tall cell variant of papillary thyroid cancer (TCV-PTC) carries a poor prognosis relative to other histologies, with first site of failure most often in the neck. Several small studies suggest there may be a disease control benefit to adjuvant external beam radiotherapy (EBRT) for certain high-risk DTC populations; however, data is limited. In this study we aim to shed light on both histopathologic prognostic factors and survival outcomes of patients with TCV-PTC carcinoma treated with surgery followed by EBRT and Radioactive Iodine (RAI) or RAI alone. We hypothesize that EBRT with RAI leads to better disease control than RAI alone. Patients with TCV-PTC diagnosed between 1997-2020 at a single institution were included in the analysis. TNM staging was standardized to AJCC 8th edition. Demographics, staging, and histologic characteristics were compared between the two treatment groups using T-tests and Fisher's exact tests. Kaplan-Meier survival analyses were performed between patients receiving EBRT vs. RAI alone for disease-free survival (DFS), cancer-specific survival (CSS) and overall survival (OS), along with Cox Proportional Hazards analysis. A total of 93 patients were included. Of these patients, 22 received adjuvant RAI and EBRT, and 71 received RAI alone. There was no statistical difference in race, gender, tall cell percentage in the pathology specimen, TNM stage, AJCC group stage, or disease recurrence in patients receiving EBRT vs. RAI alone. However, those receiving EBRT were significantly older (RAI mean age (SD): 50.6 (18.7), EBRT mean age (SD): 59.7 (14.4), p = 0.02) and length of follow-up was shorter for the EBRT cohort (RAI mean (SD): 8.80 (5.81) years, EBRT mean (SD): 4.53 (2.14) years, p < 0.01). Multifocal disease (HR: 3.04, 95% CI: 1.30 - 7.08, p = 0.01) and soft tissue invasion (HR: 2.93, 95% CI: 1.28 - 6.75, p = 0.01) were associated with decreased DFS, whilst age (HR 1.08, 1.01 - 1.15: p = 0.03) was associated with decreased CSS; tall cell percentage in the pathology specimen, extra-thyroidal extension, vascular invasion, and positive surgical margin were not significant for either metric. There was no statistical difference in DFS (p = 0.5), CSS (p = 0.3), or OS (p = 0.6) between patients that received EBRT and RAI vs. RAI alone. DFS, CSS, and OS were not different between patients who received EBRT compared to RAI only in this high-risk subgroup of patients. Short interval follow-up for the EBRT group and significant age differences between the EBRT and RAI cohorts may confound results. Given the significant association of advanced age with CSS, an expanded, age-matched cohort analysis is underway.