The role of semaphorin 3A on chondrogenic differentiation

Osteoblast-derived semaphorin3A (Sema3A) has been reported to be involved in bone protection, and Sema3A knockout mice have been reported to exhibit chondrodysplasia. From these reports, Sema3A is considered to be involved in chondrogenic differentiation and skeletal formation, but there are many unclear points about its function and mechanism in chondrogenic differentiation. This study investigated the pharmacological effects of Sema3A in chondrogenic differentiation. The amount of Sema3A secreted into the culture supernatant was measured using an enzyme-linked immunosorbent assay. The expression of chondrogenic differentiation-related factors, such as Type II collagen (COL2A1), Aggrecan (ACAN), hyaluronan synthase 2 (HAS2), SRY-box transcription factor 9 (Sox9), Runt-related transcription factor 2 (Runx2), and Type X collagen (COL10A1) in ATDC5 cells treated with Sema3A (1,10 and 100 ng/mL) was examined using real-time reverse transcription polymerase chain reaction. Further, to assess the deposition of total glycosaminoglycans during chondrogenic differentiation, ATDC5 cells were stained with Alcian Blue. Moreover, the amount of hyaluronan in the culture supernatant was measured by enzyme-linked immunosorbent assay. The addition of Sema3A to cultured ATDC5 cells increased the expression of Sox9, Runx2, COL2A1, ACAN, HAS2, and COL10A1 during chondrogenic differentiation. Moreover, it enhanced total proteoglycan and hyaluronan synthesis. Further, Sema3A was upregulated in the early stages of chondrogenic differentiation, and its secretion decreased later. Sema3A increases extracellular matrix production and promotes chondrogenic differentiation. To the best of our knowledge, this is the first study to demonstrate the role of Sema3A on chondrogenic differentiation.

Infant outcome at 3 years of age of monochorionic twins with Type-II or -III selective fetal growth restriction and isolated oligohydramnios that underwent fetoscopic laser photocoagulation

OBJECTIVE

To examine infant outcomes at 3 years of age in monochorionic twin pregnancies with Type-II or -III selective fetal growth restriction (sFGR) and isolated oligohydramnios who underwent fetoscopic laser photocoagulation (FLP).

METHODS

This multicenter prospective cohort study included monochorionic diamniotic twins that underwent FLP for sFGR between 16 and 25 weeks' gestation. The indication for performing FLP was Type-II or -III sFGR with oligohydramnios of the growth-restricted (FGR) twin in which the maximum vertical pocket of amniotic fluid was ≤ 2 cm. This was done in the absence of a typical diagnosis of twin-twin transfusion syndrome. The primary outcome was intact survival rate of both infants at the corrected gestational age of 40 weeks and at 3 years of age. Intact survival at the corrected age of 40 weeks was defined as survival without Grade-III or -IV intraventricular hemorrhage or cystic periventricular leukomalacia. Intact survival at 3 years of age was defined as survival without neurodevelopmental morbidity, which included cerebral palsy, neurodevelopmental impairment with a total developmental quotient of < 70, bilateral deafness or bilateral blindness.

RESULTS

Among 45 patients with sFGR, 30 (66.7%) were classified as having Type-II and 15 (33.3%) as Type-III sFGR. The prevalence of intact survival at the corrected age of 40 weeks was 51.1% (n = 23) in FGR twins and 95.5% (n = 42) in larger twins. The prevalence of intact survival at 3 years of age was 46.7% (n = 21) in FGR twins and 86.4% (n = 38) in larger twins. There was one case of miscarriage. Among the 24 FGR twins who were not classified as having intact survival at 3 years of age, 22 (91.7%) cases suffered fetal or infant demise (other than miscarriage), and there was one case of neurodevelopmental impairment. All larger twins who were not diagnosed with intact survival at 3 years of age (n = 6 (13.6%)) had neurological morbidity.

CONCLUSIONS

FGR twins and their larger cotwins, when subjected to FLP owing to sFGR coupled with umbilical artery Doppler abnormalities and isolated oligohydramnios, exhibit low rates of neurological morbidity and low mortality, respectively. Therefore, FLP for Type-II or -III sFGR with oligohydramnios may be a feasible management option and one that is preferable to expectant management. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Epidemiological shifts in and impact of COVID-19 on streptococcal toxic shock syndrome in Japan: A genotypic analysis of group A Streptococcus isolates

OBJECTIVES

Streptococcal toxic shock syndrome (STSS) is caused by group A Streptococcus (GAS; Streptococcus pyogenes) strains. In Japan, the number of STSS cases has decreased; however, the underlying reason remains unclear. Moreover, information on distribution and prevalence of specific emm types in STSS cases is scarce. Hence, we investigated the reason for the decreased number of STSS cases in Japan.

METHODS

We genotyped emm of 526 GAS isolates obtained from 526 patients with STSS between 2019 and 2022. The distributions of emm types in each year were compared.

RESULTS

The emm1 type was predominant, with the highest proportion in 2019, which decreased after 2020 following the onset of the coronavirus disease 2019 (COVID-19) pandemic. Strains isolated during the pandemic correlated with strains associated with skin infection, whereas those isolated during the prepandemic period correlated with strains associated with both throat and skin infections. The decrease in the annual number of STSS cases during the COVID-19 pandemic could be due to a decreased proportion of strains associated with pharyngeal infections.

CONCLUSIONS

Potential associations between pandemic and STSS numbers with respect to public health measures, such as wearing masks and changes in healthcare-seeking behavior, may have affected the number of GAS-induced infections.

Serotype Distribution and Antimicrobial Resistance of Streptococcus agalactiae Isolates in Nonpregnant Adults with Streptococcal Toxic Shock Syndrome in Japan in 2014 to 2021

The incidence of streptococcal toxic shock syndrome (STSS) due to group B Streptococcus (GBS) has been increasing annually in Japan and is becoming a serious challenge. Furthermore, in recent years, penicillin- or clindamycin-resistant strains used in treating streptococcal toxic shock syndrome have been reported. However, no report analyzed >100 isolates of group B Streptococcus causing streptococcal toxic shock syndrome. Therefore, we aimed to perform serotyping and antimicrobial susceptibility testing of 268 isolated group B Streptococcus strains from streptococcal toxic shock syndrome cases involving nonpregnant adult patients in Japan between 2014 and 2021. The most prevalent serotype was Ib, followed by serotypes V, III, and Ia. Seven isolates were resistant to penicillin G, and 17.9% (48 isolates) were resistant to clindamycin. Of the penicillin-resistant group B Streptococcus isolates, 71.4% (5 isolates) were clindamycin resistant. In addition, group B Streptococcus strains resistant to penicillin and clindamycin were isolated from patients with streptococcal toxic shock syndrome. Therefore, before these strains become prevalent, introduction of the group B Streptococcus vaccine is essential for disease prevention. IMPORTANCE Group B Streptococcus (GBS) has been increasingly associated with invasive disease in nonpregnant adults. Such infections are responsible for substantial morbidity and mortality, particularly in individuals with underlying chronic conditions. Streptococcal toxic shock syndrome (STSS) is a severe invasive infection characterized by the sudden onset of shock, multiorgan failure, and high mortality. In this study, we assessed 268 GBS-related STSS cases in nonpregnant adults in Japan between 2014 and 2021. Serotype Ib was the most prevalent, followed by serotypes V, III, and Ia, which were identified in more than 80% of STSS isolates. We found that 48 clindamycin-resistant strains and 7 penicillin G-resistant strains were isolated between 2014 and 2021. We believe that our study makes a significant contribution to the literature because we show that the GBS vaccine, particularly the hexavalent conjugate vaccine, is important to reduce the number of patients with STSS.

Combination of fluorescence visualization and iodine solution-guided surgery for local control of early tongue cancer

The control of enclosed oral epithelial dysplasia is important for the control of oral cancer. Fluorescence visualization and iodine solution are able to detect oral epithelial dysplasia and surrounding oral cancer. The purpose of this study was to clarify the effectiveness of combining fluorescence visualization and iodine solution-guided surgery for early tongue cancer. Participants comprised 264 patients with primary early tongue cancer who underwent surgery. The surgical margin was set at 10 mm outside the clinical tumour, and 5 mm outside the area of fluorescence visualization loss, and 5mm outside the iodine unstained area. The 5-year disease-free survival rate was 87.1% vs 76.1% (P = 0.016) and the 5-year local control rate was 98.6% vs 93.0% (P = 0.008) for combination-guided surgery when compared to conventional surgery. Positive margin rates were 0% for cancer, and 6.5% and 0% for low- and high-grade dysplasia, respectively, with combination-guided surgery (P = 0.257). Multivariate analysis revealed that combination-guided surgery (odds ratio 0.140, 95% confidence interval 0.045-0.437; P < 0.001) and intraoperative frozen section examination (odds ratio 0.302; 95% confidence interval 0.115-0.791; P = 0.015) were significantly associated with local control. The combination of fluorescence visualization and iodine solution are effective in selecting surgical margins for early tongue cancer.

Technical methods employed for the On-Site Inspection

In the paper, the technical methods to be used for the on-site inspection (OSI) are reviewed. The main purpose of the OSI is to find evidences of a nuclear explosion conducted anyplace in the world, however, the technical methods described in the paper might be employed for a suspected underground explosion. Various technical methods are described but they can be classified into two categories, namely, technical methods, 1) to identify fission products, and 2) to identify underground evidences. Fission products can be identified by conventional gamma spectrum analysis, however, for the OSI, radioactive Xe and Ar are important nuclides since they are supposed to leak to the ground surface even when the explosion is conducted in deep underground. The seismic and various other technical methods, which might be commonly used by mining industry, can identify the underground evidences, such as a cavity. However, these technical methods might be necessary to be verified to confirm the applicability and effectiveness to OSI objectives.

ANGPTL2 Promotes Inflammation via Integrin α5β1 in Chondrocytes

BACKGROUND

Angiopoietin-like protein 2 (ANGPTL2) is a secreted molecule with numerous physiologic and pathologic functions, for example, in angiogenesis, hematopoiesis, and tumorigenesis. Although recent studies implicated ANGPTL2 in chronic inflammation in mouse peritoneal macrophages, human ligamentum flavum fibroblasts, and human retinal microvascular endothelial cells, the mechanism underlying ANGPTL2-associated inflammation in chondrocytes remains unclear. Therefore, it was investigated whether ANGPTL2 is expressed in or functions in chondrocytes.

METHODS

Expression of ANGPTL2 and its receptor, integrin α5β1 were examined over time in ATDC5 cells using real-time RT-PCR (reverse transcription-polymerase chain reaction) analysis. ATDC5 cells were then incubated with or without ANGPTL2 for 3 hours, and expression of the IL-1β, TNF-α, COX-2, aggrecanase (ADAMTS)-5, matrix metalloproteinase (MMP)-3, and MMP-13 genes were examined using real-time RT-PCR. Additionally, phosphorylation of ERK, JNK, p38, Akt, and NF-κB was examined by western blotting. Furthermore, it was also investigated for the effect of anti-integrin α₅β₁ antibody on the expression of inflammatory markers and intracellular signaling pathways.

RESULTS

ANGPTL2 induced the phosphorylation of all 3 MAPKs, Akt, and NF-κB and dramatically upregulated the expression of inflammation-related factor genes. Inhibiting the activation of integrin α5β1 suppressed these reactions.

CONCLUSION

ANGPTL2 may induce inflammatory factors by stimulating the integrin α5β1/MAPKs, Akt, and NF-κB signaling pathway.

Functional expression of equilibrative and concentrative nucleoside transporters in alveolar epithelial cells

Equilibrative nucleoside transporters (ENTs) and concentrative nucleoside transporters (CNTs) mediate the cellular uptake of nucleosides and nucleobases across the plasma membrane and play important roles in the salvage pathways of nucleotide synthesis. However, information about nucleoside transport systems in the lung alveolar epithelial cells is limited. Therefore, in the present study, we examined the function and expression of nucleoside transporters using primary cultured alveolar type II cells and transdifferentiated type I-like cells. The uptake of uridine, a substrate for ENTs and CNTs, in type II and type I-like cells was time, temperature, and concentration dependent, and was inhibited by other nucleoside transporter substrates such as adenosine. Uridine uptake in both cells was insensitive to nanomolar concentrations of NBMPR, a potent ENT1 inhibitor, while it was inhibited by higher concentrations of NBMPR, suggesting that ENT2, but not ENT1, is involved in uridine uptake in these cells. Additionally, uridine uptake was higher in the presence of Na⁺ than in the absence of Na + and was partially inhibited by a CNT inhibitor phloridzin in these cells, suggesting that CNT is also involved in uridine uptake. In both cells, the mRNA expression of ENT1, ENT2, CNT2, and CNT3 was observed. Finally, the activity of uridine uptake was considerably higher in type II cells than in type I-like cells. In addition, the mRNA expression of ENT2, CNT2, and CNT3, but not ENT1, was lower in type I-like cells than in type II cells. These findings would help understand the functional roles of equilibrative and concentrative nucleoside transporters in alveolar epithelial cells.

ANGPTL2 Induces Synovial Inflammation via LILRB2

Angiopoietin-like proteins (ANGPTLs) are circulating proteins that are expressed in various cells and tissues and are thought to be involved in the repair and remodeling of damaged tissues; however, ANGPTL2 hyperfunction has been shown to cause chronic inflammation, leading to the progression of various diseases. ANGPTL2 is known to exert cellular effects via receptors such as integrin α5β1 and leukocyte immunoglobulin-like receptor subfamily B member 2 (LILRB2); however, their roles in ANGPTL2-induced inflammation remain unclear. In this study, we investigated the mechanisms underlying ANGPTL2-induced inflammation involving LILRB2 and various signaling pathways in human fibroblast-like synoviocytes (HFLS). The effects of ANGPTL2 and an anti-LILRB2 antibody on the gene expression of various inflammation-related factors were examined using real-time RT-PCR, while their effects on MAPK, NF-κB, and Akt phosphorylation were analyzed by western blotting. We found that the addition of ANGPTL2 enhanced the gene expression of inflammatory factors, whereas pretreatment with the anti-LILRB2 antibody for 12 h decreased the expression of these factors. Similarly, ANGPTL2 addition activated the phosphorylation of ERK, p38, JNK, NF-κB, and Akt in HFLS; however, this effect was significantly inhibited by pretreatment with the anti-LILRB2 antibody. Together, the findings of this study demonstrate that ANGPTL2 induces the expression of inflammatory factors via LILRB2 in synovial cells. Therefore, LILRB2 could be a potential therapeutic agent for treating matrix degradation in osteoarthritis.

Transport of ribavirin in human myelogenous leukemia cell line K562

The anticancer effect of ribavirin, a purine nucleoside analogue, has been studied using cultured cancer cells such as the human myelogenous leukemia cell line K562. In order to exert its pharmacological effect, ribavirin has to enter cancer cells. However, there is little information concerning the transport mechanism of ribavirin into K562 cells. In this study, therefore, we examined the uptake mechanism of ribavirin in K562 cells. The uptake of ribavirin in K562 cells was time- and temperature-dependent, and was saturable with a Km value of 1.5 mM. Ribavirin uptake was inhibited by nucleosides such as adenosine and uridine, and by inhibitors of equilibrative nucleoside transporter 1 (ENT1) such as S-(4-nitrobenzyl)-6-thioinosine and dipyridamole in a concentration-dependent manner. In addition, the expression of ENT1 mRNA in K562 cells was confirmed by real-time PCR. On the other hand, Na⁺-dependence of ribavirin uptake was not observed, suggesting the involvement of ENT1, but not Na⁺-dependent concentrative nucleoside transporters, in ribavirin uptake in K562 cells. Treatment of K562 cells with sodium butyrate induced erythroid differentiation, but ribavirin uptake activity and sensitivity of the uptake to various inhibitors were not different between native and differentiated K562 cells. These results suggest that ribavirin uptake into K562 cells is mainly mediated by ENT1, which may have a pivotal role in anticancer effect of ribavirin.

Protective effects of cilengitide on inflammation in chondrocytes under excessive mechanical stress

Chondrocytes constantly receive external stimuli, which regulates remodeling. An optimal level of mechanical stress is essential for maintaining chondrocyte homeostasis, however, excessive mechanical stress induces inflammatory cytokines and protease, such as matrix metalloproteinases (MMPs). Therefore, excessive mechanical stress is considered to be one of the main causes to cartilage destruction leading to osteoarthritis (OA). Integrins are well-known as cell adhesion molecules and act as receptors for extracellular matrix (ECM), and are believed to control intracellular signaling pathways both physically and chemically as a mechanoreceptor. However, few studies have focused on the roles and functions of integrins in inflammation caused by excessive mechanical stress. In this study, we examined the relationship between integrins (αVβ3 and αVβ5) and the expression of inflammatory factors under mechanical loading in chondrocytes by using an integrin receptor antagonist (cilengitide). Cilengitide suppressed the gene expression of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-3 (MMP-3), and MMP-13 induced by excessive mechanical stress. In addition, the protein expression of IL1-β and MMP-13 was also inhibited by the addition of cilengitide. Next, we investigated the involvement of intracellular signaling pathways in stress-induced integrin signaling in chondrocytes by using western blotting. The levels of p-FAK, p-ERK, p-JNK, and p-p38 were enhanced by excessive mechanical stress and the enhancement was suppressed by treatment with cilengitide. In conclusion, this study revealed that excessive mechanical stress may activate integrins αVβ3 and αVβ5 on the surface of chondrocytes and thereby induce an inflammatory reaction by upregulating the expression of IL-1β, TNF-α, MMP-3, and MMP-13 through phosphorylation of FAK and MAPKs.

P2651Seasonal variations in the pathogenesis of acute coronary syndromes

Background

Seasonal variations in acute coronary syndrome (ACS) has been known with the winter being the peak in incidence and mortality. However, underlying pathophysiology for this variation has not been studied.

Purpose

We sought to compare pathobiology of the culprit lesions assessed by optical coherence tomography (OCT) among the four seasons.

Methods

Patients with ACS who underwent OCT were recruited from 6 countries in the Northern Hemisphere. The prevalence of 3 most common pathologies, plaque rupture, plaque erosion and calcified plaque, and other features of coronary plaques were compared among the four seasons.

Results

In 1113 patients with ACS, 284 (25%) patients were admitted in spring, 243 (22%) patients in summer, 290 (26%) patients in autumn and 296 (27%) patients in winter. The proportion of underlying 3 pathologies was significantly different in each season (prevalence of plaque rupture, plaque erosion, calcified plaque was 50%, 39%, and 11%, respectively in the spring; 44%, 43%, and 13% in the summer; autumn: 49%, 39%, and 12% in the autumn; 57%, 30%, and 13% in the winter; P=0.039). The proportion of plaque rupture was higher in winter but lower in summer, and that of plaque erosion was higher in summer, but lower in winter. Maximum and minimum temperatures on the day of OCT procedure were significantly lower in the plaque rupture group than in the plaque erosion group (P=0.02 and P=0.012, respectively). In the rupture group, the prevalence of hypertension was significantly higher in winter, but in the erosion group, it was not different among the four seasons.

Figure 1. The proportion of culprit lesion characteristics were significantly different among the 4 season groups. (P=0.039) The proportion of plaque rupture was significantly higher in winter but lower in summer. In contrast, the proportion of plaque erosion was higher in summer, but lower in winter.

Conclusions

Seasonal variation of the underlying mechanisms of ACS reflects different pathobiology. The proportion of plaque rupture is highest in winter and the proportion of plaque erosion is highest in summer. A different approach may be needed for the prevention and treatment of ACS depending on the season of its occurrence.

Functional expression of breast cancer resistance protein and cholesterol effect in human erythrocyte membranes

In human erythrocyte membranes, various influx and efflux transporters are functionally expressed. However, their transport characteristics and modulation under disease states are not fully understood. In this study, we first examined the expression and detailed transport characteristics of breast cancer resistance protein (BCRP), an efflux ABC transporter, using inside-out membrane vesicles (IOVs) prepared from human erythrocytes, and then studied the effect of membrane cholesterol on BCRP function. The expression of BCRP was confirmed by western blotting; most of them being homodimers. The uptake of lucifer yellow (LY), a fluorescent BCRP substrate, into IOVs was time-, temperature-, and ATP-dependent, and the concentration of ATP which induced half-maximal stimulation of LY uptake was calculated to be 0.39 mM. The uptake of LY by IOVs was saturable with a Km value of 166 μM, and was inhibited by various BCRP inhibitors and substrates, such as fumitremorgin C and mitoxantrone. When membrane cholesterol content was increased by treating IOVs with cholesteryl hemisuccinate, LY uptake decreased with increasing cholesterol content. These results suggest that transport activity of BCRP in human erythrocyte membranes may be suppressed under disease states, such as hypercholesterolemia, that increase membrane cholesterol content.

P-gp modulating effect of Azadirachta indica extract in multidrug-resistant cancer cell lines

The extract of Azadirachta indica, commonly known as neem, has found extensive use in traditional medicine for treating various human diseases. In this study, the effect of the 50% ethanol extract of A. indica (AI01) on P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) was examined using MDR cell lines, specifically paclitaxel-resistant HepG2 (PR-HepG2) and doxorubicin (DOX)-resistant (DR) colon-26 cells. 96-h treatment of the two cell lines with AI01 (30 μg/mL) showed no effect on the expression of P-gp mRNA (human MDR1 and mouse mdr1b) and protein, while AI01 increased the accumulation of rhodamine 123, a P-gp substrate, in both PR-HepG2 and DR-colon-26 cells. The cytotoxic effects of 48-h treatment with AI01 on the viability of PR-HepG2 and DR-colon-26 cells were not observed. Therefore, 30 μg/mL AI01 may have no cytotoxic and P-gp-inducing effects. Finally, AI01 potentiated the sensitivity of PR-HepG2 and DR-colon-26 cell lines to DOX by 8.6- and 15.3-fold, respectively. These findings suggest that A. indica may be a promising source for a new class of P-gp modulators without cytotoxic/P-gp induction effects.

Assessment of diastolic function of normal fetal heart using dual-gate Doppler

OBJECTIVES

The ratio of mitral peak early diastolic filling to early diastolic mitral annular velocity (E/e') reflects diastolic cardiac function in adults. Dual-gate Doppler (DD) enables measurements of E/e' in the same heart beat. This study was designed to assess the utility of the DD method for measurement of fetal E/e' and determine reference ranges for normal fetuses.

METHODS

This prospective study comprised normal singleton pregnancies undergoing fetal echocardiography between 16 and 36 weeks of gestation. According to the DD method, E-wave velocity on pulsed-wave Doppler and e'-wave on tissue Doppler imaging were measured simultaneously on an apical or basal four-chamber view, and fetal E/e' was calculated. Spearman's correlation coefficient was used to assess the relationship between gestational age (GA) and E-wave and e'-wave velocities and E/e'.

RESULTS

A total of 133 pregnancies were included in this study and all E/e' measurements were successful. Significant correlation was observed between GA and both left ventricular (LV) E/e' (r _s  = -0.666, P < 0.001) and right ventricular (RV) E/e' (r _s  = -0.607, P < 0.001). The regression equations for bilateral E/e' were: LV-E/e' = 17.341 - 0.631GA + 0.008 × GA² (mean ± SD, R ²  = 0.440 ± 1.333); and RV-E/e' = 19.156 - 0.794GA + 0.012GA² (R ²  = 0.419 ± 1.329).

CONCLUSIONS

Bilateral E/e' of normal fetuses, measured using the DD method, decreased with GA, which is considered to be related to myocardial maturity. DD is a useful and convenient method for evaluating fetal E/e' in order to assess diastolic function in the prenatal period. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Reappraisal of classification of distal cholangiocarcinoma based on tumour depth

Background

In the eighth edition of the AJCC cancer staging classification, the T system for distal cholangiocarcinoma (DCC) has been revised from a layer-based to a depth-based approach. The aim of this study was to propose an optimal T classification using a measured depth in resectable DCC.

Methods

Patients who underwent pancreatoduodenectomy for DCC at 32 hospitals between 2001 and 2010 were included. The distance between the level of the naive bile duct and the deepest cancer cells was measured as depth of invasion (DOI). Invasive cancer foci were measured as invasive tumour thickness (ITT). Log rank χ2 scores were used to determine the cut-off points, and concordance index (C-index) to assess the survival discrimination of each T system.

Results

Among 404 patients, DOI was measurable in 182 (45·0 per cent) and ITT was measurable in all patients, with median values of 2·3 and 5·6 mm respectively. ITT showed a positive correlation with DOI (rs = 0·854, P &lt; 0·001), and the cut-off points for prognosis were 1, 5 and 10 mm. Median survival time was shorter with increased ITT: 12·4 years for ITT below 1 mm, 5·2 years for ITT at least 1 mm but less than 5 mm, 3·0 years for ITT at least 5 mm but less than 10 mm, and 1·5 years for ITT 10 mm or more (P &lt; 0·001). This classification exhibited more favourable prognostic discrimination than the T systems of the seventh and eighth editions of the AJCC (C-index 0·646, 0·622 and 0·624 respectively).

Conclusion

ITT is an accurate approach for depth assessment in DCC. The four-tier ITT classification with cut-off points of 1, 5 and 10 mm seems to be a better T system than those in the seventh and eighth editions of the AJCC classification.