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Advances in diagnostic techniques and treatment modalities have impacted head and neck cancer (HNC) prognosis, but their effects on subsite‐specific prognosis remain unclear. This study aimed to assess subsite‐specific trends in mid‐ and long‐term survival for HNC patients diagnosed from 1993 to 2011 using data from population‐based cancer registries in Japan. We estimated the net survival (NS) for HNC by subsite using data from 13 prefectural population‐based cancer registries in Japan. Changes in survival over time were assessed by multivariate excess hazard model of mortality. In total, 68,312 HNC patients were included in this analysis. We observed an overall improvement in 5‐year NS for HNC patients in Japan. However, survival varied among subsites of HNC, with some, such as naso‐, oro‐ and hypopharyngeal cancers, showing significant improvement in both 5‐ and 10‐year NS, whereas others such as laryngeal cancer showed only a slight improvement in 5‐year NS and no significant change in 10‐year NS after adjustment for age, sex and stage. In conclusion, the study provides insights into changing HNC survival by site at the population level in Japan. Although advances in diagnostic techniques and treatment modalities have improved survival, these improvements are not shared equally among subsites. We evaluated trends of head and neck cancer survival by subsite in Japan using population‐basedcancer registry data. During the observation periods, each pharyngeal cancer showed an upward trend, although laryngeal cancer showed no significant trend in long‐term survival. These findings may reflect the change in mainstream treatment.

Mounting evidence suggests that body mass index (BMI) is inversely associated with the risk of lung cancer. However, relatively few studies have explored this association in Asian people, who have a much lower prevalence of obesity than Caucasians. We pooled data from 10 prospective cohort studies involving 444,143 Japanese men and women to address the association between BMI and the risk of lung cancer. Study‐specific hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated in each cohort using the Cox proportional hazards model. A meta‐analysis was undertaken by combining the results from each cohort. Heterogeneity across studies was evaluated using Cochran's Q and I2statistics. During 5,730,013 person‐years of follow‐up, 6454 incident lung cancer cases (4727 men and 1727 women) were identified. Baseline BMI was inversely associated with lung cancer risk in men and women combined. While leanness (BMI <18.5) was associated with a higher risk of lung cancer (HR 1.35; 95% CI, 1.16–1.57), overweight and obesity were associated with a lower risk, with HRs of 0.77 (95% CI, 0.71–0.84) and 0.69 (95% CI, 0.45–1.07), respectively. Every 5 kg/m2 increase in BMI was associated with a 21% lower risk of lung cancer (HR 0.79; 95% CI, 0.75–0.83; p < 0.0001). Our pooled analysis indicated that BMI is inversely associated with the risk of lung cancer in the Japanese population. This inverse association could be partly attributed to residual confounding by smoking, as it was more pronounced among male smokers.

Although immune checkpoint inhibitors (ICIs) are effective in some patients with salivary gland carcinoma (SGC), biomarkers which predict the efficacy and prognosis of SGC patients treated with pembrolizumab have not been identified. We conducted a multi-institutional retrospective cohort study to evaluate the efficacy and safety of pembrolizumab monotherapy in patients with recurrent and/or metastatic SGC and to determine optimal cut-off values of the combined positive score (CPS) and tumor proportion score (TPS) as numerical expression levels of programmed death-ligand 1 (PD-L1), which predict the efficacy of pembrolizumab. Furthermore, we investigated the association of patient characteristics and hematological markers with clinical outcomes, including overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). From 2016 to 2021, 27 patients were included in the analysis. ORR of SGC was 25.9%. Optimal cut-off values of CPS and TPS were 15 and 25%, respectively. ORRs of CPS-high and TPS-high were 55.6 and 75.0%, respectively, and significantly higher than those of CPS-low and TPS-low. Furthermore, patients with a low platelet-lymphocyte ratio (PLR) had a significantly longer PFS. No grade 4 or greater adverse events were observed. This study demonstrated the efficacy and safety of pembrolizumab monotherapy and identified optimal cut-off values of CPS and TPS.

Immune checkpoint inhibitors (ICIs) have become the standard treatment for recurrent or metastatic head and neck cancer (RM-HNC). However, many patients fail to benefit from the treatment. Previous studies have revealed that tumor burden predicts the efficacy of ICIs, but this association remains unclear for RM-HNC. We retrospectively analyzed 94 patients with RM-HNC treated with ICI monotherapy. We estimated the tumor burden using the baseline number of metastatic lesions (BNML) and the baseline sum of the longest diameters of the target lesions (BSLD), and evaluated the association between BNML, BSLD, and standardized uptake value (SUV) and clinical outcomes. The median progression-free survival (PFS) was 7.1 and 3.1 months in the low-BNML and high-BNML groups, respectively (p = 0.010). The median PFS was 9.1 and 3.5 months in the low-BSLD and high-BSLD groups, respectively (p = 0.004). Moreover, patients with high SUVmax levels had worse overall survival (OS) and PFS. BNML, BSLD, and SUVmax are useful prognostic factors in patients with RM-HNC treated with ICIs. Imaging examinations before ICI treatment are recommended to predict the efficacy of ICIs. If the tumor burden is high, cytotoxic anticancer agents may be administered concomitantly with or prior to ICI monotherapy.

Although several prognostic factors in nivolumab therapy have been reported in recurrent or metastatic head and neck cancer (RM-HNC) patients, these factors remain controversial. Here, we conducted a multicenter retrospective cohort study to investigate the impact of clinico-hematological factors on survival in RM-HNC patients treated with nivolumab. We reviewed 126 RM-HNC patients from seven institutes. We evaluated the prognostic effects of clinico-hematological factors on survival. The median overall survival (OS) was 12.3 months, and the 1 year-OS rate was 51.2%. Patients without immune-related adverse events, lower relative eosinophil count, worse best overall response, higher performance status, and higher modified Glasgow Prognostic Score had worse survival. The score, generated by combining these factors, was associated with survival. Patients with score of 4–5 had worse survival than those with score of 2–3 and 0–1 [adjusted HR for PFS: score of 4–5, 7.77 (3.98–15.15); score of 2–3, 3.44 (1.95–6.06), compared to score of 0–1], [adjusted HR for OS: score of 4–5, 14.66 (4.28–50.22); score of 2–3, 7.63 (2.29–25.37), compared to score of 0–1]. Our novel prognostic score utilizing clinico-hematological factors might be useful to establish an individual treatment strategy in RM-HNC patients treated with nivolumab therapy.

We investigated the run-to-run fluctuation in growth conditions of physical vapor transport growth of 4H-SiC boules through observations of surface morphology on the (000-1) facet of the boules. The boules, which were grown under the same macroscopic growth conditions, exhibited slightly different surface morphologies. This indicates that some microscopic growth parameters that influence the surface morphology fluctuate between growth runs. We have considered the C/Si ratio of the vapor sublimed from the source material as a major parameter and discussed the associated variations in the physical and surface properties of the grown crystals.

The annealing behavior of electrical resistivities perpendicular and parallel to the basal plane of heavily nitrogen-doped 4H-SiC crystals was investigated. The temperature dependencies of the resistivities exhibited characteristic behaviors after multiple rounds of high-temperature annealing (1100°C, 30 min). High-temperature annealing induced stacking fault formation to various extents in heavily nitrogen-doped 4H-SiC crystals. Based on these results, we discuss the cause and mechanism of the observed annealing-induced changes in electrical resistivities of the crystals.

The defect structure at the growth front of 4H-SiC boules grown using the physical vapor transport (PVT) method has been investigated using high resolution x-ray diffraction and x-ray topography. The crystal parameters such as the c-lattice constant exhibited characteristic variations across the growth front, which appeared to be caused by variation in surface morphology of the as-grown surface of the boules rather than the defect structure underneath the surface. X-ray topography also revealed that basal plane dislocations are hardly nucleated at the growth front during PVT growth of 4H-SiC crystals.

The strain fields in a 4H-SiC homo-epitaxial layer deposited on a nitrogen-doped 4H-SiC substrate were studied using Raman scattering microscopy. The cross-sectional (1-100) and (11-20) surfaces of the epitaxial substrate were examined through the peak shifts of several Raman-active phonon modes for 4H-SiC, and tensile strain was found along the direction of 4° off the c-axis at the epilayer/substrate interface. The effect of the facet trace in the substrate, which has a higher nitrogen concentration than the other parts of the substrate, was also studied. The tensile strain at the epilayer/substrate interface was found to be hardly enhanced for the epilayer deposited on the facet trace.

The stacking fault formation during physical vapor transport growth of heavily nitrogen-doped (mid-10 19 cm -3 ) 4H-SiC crystals was investigated. Low-voltage scanning electron microscopy (LVSEM) observations detected the stacking fault formation on the (000-1) facet of heavily nitrogen-doped 4H-SiC crystals. Stacking faults showed characteristic morphologies, and atomic force microscopy (AFM) studies revealed that these morphologies of stacking faults stemmed from the interaction between surface steps and stacking faults. Based on these results, the stacking fault formation mechanism in heavily nitrogen-doped 4H-SiC crystals is discussed.