Diagnostic accuracy of preoperative quantitative susceptibility mapping for detecting histologic intraplaque hemorrhage in cervical ICA stenosis in patients undergoing carotid endarterectomy.

BACKGROUND AND PURPOSE: Quantitative susceptibility mapping (QSM) has been proposed to assess intraplaque hemorrhage (IPH) in the carotid artery. The purpose of this study was to compare the diagnostic accuracy of preoperative QSM with that of the conventional T1-weighed (T1W) three-dimensional (3D)-FSE sequence for detecting IPH in cervical ICA stenosis in patients undergoing carotid endarterectomy (CEA) using histology as the reference standard. MATERIALS AND METHODS: Carotid T1W 3D-FSE and QSM images were obtained from 16 patients with cervical ICA stenosis before CEA. Relative signal intensity (RSI) and susceptibility of the ICA were measured on three axial images including the location of most severe stenosis on T1W 3D-FSE and QSM images, respectively. Three transverse sections of carotid plaques excised by CEA, which corresponded with images on MRI, were stained with H&E, antibody against glycophorin A and Prussian blue, and the relative area (RA) of histologic IPH was calculated. RESULTS: The correlation coefficient was significantly greater between susceptibility and RA-histologic IPH (ρ = 0.691) than between RSI and RA-histologic IPH (ρ = 0.413; P = .0259). The areas under the receiver operating characteristic curves for detecting histologic sections consisting primarily of IPH (RA-histologic IPH > 40.7%) tended to be greater for susceptibility (0.964) than for T1WI FSE-RSI (0.811). Marginal homogeneity was observed between susceptibility and histologic sections consisting primarily of IPH (P = .0412) but not between T1W FSE-RSI and histologic sections consisting primarily of IPH (P = .1824). CONCLUSIONS: Pre-CEA QSM detects histologic IPH in cervical ICA stenosis more accurately than preoperative T1W 3D-FSE imaging. ABBREVIATIONS: QSM = quantitative susceptibility mapping; IPH = intraplaque hemorrhage; T1W = T1-weighed; 3D = three-dimensional; CEA = carotid endarterectomy; RSI = relative signal intensity; RA = relative area.

Assessment of magnetic field interactions and heating for cerebral aneurysm flow diverters during 7T MRI.

Flow diverters (FDs) are utilized for a wide range of aneurysms, but show safety issues such as adverse interactions with static magnetic fields (displacement force and torque) and radiofrequency-induced heating during magnetic resonance imaging (MRI). The present study aimed to assess these adverse interactions in a 7-tesla (7T) static magnetic field and radiofrequency-induced heating during a 7T MRI for two types of FD. Displacement force and magnetically induced torque were assessed using the deflection angle method and low friction surface method, respectively. To assess heating, each FD was set in a phantom filled with gelled-saline mixed with polyacrylic acid and underwent a 7T MRI using a three-dimensional fast spin echo method. Displacement force and magnetically induced torque in the 7T static magnetic field were undetectable, and radiofrequency-induced heating during 7T MRI remained ≤ 0.6 °C for both types of FD, suggesting that magnetic field interactions and heating on FDs during a 7T MRI are acceptable from a safety perspective.

[A Retrospective Study on the Malignancies after Renal Transplantation].

Detection of post-transplant malignant tumors and the analysis of the associated risk factors is important for monitoring the progress after renal transplantation. In this study, we retrospectively examined the medical records of 298 patients who underwent renal transplantation at two facilities in Nagasaki Prefecture (Nagasaki University Hospital and National Hospital Organization Nagasaki Medical Center). Of the 298 patients, 45 (15.1%) patients had developed malignant tumors with 50 lesions. The most common type of malignant tumor was skin cancer (eight patients; 17.8%), followed by renal cancer (six patients; 13.3%), and pancreatic cancer and colorectal cancer, (four patients; 9.0% each). Five patients (11.1%) had multiple cancers, four of whom had skin cancer. The cumulative incidence within 10 and 20 years after renal transplantation was 6.0 and 17.9%, respectively. Univariate analysis identified age at transplantation and administration of cyclosporine and rituximab as risk factors, while multivariate analysis identified age at transplantation and administration of rituximab as independent factors. The administration of rituximab was associated with the development of malignant tumors. However, further investigation is required to establish the association with post-transplant malignant neoplasms.

Using Phase Difference Information to Detect Errors in the Flip Angle Measured with Actual Flip Angle Imaging at 7T.

Flip angle (FA) measurements using the actual flip angle imaging (AFI) method may induce significant errors in ultrahigh fields. We aimed to develop a method for detecting errors in FA measurements using phase information at 7 tesla. We performed computer simulations to elucidate the relationship between the FA calculation errors and the phase difference between the two AFI source images. We then examined whether a method based on the phase difference could detect FA calculation errors and determine the prescribed nominal FA of the scanner for accurate measurements in phantoms and healthy volunteers. The simulations confirmed that the calculated FA values erroneously decreased when the longitudinal magnetization and phase in one of the source images were inverted. Tests on phantoms and human subjects demonstrated that the phase difference information between the source images with a cut-off of 90° could readily detect FA calculation errors in the AFI method.

Alternative Treatment with Every-Other-Day Dosing of Sunitinib for Metastatic Renal Cell Carcinoma: Extended Follow-Up.

INTRODUCTION: We investigated the efficacy and safety of every-other-day dosing of sunitinib for the treatment of metastatic renal cell carcinoma (mRCC) with extended follow-up and the impact of immune checkpoint inhibitor (ICI) drugs. METHODS: Thirty-two patients received standard dosing treatment (standard group), and 32 received every-other-day treatment (experimental group). Efficacy endpoints included progression-free survival (PFS), overall survival (OS), and objective response rate. We also analyzed the clinical course of patients treated with nivolumab after sunitinib. RESULTS: The minimum follow-up was 42 months. Median PFS and OS were significantly longer in the experimental group compared with the standard group (27.6 vs. 6.2 and 87.1 vs. 24.6 months, respectively). The incidence of dose interruption of sunitinib caused by adverse events was significantly lower in the experimental group than in the standard group (28.1% vs. 56.3%, p = 0.042). Multivariate analysis showed that every-other-day dosing was a significant independent prognostic factor (p = 0.038), although nivolumab use was not (p = 0.232). Twelve patients were treated with nivolumab after sunitinib, and patients who did not respond to nivolumab tended to respond to pretreatment sunitinib for a long period. DISCUSSION/CONCLUSION: Long-term follow-up confirmed the efficacy and safety of every-other-day dosing of sunitinib for mRCC patients in the ICI era.

A case of early recurrent immunoglobulin A nephropathy and T-cell-mediated rejection in a transplant patient with Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is an X-chromosome recessive immunodeficiency disease characterized by the triad of thrombocytopenia, eczema, and susceptibility to infection owing to WAS protein gene abnormalities. Kidney transplantation is rarely offered to WAS patients with end-stage renal disease because of concerns that thrombocytopenia and immune disorders may affect the clinical outcome. Here, we report the case of a 20-year-old kidney transplant patient who developed end-stage renal disease owing to immunoglobulin (Ig)A nephropathy caused by WAS. Despite recurrent IgA nephropathy and T-cell-mediated rejection 7 months after transplantation, two rounds of steroid pulse therapy attenuated his renal function and urinary abnormality. His serum creatinine level was maintained at approximately 1.5 mg/dL 1 year after transplantation. No other WAS-related complications were observed throughout the clinical course. Although WAS can cause poor prognosis in kidney transplant patients, careful follow-up may allow kidney transplantation to be performed.

Separating spin compartments in arterial spin labeling using delays alternating with nutation for tailored excitation (DANTE) pulse: A validation study using T2 -relaxometry and application to arterial cerebral blood volume imaging.

PURPOSE: To clarify the type of spin compartment in arterial spin labeling (ASL) that is eliminated by delays alternating with nutation for tailored excitation (DANTE) pulse using T2 -relaxometry, and to demonstrate the feasibility of arterial cerebral blood volume (CBVa ) imaging using DANTE-ASL in combination with a simplified two-compartment model. METHOD: The DANTE and T2 -preparation modules were combined into a single ASL sequence. T2 values under the application of DANTE were determined to evaluate changes in T2 , along with the post-labeling delay (PLD) and the relationship between transit time without DANTE (TTnoVS ) and T2 . The reference tissue T2 (T2_ref ) was also obtained. Subsequently, the DANTE module was embedded into the Hadamard-encoded ASL. Cerebral blood flow (CBF) and CBVa were computed using two Hadamard-encoding datasets (with and without DANTE) in a rest and breath-holding (BH) task. RESULTS: While T2 without DANTE (T2_noVS ) decreased as the PLD increased, T2 with DANTE (T2_DANTE ) was equivalent to T2_ref and did not change with the PLD. Although there was a significant positive correlation between TTnoVS and T2_noVS with short PLD, T2_DANTE was not correlated with TTnoVS nor PLD. Baseline CBVa values obtained at rest were 0.64 ± 0.12, 0.64 ± 0.11, and 0.58 ± 0.15 mL/100 g for anterior, middle, and posterior cerebral arteries, respectively. Significant CBF and CBVa elevations were observed in the BH task. CONCLUSION: Microvascular compartment signals were eliminated from the total ASL signals by DANTE. CBVa can be measured using Hadamard-encoded DANTE-ASL in combination with a simplified two-compartment model.

[Renal Cell Carcinomas in Patients on Chronic Dialysis].

Patients on chronic dialysis for end-stage renal disease (ESRD) show an increased incidence of renal cell carcinoma (RCC). We investigated the clinicopathological characteristics and outcomes of 54 patients who underwent nephrectomy for RCC due to ESRD between 1992 and 2019. The patients consisted of 44 men and 10 women, with a median age of 62.9 years. The median duration of dialysis before surgery was 12.9 years. The clinical stage of the 54 RCCs was stage I in 44, stage II in 1, stage III in 1, and stage IV in 8. With a median follow-up of 5.1 years after surgery, the 5-year cancer-specific and overall survival rates were 84.3 and 61.8%, respectively. Patients with symptomatic RCC had a longer period of dialysis, presented with larger tumors of higher grade and stage, and had worse prognosis compared with those with incidentally discovered RCC. Cox proportional hazards analysis performed with clinicopathological features and symptomatic/incidental detection showed that older age and symptomatic RCC were independently associated with worse overall survival. Our data show that early detection is important for a good prognosis.

Oral administration of E-type prostanoid (EP) 1 receptor antagonist suppresses carcinogenesis and development of prostate cancer via upregulation of apoptosis in an animal model.

Prostaglandin E2 plays an important role in carcinogenesis and malignant potential of prostate cancer (PC) cells by binding to its specific receptors, E-type prostanoid (EP) receptors. However, anti-carcinogenic effects of the EP receptor antagonist are unclear. In this study, we used a mouse model of PC. The mice were provided standard feed (control) or feed containing the EP1 receptor antagonist and were sacrificed at 10, 15, 30, and 52 weeks of age. Apoptosis was evaluated by immunohistochemical analysis using a cleaved caspase-3 assay. The incidence of cancer in the experimental group was significantly lower than that in the control group at 15, 30, and 52 weeks of age. The percentage of poorly differentiated PC cells was significantly lower in the experimental group than in the control group at 30 and 52 weeks of age. The percentage of apoptotic cells in the experimental group was significantly higher than that in the control group at 15, 30, and 52 weeks of age. These findings indicate that feeding with the addition of EP1 receptor antagonist delayed PC progression via the upregulation of apoptosis. We suggest that the EP1 receptor antagonist may be a novel chemopreventive agent for PC.

Pathological significance and prognostic role of LATS2 in prostate cancer.

BACKGROUND: Large tumor suppressor 2 (LATS2) is an important regulator of the Hippo pathway and it plays crucial roles in cell survival and behaviors. Herein, we evaluated the pathological roles of LATS2 in prostate cancer (PC), for which very little information is available. METHODS: Cell proliferation, migration, and invasion in response to the siRNA-mediated knockdown (KD) LATS2 expression were evaluated in two PC cell lines (LNCaP and PC3). The expression of LATS2 in specimens from 204 PC patients was investigated immunohistochemically, and the relationships between its expression and clinicopathological features, proliferation index (PI; measured using an anti-KI-67 antibody), and biochemical recurrence (BCR) were investigated. RESULTS: KD of LATS2 increased the growth, migration, and invasion in LNCaP cells and only increased migration in PC3 cells. The expression of LATS2 was negatively associated with the grade group, T, N, M stage, and PI. In addition, the expression of LATS2 was a useful predictor of the histological effects of neoadjuvant hormonal therapy and BCR-free survival periods. A multivariate analysis model including clinicopathological features showed that negative expression of LATS2 had a significantly higher risk of BCR (odds ratio = 2.95, P < 0.001). CONCLUSIONS: LATS2 acts as a tumor suppressor in PC. LATS2 expression is a useful predictor for BCR. LATS2-related activities are possibly dependent on the androgen-dependency of PC cells. Therefore, we suggest that LATS2 could be a potential therapeutic target and a useful predictor for outcome in patients with PC.

Assessment of Impaired Cerebrovascular Reactivity in Chronic Cerebral Ischemia using Intravoxel Incoherent Motion Magnetic Resonance Imaging.

BACKGROUND: The severity of chronic cerebral ischemia can be assessed using cerebrovascular reactivity (CVR) to acetazolamide (ACZ) challenge, which is measured by single-photon emission computed tomography (SPECT); however, this is an invasive method. We investigated whether intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) can assess impaired CVR in preoperative patients with chronic cerebral ischemia and compared it to SPECT-CVR. METHODS: Forty-seven patients with unilateral cervical carotid artery stenosis underwent diffusion-weighted MRI with 11 b-values in the range of 0-800 s/mm2 and cerebral perfusion SPECT with the ACZ challenge. The perfusion fraction (f) and diffusion coefficient (D) of the IVIM parameters were calculated using a bi-exponential model. The f and D values and these ratios of the ipsilateral middle cerebral artery territory against the contralateral side were compared with the CVR values of the affected side calculated from the SPECT data. RESULTS: The IVIM-f and D values in the affected side were significantly higher than those in the unaffected side (median: 7.74% vs. 7.45%, p = 0.027; 0.816 vs. 0.801 10-3mm2/s, p < 0.001; respectively). However, there were no significant correlations between the f or D values and SPECT-CVR values in the affected side. In contrast, the f ratio showed a moderate negative correlation with the SPECT-CVR values (r = -0.40, p = 0.006) and detected impaired CVR (< 18.4%) with a sensitivity/specificity of 0.71/0.90. CONCLUSION: The IVIM perfusion parameter, f, can noninvasively assess impaired CVR with high sensitivity and specificity in patients with unilateral cervical carotid artery stenosis.

Pathological Roles of Prostaglandin E2-specific E-type Prostanoid Receptors in Hormone-sensitive and Castration-resistant Prostate Cancer.

BACKGROUND/AIM: Prostaglandin (PG) E2 mediates malignant aggressiveness by binding to four specific E-type prostanoid receptors (EP1R - 4R). This study aimed to clarify the pathological significance of EPRs in hormone-sensitive prostate cancer (HSPC) and castration-resistant prostate cancer (CRPC). MATERIALS AND METHODS: EP1R - 4R expression was examined in 102 HSPC and 27 CRPC specimens. The relationships between their expression and proliferation index (PI), apoptotic index (AI), and vascular endothelial growth factor (VEGF)-A expression were analyzed. RESULTS: EP4R expression in CRPC was significantly higher compared to that in HSPC, even in advanced disease (T3/4, N1, and/or M1). EP4R expression was significantly correlated with PI, AI, and VEGF-A expression in CRPC. Such significant relationships were not detected between EP1R - 3R and CRPC. CONCLUSION: EP4R expression in CRPC was significantly higher than that in HSPC and was associated with cancer cell proliferation, apoptosis, and pro-angiogenetic potential.

Ceruloplasmin Levels in Cancer Tissues and Urine Are Significant Biomarkers of Pathological Features and Outcome in Bladder Cancer.

BACKGROUND/AIM: A previous report showed that immune complex-ceruloplasmin (CP) in urine is associated with carcinogenesis and malignant behavior in bladder cancer (BC). We investigated the pathological significance and prognostic roles of urine and tissue levels of CP protein in BC patients. MATERIALS AND METHODS: Urine CP levels were measured using an enzyme-linked immunosorbent assay in 97 patients. CP expression in BC tissues was evaluated by immunohistochemical analysis in 176 patient samples. RESULTS: Urine CP levels were positively associated with tumor grade and pT stage in non-muscle invasive BC (NMIBC). CP expression in BC tissues was positively associated with tumor growth and progression. Multivariate analysis demonstrated that high urine CP levels was an independent predictor of recurrence in the urinary tract in NMIBC (hazard ratio=2.87, p=0.016). CONCLUSION: CP-related markers, especially urine CP levels, are useful biomarkers of malignant potential and prognosis in NMIBC.

Stage-specific Embryogenic Antigen-4 Expression in Castration-resistant Prostate Cancer and its Correlation With the Androgen Receptor.

BACKGROUND/AIM: Stage-specific embryonic antigen (SSEA)-4 plays important roles in the malignant aggressiveness of various cancers. The aim of this study was to investigate the pathological characteristics of SSEA-4 in castration-resistant prostate cancer (CRPC). MATERIALS AND METHODS: SSEA-4 expression and its pathological roles were evaluated in five prostate cancer (PC) cell lines and 27 CRPC tissues. The relationship between SSEA-4 and the androgen receptor (AR) was also examined. RESULTS: SSEA-4 expression was detected in AR-negative cells (PC3, DU145, and AICaP1) but was not detected in AR-positive cells (LNCaP and AICaP2). SSEA-4 expression in human CRPC tissues was significantly higher than that in locally advanced or metastatic hormone sensitive PC (HSPC) tissues. A negative correlation was also detected between SSEA-4 and AR in CRPC tissues but not in HSPC tissues. CONCLUSION: SSEA-4 was over-expressed in CRPC and the changes were mediated by complex mechanisms that related to the AR and hormonal therapy.

Pathological Significance and Prognostic Roles of Thrombospondin-3, 4 and 5 in Bladder Cancer.

BACKGROUND/AIM: The pathological significance of thrombospondin (TSP)-1 and -2 in bladder cancer (BC) is well-known whereas that of TSP-3, 4 and 5 remains unclear. Our aim is to clarify the pathological significance and prognostic roles of TSP-3 to 5 expression in BC patients. PATIENTS AND METHODS: TSP-3 to 5 expression, proliferation index (PI), apoptotic index (AI) and microvessel density (MVD) were evaluated in 206 BC patients by immunohistochemical techniques. RESULTS: TSP-5 expression was positively associated with grade, T stage, metastasis, and worse prognosis. PI in TSP-5-positive tissues was significantly higher compared to negative tissues. In contrast, AI in TSP-5-positive tissues was significantly lower compared to negative tissues. Expressions of TSP-3 and 4 were not associated with any clinicopathological features, survival, PI, or AI. CONCLUSION: TSP-5 plays important roles in malignant behavior via cell survival regulation whereas the pathological significance of TSP-3 and TSP-4 in BC might be minimal.

Spatial and temporal variations of flip-angle distributions in the human brain using an eight-channel parallel transmission system at 7T: comparison of three radiofrequency excitation methods.

We investigated the spatial and temporal variations of flip-angle (FA) distributions in the human brain from multiple scans, using an eight-channel parallel transmission (pTx) system at 7T. Nine healthy volunteers were scanned in five sessions using three radiofrequency excitation techniques each time: circular polarization (CP), static pTx, and dynamic pTx. We calculated the coefficients of variation of the FA values within the brain area to evaluate the variations, and the maximum intersession differences in the FA values (Dmax), comparing them between the three methods. The coefficients of variation decreased in the following order: CP, static pTx, and dynamic pTx (median: 20.1%, 13.6%, and 5.7%, respectively; p < 0.001). The average Dmax values were significantly higher for the static pTx (5.4°) than for the dynamic pTx (2.8°) and CP (1.7°) methods (p = 0.004 and 0.001, respectively). Compared to the CP method, the dynamic pTx method at 7T can efficiently minimize spatial variations in the FA distribution with a mild increase in temporal variations. The static pTx method exhibited a remarkably wide temporal variation.

Pharmacological Effects and Potential Clinical Usefulness of Polyphenols in Benign Prostatic Hyperplasia.

Benign prostatic hyperplasia (BPH) is arguably the most common benign disease among men. This disease is often associated with lower urinary tract symptoms (LUTS) in men and significantly decreases the quality of life. Polyphenol consumption reportedly plays an important role in the prevention of many diseases, including BPH. In recent years, in addition to disease prevention, many studies have reported the efficacy and safety of polyphenol treatment against various pathological conditions in vivo and in vitro. Furthermore, numerous studies have also revealed the molecular mechanisms of the antioxidant and anti-inflammatory effects of polyphenols. We believe that an improved understanding of the detailed pharmacological roles of polyphenol-induced activities at a molecular level is important for the prevention and treatment of BPH. Polyphenols are composed of many members, and their biological roles differ. In this review, we first provide information regarding the pathological roles of oxidative stress and inflammation in BPH. Next, the antioxidant and anti-inflammatory effects of polyphenols, including those of flavonoids and non-flavonoids, are discussed. Finally, we talk about the results and limitations of previous clinical trials that have used polyphenols in BPH, with particular focus on their molecular mechanisms of action.

GlyCEST: Magnetic Resonance Imaging of Glycine-Distribution in the Normal Murine Brain and Alterations in 5xFAD Mice.

The glycine level in the brain is known to be altered in neuropsychiatric disorders, such as schizophrenia and Alzheimer's disease (AD). Several studies have reported the in vivo measurement of glycine concentrations in the brain using proton magnetic resonance spectroscopy (1H-MRS), but 1H-MRS is not capable of imaging the distribution of glycine concentration with high spatial resolution. Chemical exchange saturation transfer magnetic resonance imaging (CEST-MRI) is a new technology that can detect specific molecules, including amino acids, in tissues. To validate the measurements of glycine concentrations in living tissues using CEST from glycine to water (GlyCEST), we extracted the brain tissues from mice and performed biochemical tests. In wild-type C57BL/6 mice, GlyCEST effects were found to be higher in the thalamus than in the cerebral cortex (P < 0.0001, paired t-test), and this result was in good agreement with the biochemical results. In 5xFAD mice, an animal model of AD, GlyCEST measurements demonstrated that glycine concentrations in the cerebral cortex (P < 0.05, unpaired t-test) and thalamus (P < 0.0001, unpaired t-test), but not in the hippocampus, were decreased compared to those in wild-type mice. These findings suggest that we have successfully applied the CEST-MRI technique to map the distribution of glycine concentrations in the murine brain. The present method also captured the changes in cerebral glycine concentrations in mice with AD. Imaging the distribution of glycine concentrations in the brain can be useful in investigating and elucidating the pathological mechanisms of neuropsychiatric disorders.

Present Status, Limitations and Future Directions of Treatment Strategies Using Fucoidan-Based Therapies in Bladder Cancer.

Bladder cancer (BC) is a common urological cancer, with poor prognosis for advanced/metastatic stages. Various intensive treatments, including radical cystectomy, chemotherapy, immune therapy, and radiotherapy are commonly used for these patients. However, these treatments often cause complications and adverse events. Therefore, researchers are exploring the efficacy of natural product-based treatment strategies in BC patients. Fucoidan, derived from marine brown algae, is recognized as a multi-functional and safe substrate, and has been reported to have anti-cancer effects in various types of malignancies. Additionally, in vivo and in vitro studies have reported the protective effects of fucoidan against cancer-related cachexia and chemotherapeutic agent-induced adverse events. In this review, we have introduced the anti-cancer effects of fucoidan extracts in BC and highlighted its molecular mechanisms. We have also shown the anti-cancer effects of fucoidan therapy with conventional chemotherapeutic agents and new treatment strategies using fucoidan-based nanoparticles in various malignancies. Moreover, apart from the improvement of anti-cancer effects by fucoidan, its protective effects against cancer-related disorders and cisplatin-induced toxicities have been introduced. However, the available information is insufficient to conclude the clinical usefulness of fucoidan-based treatments in BC patients. Therefore, we have indicated the aspects that need to be considered regarding fucoidan-based treatments and future directions for the treatment of BC.

Pathological and Pharmacological Roles of Mitochondrial Reactive Oxygen Species in Malignant Neoplasms: Therapies Involving Chemical Compounds, Natural Products, and Photosensitizers.

Oxidative stress plays an important role in cellular processes. Consequently, oxidative stress also affects etiology, progression, and response to therapeutics in various pathological conditions including malignant tumors. Oxidative stress and associated outcomes are often brought about by excessive generation of reactive oxygen species (ROS). Accumulation of ROS occurs due to dysregulation of homeostasis in an otherwise strictly controlled physiological condition. In fact, intracellular ROS levels are closely associated with the pathological status and outcome of numerous diseases. Notably, mitochondria are recognized as the critical regulator and primary source of ROS. Damage to mitochondria increases mitochondrial ROS (mROS) production, which leads to an increased level of total intracellular ROS. However, intracellular ROS level may not always reflect mROS levels, as ROS is not only produced by mitochondria but also by other organelles such as endoplasmic reticulum and peroxisomes. Thus, an evaluation of mROS would help us to recognize the biological and pathological characteristics and predictive markers of malignant tumors and develop efficient treatment strategies. In this review, we describe the pathological significance of mROS in malignant neoplasms. In particular, we show the association of mROS-related signaling in the molecular mechanisms of chemically synthesized and natural chemotherapeutic agents and photodynamic therapy.