Event-free survival at 36 months is a suitable endpoint for diffuse large B-cell lymphoma patients treated with immunochemotherapy: real-world evidence from the North Japan Hematology Study Group.

Information regarding follow-up duration after treatment for newly diagnosed diffuse large B-cell lymphoma (DLBCL) is important. However, a clear endpoint has yet to be established. We totally enrolled 2182 patients newly diagnosed with DLBCL between 2008 and 2018. The median age of the patients was 71 years. All patients were treated with rituximab- and anthracycline-based chemotherapies. Each overall survival (OS) was compared with the age- and sex-matched Japanese general population (GP) data. At a median follow-up of 3.4 years, 985 patients experienced an event and 657 patients died. Patients who achieved an event-free survival (EFS) at 36 months (EFS36) had an OS equivalent to that of the matched GP (standard mortality ratio [SMR], 1.17; P=0.1324), whereas those who achieved an EFS24 did not have an OS comparable to that of the matched GP (SMR, 1.26; P=0.0095). Subgroup analysis revealed that relatively old patients (>60 years), male patients, those with limited-stage disease, those with a good performance status, and those with low levels of soluble interleukin 2 receptor already had a comparable life expectancy to the matched GP at an EFS24. In contrast, relatively young patients had a shorter life expectancy than matched GP, even with an EFS36. In conclusion, an EFS36 was shown to be a more suitable endpoint for newly diagnosed DLBCL patients than an EFS24. Of note, younger patients require a longer EFS period than older patients in order to obtain an equivalent life expectancy to the matched GP.

Subclinical minute FLT3-ITD clone can be detected in clinically FLT3-ITD-negative acute myeloid leukaemia at diagnosis.

Recent advances in next-generation sequencing (NGS) have enabled the detection of subclinical minute FLT3-ITD. We selected 74 newly diagnosed, cytogenetically normal acute myeloid leukaemia (AML) samples in which FLT3-ITD was not detected by gel electrophoresis. We sequenced them using NGS and found minute FLT3-ITDs in 19 cases. We compared cases with clinically relevant FLT3-ITD (n = 37), cases with minute FLT3-ITD (n = 19) and cases without detectable FLT3-ITD (n = 55). Molecular characteristics (location and length) of minute FLT3-ITD were similar to those of clinically relevant FLT3-ITD. Survival of cases with minute FLT3-ITD was similar to that of cases without detectable FLT3-ITD, whereas the relapse rate within 1 year after onset was significantly higher in cases with minute FLT3-ITD. We followed 18 relapsed samples of cases with clinically FLT3-ITD-negative at diagnosis. Two of 3 cases with minute FLT3-ITD relapsed with progression to clinically relevant FLT3-ITD. Two of 15 cases in which FLT3-ITD was not detected by NGS relapsed with the emergence of minute FLT3-ITD, and one of them showed progression to clinically relevant FLT3-ITD at the second relapse. We revealed the clonal dynamics of subclinical minute FLT3-ITD in clinically FLT3-ITD-negative AML. Minute FLT3-ITD at the initial AML can expand to become a dominant clone at relapse.

Shorter duration of venetoclax administration to 14 days has same efficacy and better safety profile in treatment of acute myeloid leukemia.

Venetoclax (VEN) is now widely used in the treatment of acute myelogenous leukemia (AML) in elderly patients who are not eligible for intensive remission induction therapy. Prolonged myelosuppression, increased incidence of infection, and long duration of hospital stay were major concerns for VEN treatment cases, and we thought that shortening the duration of VEN administration during induction therapy might solve these problems. Thirteen newly diagnosed AML patients who underwent VEN+azacitidine (AZA) induction therapy from March 2021 to June 2022 at Kushiro Rosai Hospital were analyzed retrospectively. The median age was 79 (range, 68-86) years, and 8 of the patients (61.5%) were classified as high risk according to the ELN 2017 risk stratification. Eight patients received VEN for 14 days (VEN14 group), and 5 patients received VEN for 28 days (VEN28 group). The composite complete remission (CRc) rate was 76.9% in total, and the CRc rates in the VEN14 and VEN28 groups were almost the same (75.0% and 80.0%, respectively). The median overall survival (OS) was not reached in the VEN14 group and was 254 days in the VEN28 group. The median event-free survival (EFS) was not reached in the VEN14 group and was 178 days in the VEN28 group. The VEN14 group might have a possibility to reduce febrile neutropenia (37.5% vs. 80%) and reduce the duration of hospital stay (median, 21.5 vs. 31 days) compared with the VEN28 group. VEN14 produced the same CRc rate and survival rate, safer profile, and shorter duration of hospital stay than VEN28.

Clinical implications of NUP98::NSD1 fusion at diagnosis in adult FLT3-ITD positive AML.

OBJECTIVES: The cryptic fusion oncogene NUP98::NSD1 is known to be associated with FLT3-ITD mutation in acute myeloid leukemia (AML), and an independent poor prognostic factor in pediatric AML. However, there are little data regarding the clinical significance of NUP98::NSD1 in adult cohort. METHODS: We conducted a multicenter retrospective study to investigate the prevalence, clinical characteristics, and prognostic impact of NUP98::NSD1 in adult FLT3-ITD-positive AML patients. RESULTS: In a total of 97 FLT3-ITD-positive AML patients, six cases (6.2%) were found to harbor the NUP98::NSD1 fusion transcript. NUP98::NSD1 positive cases had significantly higher platelet counts and a higher frequency of FAB-M4 morphology than NUP98::NSD1 negative cases. NUP98::NSD1 was found to be mutually exclusive with NPM1 mutation, and was accompanied by the WT1 mutation in three of the six cases. The presence of NUP98::NSD1 fusion at the time of diagnosis predicted poor response to cytarabine-anthracycline-based intensive induction chemotherapy (induction failure rate: 83% vs. 36%, p = .038). Five of the six cases with NUP98::NSD1 underwent allogeneic hematopoietic stem cell transplantation (HSCT). Two of the five cases have successfully maintained remission, with one of them being rescued through a second HSCT. CONCLUSIONS: Detecting NUP98::NSD1 in adult FLT3-ITD-positive AML is crucial to recognizing chemotherapy-resistant group.

Novel Ultrasonographic Scoring System of Sinusoidal Obstruction Syndrome after Hematopoietic Stem Cell Transplantation.

Sinusoidal obstruction syndrome (SOS)/hepatic veno-occlusive disease (VOD) is a well-documented complication after hematopoietic stem cell transplantation (HSCT). Transabdominal ultrasonography (US) enables the visualization of blood flow abnormalities and is therefore useful for the diagnosis of SOS/VOD. We herein prospectively evaluated accuracy of a novel US diagnostic scoring system of SOS/VOD based on US findings. We carried out US in 106 patients on day 14 and when SOS/VOD was suspected after allogeneic HSCT. Among 106 patients, 10 patients (9.4%) were diagnosed as SOS/VOD by Baltimore or Seattle criteria. According to univariate analysis of 17 US findings (US-17 screening), we established a novel scoring system (HokUS-10) consisting of 10 parameters, such as gallbladder wall thickening, ascites, and blood flow signal in the paraumbilical vein. The sensitivity and specificity were 100% and 95.8%, respectively. Diagnostic performance of the HokUS-10 was significantly better than US-17 screening. In 4 of 10 patients US detection of SOS/VOD preceded to clinical diagnosis. The HokUS-10 scoring system is useful in the diagnosis of SOS/VOD; however, our results should be validated in other cohorts.

Improved prognosis with additional medium-dose VP16 to CY/TBI in allogeneic transplantation for high risk ALL in adults.

Allogeneic hematopoietic stem cell transplantation (HSCT) with the conventional cyclophosphamide and total body irradiation (CY/TBI) regimen is an essential therapeutic strategy for acute lymphoblastic leukemia (ALL) in adults. Medium-dose etoposide (VP16, 30-40 mg/kg) can be added to intensify this CY/TBI regimen and reduce relapse; however, differences in prognosis between the VP16/CY/TBI and CY/TBI regimens have not yet been fully analyzed. We conducted a retrospective cohort study using a Japanese transplant registry database to compare the prognosis between the VP16/CY/TBI (VP16, total 30-40 mg/kg) (N = 376) and CY/TBI (N = 1178) regimens in adult patients with ALL transplanted at complete remission (CR) between January 1, 2000 and December 31, 2014. Our analyses indicated that VP16/CY/TBI significantly reduced relapse compared with CY/TBI (risk ratio, 0.75; 95% confidence interval [CI], 0.56-1.00; P = .05) with a corresponding improvement in leukemia-free survival (hazard ratio [HR], 0.76; 95%CI, 0.62-0.93; P = .01), particularly in patients transplanted at CR1 with advanced-risk (positive minimal residual disease, presence of poor-risk cytogenetics, or an initial elevated leukocyte count) (HR, 0.75; 95%CI, 0.56-1.00; P = .05) or those transplanted beyond CR2 (HR, 0.58; 95%CI, 0.39-0.88; P = .01). The addition of VP16 did not increase post-transplant complications or nonrelapse mortality (HR, 0.88; 95%CI, 0.65-1.18; P = .38). This study is the first to reveal the efficacy of the addition of medium-dose VP16 to CY/TBI in high-risk ALL. To establish new myeloablative conditioning regimens including VP16, a large-scale prospective study is necessary.

Disseminated fusariosis emerged from prolonged local genital infection after cord blood transplantation.

Disseminated fusariosis (DF) is a rare life threatening fungal infection in immunocompromised hosts. We herein report a case of a fatal DF mimicking varicella zoster virus (VZV) infection that was emerged from a localized genital infection during cord blood transplantation (CBT) in a patient with severe aplastic anemia (SAA). The patient developed an ulcer following small painful vesicles mimics herpes simplex virus infection (HSV) on the glans penis before CBT, but a Fusarium species was identified. Despite administration of voriconazole, liposomal amphotericin B and granulocyte transfusion, the lesion was extended to extensive skin looked like VZV infection and the patients died after CBT. Massive fusarium infiltration was detected in multiple organs at autopsy. A genetic analysis of the mold identified Fusarium solani after his death. It should be noted that in patients with fusarium infection, localized and disseminated lesions of fusarium infection sometimes mimic HSV and VZV infections, which hampers an early diagnosis.

Increased non-relapse mortality due to high-dose cytarabine plus CY/TBI in BMT/PBSCT for acute lymphoblastic leukaemia in adults.

The efficacy of high-dose cytarabine (HDCA) plus cyclophosphamide/total-body irradiation (CY/TBI) has been proved in cord blood transplantation (CBT) for acute lymphoblastic leukaemia (ALL), but not in bone marrow or peripheral blood stem cell transplantation (BMT/PBSCT). In this cohort study, we compared the prognosis of CY/TBI (N = 1244) and HDCA/CY/TBI (N = 316) regimens in BMT/PBSCT for ALL. The addition of HDCA decreased post-transplant relapse, while significantly increasing non-relapse mortality (risk ratio, 1·33), and overall survival was not improved. The positive effects of HDCA reported in CBT cannot be extrapolated to BMT/PBSCT, and HDCA may not be recommended in these procedures.

Comparison of Cyclophosphamide Combined with Total Body Irradiation, Oral Busulfan, or Intravenous Busulfan for Allogeneic Hematopoietic Cell Transplantation in Adults with Acute Lymphoblastic Leukemia.

We conducted a retrospective analysis to compare outcomes in adult patients with acute lymphoblastic leukemia (ALL) who underwent allogeneic hematopoietic cell transplantation (allo-HCT) with conditioning regimens containing cyclophosphamide (CY) in combination with total body irradiation (TBI), oral busulfan (p.o. BU), or intravenous busulfan (i.v. BU). We used data for January 2000 to December 2012 from the Transplant Registry Unified Management Program of the Japan Society of Hematopoietic Cell Transplantation. We identified 2130 patients treated with TBI/CY (n = 2028), p.o. BU/CY (n = 60), or i.v. BU/CY (n = 42). Two-year overall survival (OS) and 2-year relapse-free survival rates were 69.0% and 62.1%, respectively, in the TBI/CY group, 55.9% and 54.2% in the p.o. BU/CY group, and 71.0% and 46.8% in the i.v. BU/CY group. In multivariate analysis, compared with TBI/CY, p.o. BU/CY, but not i.v. BU/CY, was associated with lower OS (hazard ratio [HR], 1.46; P = .047) and a higher incidence of sinusoidal obstruction syndrome (HR, 3.36; P = .030). No between-group differences were seen in the incidence of nonrelapse mortality, relapse, acute graft-versus-host disease (GVHD), or chronic GVHD. We suggest that i.v. BU/CY might be a possible alternative allo-HCT conditioning regimen for adults with ALL who are not suitable for TBI.

Allogeneic hematopoietic stem cell transplantation following reduced-intensity conditioning for mycosis fungoides and Sezary syndrome.

Advanced-stage mycosis fungoides and Sezary syndrome (MF/SS) have a poor prognosis. Allogeneic hematopoietic stem cell transplantation (HSCT), particularly using a reduced-intensity conditioning (RIC) regimen, is a promising treatment for advanced-stage MF/SS. We performed RIC-HSCT in nine patients with advanced MF/SS. With a median follow-up period of 954 days after HSCT, the estimated 3-year overall survival was 85.7% (95% confidence interval, 33.4-97.9%) with no non-relapse mortality. Five patients relapsed after RIC-HSCT; however, in four patients whose relapse was detected only from the skin, persistent complete response was achieved in one patient, and the disease was manageable in other three patients by the tapering of immunosuppressants and donor lymphocyte infusion, suggesting that graft-versus-lymphoma effect and 'down-staging' effect from advanced stage to early stage by HSCT improve the prognosis of advanced-stage MF/SS. These results suggest that RIC-HSCT is an effective treatment for advanced MF/SS.

Ultrasonographic evaluation of gastrointestinal graft-versus-host disease after hematopoietic stem cell transplantation.

Gastrointestinal graft-versus-host disease (GI-GVHD) is a major and life-threatening complication of hematopoietic stem cell transplantation (HSCT). This study evaluated the efficacy of ultrasonography (US) for assessing and monitoring GI-GVHD. GI tract was evaluated by US in 81 patients. US findings were positive in 43 patients, including 11 false positive, and negative in 38 patients. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of US for the diagnosis of GI-GVHD were 100%, 78%, 74%, 100%, and 86%, respectively. Diffuse wall thickening of the ileum was the most frequent finding in patients with GI-GVHD. Severity of GI-GVHD was correlated with the thickness of internal low echoic layer of the wall, the echogenicity of mesenteric fat tissue, and the intensity of Doppler signaling. We classified US findings of GI-GVHD into four US grades. There was a significant correlation between clinical stage of GI-GVHD and the US grade. These ultrasonographic abnormalities were improved with clinical improvement of GI-GVHD upon treatment. Thus, US is an effective and efficient non-invasive means of identifying the extent and severity of GI-GVHD and monitoring response to treatment.

High level of serum soluble interleukin-2 receptor at transplantation predicts poor outcome of allogeneic stem cell transplantation for adult T cell leukemia.

The prognosis for adult T cell leukemia/lymphoma (ATL) is very poor, and only allogeneic hematopoietic stem cell transplantation (allo-SCT) has been considered to be a curative treatment for ATL. In this study, we retrospectively analyzed data for patients who had received allo-SCT for ATL in Hokkaido, the northernmost island of Japan, to determine prognostic factors. Fifty-six patients with a median age of 57 years received allo-SCT. Twenty-eight (50.0%) patients had acute type and 22 (46.4%) had lymphoma type. Twenty-three (41.1%) patients received allo-SCT in complete remission (CR), whereas the others were in non-CR. Seventeen (30.4%) patients received myeloablative conditioning and the others received reduced-intensity conditioning. With a median follow-up period of 48 months (range, 17 to 134 months), 1-year overall survival (OS) and 5-year OS rates were 55.4% and 46.1%, respectively. The survival curve reached a plateau at 22 months after stem cell transplantation (SCT). Male sex, high level of serum soluble interleukin-2 receptor (sIL-2R) at SCT, and non-CR at SCT were determined to be significant risk factors for OS. A high level of sIL-2R at SCT was a risk factor for poor OS in patients with non-CR at SCT by univariate analysis (P = .02), and it remained significant after adjustment by sex (hazard ratio, 2.73 [95% confidence interval, 1.07 to 7.90]). A high level of sIL-2R at SCT was also determined to be a risk factor for disease progression (P = .02). This region-wide study showed encouraging results for survival after allo-SCT for ATL and demonstrated for the first time that a high level of sIL-2R at SCT predicts worse SCT outcome.

Bone marrow graft-versus-host disease: evaluation of its clinical impact on disrupted hematopoiesis after allogeneic hematopoietic stem cell transplantation.

Idiopathic cytopenias are frequently observed in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We have previously reported the effect of graft-versus-host disease (GVHD) on bone marrow (BM) in murine models, indicating that the osteoblast injury mediated by donor T cells was associated with bone marrow suppression and delayed immune reconstitution. In this study, we prospectively evaluated the relevance of these findings in 51 patients. Patients with chronic GVHD manifested the loss of osteoblasts, contributing to cytopenic symptoms (P = .0427 compared with patients without cytopenic symptoms). The loss of osteoblasts was significantly associated with the extensive type of chronic GVHD (P = .012), and flow cytometric analyses revealed lower numbers of CD19(+) B cells and a significantly increased CD4 to CD8 ratio (P = .0002) in these patients. Our data, for the first time to our knowledge, summarize the detailed analyses of the effect of GVHD on BM in the clinical allo-HSCT patients.

Stenotrophomonas maltophilia infection during allogeneic hematopoietic stem cell transplantation: a single-center experience.

To examine risk factors for Stenotrophomonas maltophilia (S. maltophilia) infection during allogeneic hematopoietic stem cell transplantation (allo-HSCT), we retrospectively analyzed 259 patients who underwent allo-HSCT. Not only S. maltophilia infection but also S. maltophilia colonization was associated with mortality during allo-HSCT. Among 52 episodes in 39 patients in whom S. maltophilia was detected, documented infection developed in 33 episodes (25 patients). The onset of S. maltophilia infection in the period from the conditioning regimen to engraftment was associated with a high mortality rate. Breakthrough S. maltophilia infection developed in 24% of the patients during prophylactic administration of fluoroquinolones, to which S. maltophilia is sensitive. Reinsertion of a central venous catheter (CVC) immediately after removal was suggested to be a risk for persistent S. maltophilia infection in the period of neutropenia. Our results indicated that (i) onset of S. maltophilia infection in the period from the conditioning therapy to engraftment and (ii) removal and immediate reinsertion of a CVC as treatment after the onset of S. maltophilia infection are possible risk factors for S. maltophilia-related mortality during allo-HSCT.

Outcome after first relapse in adult patients with Philadelphia chromosome-negative acute lymphoblastic leukaemia.

To analyse the outcome of adult patients who developed a first relapse of acute lymphoblastic leukaemia (ALL), we collected the clinical data of 332 patients with Philadelphia-chromosome (Ph) negative ALL, aged 16-65 years, who relapsed after first complete remission (CR1) between 1998 and 2008 in 69 institutions all over Japan, including 58 patients who relapsed after allogeneic haematopoietic stem cell transplantation (Allo-HSCT) in CR1. The overall survival (OS) was 43·4% at 1 year, and 16·3% at 5 years from relapse in patients who received chemotherapy alone in CR1. Among patients who relapsed after chemotherapy alone in CR1, 123 (52·5%) achieved a second remission (CR2) following salvage chemotherapy, of whom 62 subsequently underwent Allo-HSCT during CR2. Allo-HSCT in CR2 was significantly associated with better OS. Moreover, the type of salvage chemotherapy influenced OS from relapse. A doxorubicin, vincristine, and predonisone-based (AdVP-type) regimen was related to better OS in patients with longer CR1 (more than 1 year), but was related to worse OS in patients with shorter CR1. In conclusion, the prognosis of patients with relapsed Ph-negative ALL is poor. Allo-HSCT after a first relapse could improve the prognosis. Selection of the optimal salvage chemotherapy might depend on the duration of CR1.

Use of Mixed Lymphocyte Reaction Assay to Evaluate Immune Tolerance before Kidney Transplantation with an Immunosuppression-Free Protocol following Hematopoietic Stem Cell Transplantation from the Same Donor.

Several cases of kidney transplantation after hematopoietic stem cell transplantation (HSCT) from the same donor for end-stage renal disease have been reported. In those cases, immunosuppressive drugs were discontinued since immune tolerance was supposed to be induced. Theoretically, the recipient's immune system recognizes the kidney allograft as its own tissue with the same human leukocyte antigen (HLA) profile, and the kidney allograft will not be rejected, even without the use of immunosuppressive agents. However, almost all recipients receive immunosuppressants in the early stages after kidney transplantation owing to concerns of acute rejection. Here, we report a successful case of post-HSCT kidney transplantation without the use of immunosuppressive drugs, in which a mixed lymphocyte reaction (MLR) assay was used to evaluate immune tolerance before kidney transplantation. The patient was a 25-year-old woman. Five years prior, she developed acute myeloid leukemia and underwent HLA-half-matched peripheral blood stem cell transplantation. Thereafter, she was in remission of the acute myeloid leukemia, but 1 year later, she developed renal graft-versus-host disease. Subsequently, the patient's renal function gradually deteriorated to end-stage renal failure, and she underwent kidney transplantation with the previous stem cell donor: her mother. HLA typing of donor and recipient showed a complete chimerism in the peripheral blood. The pretransplantation complement-dependent cytotoxic crossmatch and flow cytometric T-cell crossmatch results were both negative, and HLA antibody measurements were all negative. The MLR assay revealed no T-lymphocyte reaction to the donor; therefore, immunosuppressants were not used. Two years after transplantation, the patient's serum creatinine concentration was around 0.8 mg/dL (down from 4 mg/dL before transplantation). No abnormalities were observed in a renal biopsy performed after 3 months. Our study, along with others, indicates that immune tolerance to a donor develops in post-HSCT kidney transplantation from the same donor.

Clinical features of complex karyotype in newly diagnosed acute myeloid leukemia.

Complex karyotype acute myeloid leukemia (CK-AML) has been classified as an adverse-risk subtype. Although a few reports have further classified CK-AML as typical (including monosomy of chromosomes 5, 7 and 17 or deletion of 5q, 7q and/or 17p) or atypical, the clinical features of these subtypes in Japanese patients remain unclear. We retrospectively analyzed a total of 115 patients with CK-AML, including 77 with typical CK-AML and 38 with atypical CK-AML. Median overall survival (OS) was significantly shorter in patients with typical CK-AML than atypical CK-AML (143 days vs. 369 days, P = 0.009). Among patients with typical CK-AML, those with monosomy 17 or deletion of 17p had significantly shorter OS than patients without such abnormalities (105 days vs. 165 days, P = 0.033). TP53 mutations were more predominant in patients with typical CK-AML than in patients with atypical CK-AML (69.7% vs. 32.4%, P < 0.001). Patients with typical CK-AML had a poor prognosis regardless of TP53 mutation status. Among patients with atypical CK-AML, however, prognosis was worse for those with the TP53 mutation than those without the mutation. In conclusion, prognosis is extremely poor for both typical CK-AML and atypical CK-AML with TP53 mutation.

Professional oral health care reduces oral mucositis and febrile neutropenia in patients treated with allogeneic bone marrow transplantation.

GOAL OF WORK: Little is known about the effects of professional oral health care (POHC) on the outcome of hematopoietic stem cell transplantation (HSCT). We evaluated the effects of POHC given by dentists and dental hygienists on the development of oral mucositis and febrile neutropenia (FN) after allogeneic bone marrow transplantation (BMT). PATIENTS AND METHODS: We retrospectively studied 140 adult patients who had received allogeneic BMT, with or without POHC, in our hospital consecutively between February 2002 and December 2009. Oral mucositis was evaluated according to the World Health Organization scale. MAIN RESULTS: The incidence of oral mucositis was 66.7% (52/78) in the patients who had received POHC, compared to 93.5% (58/62) in the non-POHC group (P < 0.001). The incidence of FN and the maximal level of CRP were also significantly lower in the POHC group. Multivariate analysis revealed that the POHC was significantly associated with the incidence of oral mucositis (odds ratio, 7.58; 95%CI, 2.45-23.34; P < 0.001). CONCLUSIONS: We concluded that POHC reduced the incidences of oral mucositis and FN by upgrading the overall oral hygiene during HSCT.

A comparison of oral mucositis in allogeneic hematopoietic stem cell transplantation between conventional and reduced-intensity regimens.

Severe oral mucositis developed in allogeneic hematopoietic stem cell transplantation (HSCT) accompanies intolerable pain and risk for systemic bacteremia infection. Conventional stem cell transplantation (CST) and reduced-intensity regimens for allogeneic HSCT (RIST) may differently affect the occurrence and severity of oral mucositis. Here, we comparatively examined oral mucositis in patients undergoing CST and that in RIST patients to search for measures to alleviate oral mucositis. We retrospectively analyzed the data of 130 consecutive patients undergoing HSCT (conventional, 60; RIST, 70). Oral mucositis was evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. We also investigated the risk factors for severe oral mucositis in each regimen. The incidence of oral mucositis was not significantly different between RIST and CST patients. The use of opioid analgesics to control pain due to oral mucositis was significantly less in patients undergoing RIST compared with those receiving CST. The risk factors for severe oral mucositis, determined by univariate and multivariate analyses, were "younger age (<40)" in CST and "longer duration of neutropenia (≥ 14 days)" in RIST. Although the incidences of oral mucositis were almost the same, the need for opioid analgesics and the risk factors for severe oral mucositis differed between CST and RIST patients.