Real-World Impact of Routine Addition of Antithymocyte Globulin to Standard GVHD Prophylaxis in Myeloablative Unrelated Donor Transplants: Important Gains in Graft-versus-Host Disease Prevention though No Difference in Overall Survival.

INTRODUCTION: Antithymocyte globulin (ATG) has been demonstrated to reduce the incidence of graft-versus-host disease (GVHD); however, it remains controversial whether these gains are offset by an increase in relapse. METHODS: We conducted a retrospective historical control study consisting of patients (n = 210) who underwent myeloablative allogeneic hematopoietic stem-cell transplantation (HSCT) from 2014 to 2020. RESULTS: The incidence of acute GVHD was lower in the ATG group (51.4%) than the non-ATG group (control) (70.0%, p = 0.010). The incidence of chronic GVHD was also lower in the ATG group at 1-year (36.4% vs. 62.9%, p < 0.001) and 2-year (40.0% vs. 65.7%, p < 0.001) post-HSCT. The mortality due to GVHD was higher in the control (18.5%) than the ATG group (4.3%; p = 0.024). The severe GVHD-relapse-free survival was higher in the ATG group (36.4%) than the control (12.9%; p < 0.001). Nevertheless, the 2-year overall survival was similar. CONCLUSION: Our results confirm the effectiveness of ATG in prevention of GVHD in the real-world setting and enhanced GVHD-free survival. An important result is the equalization of overall survival between the ATG and control groups at 1- and 2-year post-HSCT and implies that earlier GVHD-associated mortality may be offset by later relapse mortality producing similar overall survival over time.

Incidence and socioeconomic factors in older adults with acute myeloid leukaemia: Real-world outcomes from a population-based cohort.

OBJECTIVES: Acute myeloid leukaemia (AML) is a disease of older adults, who are vulnerable to socio-economic factors. We determined AML incidence in older adults and the impact of socio-economic factors on outcomes. METHODS: We included 3024 AML patients (1996-2016) identified from a population-based registry. RESULTS: AML incidence in patients ≥60 years increased from 11.01 (2001-2005) to 12.76 (2011-2016) per 100 000 population. Among 879 patients ≥60 years in recent eras (2010-2016), rural residents (<100 000 population) were less likely to be assessed by a leukaemia specialist (39% rural, 47% urban, p = .032); no difference was seen for lower (43%, quintile 1-3) vs. higher (47%, quintile 4-5) incomes (p = .235). Similar numbers received induction chemotherapy between residence (16% rural, 18% urban, p = .578) and incomes (17% lower, 17% high, p = 1.0). Differences between incomes were seen for hypomethylating agent treatment (14% low, 20% high, p = .041); this was not seen for residence (13% rural, 18% urban, p = .092). Among non-adverse karyotype patients ≥70 years, 2-year overall survival was worse for rural (5% rural, 12% urban, p = .006) and lower income (6% low, 15% high, p = .017) patients. CONCLUSIONS: AML incidence in older adults is increasing, and outcomes are worse for older rural and low-income residents; these patients face treatment barriers.

Reevaluating Patient Eligibility for Inotuzumab Ozogamicin Based on CD22 Expression: Is Dim Expression Sufficient?

Salvage options for patients with relapsed B-cell acute lymphoblastic leukemia (B-ALL) include inotuzumab ozogamicin (InO), a recombinant, humanized anti-CD22 monoclonal antibody conjugated to the cytotoxic antibiotic calicheamicin. However, the benefit of InO in patients with dim CD22 expression remains unclear. We present a case of a patient with B-ALL who responded to InO despite only dim surface expression of CD22 by flow cytometry, achieving a survival benefit concordant with that reported in the literature and maintaining a good quality of life as a transfusion-independent outpatient. Our observation has broad relevance to clinicians who manage patients with B-ALL who are candidates for InO.

Outpatient Autologous Stem Cell Transplants for Multiple Myeloma: Analysis of Safety and Outcomes in a Tertiary Care Center.

BACKGROUND: Autologous stem cell transplant (ASCT) is the preferred consolidation strategy to treat eligible patients with multiple myeloma (MM) and related plasma cell dyscrasias. Given the increasing volume of patients and longer wait time, outpatient ASCT for MM is the standard of care at the Vancouver General Hospital. PATIENTS AND METHODS: Patients with MM, POEMS syndrome, and amyloidosis undergoing ASCT were included in this analysis. We analyzed patient characteristics, the number of patients requiring admission, duration of admission, 30-day and 100-day mortality, and overall survival. RESULTS: Between January 2007 and June 2016, 724 patients underwent 752 ASCTs. Of these, 702 were first ASCTs, 44 were second, and 6 were third. The median age was 60 years (interquartile range [IQR], 54-65 years). Reasons for ASCTs were MM (96.9%) amyloidosis (2.4%), and POEMS syndrome (0.7%). There were 431 (59.5%) males in this group. The median time from diagnosis to transplant was 5 months. Conditioning was melphalan 200 mg/m2 for 89.6% of the patients. Admission to the inpatient ward was required by 245 (32.6%) patients within the first 30 days. The median time to admission was 9 days post-transplant (IQR, 5-13 days). The median duration of admission was 6 days (IQR, 3-9 days). The day 100 all-cause mortality rate was 0.9%, and transplant-related mortality was 0.4%. CONCLUSION: Outpatient ASCT is a safe and feasible treatment strategy with low transplant-related mortality. Overall resource utilization is significantly lower than inpatient ASCT: however, this requires a multidisciplinary approach with close follow-up.

Fludarabine, busulfan, and low-dose TBI conditioning versus cyclophosphamide and TBI in allogeneic hematopoietic cell transplantation for adult acute lymphoblastic leukemia.

The optimal conditioning regimen for adults undergoing transplantation for acute lymphoblastic leukemia (ALL) remains undetermined. Cyclophosphamide and total body irradiation (Cy/TBI) has emerged as a standard myeloablative regimen but is associated with significant toxicity. We compared outcomes between patients undergoing transplant for ALL at centers using Cy/TBI as standard of care and another center using fludarabine, busulfan, and low-dose TBI (400 cGy) in combination with anti-thymocyte globulin as its standard. Among 146 patients (74 Cy/TBI and 72 Flu/Bu/TBI) there were no significant differences in overall or progression-free survival between groups. Non-relapse mortality was similar (12% vs. 16.7% for Cy/TBI and Flu/Bu/TBI, respectively, p = .62) despite the Flu/Bu/TBI group having significantly worse performance status. Flu/Bu/TBI resulted in significantly lower cumulative incidence of relapse compared with Cy/TBI (2-year point estimate 18.5% vs. 31.5%, p = .05). These results demonstrate similar outcomes for patients receiving Flu/Bu/TBI versus Cy/TBI. Flu/Bu/TBI may allow the possibility of providing myeloablative conditioning to patients with poor performance status.

Excellent real-world outcomes of adults with Burkitt lymphoma treated with CODOX-M/IVAC plus or minus rituximab.

Treatment of Burkitt lymphoma (BL) with intensive, multi-agent chemotherapy with aggressive central nervous system (CNS) prophylaxis results in high cure rates, although no regimen is standard of care. We examined population-based survival outcomes of adults with BL treated with a modified combination of cyclophosphamide, vincristine, doxorubicin, prednisone and systemic high-dose methotrexate (MTX) (CODOX-M) with IVAC (ifosfamide, mesna, etoposide, cytarabine and intrathecal MTX) (CODOX-M/IVAC) ± rituximab over a 15-year period in British Columbia. For the 81 patients identified (including 8 with CNS involvement and 18 with human immunodeficiency virus-associated BL), 5-year progression-free survival (PFS) and overall survival (OS) were 75% [95% confidence interval (CI): 63-83%] and 77% (95% CI: 66-85%), respectively, with no treatment-related deaths. Those who completed the regimen per protocol (n = 38) had significantly improved 5-year PFS 86% (P = 0·04) and OS 92% (P = 0·008), as did those under 60 years with 5-year PFS 82% (P = 0·005) and OS 86% (P = 0·002), which remained significant in multivariate analysis [PFS: hazard ratio (HR) 3·36, P = 0·018; OS HR 4·03, P = 0·012]. Incorporation of high-dose systemic methotrexate also significantly affected multivariate survival outcomes (OS HR 0·28, P = 0·025). Stem cell transplant in first remission had no effect on OS or PFS. This large, real-world analysis of BL patients treated with CODOX-M/IVAC ± rituximab demonstrates excellent survival outcomes comparable to clinical trials. These results help to serve as a benchmark when comparing curative therapies for BL patients as novel regimens are incorporated into clinical practice.

Improving Revised International Prognostic Scoring System Pre-Allogeneic Stem Cell Transplantation Does Not Translate Into Better Post-Transplantation Outcomes for Patients with Myelodysplastic Syndromes: A Single-Center Experience.

The natural history of patients with myelodysplastic syndromes (MDS) is variable. The Revised International Prognostic Score (IPSS-R) is commonly used in practice to predict outcomes in patients with MDS at both diagnosis and before hematopoietic stem cell transplantation (HSCT). However, the effect of change in the IPSS-R before allogeneic HSCT with chemotherapy or hypomethylating agents on post-transplantation outcomes is currently unknown. We assessed whether improvement in IPSS-R prognostic score pre-HSCT would result in improvement in clinical outcomes post-HSCT. Secondary goals included studying the effect of prognostic factors on post-transplantation survival. All patients with MDS who underwent allogeneic HSCT at the Leukemia/BMT Program of British Columbia between February 1997 and April 2013 were included. Pertinent information was reviewed from the program database. IPSS-R was calculated based on data from the time of MDS diagnosis and before HSCT. Outcomes of patients who had improved IPSS-R pre-HSCT were compared with those with stable or worse IPSS-R. Overall survival (OS) and event-free survival (EFS) were estimated using the Kaplan-Meier method, with P values determined using the log-rank test. Hazard ratios were calculated using multivariable Cox proportional hazards regression models to study the effects of the prognostic variables on OS and EFS. A total of 138 consecutive patients were included. IPSS-R improved in 62 of these patients (45%), worsened in 23 (17%), remained stable in 41 (30%), and was unknown in 12 (9%). OS was not statistically different across the improved, worsened, and stable groups (30% versus 22% versus 40%, respectively; P = .63). The cumulative incidences of relapse and nonrelapse mortality at 5 years were 28.4% (95% confidence interval [CI], 21.1 to 36.1) and 31.6% (95% CI, 23.8 to 39.7), respectively. The rate of relapse was 23% in patients with <5% blasts at the time of HSCT, 69% in those with 5% to 20% blasts, and 66% in those with >20% blasts (P = .0004). In the entire cohort OS was 34% and EFS was 33%. There was no significant difference in outcomes between patients who received myeloablative conditioning and those who received nonmyeloablative conditioning before HSCT (OS, 34% and 39%, respectively; P = .63 and EFS, 34% and 32%, respectively; P = .86). OS was not statistically different among patients with improved, worsened, or stable IPSS-R. On multivariate analysis, only 3 factors were associated with OS: cytogenetic risk group at diagnosis, blast count at transplantation, and the presence or absence of chronic graft-versus-host disease. Improving IPSS-R before HSCT does not translate into better survival outcomes. Blast count pretransplantation was highly predictive of post-transplantation outcomes.

Comparison of a pediatric-inspired treatment protocol versus standard-intensity chemotherapy for young adults with standard-risk BCR-ABL negative acute lymphoblastic leukemia.

We investigated the utility of a pediatric-inspired protocol in adults aged 18-40 years with standard-risk BCR-ABL negative acute lymphoblastic leukemia (ALL). Retrospective outcomes of 25 patients treated with a pediatric protocol between 2008 and 2014 were compared with 22 similarly aged patients treated with an adult protocol between 2003 and 2008. Twenty-five (100%) and 19 (86%) patients achieved complete remission, respectively. At median follow-up of 36.8 months, 3-year event-free survival was increased in patients on the pediatric protocol at 80% versus 45% (p = .019). There was a trend toward improved overall survival at 80% versus 59% (p = .12). Treatment-related toxicity was not increased despite the increased treatment intensity. Patients with BCR and/or ABL copy number variation demonstrated comparatively poorer outcomes in both cohorts. In our experience with this cohort of patients, pediatric-based protocols are safe and effective, justifying their use in younger adults with ALL.

Allogeneic Hematopoietic Stem Cell Transplantation Is an Effective Salvage Therapy for Patients with Chronic Myeloid Leukemia Presenting with Advanced Disease or Failing Treatment with Tyrosine Kinase Inhibitors.

Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only known curative therapy for chronic myeloid leukemia (CML); however, it is rarely utilized given the excellent long-term results with tyrosine kinase inhibitor (TKI) treatment. The purpose of this study is to examine HSCT outcomes for patients with CML who failed TKI therapy or presented in advanced phase and to identify predictors of survival, relapse, and nonrelapse mortality (NRM). Fifty-one patients with CML underwent HSCT for advanced disease at diagnosis (n = 15), TKI resistance as defined by the European LeukemiaNet guidelines (n = 30), TKI intolerance (n = 2), or physician preference (n = 4). At a median follow-up of 71.9 months, the 8-year overall survival (OS), event-free survival (EFS), relapse, and NRM were 68%, 46%, 41%, and 23%, respectively. In univariate analysis, predictors of OS included first chronic phase (CP1) disease status at HSCT (P = .0005), European Society for Blood and Marrow Transplantation score 1 to 4 (P = .04), and complete molecular response (CMR) to HSCT (P < .0001). Donor (female) to patient (male) gender combination (P = .02) and CMR to HSCT (P < .0001) predicted lower relapse. In multivariate analysis, CMR to HSCT remained an independent predictor of OS (odds ratio [OR], 43), EFS (OR, 56) and relapse (OR, 29). This report indicates that the outlook is excellent for those patients who remain in CP1 at the time of HSCT and achieve a CMR after HSCT. However, only approximately 50% of those in advanced phase at HSCT are long-term survivors. This highlights the ongoing need to try to identify patients earlier, before disease progression, who are destined to fail this treatment to optimize transplantation outcomes.

Outcome of Patients With Non-Hodgkin Lymphomas With Concurrent MYC and BCL2 Rearrangements Treated With CODOX-M/IVAC With Rituximab Followed by Hematopoietic Stem Cell Transplantation.

BACKGROUND: Double-hit lymphoma is characterized by the presence of concurrent MYC (myelocytomatosis oncogene) and BCL2 (B-cell lymphoma 2) gene rearrangements. Prognosis is poor with standard chemoimmunotherapy. Since 2003, the British Columbia Cancer Agency has used CODOX-M/IVAC+R (cyclophosphamide, vincristine, doxorubicin, methotrexate, cytarabine, ifosfamide, and etoposide, combined with rituximab) followed by consolidative hematopoietic cell transplantation as definitive treatment for double-hit lymphoma. PATIENTS AND METHODS: A retrospective review of the survival outcomes of patients with double-hit lymphoma treated at our institution was conducted. Thirty-two patients diagnosed with non-Hodgkin lymphoma with concurrent MYC and BCL2 translocations from 2003 to 2013 were identified. Cases with MYC or BCL2 amplification and those with overexpression in immunohistochemistry analysis were excluded. RESULTS: Median age at diagnosis was 53.0 years (range, 35.5-70.9 years), 23 (72%) were male, and 30 (94%) had stage III to IV disease. CODOX-M/IVAC+R was administered in 25 (78%) patients and 20 (80%) achieved a partial remission or better, of which 9 (36%) had a complete remission. Nineteen of the 32 (59%) patients underwent upfront hematopoietic cell transplantation. At a median follow-up of living patients of 26.4 months, 14 (44%) were alive in remission, 15 (47%) died, and 3 (9%) were alive in relapse. The 2-year progression-free survival (PFS) and overall survival (OS) of all patients were 41% and 53%, respectively. The sixteen patients treated with CODOX-M/IVAC+R followed by hematopoietic cell transplantation had a 2-year PFS of 60% and 2-year OS of 82%. CONCLUSION: Patients with double-hit lymphoma treated with CODOX-M/IVAC+R followed by hematopoietic cell transplantation can achieve durable remissions, although disease progression before transplantation remains a significant problem.

Aberrant expression of CD13 identifies a subgroup of standard-risk adult acute lymphoblastic leukemia with inferior survival.

BACKGROUND: The standard-risk (SR) subgroup of acute lymphoblastic leukemia in adults (aALL) is a heterogeneous category, with a 20% to 40% relapse rate and a wide range of relapse-free survival (RFS) and overall survival (OS). There is a need to identify at the outset those patients with SR-aALL who are likely to have shorter RFS and OS, so they can be treated more aggressively. PATIENTS AND METHODS: Flow cytometric data of 81 patients with SR-aALL treated with a standardized protocol were retrospectively analyzed. Thirty-two patients (40%) relapsed; the median RFS and OS were 12.5 months (range, 1-136 months) and 30 months (range, 3-235 months), respectively. Twenty-six patients survived ≥ 48 months. RESULTS: Expression of myeloid antigen CD13, using the conventional ≥ 20% threshold and a lower ≥ 5% threshold, was seen in 17 (29%) of 59 and 29 (49%) of 59 patients, respectively, whereas dual expression of CD13 and CD33 was seen in 8 patients. CD13 positivity at ≥ 20% and ≥ 5% threshold was associated with a shorter RFS (P = .0158 and P < .0001, respectively) and OS (P = .0072 and P < .0001, respectively). Dual expression of CD13 (at ≥ 5% or ≥ 20% threshold) and CD33 was associated with inferior OS (P = .0038 and P = .0032, respectively) and RFS (P = .0705 and P = .2516, respectively). For ≥ 20% and ≥ 5% threshold of positivity, 16 of 42 and 28 of 42 who survived < 48 months were positive, compared with 1 of 17 and 1 of 17 who survived ≥ 48 months (P = .0133 and P < .0001, respectively). CONCLUSION: Aberrant expression of CD13 in ≥ 5% of blasts of patients with SR-aALL is an adverse prognostic factor, delineating a subgroup of patients with SR-aALL that should be considered for more aggressive treatment.

Normal karyotype CALLA-positive adult pre-B ALL: dismal outcome with chemotherapy for patients with loss/gain of ABL1 and/or BCR FISH signals.

BACKGROUND: Diagnostic karyotype and molecular studies represent the most powerful prognostic indicators in acute myeloid leukemia and provide the framework for risk stratification. Risk stratification in ALL has also a vital role in predicting outcome and identifying patients at higher risk of relapse with multiagent chemotherapy, but the role of diagnostic karyotype and molecular markers in adult ALL is limited to few well recognized cytogenetic abnormalities. PATIENTS AND METHODS: We report a case series of 6 adult ALL patients with a characteristic molecular abnormality that have done poorly with chemotherapy. Between April 2004 and November 2009, 72 adult ALL patients (Pre-B-cell 61; T-cell 11) were referred to and treated at the Leukemia/BMT Program of BC in Vancouver, Canada. FISH for BCR-ABL fusion was positive in 12 of 61 Pre-B cell ALL patients. An additional 6 patients were negative for this typical fusion but had FISH abnormalities related to BCR and/or ABL1. RESULTS: In this report, we describe the clinical and hematopathologic characteristics of these 6 patients and their poor outcome. We review the literature where only 2 similar cases with normal karyotype Pre-B ALL and associated FISH BCR/ABL1 numerical abnormalities were found. CONCLUSION: We recommend screening all adult pre-B ALL patients with normal karyotype for this clonal abnormality and suggest classifying these ALL patients into the high-risk category.

Allogeneic haematopoietic stem cell transplantation for chronic lymphocytic leukaemia: outcome in a 20-year cohort.

The curative potential of allogeneic haematopoietic stem cell transplant (allo HSCT) in chronic lymphocytic leukaemia CLL is established, with a demonstrated role for graft-versus-leukaemia and less certainty for other factors in determining outcome. The first two decades of CLL patients proceeding to allo HSCT at the Leukaemia/Bone Marrow Transplant Program of British Columbia (n = 49 consecutive, 1991-2009) were studied to clarify factors predicting outcome. The donor was related in 29 (59%) and unrelated in 20 (41%). Conditioning was reduced-intensity in 27 (55%) and myeloablative in 22 (45%). Thirty-one of 49 patients survive with median follow-up of 5 years (0·2-15). Cumulative incidence of non-relapse mortality; complete remission (CR); clearance of fluorescence in situ hybridization (FISH) abnormality and progression at 10 years was 36%; 69%; 55% and 22%. Overall survival (OS) was 63% at 2 years; 55% at 5 years and beyond. Factors predicting OS (P value by log rank <0·05) were: comorbidity index <3, FISH rank (Dohner) and 17p deletion, alemtuzumab pre-HSCT, achievement of CR post-HSCT, donor chimerism >90%, clearance of FISH abnormality post-HSCT and absence of high-grade (3-4) graft-versus-host disease. Results from this province-wide, two-decade cohort demonstrated that a substantial proportion of patients with high-risk CLL become long term disease-free survivors.

Long-term follow-up of patients with chronic myeloid leukemia in chronic phase developing sudden blast phase on imatinib therapy.

Sudden blast phase (SBP) is a rare event that occurs in an unpredictable fashion amongst patients with chronic myeloid leukemia (CML) who otherwise appear to be responding satisfactorily to imatinib (IM) treatment. We investigated the incidence, clinical characteristics, treatment outcome and long-term follow-up of 213 patients with chronic phase CML treated with IM according to the European LeukemiaNet guidelines. Nine patients, eight of whom received IM as first-line therapy, developed SBP (4.2% of the total). They tended to have low or intermediate risk Sokal scores at diagnosis, a predominance of the lymphoid phenotype and a short interval from "optimal" response to the development of BP. Five of the nine patients with SBP are alive in complete molecular remission; however, all of them underwent allogeneic hematopoietic stem cell transplant. The cumulative incidence of SBP for the patients who received IM as first-line therapy was 5.9% and the 2-year overall survival of the nine patients who developed SBP was 56%. Despite the improved outcome for patients with SBP receiving tyrosine kinase inhibitors (TKIs) and transplant, many of these patients are not salvaged with these therapies. This illustrates the need to develop predictive models to identify patients early whose response to TKI therapy will not be durable and hopefully prevent the transformation to advanced disease.

Response to tyrosine kinase inhibitor therapy in patients with chronic myelogenous leukemia relapsing in chronic and advanced phase following allogeneic hematopoietic stem cell transplantation.

Tyrosine kinase inhibitors (TKI) have been used to treat relapse of chronic myelogenous leukemia (CML) after allogeneic stem cell transplant (HSCT), with responses seen predominantly in chronic phase (CP) patients. This study aimed to analyze the response to TKI therapy and overall survival for patients relapsing predominantly in advanced phase. We retrospectively reviewed 22 patients treated with imatinib (n=20) and/or dasatinib (n=6) for relapsed CML after HSCT; 8 patients were in CP, and 14 patients had advanced disease. Seven patients also received donor lymphocyte infusions. Hematologic, cytogenetic, and molecular responses were analyzed. Nineteen patients (86%) achieved complete hematologic response (CHR), 17 patients (77%) achieved complete cytogenetic response (CCR), and 14 patients (64%) achieved complete molecular response (CMR). In advanced phase patients, 11 (79%) achieved CHR, 10 (71%) CCR, and 8 (57%) achieved CMR. Grade 3 or 4 cytopenias occurred in 10 cases. With median follow-up of 31.5 months from relapse, 14 (64%) patients remain alive, 13 in CMR. In multivariate analysis, the achievement of CMR was significantly correlated with OS with an odds ratio of 20.5 (95% confidence interval 2.3-182) P=.007. TKI therapy is capable of inducing durable molecular responses for CML relapsing after HSCT, both in chronic and advanced phases. The achievement of CMR appears to be crucial in providing long-term disease control for these patients.

Current status of allogeneic hematopoietic stem cell transplantation for paroxysmal nocturnal hemoglobinuria.

Treatment of patients with paroxysmal nocturnal hemoglobinuria (PNH) has been traditionally empirical, primarily aiming at ameliorating symptoms or treating complications resulting from the disease. Novel therapies such as eculizumab result in stabilization of hemoglobin levels and improvement in quality of life, but does not cure PNH. Nonrandomized studies suggest that long-term remissions are achievable when using myeloablative or nonmyeloablative/reduced-intensity (NMT/RIC) allogeneic hematopoietic stem cell transplantation (HSCT) as treatment for PNH. Nevertheless, patients with previous life-threatening complications from PNH may be more appropriately treated with an NMT/RIC regimen, rather than a myeloablative approach, because of the increased transplant mortality associated with the latter. The decision to perform an allogeneic HSCT (allo-HSCT) should weigh disease prognosis, by incorporating known adverse prognostic factors such as previous history of thrombosis and/or evolution to pancytopenia, among others, against the risk of transplant-related complications. Selection of the appropriate candidate and, equally important, the right time to perform an allo-HCT are important questions that need to be answered in the context of large prospective randomized trials.