High-dose vitamin D to attenuate bone loss in patients with prostate cancer on androgen deprivation therapy: A phase 2 RCT.

BACKGROUND: Androgen deprivation therapy (ADT) inhibits prostate cancer growth. However, ADT causes loss of bone mineral density (BMD) and an increase in fracture risk; effective interventions for ADT-induced bone loss are limited. METHODS: A phase 2 randomized controlled trial investigated the feasibility, safety, and preliminary efficacy of high-dose weekly vitamin D (HDVD, 50,000 IU/week) versus placebo for 24 weeks in patients with prostate cancer receiving ADT, with all subjects receiving 600 IU/day vitamin D and 1000 mg/day calcium. Participants were ≥60 years (mean years, 67.7), had a serum 25-hydroxyvitamin D level <32 ng/mL, and initiated ADT within the previous 6 months. At baseline and after intervention, dual-energy x-ray absorptiometry was used to assess BMD, and levels of bone cell, bone formation, and resorption were measured. RESULTS: The HDVD group (N = 29) lost 1.5% BMD at the total hip vs. 4.1% for the low-dose group (N = 30; p = .03) and 1.7% BMD at the femoral neck vs. 4.4% in the low-dose group (p = .06). Stratified analyses showed that, for those with baseline 25-hydroxyvitamin D level <27 ng/mL, the HDVD group lost 2.3% BMD at the total hip vs 7.1% for the low-dose group (p < .01). Those in the HDVD arm showed significant changes in parathyroid hormone (p < .01), osteoprotegerin (p < 0.01), N-terminal telopeptide of type 1 collagen (p < 0.01) and C-terminal telopeptide of type 1 collagen (p < 0.01). No difference in adverse events or toxicity was noted between the groups. CONCLUSIONS: HDVD supplementation significantly reduced hip and femoral neck BMD loss, especially for patients with low baseline serum 25-hydroxyvitamin D levels, although demonstrating safety and feasibility in prostate cancer patients on ADT.

Classic Hodgkin Lymphoma in Adolescents and Young Adults.

Hodgkin lymphoma (HL) represents one of the more common cancers occurring in adolescent and young adults (AYAs) age 15-39 years. Despite a generally high cure rate, age-related differences in HL biology and the optimal therapeutic approaches including supportive care and risks for long-term adverse effects in the AYA population remain understudied. After an overview of HL epidemiology and biology in the AYA population, this review will cover frontline pediatric and adult treatment approaches. Recently completed and ongoing studies will foster harmonization of risk group definition and trial eligibility criteria across the AYA spectrum, enabling more rapid progress. In addition to treatment approaches, an evolving holistic care approach to AYA HL will result in enhanced understanding of unique challenges, and continued improved short- and long-term outcome for these patients.

State of the Science: Cancer Complementary and Alternative Medicine Therapeutics Research-NCI Strategic Workshop Highlights of Discussion Report.

In May 2016, the Office of Cancer Complementary and Alternative Medicine, Division of Cancer Diagnosis and Treatment, of the National Cancer Institute convened a special workshop focused on the State of the Science: Cancer Complementary and Alternative Medicine Therapeutics Research. The current state of the science, gaps, and future opportunities were reviewed and discussed by a distinguished panel of experts in this field of research, and the highlights of this meeting are reported herein.

Low Serum Vitamin D Levels Are Associated With Inferior Survival in Follicular Lymphoma: A Prospective Evaluation in SWOG and LYSA Studies.

PURPOSE: Recent literature reports a potential association between high vitamin D and improved lymphoma prognosis. We evaluated the impact of pretreatment vitamin D on follicular lymphoma (FL) outcome. PATIENTS AND METHODS: SWOG participants were previously untreated patients with FL enrolled onto SWOG clinical trials (S9800, S9911, or S0016) involving CHOP chemotherapy plus an anti-CD20 antibody (rituximab or iodine-131 tositumomab) between 1998 and 2008. Participants included in our second independent cohort were also previously untreated patients with FL enrolled onto the Lymphoma Study Association (LYSA) PRIMA trial of rituximab plus chemotherapy (randomly assigned to rituximab maintenance v observation) between 2004 and 2007. Using the gold-standard liquid chromatography-tandem mass spectrometry method, 25-hydroxyvitamin D was measured in stored baseline serum samples. The primary end point was progression-free survival (PFS). RESULTS: After a median follow-up of 5.4 years, the adjusted PFS and overall survival hazard ratios for the SWOG cohort were 1.97 (95% CI, 1.10 to 3.53) and 4.16 (95% CI, 1.66 to 10.44), respectively, for those who were vitamin D deficient (< 20 ng/mL; 15% of cohort). After a median follow-up of 6.6 years, the adjusted PFS and overall survival hazard ratios for the LYSA cohort were 1.50 (95% CI, 0.93 to 2.42) and 1.92 (95% CI, 0.72 to 5.13), respectively, for those who were vitamin D deficient (< 10 ng/mL; 25% of cohort). CONCLUSION: Although statistical significance was not reached in the LYSA cohort, the consistent estimates of association between low vitamin D levels and FL outcomes in two independent cohorts suggests that serum vitamin D might be the first potentially modifiable factor to be associated with FL survival. Further investigation is needed to determine the effects of vitamin D supplementation in this clinical setting.

Radiation for diffuse large B-cell lymphoma in the rituximab era: analysis of the National Comprehensive Cancer Network lymphoma outcomes project.

BACKGROUND: The role of consolidation radiotherapy was examined for patients with diffuse large B-cell lymphoma who were treated at institutions of the National Comprehensive Cancer Network during the rituximab era. METHODS: Failure-free survival (FFS) and overall survival (OS) were analyzed in terms of patient and treatment characteristics. Potential associations were investigated with univariate and multivariate survival analysis and matched pair analysis. RESULTS: There were 841 patients, and most (710 or 84%) received 6 to 8 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP); 293 (35%) received consolidation radiation therapy (RT). Failure occurred for 181 patients: 126 patients (70%) who did not receive RT and 55 patients (30%) who did. At 5 years, both OS and FFS rates were better for patients who had received RT versus those who did not (OS, 91% vs 83% [P = .01]; FFS, 83% vs 76% [P = .05]). A matched pair analysis (217 pairs matched by age, stage, International Prognostic Index [IPI] score, B symptoms, disease bulk, and response to chemotherapy) showed that the receipt of RT improved OS (hazard ratio [HR], 0.53 [P = .07]) and FFS (HR, 0.77 [P = .34]) for patients with stage III/IV disease, but too few events took place among those with stage I/II disease for meaningful comparisons (HR for OS, 0.94 [P = .89]; HR for FFS, 1.81 [P = .15]). A multivariate analysis suggested that the IPI score and the response to chemotherapy had the greatest influence on outcomes. CONCLUSIONS: There was a trend of higher OS and FFS rates for patients who had received consolidation RT after R-CHOP (especially for patients with stage III/IV disease), but the difference did not reach statistical significance.

Interinstitutional variation in management decisions for treatment of 4 common types of cancer: A multi-institutional cohort study.

BACKGROUND: When clinical practice is governed by evidence-based guidelines and there is consensus about their validity, practice variation should be minimal. For areas in which evidence gaps exist, greater variation is expected. OBJECTIVE: To systematically assess interinstitutional variation in management decisions for 4 common types of cancer. DESIGN: Multi-institutional, observational cohort study of patients with cancer diagnosed between July 2006 through May 2011 and observed through 31 December 2011. SETTING: 18 cancer centers participating in the formulation of treatment guidelines and systematic outcomes assessment through the National Comprehensive Cancer Network. PATIENTS: 25 589 patients with incident breast cancer, colorectal cancer, lung cancer, or non-Hodgkin lymphoma. MEASUREMENTS: Interinstitutional variation for 171 binary management decisions with varying levels of supporting evidence. For each decision, variation was characterized by the median absolute deviation of the center-specific proportions. RESULTS: Interinstitutional variation was high (median absolute deviation >10%) for 35 of 171 (20%) oncology management decisions, including 9 of 22 (41%) decisions for non-Hodgkin lymphoma, 16 of 76 (21%) for breast cancer, 7 of 47 (15%) for lung cancer, and 3 of 26 (12%) for colorectal cancer. Forty-six percent of high-variance decisions involved imaging or diagnostic procedures and 37% involved choice of chemotherapy regimen. The evidence grade underpinning the 35 high-variance decisions was category 1 for 0%, 2A for 49%, and 2B/other for 51%. LIMITATION: Physician identifiers were unavailable, and results may not generalize outside of major cancer centers. CONCLUSION: The substantial variation in institutional practice manifest among cancer centers reveals a lack of consensus about optimal management for common clinical scenarios. For clinicians, awareness of management decisions with high variation should prompt attention to patient preferences. For health systems, high variation can be used to prioritize comparative effectiveness research, patient-provider education, or pathway development. PRIMARY FUNDING SOURCE: National Cancer Institute and National Comprehensive Cancer Network.

Comparison of referring and final pathology for patients with T-cell lymphoma in the National Comprehensive Cancer Network.

BACKGROUND: T-cell lymphomas (TCLs) are uncommon in the United States. The accurate diagnosis of TCL is challenging and requires morphologic interpretation, immunophenotyping, and molecular techniques. The authors compared pathologic diagnoses at referring centers with diagnoses from expert hematopathology review to determine concordance rates and to characterize the usefulness of second-opinion pathology review for TCL. METHODS: Patients in the National Comprehensive Cancer Network non-Hodgkin lymphoma database with peripheral TCL, not otherwise specified (PTCL-NOS), angioimmunoblastic TCL (AITL), and anaplastic lymphoma kinase (ALK)-positive and ALK-negative anaplastic large cell lymphoma (ALCL) were eligible if they had prior tissue specimens examined at a referring institution. Pathologic concordance was evaluated using available pathology and diagnostic testing reports and provider progress notes. The etiology of discordance and the potential impact on treatment were examined. RESULTS: Among 131 eligible patients, 57 (44%) had concordant results, totaling 64% of the 89 patients who were referred with a final diagnosis. Thirty-two patients (24%) had discordant results, representing 36% of those who were referred with a final diagnosis. The rates of discordance among patients with of PTCL-NOS, AITL, ALK-negative ALCL, and ALK-positive ALCL were 19%, 33%, 34%, and 6%, respectively. In 14 patients (44% of discordant results), pathologic reclassification could have resulted in a different therapeutic strategy. Forty-two patients (32%) were referred for classification with a provisional diagnosis. CONCLUSIONS: In a large cohort of patients with TCL who were referred to National Comprehensive Cancer Network centers, the likelihood of a concordant final diagnosis at a referring institution was low. As current and future therapies target TCL subsets, these data suggest that patients with suspected TCLs would benefit from evaluation by an expert hematopathologist.

An enhanced International Prognostic Index (NCCN-IPI) for patients with diffuse large B-cell lymphoma treated in the rituximab era.

The International Prognostic Index (IPI) has been the basis for determining prognosis in patients with aggressive non-Hodgkin lymphoma (NHL) for the past 20 years. Using raw clinical data from the National Comprehensive Cancer Network (NCCN) database collected during the rituximab era, we built an enhanced IPI with the goal of improving risk stratification. Clinical features from 1650 adults with de novo diffuse large B-cell lymphoma (DLBCL) diagnosed from 2000-2010 at 7 NCCN cancer centers were assessed for their prognostic significance, with statistical efforts to further refine the categorization of age and normalized LDH. Five predictors (age, lactate dehydrogenase (LDH), sites of involvement, Ann Arbor stage, ECOG performance status) were identified and a maximum of 8 points assigned. Four risk groups were formed: low (0-1), low-intermediate (2-3), high-intermediate (4-5), and high (6-8). Compared with the IPI, the NCCN-IPI better discriminated low- and high-risk subgroups (5-year overall survival [OS]: 96% vs 33%) than the IPI (5 year OS: 90% vs 54%), respectively. When validated using an independent cohort from the British Columbia Cancer Agency (n = 1138), it also demonstrated enhanced discrimination for both low- and high-risk patients. The NCCN-IPI is easy to apply and more powerful than the IPI for predicting survival in the rituximab era.

Stem cell transplantation for follicular lymphoma relapsed/refractory after prior rituximab: a comprehensive analysis from the NCCN lymphoma outcomes project.

BACKGROUND: Stem cell transplant (SCT)-related outcomes and prognostication for relapsed/refractory follicular lymphoma (FL) are not well-defined in the post-rituximab era. METHODS: Through the National Comprehensive Cancer Network (NCCN) lymphoma outcomes study, 184 patients with relapsed/refractory FL who underwent autologous SCT (autoSCT) or allogenic SCT (alloSCT) following disease relapse after prior rituximab-based therapy were examined. RESULTS: Patients who underwent autoSCT (N=136) were older compared with patients who underwent alloSCT (N=48) (54 versus 51 years, respectively, P=.01) and more frequently had grade 3 FL (35% versus 8%, respectively, P=.006). Patients who underwent alloSCT received more prior therapies (4 versus 3, respectively, P<.0001) and more often had resistant disease at SCT (19% versus 6%, respectively, P=.008). Cumulative 100-day nonrelapse mortality (NRM) for autoSCT and alloSCT were 1% and 6%, respectively (P<.0001), whereas 3-year NRM rates were 3% versus 24%, respectively (P<.0001). For autoSCT and alloSCT, cumulative rates of relapse, progression, and/or transformation were 32% versus 16%, respectively (P=.03), whereas 3-year overall survival rates were 87% versus 61% (P<.0001); there were no differences in failure-free survival. AlloSCT was associated with increased risk of death on multivariate analysis (hazard ratio=2.77, 95% confidence interval=1.46-5.26, P=.002). This finding persisted on propensity scoring/matching. Multivariate analysis for autoSCT patients identified age>60 years and>3 prior therapies as adverse factors. Furthermore, a survival model was created for the autoSCT cohort based on number of factors present (0, 1, 2); 3-year failure-free survival was 72%, 47%, and 20%, respectively (P=.0003), and 3-year overall survival was 96%, 82%, and 62%, respectively (P<.0001). CONCLUSIONS: AutoSCT remains an effective therapy for patients with FL. For alloSCT, continued strategies to reduce NRM are needed.

Patterns of use of 18-fluoro-2-deoxy-D-glucose positron emission tomography for initial staging of grade 1-2 follicular lymphoma and its impact on initial treatment strategy in the National Comprehensive Cancer Network Non-Hodgkin Lymphoma Outcomes database.

We describe the patterns of use of 18-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for the initial staging of patients with newly diagnosed grade 1-2 follicular lymphoma (FL) and its potential impact on treatment. Data were obtained from the National Comprehensive Cancer Network Non-Hodgkin Lymphoma Outcomes database. Patients who presented between 1 January 2001 and 30 September 2009 with newly diagnosed grade 1-2 FL, with at least 6 months of follow-up, were included. We identified 953 eligible patients and 532 (56%) underwent FDG-PET as part of initial staging. Among patients who underwent FDG-PET for initial staging, 438 (82%) received early treatment compared to 259 (61.5%) of those staged without FDG-PET (p < 0.0001). Of all patients with stage I FL (n = 100), 47% were treated with radiotherapy (RT) alone, and the choice of initial treatment strategy for stage I FL did not vary significantly by use of FDG-PET (p = 0.22). The use of FDG-PET for staging of FL is widespread and is associated with a greater proportion of patients receiving early therapy. Given the widespread use and high cost of FDG-PET, its clinical utility in stage I FL should be further evaluated.

Comparative outcome of initial therapy for younger patients with mantle cell lymphoma: an analysis from the NCCN NHL Database.

Few randomized trials have compared therapies in mantle cell lymphoma (MCL), and the role of aggressive induction is unclear. The National Comprehensive Cancer Network (NCCN) Non-Hodgkin Lymphoma (NHL) Database, a prospective cohort study collecting clinical, treatment, and outcome data at 7 NCCN centers, provides a unique opportunity to compare the effectiveness of initial therapies in MCL. Patients younger than 65 diagnosed between 2000 and 2008 were included if they received RHCVAD (rituximab fractionated cyclophosphamide, vincristine, adriamycin, and dexamethasone), RCHOP+HDT/ASCR (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone + high-dose therapy/autologous stem cell rescue), RHCVAD+HDT/ASCR, or RCHOP. Clinical parameters were similar for patients treated with RHCVAD (n = 83, 50%), RCHOP+HDT/ASCR (n = 34, 20%), RCHOP (n = 29, 17%), or RHCVAD+HDT/ASCR (n = 21, 13%). Overall, 70 (42%) of the 167 patients progressed and 25 (15%) expired with a median follow-up of 33 months. There was no difference in progression-free survival (PFS) between aggressive regimens (P > .57), which all demonstrated superior PFS compared with RCHOP (P < .004). There was no difference in overall survival (OS) between the RHCVAD and RCHOP+HDT/ASCR (P = .98). RCHOP was inferior to RHCVAD and RCHOP+HDT/ASCR, which had similar PFS and OS. Despite aggressive regimens, the median PFS was 3 to 4 years. Future trials should focus on novel agents rather than comparing current approaches.

High rates of surveillance imaging for treated diffuse large B-cell lymphoma: findings from a large national database.

We aimed to characterize surveillance imaging and circumstances of relapse for patients with diffuse large B-cell lymphoma (DLBCL) in the National Comprehensive Cancer Network Non-Hodgkin's Lymphoma Outcomes Database, a prospective cohort study collecting clinical and outcome data at seven comprehensive cancer centers. Patients presenting with newly diagnosed DLBCL in remission ≥3 months after initial therapy and who had accrued 2 years of follow-up were eligible for analysis (n = 625). The median number of imaging studies was 2.5/year (institutional range 0.5-3.5, p < 0.0001); 48.4% received only dedicated computed tomography (CT) scans, 14.6% received only positron emission tomography (PET)-inclusive modalities, 32.8% received a combination and 4.2% received no imaging. Among all eligible patients, 50 (8.0%) experienced relapse, and approximately one-quarter of subclinical relapses were detected through routine imaging. Our results suggest that despite limited data regarding its effect on outcomes, surveillance imaging is prevalent in DLBCL, and a majority of patients receive PET scans at some point during follow-up.

Lack of benefit of central nervous system prophylaxis for diffuse large B-cell lymphoma in the rituximab era: findings from a large national database.

BACKGROUND: Little is known about the utility of central nervous system (CNS) prophylaxis for diffuse large B-cell lymphoma (DLBCL) in the rituximab era. The objective of this study was to characterize patterns of CNS prophylaxis for patients who received combined rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy using the National Comprehensive Cancer Network Non-Hodgkin Lymphoma Outcomes Database, a prospective cohort study that collects clinical and outcomes data for patients at 7 participating centers. METHODS: Patients who were eligible for this analysis presented with newly diagnosed DLBCL between January 2001 and July 2008, had no evidence of baseline CNS disease, and had received R-CHOP within 180 days of diagnosis. The authors assessed incidence and covariates of prophylaxis, prophylaxis modality, and, using propensity score analysis, outcomes such as overall survival. RESULTS: Of 989 eligible patients, 117 received CNS prophylaxis (11.8%), most intrathecally (71.8%). Involvement of bone marrow, other high-risk site, >1 extranodal site, higher International Prognostic Index score, and higher stage were associated individually with the receipt of prophylaxis (all P < .0001). At a median follow-up of 2.5 years, there were 20 CNS recurrences (2% [95% confidence interval, 1.1%-2.9%]) among all patients, and overall survival was not affected by prophylaxis. CONCLUSIONS: Given the overall low rate of CNS recurrence and lack of prophylaxis-associated survival benefit, the current data called into question the practice of CNS prophylaxis in the rituximab era.

Vitamin D and non-Hodgkin lymphoma risk in adults: a review.

Animal and human studies support a protective effect of vitamin D sufficiency related to malignancy by uncovering paracrine and autocrine effects of extra-renal 25-hydroxyvitamin D (25(OH)D) activation including regulation of cell cycle proliferation, apoptosis induction, and increased cell differentiation signaling. Recent epidemiologic studies demonstrate a reduction in non-Hodgkin lymphoma (NHL) risk with increased sunlight exposure. As sunlight is a major vitamin D source, it has been suggested that vitamin D status may mediate this observed association. This review provides a comprehensive discussion of the current epidemiologic evidence with regard to the investigation of an association between vitamin D status and NHL risk.

Salvage therapy in Hodgkin's lymphoma.

Hodgkin's lymphoma (HL) is a commonly cured malignancy. Unfortunately, patients who are refractory to or relapse after first-line treatment pose a significant therapeutic challenge. There is evidence that these patients are best treated with an approach involving salvage chemotherapy followed by high-dose chemotherapy and autologous stem cell transplant (HDCT/ASCT). This approach may result in cure, with better results in patients with low-risk relapse. In patients with high-risk relapse and refractory disease, HDCT/ASCT is rarely curative. More aggressive transplant approaches have shown promising results in this group and are currently under active investigation. For those relapsing after HDCT/ASCT, there exists a range of therapeutic options, including further salvage chemotherapy, reduced-intensity allogeneic transplantation, monoclonal antibody therapy, and novel agents. All patients in this category should be considered for enrollment in clinical trials. This review discusses the evidence behind the current practice in patients with relapsed or refractory HL. Specifically, the efficacy of various salvage chemotherapy regimens, the risk factors influencing outcome with HDCT/ASCT, and the results with alternative transplant approaches, monoclonal antibody therapies, and novel agents are addressed. We conclude by providing our approach to these patients, with the hope that this will serve as a framework for the practicing oncologist.

Reliability of staging, prognosis, and comorbidity data collection in the National Comprehensive Cancer Network (NCCN) non-Hodgkin lymphoma (NHL) multicenter outcomes database.

BACKGROUND: Clinical trials and outcomes studies often rely on nonphysicians to abstract complex data from medical records, but the reliability of these data are rarely assessed. METHODS: We used standardized charts of patients with non-Hodgkin lymphoma to assess the reliability of key clinical data elements abstracted by 6 clinical research associates (CRAs), 3 project staff, and 3 medical oncologists. We assessed reliability on 5 variables: MD-reported and rater-determined disease stage; International Prognostic Index (IPI; low-low intermediate, intermediate-high, high); Charlson comorbidity index score; and presence of any item from the Charlson index. Intraclass correlation coefficients (ICCs) of 0-0.20 were indicative of "slight", 0.21-0.40 indicated "fair", 0.41-0.60 indicated "moderate", 0.61-0.80 "substantial" and >0.80 "almost perfect" reliability. RESULTS: By outcome, the ICC (95% confidence interval) values for MD-reported stage, rater-determined stage, and IPI were 0.86 (0.67, 0.94), 0.82 (0.59, 0.93), and 0.80 (0.55, 0.92), respectively. In contrast, the ICC (95% confidence interval) of the Charlson score, or presence of any Charlson comorbidity item was 0.47 (0.03, 0.75) and 0.61 (0.23, 0.83), respectively. Reliability varied by rater group; no rater group was consistently more reliable than others. CONCLUSIONS: Trained CRAs abstracted key clinical variables with a very high degree of reliability, and performed at a level similar to study trainers and oncologists. Elements of the Charlson index were less reliable than other data types, possibly because of inherent ambiguity in the index itself.

Comparison of referring and final pathology for patients with non-Hodgkin's lymphoma in the National Comprehensive Cancer Network.

PURPOSE: Before the implementation of the WHO lymphoma classification system, disagreement about pathologic diagnosis was common. We sought to estimate the impact of expert review in the modern era by comparing final pathologic diagnoses at five comprehensive cancer centers with diagnoses assigned at referring centers. PATIENTS AND METHODS: Patients in the National Comprehensive Cancer Network (NCCN) non-Hodgkin's lymphoma (NHL) database with a documented pathologic diagnosis before presentation and a final pathologic diagnosis of any of five common B-cell NHLs were eligible. After central review of discordant cases, we estimated the rate of pathologic concordance, then investigated the etiology of discordance as well its potential impact on prognosis and treatment. RESULTS: The overall pathologic discordance rate was 6% (43 of 731 patients; 95% CI, 4% to 8%). For the majority of cases in which the referring diagnosis was apparently final, no additional studies were conducted at the NCCN center, and the change in diagnosis reflected a different interpretation of existing data. Concordance was highest for diffuse large B-cell lymphoma (95%) and follicular lymphoma (FL; grades 1, 2, and not otherwise specified, 95%) and lowest for grade 3 FL (88%). Of the 43 pathologically discordant cases, 81% (35 patients) might have experienced a change in treatment as a result of the pathologic reclassification. CONCLUSION: In the era of the WHO lymphoma classification system, the majority of common B-cell NHLs diagnosed in the community were unchanged by second opinion review by an expert hematopathologist. However, for one patient in 20, there was a discordance in diagnosis that could have altered therapy.

Novel concepts in radioimmunotherapy for non-Hodgkin's lymphoma.

Tositumomab/iodine-131 tositumomab (Bexxar) and ibritumomab tiuxetan (Zevalin) are radioimmunoconjugates targeting the CD20 antigen. Both agents are approved in the United States for use in relapsed or refractory, indolent or transformed, B-cell lymphoma. These agents are well tolerated and have the highest levels of single-agent activity observed in these histologies. This review will summarize the key trials that led to approval of both I-131 tositumomab and ibritumomab tiuxetan, and then focus on four novel therapeutic concepts in radioimmunotherapy: retreatment, therapy of de novo indolent lymphoma, therapy of aggressive histologies, and incorporation in high-dose therapy programs utilizing autologous stem cell support.

Iodine-131 tositumomab (Bexxar): radioimmunoconjugate therapy for indolent and transformed B-cell non-Hodgkin's lymphoma.

Tositumomab is an immunoglobulin G murine monoclonal antibody that binds to the CD20 antigen on the surface of normal and malignant human B-cells. Tositumomab is linked covalently with iodine-131 to produce the radioimmunoconjugate iodine-131 tositumomab (Bexxar). The iodine-131 tositumomab regimen was approved by the US Food and Drug Administration in June 2003 for the treatment of patients with CD20-positive, follicular non-Hodgkin's lymphoma, both with and without transformation, whose disease is refractory to rituximab (Rituxan) and has relapsed following chemotherapy. The dose-limiting toxicity of iodine-131 tositumomab is bone marrow suppression and resulting cytopenias. Unlike chemotherapy, the majority of nonhematologic adverse events associated with iodine-131 tositumomab are mild to moderate in nature and usually self limited. Iodine-131 tositumomab represents one of the most active single agents for the treatment of recurrent indolent and transformed B-cell non-Hodgkin's lymphoma, as demonstrated by several clinical trials summarized in this review. At the present time, the use of radioimmunoconjugate therapy is largely limited to patients with disease refractory to rituximab therapy and transformed disease not amenable to high-dose therapy and autologous stem cell support. Longer follow-up of ongoing clinical trials should provide reassurance as to safety and insights as to the additive stem cell toxicity from iodine-131 tositumomab administration. Studies are also addressing the role of iodine-131 tositumomab as a component of initial therapy for indolent non-Hodgkin's lymphoma and in additional histologies of non-Hodgkin's lymphoma.