The impact of external beam radiation therapy prior to autologous bone marrow transplantation in patients with non-Hodgkin's lymphoma

Cardiovascular events among recipients of hematopoietic stem cell transplantation-A systematic review and meta-analysis

Cardiovascular diseases are an emerging cause of mortality and morbidity in survivors of hematopoietic stem cell transplantation (HSCT); however, the incidence of cardiovascular events (CVEs) in this population is not well described. This systematic review summarizes the evidence on the incidence of CVEs in HSCT recipients. Medline and Embase were searched from inception to December 2020. Inclusion criteria were cohort studies and phase 3 randomized controlled trials that reported CVEs among adults who underwent HSCT for hematological malignancies. After reviewing 8386 citations, 57 studies were included. The incidence of CVEs at 100 days was 0.19 (95% CI: 0.17-0.21) per 100 person-days after autologous HSCT and 0.06 (95% CI: 0.05-0.07) per 100 person-days after allogeneic HSCT. This higher incidence after autologous HSCT was driven by reports of arrhythmia from one population-based study in patients with multiple myeloma. The incidence of long-term CVEs was 3.98 (95% CI; 3.44-4.63) per 1000 person-years in survivors of autologous HSCT and 3.06 (95% CI; 2.69-3.48) per 1000 person-years in survivors of allogeneic HSCT. CVEs remain an important but under-reported cause of morbidity and mortality in recipients of HSCT. Future studies are required to better understand the incidence and risk factors for CVEs in HSCT recipients.

Long-term remissions in patients with early relapse of diffuse large B-cell lymphoma following high-dose chemotherapy, autologous stem cell transplantation, and radiotherapy of residual disease

PURPOSE

The prognosis of an early relapse of diffuse large B-cell lymphoma (DLBCL) appears to be poor following autologous stem cell transplantation (ASCT). The aim of this study is to contribute data to the open question on whether additional radiotherapy can improve the outcome.

PATIENTS AND METHODS

Forty-eight patients with an early relapse (median 4 months after the end of initial immunochemotherapy, range 1-11) of DLBCL have been treated in our institution with high-dose therapy (usually the BEAM protocol) and ASCT since 2008 (median age 61 years, range 28-73). Twenty-three patients received ASCT in a second treatment line, 25 in a third line (19 refractory to second-line salvage therapy, 5 after second relapse). Fifteen of these 48 patients received radiotherapy (36-50 Gy, median 40) of residual masses after ASCT.

RESULTS

Three-year overall survival (OS) and progression-free survival (PFS) after second-line ASCT were 61 and 57%, after third-line ASCT 47 and 44%, respectively, without significant differences. A prognostic factor was the International Prognostic Index (IPI) at the start of salvage therapy. Three-year OS and PFS in low-risk patients were 69 and 69%, in low-intermediate-risk 63 and 53%, and in high-intermediate-risk 23 and 23%, respectively (p = 0.033). Twenty-three patients achieved a sustained complete remission (13-146 months, median 62).

CONCLUSION

Sustained long-term remissions can be achieved in patients with early relapse of DLBCL following ASCT in a second or third treatment line, particularly in patients with low- and low-intermediate-risk IPI, following radiotherapy of residual disease after ASCT. Further investigations are required to clarify which patients need an alternative therapy (potentially CAR T‑cells or allogeneic transplantation).

Palliative Radiotherapy for Diffuse Large B-cell Lymphoma

Recent improvements in chemoimmunotherapies, targeted agents, hematopoietic stem cell transplants, and cellular therapies have revolutionized treatment paradigms for patients with diffuse large B-cell lymphoma (DLBCL). Even in the relapsed or refractory setting, contemporary treatment options are delivered with curative intent and can lead to lasting remissions. Although such therapies have improved overall outcomes, they have increasingly led to a wide variety of presentations of recurrent tumors in need of palliation. Here, we review the use of radiotherapy (RT) in the palliation of DLBCL. We draw particular attention to the evolving role for hypofractionated RT and low-dose RT for DLBCL. We review the available literature on these topics and focus on commonly encountered clinical scenarios.

Radiotherapy for Non-Hodgkin Lymphomas

Radiotherapy (RT) plays a diverse and essential role in the contemporary management of non-Hodgkin lymphoma (NHL) and remains the single most powerful monotherapeutic intervention for both aggressive and indolent subtypes. Over the past decade, there have been significant advancements in radiation oncology practice, which have made modern treatments safer and more conformal. Despite this sophistication and evidence supporting a continued role for RT, numerous data suggest that utilization is on the decline. In this review, we discuss the rationale for RT in 4 commonly encountered scenarios: combined modality therapy for limited-stage aggressive NHL, consolidation therapy for advanced-stage aggressive NHL, and the changing roles of salvage RT for relapsed/refractory NHL in an era of new frontiers such as cellular therapies. We also evaluate current strategies to treat indolent histologies. We conclude with perspectives on how RT for the hematological malignancies may continue to evolve.

Risk of Pneumonitis and Outcomes After Mediastinal Proton Therapy for Relapsed/Refractory Lymphoma: A PTCOG and PCG Collaboration

PURPOSE

Despite high response rates, there has been reluctance to use radiation therapy for patients with relapsed/refractory (r/r) Hodgkin (HL) or aggressive non-Hodgkin lymphoma (NHL) given concerns for subacute and late toxicities. Symptomatic pneumonitis, a subacute toxicity, has an incidence of 17% to 24% (≥grade 2) even with intensity modulated radiation therapy. Proton therapy (PT), which has no exit radiation dose, is associated with a lower dose to lung compared with other radiation techniques. As risk of radiation pneumonitis is associated with lung dose, we evaluated whether pneumonitis rates are lower with PT.

METHODS AND MATERIALS

Within an international, multi-institutional cohort, we retrospectively evaluated the incidence and grade of radiation pneumonitis (National Cancer Institute Common Terminology Criteria for Adverse Events v4) among patients with r/r HL or NHL treated with PT.

RESULTS

A total of 85 patients with r/r lymphoma (66% HL, 34% NHL; 46% primary chemorefractory) received thoracic PT from 2009 to 2017 in the consolidation (45%) or salvage (54%) setting. Median dose was 36 Gy(RBE). Before PT, patients underwent a median of 1 salvage systemic therapy (range, 0-4); 40% received PT within 4 months of transplant. With a median follow-up of 26.3 months among living patients, 11 patients developed symptomatic (grade 2) pneumonitis (12.8%). No grade 3 or higher pneumonitis was observed. Dose to lung, including mean lung dose, lung V5, and V20, significantly predicted risk of symptomatic pneumonitis, but not receipt of brentuximab, history of bleomycin toxicity, sex, or peritransplant radiation.

CONCLUSIONS

PT for relapsed/refractory lymphoma was associated with favorable rates of pneumonitis compared with historical controls. We confirm that among patients treated with PT, pneumonitis risk is associated with mean lung and lung V20 dose. These findings highlight how advancements in radiation delivery may improve the therapeutic ratio for patients with relapsed/refractory lymphoma. PT may be considered as a treatment modality for patients with relapsed/refractory lymphoma in the consolidation or salvage setting.

Role of Radiation Therapy in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma: Guidelines from the International Lymphoma Radiation Oncology Group

Approximately 30% to 40% of patients with diffuse large B-cell lymphoma (DLBCL) will have either primary refractory disease or relapse after chemotherapy. In transplant-eligible patients, those with disease sensitive to salvage chemotherapy will significantly benefit from high-dose therapy with autologous stem cell transplantation. The rationale for considering radiation therapy (RT) for selected patients with relapsed/refractory DLBCL as a part of the salvage program is based on data regarding the patterns of relapse and retrospective series showing improved local control and clinical outcomes for patients who received peritransplant RT. In transplant-ineligible patients, RT can provide effective palliation and, in selected cases, be administered with curative intent if the relapsed/refractory disease is localized. We have reviewed the indications for RT in the setting of relapsed/refractory DLBCL and provided recommendations regarding the optimal timing of RT, dose fractionation scheme, and treatment volume in the context of specific case scenarios.

The role of radiotherapy as salvage and/or consolidation treatment in relapsed/refractory and high-risk diffuse large B-cell lymphoma

OBJECTIVE

Many salvage therapies have been proposed for relapsed/refractory (R/R) diffuse large B-cell lymphomas or for consolidation in the case of suboptimal response. Radiotherapy (RT) is one modality of salvage therapy, but its place is currently not well defined.

METHOD

This study reports a retrospective review of patients receiving unplanned radiotherapy for R/R diffuse large B-cell lymphoma (DLBCL) or primary mediastinal B-cell lymphoma (PMBCL), or as consolidation therapy after second-line chemotherapy, treated in our hospital.

RESULTS

Fifty-one patients with a median age of 53.5 years [19-89] were selected. The histologic type was DLBCL in 35 cases (68%), PMBCL in 8 cases (16%), and secondary transformed NHL in 8 cases (16%). Median aaIPI was 1 [0-4], and 17 patients (33%) had a high tumor burden (bulky disease). Sixteen patients (31%) were irradiated for a response considered to be insufficient, 18 patients (36%) were refractory, and 17 patients (33%) had relapsed. Patients were irradiated with a median dose of 40 Gy [15-44], 29 (57%) by a conformal 3D technique and 22 (43%) by tomotherapy. With a median follow-up of 36 months [1.0-127.8] after irradiation, 5-year progression-free survival (PFS) and overall survival (OS) were 62% and 72%, respectively. In multivariate analysis, adverse factors associated with PFS and OS in our cohort were age >70 years (HR = 5.06, P = .02) and post-RT relapse (HR = 12.24, P = .002), whereas favorable factors were number of lines of chemotherapy <3 (HR = 0.02, P = .03) and bulky disease (HR = 0.02, P = .009).

CONCLUSION

Due to its low toxicity and ease of use, radiotherapy should therefore remain an available option in patients with R/R DLBCL or as consolidation therapy in patients with high-risk disease, mostly in patients with chemo-sensitive disease or bulky disease.

Consolidative Radiotherapy After Autologous Stem Cell Transplantation for Relapsed or Refractory Diffuse Large B-cell Lymphoma

INTRODUCTION

We evaluated the role of consolidative radiotherapy (RT) for patients undergoing high-dose chemotherapy (HDC) and autologous stem cell transplantation (ASCT) for relapsed or refractory diffuse large B-cell lymphoma (DLBCL).

MATERIALS AND METHODS

We reviewed the medical records of 72 consecutive patients who had undergone ASCT for relapsed or refractory DLBCL at our institution from 2006 to 2014. Pretransplant conditioning consisted of HDC and total body irradiation. Of the 72 patients, 13 received post-transplant consolidative RT at the discretion of the consulted radiation oncologist.

RESULTS

Consolidative RT was associated with significantly improved 2-year locoregional control (LRC) (92% vs. 68%; P = .04). However, no difference was seen in either the 2-year progression-free survival (PFS) (69% vs. 54%; P = .25) or overall survival (OS) (85% vs. 59%; P = .44). Analysis of the subgroup of 19 patients with persistent residual masses ≥ 2 cm on post-transplant imaging demonstrated a significant improvement in LRC (100% vs. 36%; P < .01), PFS (88% vs. 27%; P = .01), and OS (100% vs. 45%; P = .02) with consolidative RT.

CONCLUSION

The use of consolidative RT after HDC and ASCT for relapsed or refractory DLBCL appears to significantly improve LRC. For patients with masses ≥ 2 cm after ASCT, improved 2-year PFS and OS were seen. Prospective trials are needed to further identify the patients who would derive the most benefit from consolidative RT in the ASCT setting.

Excessive toxicity of the high dose thiotepa and etoposide regimen when combined with radiation: Long-term autologous transplantation experience in follicular and mantle cell lymphoma

We recently described a novel thiotepa plus etoposide high-dose therapy (HDT) conditioning regimen for aggressive histology non-Hodgkin's lymphoma (NHL) that had low regimen-related toxicity (RRT) and an efficacy rate comparable to other NHL HDT regimens. In this report, we describe the UW experience with the addition of total body irradiation (TBI) and pre-transplant involved-field radiation (IFRT) to the thiotepa + etoposide HDT regimen. Between 1992 and 1999, 28 patients with indolent or mantle cell lymphoma were treated on this protocol. With a median follow-up of 64 mo, the median event-free survival (EFS) was 24 months, and the median overall survival (OS) had not been reached. The median number of grade 3 - 4 non-hematologic toxicities was five. There were five deaths (18%) in the first three months after HDT due to RRT. In contrast, the thiotepa + etoposide conditioning regimen (without TBI or IFRT) given to 65 intermediate grade NHL patients resulted in only one treatment-related death and considerably fewer grade 3 - 4 toxicities. Given the relatively short EFS in this cohort of indolent NHL patients, we conclude that the combination of IFRT and TBI plus thiotepa and etoposide resulted in a HDT regimen with excessive toxicity and this protocol was closed at our institution.

Involved-Field Radiotherapy Before High-Dose Therapy and Autologous Stem-Cell Rescue in Diffuse Large-Cell Lymphoma: Long-Term Disease Control and Toxicity

Purpose

To analyze outcome, prognostic factors, and toxicities in patients with diffuse large-cell lymphoma (DLCL) who received involved-field radiotherapy (IFRT) before high-dose chemotherapy with autologous stem-cell rescue (ASCR).

Patients and Methods

Between January 1990 and August 2006, 164 patients with relapsed or refractory DLCL received IFRT at Memorial Sloan-Kettering Cancer Center (New York, NY) before high-dose chemotherapy and ASCR. IFRT was delivered to involved sites measuring more than 5 cm or to sites with residual disease more than 2 cm. Radiotherapy was administered in 1.5-Gy fractions twice daily to a total dose of 30 Gy. Progression-free survival and overall survival were calculated, and short- and long-term toxicity was assessed according to National Cancer Institute Common Toxicity Criteria (version 2.0). Median follow-up was 60 months (range, 2 to 187 months).

Results

Two- and 5-year progression-free survival was 62% and 53%; 2- and 5-year overall survival was 67% and 58%, respectively. Sixty-seven patients relapsed; only 10 patients relapsed completely within the radiotherapy field. There were seven early treatment-related mortalities and 11 secondary cancers (including four myelodysplastic syndromes), one of which occurred within the IFRT site and five after total-body irradiation.

Conclusion

Minimal treatment-related mortality and morbidity resulted from short, intensive, involved-field radiotherapy before high-dose chemotherapy and ASCR, which was incorporated into a salvage regimen for patients with relapsed/refractory DLCL. This chemoradiotherapy salvage regimen resulted in a low local relapse rate that could potentially translate into an improved total outcome.

The impact of involved field radiation therapy in the treatment of relapsed or refractory non-Hodgkin lymphoma with high-dose chemotherapy followed by hematopoietic progenitor cell transplant

BACKGROUND

Patients with refractory/relapsed non-Hodgkin lymphoma (NHL) often receive high-dose chemotherapy (HDCT) followed by hematopoietic progenitor cell transplant (HPCT) as salvage therapy. We examined the role of involved field radiation therapy (IFRT) in this setting.

METHODS

The records of 167 patients with refractory/relapsed NHL who underwent HDCT followed by HPCT between February 1990 and November 2003 were reviewed. Fifty-three patients received IFRT and 114 did not receive IFRT in the peritransplant period.

RESULTS

Eighty patients were alive at the time of analysis with a median follow up for alive patients of 4.5 years in the no IFRT group and 4.2 years in the IFRT group (P = 0.53). Patients undergoing IFRT were more likely to have bulky (P = 0.02) and extranodal (P= 0.04) disease at initial diagnosis. There was no significant difference between the treatment groups regarding mortality in the first 100 days after HPCT (P = 0.31). Five-year overall survival rates were 46.7% for the no IFRT group and 40.0% for the IFRT group (P= 0.15). Disease-free survival was significantly worse for patients receiving IFRT (P = 0.02); however, when considering local control, the addition of IFRT resulted in a 5-year rate similar to that for patients who did not receive IFRT (68.6% vs. 72.0% respectively, P= 0.73).

CONCLUSIONS

Although disease-free survival was inferior in patients who received IFRT, despite more adverse clinical features the use of IFRT resulted in similar rates of local control and overall survival compared with those who did not receive IFRT. The use of IFRT was not associated with an increase in the risk of acute mortality or late events.

Increasing incidence of late second malignancies after conditioning with cyclophosphamide and total-body irradiation and autologous bone marrow transplantation for non-Hodgkin's lymphoma

PURPOSE

Although the risk of myelodysplastic syndrome (MDS) has been well-described following autologous bone marrow transplantation (ABMT), the risk of solid tumors has been poorly characterized. We report the incidence and outcome of solid tumors at 10-year follow-up in a large cohort of uniformly treated patients who underwent ABMT for non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Between 1982 and 1997, 605 patients underwent ABMT for B-cell NHL, with uniform conditioning with cyclophosphamide and total-body irradiation followed by reinfusion of autologous bone marrow purged with anti-B-cell monoclonal antibodies. Current information on relapse of disease and second malignancies was obtained via an institutional review board-approved questionnaire sent to the referring oncologists.

RESULTS

Forty-two solid tumors, six non-MDS hematologic malignancies, 39 nonmelanoma skin cancers, and 68 cases of MDS/acute myelogenous leukemia (AML) were observed at a median follow-up of 9.5 years. A cumulative incidence model using death as a competing risk found that the 10-year incidence of second malignancy is 21%, with 10.0% non-MDS malignancies. The projected incidence of all malignancies at 15 years is 29%. The principal risk factor for second malignancy is increased age at ABMT (P = .0002). In the entire cohort, 9.6% of patients have died of second malignancy.

CONCLUSION

Lengthy follow-up demonstrates a significant incidence of second malignancies after ABMT for NHL. Although the incidence of MDS/AML starts to plateau, the incidence of solid tumors continues to rise. Second malignancies are responsible for a significant fraction of overall mortality following ABMT.

High-dose carmustine, etoposide, and cisplatin for autologous stem cell transplantation with or without involved-field radiation for relapsed/refractory lymphoma: An effective regimen with low morbidity and mortality

Over a 10-year period (January 1993 to October 2002), 101 relapsed or refractory non-Hodgkin lymphoma patients were treated at our center with high-dose chemotherapy and autologous transplantation. The median patient age was 54 years (range, 25-70 years). Thirty-two patients had indolent (low-grade), 42 had aggressive (intermediate-grade), and 27 had very aggressive (high-grade) non-Hodgkin lymphoma. Thirty-six patients had primary refractory disease, 20 had a chemoresistant relapse, 35 patients had a chemosensitive relapse, and 10 patients were "initial high risk" patients. The median number of prior chemotherapy regimens was 2 (range, 1-5). The preparative regimen (BEP) was bischloroethylnitrosourea (BCNU) 600 mg/m 2 , etoposide 2400 mg/m 2 , and Platinol (cisplatin) 200 mg/m 2 given intravenously over 5 days. Within 3 weeks before transplantation, 70 patients received involved-field radiotherapy (IFR) 20 Gy to sites of currently active (>2 cm) or prior bulky (>5 cm) disease. Most patients (n = 93) received mobilized peripheral blood stem cells (median CD34 + cell dose, 6.7 x 10 6 /kg). Median neutrophil (>500/microL) and platelet (>20 000/microL, untransfused) recoveries were 11 days (range, 7-19 days) and 14 days (range, 7-36 days), respectively. At a median follow-up of 41 months (range, 4 to 118 months) for survivors, Kaplan-Meier 5-year probabilities of overall survival (OS) and disease-free survival (DFS) were 58.6% and 51.1%, respectively. Four patients (4%) died within 30 days of stem cell infusion (1 pulmonary embolism, 2 septicemias with multiorgan failure, and 1 progressive lymphoma). Two patients (2%) developed interstitial pneumonitis most likely secondary to high-dose BCNU. Three cases (3%) of secondary acute myelogenous leukemia occurred. On multivariate analysis, age (<60 or > or =60 years), histologic grade (low versus intermediate or high), the use of IFR, and chemotherapy response at baseline did not affect OS or DFS. Of 70 patients given IFR, 27 relapsed: 10 (37%) within and 17 (63%) outside the radiation field. The use of IFR did not affect either OS or DFS, probably because IFR was offered to patients with bulky or chemoresistant disease. BEP with or without IFR is a highly effective and well-tolerated regimen in the relapsed/refractory lymphoma setting. It has low morbidity and transplant-related mortality and a low incidence (3%) of posttransplantation malignancy.

Optimal scheduling to reduce morbidity of involved field radiotherapy with transplantation for lymphomas: A Prospective Australasian Leukaemia and Lymphoma Group Study

This study evaluated delivery of involved field radiotherapy (IFRT) with transplantation for lymphomas timed to minimise toxicity. Patients transplanted for lymphoma had infradiaphragmatic disease irradiated pre-transplant and supradiaphragmatic disease post transplant. A total of 31 patients were studied, with a median follow-up duration of 4 years. Transplant conditioning was according to clinician preference. In all, 14 patients had pre-transplant abdominopelvic IFRT and 19 had post transplant IFRT (including three who had pre-transplant IFRT). Grade III-IV haematological toxicity from pre-transplant IFRT occurred in three patients and from post transplant IFRT in 10 patients. Pre-transplant IFRT had no effect on haematological recovery post transplant, but was associated with a trend towards increased gastrointestinal toxicity (P = 0.094). Pneumonitis due to post transplant thoracic IFRT occurred in one patient. Two patients failed in involved sites after completion of protocol radiotherapy. One case of myelodysplasia has been reported. As sequenced in this study, IFRT was feasible and produced a low incidence of severe pulmonary and haematological toxicities. Patient selection, field size and radiotherapy dose warrant further study.

Phase I study of involved-field radiotherapy preceding autologous stem cell transplantation for patients with high-risk lymphoma or Hodgkin's disease

PURPOSE

This Phase I study was designed to evaluate the tolerability of involved-field radiotherapy (IFRT) to areas of persistent disease in patients with high-risk Hodgkin's disease and non-Hodgkin's lymphomas before autologous stem cell transplantation (ASCT).

METHODS AND MATERIALS

Thirty-one patients with primary refractory or relapsed Hodgkin's disease (n = 13) and non-Hodgkin's lymphoma (n = 18) were treated with IFRT followed by high-dose chemotherapy and ASCT. All patients had bulky disease (> or =5 cm) and/or an inadequate response to salvage chemotherapy. The IFRT dose was escalated to a maximum of 36 Gy. Dose-limiting toxicity was defined as Grade 3-4 Bearman toxicity (life-threatening/fatal toxicity occurring within 28 days of ASCT). The chemotherapy regimen consisted of cyclophosphamide, etoposide, and carmustine.

RESULTS

The delivered dose of IFRT was 20 Gy in 9 patients, 28-30 Gy in 20, and 32-36 Gy in 2 patients to mediastinal (n = 19) and nonmediastinal (n = 12) sites. The median interval between IFRT completion and ASCT was 19 days. One patient developed Bearman Grade 3 hepatic toxicity. No other Grade 3 or 4 Bearman toxicity was observed. An increased requirement for i.v. narcotics was observed in patients treated with mediastinal IFRT vs. nonmediastinal IFRT (p = 0.02). A trend toward increased mucositis severity was seen in patients previously treated with a larger number of chemotherapy agents (p = 0.09) and in those with a shorter interval between IFRT and ASCT (p = 0.12). Pulmonary toxicity was more common in patients treated with mediastinal IFRT than in those treated with nonmediastinal IFRT (21% vs. 0%, p = 0.13). The 2-year overall and progression-free survival rate was 70% and 49% for all patients, 84% and 50% for patients with Hodgkin's disease, and 59% and 47% for patients with non-Hodgkin's lymphoma, respectively.

CONCLUSION

The maximal tolerated dose of IFRT was not reached when Grade 3-4 Bearman toxicity was dose limiting. Increased pulmonary toxicity and mucositis severity was seen after mediastinal IFRT compared with nonmediastinal IFRT. Because local control was excellent, higher doses of IFRT are not recommended. The absolute benefit of IFRT in this patient population needs investigation in future studies.

Ex vivo B cell depletion using the Eligix B Cell SC system and autologous peripheral blood stem cell transplantation in patients with follicular non-Hodgkin's lymphoma

One limitation of ASCT is the potential reinfusion of tumor cells contaminating PBSC. The Eligix B cell SC system consists of high-density microparticles coated with anti-B cell antibodies. To determine if this system eliminates B cells and lymphoma cells from PBSC, immunocytochemistry and PCR of the bcl-2/IgH rearrangement were performed, and correlated with patient outcome after ASCT. Eligible patients (n=29) had relapsed or transformed follicular NHL with bone marrow involvement <20%, and all lymph nodes <5 cm. PBSCs were mobilized with cyclophosphamide/G-CSF (n=21), and patients were conditioned with cyclophosphamide, carmustine and etoposide. Using immunocytochemistry on PBSC, the median number of CD20+ cells pre-purge was 310/10(6) (range 0-16692) and post-purge was 0.75/10(6); the median log B cell depletion was 2.7 (range 1.4-3.9). B cell depletion correlated with PFS after ASCT (P=0.06). Of 17 available samples for PCR, only four had a detectable t(14;18) breakpoint. After purging, all four remained PCR+; two had a 1-3 log depletion of lymphoma cells. At median follow-up of 18 months, 10 patients, including five infused with PCR-negative PBSC, have had disease progression. The paucity of PCR-informative patients, possibly related to in vivo rituximab therapy, limited the utility of minimal residual disease as a surrogate marker of clinical outcome.

PET Scans in the Staging of Lymphoma: Current Status

Positron emission tomography (PET) is a novel functional imaging technique that provides several inherent advantages over conventional nuclear scintigraphy. Several studies have suggested a role for PET using the positron emitter fluorine-18 in the diagnosis and follow-up of patients with lymphoma. This review summarizes the existing data evaluating the role of 2-fluoro-2-deoxy-D-glucose (FDG)-PET in both the staging and follow-up of patients with lymphoma. Most studies of PET involve patients with either Hodgkin's disease or diffuse large B-cell non-Hodgkin's lymphoma. PET detects more disease sites above and below the diaphragm on staging of lymphoma than gallium scintigraphy and may have particular utility in the evaluation of the spleen. Moreover, persistently positive PET scans during and after chemotherapy appear to have a high sensitivity for predicting subsequent relapse. A negative PET scan at the end of therapy provides very favorable prognostic information. Persistently positive PET scans at the end of therapy warrant close follow-up or additional diagnostic procedures, since some of those patients may remain in prolonged remission. Clearly, additional studies, including prospective blinded trials and cost-effectiveness analyses, are warranted to determine which subsets of patients with lymphoma ultimately will benefit from this modality.

Should involved-field radiation therapy be used as an adjunct to lymphoma autotransplantation?

Relapse at sites of prior disease involvement accounts for the majority of treatment failures following high-dose therapy and autologous transplantation for both Hodgkin's disease and non-Hodgkin's lymphoma. Several studies have demonstrated the utility of 'involved-field' radiation as a treatment modality in this setting to minimize disease bulk prior to transplants, to reduce relapse rates at sites of prior disease involvement and to improve local control for disease resistant to high-dose therapy. Other studies recommend caution due to potential toxicities including radiation-induced pneumonitis and secondary myelodysplasia. Further investigations are needed to better define the optimal extent, dose and timing of radiation in the setting of transplantation, as well as to identify those subsets of patients likely to be at a higher risk of radiation-induced morbidity.