Long-term follow-up of patients treated with radiotherapy alone for early-stage histologically aggressive non-Hodgkin's lymphoma

Survival Outcomes of Limited-Stage Diffuse Large B-Cell Lymphoma Treated With Radiation Therapy

BACKGROUND

Patients with favorable risk limited-stage (LS) diffuse large b-cell lymphoma (DLBCL) have shown excellent outcomes without radiotherapy (RT). However, the role of RT for the remainder of LS-DLBCL patients is less well defined. We aimed to investigate whether the addition of RT provided an overall survival (OS) benefit in a real-world cohort of LS-DLBCL patients based on primary site at presentation.

MATERIALS AND METHODS

Retrospective data from 39,745 patients with stage I and II DLBCL treated with front-line combination chemotherapy alone or followed by RT were identified using the National Cancer Database from 2004 to 2015.

RESULTS

The addition of RT was associated with improved 5-year OS for all LS patients as compared to those treated with chemotherapy alone (85% vs. 80%, P < .001). RT was associated with improved 5-year OS in both the nodal and extranodal disease patients (nodal: 85% vs. 80%, P < .001; extranodal: 83% vs. 79%; P < .001). Extranodal sites with prolonged OS from the addition of RT include skin and soft tissue, head and neck, testicular, and thyroid sites (all P < .02). Breast, bone, lung and gastrointestinal extranodal primary sites had no OS benefit from the inclusion of RT. In multivariate analysis, the addition of RT was an independent factor for improved survival for all LS patients ([HR] 0.84, 95% [CI] 0.81-0.88; P < .001).

CONCLUSION

Though there is no consensus on optimal treatment indications for RT in LS-DLBCL, these data suggest certain subgroups may have benefit when RT is added to front-line chemotherapy.

Evolution of therapy for limited stage diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma (NHL), with limited-stage DLBCL defined as stage I or II disease. Risk stratification, initial treatment options, and relapse patterns are distinct from advanced-stage DLBCL, but there is limited data on the impact of biologic features on outcome. Patients have excellent outcomes, with ~90% survival at 2 years. Over the past several years, sequential prospective trials and large registry studies have evaluated the optimal number of chemotherapy cycles and implemented PET-adapted approaches to reduce the need for radiotherapy. Special consideration must still be given to cases of bulky disease, extranodal disease, fully resected scenarios, and adverse biologic features such as high-grade B-cell lymphoma with double/triple hit rearrangements. This review presents the evolution of a modern management approach, with a discussion of recent treatment-defining studies.

Limited-stage Diffuse Large B-cell Lymphoma

DLBCL, the most common lymphoma subtype, is localized in 25-30% of patients. Prognosis in patients with limited-stage DLBCL (LS-DLBCL) is excellent with 10-year overall survival of at least 70-80%. Improved insights into the disease biology, the availability of positron-emission tomography (PET) scans and recent dedicated clinical trials within this unique population, have led to evolving treatment paradigms. However, no standard definition of LS-DLBCL exists, and while generally defined as Ann Arbor stages I-II disease with largest mass size <10cm in diameter, variations across studies cause challenges in interpretation. Similar to advanced-stage disease, R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) immunochemotherapy forms the basis of treatment, with combined modality therapy including 3 cycles of systemic treatment and involved-site radiation therapy being a predominant historical standard. Yet the well-described continuous risk of relapse beyond 5 years and established late complications of radiotherapy have challenged previous strategies. More rigorous baseline staging and response assessment with PET may improve decision making. Recent clinical studies have focused on minimizing toxicities while maximizing disease outcomes using strategies such as abbreviated immunochemotherapy alone and PET-adapted radiotherapy delivery. This comprehensive review provides an update of recent literature with recommendations for integration into clinical practice for LS-DLBCL patients.

Risk-adapted therapy for early-stage extranodal nasal-type NK/T-cell lymphoma: analysis from a multicenter study

Patients with early-stage extranodal nasal-type NKTCL were classified as low risk or high risk using 5 independent prognostic factors. Risk-adapted therapy of RT alone for the low-risk group and RT consolidated by CT for the high-risk group proved the most effective treatment.

Approach to therapy of diffuse large B-cell lymphoma in the elderly: the International Society of Geriatric Oncology (SIOG) expert position commentary

Diffuse large B-cell lymphoma (DLBCL) is a treatable and potentially curable malignancy that is increasing in prevalence in the elderly. Until recently, older patients with this malignancy were under-represented on clinical treatment trials, so optimal therapeutic approaches for these patients were generally extrapolated from the treatment of younger patients with this disorder. Because of heightened toxicity concerns, older patients were sometimes given reduced dose therapy, potentially negatively impacting outcome. Geriatric considerations including functional status and comorbidities often were not accounted for in treatment decisions. Because of these issues as well as the lack of treatment guidelines for the elderly population, the International Society of Geriatric Oncology convened an expert panel to review DLBCL treatment in the elderly and develop consensus guidelines for therapeutic approaches in this patient population. The following treatment guidelines address initial DLBCL therapy, in both limited and advanced stage disease, as well as approaches to the relapsed and refractory patient.

Review of current best practice and priorities for research in radiation oncology for elderly patients with cancer: the International Society of Geriatric Oncology (SIOG) task force

Radiotherapy (RT) is a key component of the management of older cancer patients. Level I evidence in older patients is limited. The International Society of Geriatric Oncology (SIOG) established a task force to make recommendations for curative RT in older patients and to identify future research priorities. Evidence-based guidelines are provided for breast, lung, endometrial, prostate, rectal, pancreatic, oesophageal, head and neck, central nervous system malignancies and lymphomas. Patient selection should include comorbidity and geriatric evaluation. Advances in radiation planning and delivery improve target coverage, reduce toxicity and widen eligibility for treatment. Shorter courses of hypofractionated whole breast RT are safe and effective. Conformal RT and involved-field techniques without elective nodal irradiation have improved outcomes in non-small-cell lung cancer (NSCLC) without increasing toxicity. Where comorbidities preclude surgery, stereotactic body radiotherapy (SBRT) is an option for early-stage NSCLC and pancreatic cancer. Modern involved-field RT for lymphoma based on pre-treatment positron emission tomography data has reduced toxicity. Significant comorbidity is a relative contraindication to aggressive treatment in low-risk prostate cancer (PC). For intermediate-risk disease, 4-6 months of hormones are combined with external beam radiotherapy (EBRT). For high-risk PC, combined modality therapy (CMT) is advised. For high-intermediate risk, endometrial cancer vaginal brachytherapy is recommended. Short-course EBRT is an alternative to CMT in older patients with rectal cancer without significant comorbidities. Endorectal RT may be an option for early disease. For primary brain tumours, shorter courses of postoperative RT following maximal debulking provide equivalent survival to longer schedules. MGMT methylation status may help select older patients for temozolomide alone. Stereotactic RT provides an alternative to whole-brain RT in patients with limited brain metastases. Intensity-modulated radiation therapy provides an excellent technique to reduce dose to the carotids in head and neck cancer and improves locoregional control in oesophageal cancer. Best practice and research priorities are summarised.

Current treatment approaches for diffuse large B-cell lymphoma

There have been two major developments over the last decade that has led to improvements in outcome and longer survival for patients with diffuse large B-cell lymphoma (DLBCL). These developments have been firstly to increase the dose of active cytotoxic drugs and shorten the time between cycles, resulting in dose-dense and/or dose-intense regimens and secondly the addition of the anti-CD20 monoclonal antibody rituximab to chemotherapy. Both strategies have been associated with higher response rates, lower relapse rates, longer event-free survival (EFS) and improved overall survival (OS), particularly in better prognostic groups. A combination of dose-dense and dose-intense chemotherapy regimens plus rituximab is currently being tested to confirm that the use of both approaches confers survival advantage. High-risk, poorer-prognosis DLBCL remains a challenge, and new treatment strategies are required for these patients. Improvements in outcome may potentially be achieved through a greater understanding of the genetic abnormalities specifically associated with poorer-prognosis disease, and factors that lead to unresponsiveness to chemotherapy. The role of radiotherapy is currently less clearly defined than at anytime in the management of DLBCL and the current evidence for using radiotherapy in this disease is therefore rigorously reviewed.

Radiotherapy as primary treatment for stage IE and IIE nasal natural killer/T-cell lymphoma

PURPOSE The optimal therapy remains unclear for nasal natural killer (NK)/T-cell lymphoma. The purpose of this study is to analyze the outcome of radiotherapy as the primary treatment for localized stage IE and IIE diseases.

PATIENTS AND METHODS

One hundred five patient cases were reviewed. There were 83 stage IE and 22 stage IIE patients. All except three patients received radiotherapy (RT) alone or RT combined with chemotherapy (CT; combined-modality therapy [CMT]). Overall, 31 patients were treated with RT alone, 34 with RT followed by CT, 37 with CT followed by RT, and three with CT alone.

RESULTS

Five-year overall survival (OS) and progression-free survival (PFS) for all patients were 71% and 59%, respectively. The 5-year OS and PFS were 78% and 63% for stage IE, and 46% and 40% for stage IIE, respectively. Complete response (CR) was achieved in 91 patients (87%) after RT and/or CT. Initial RT resulted in a superior CR as compared with initial CT, with 54 (83%) of 65 patients achieving CR with initial RT, versus only eight (20%) of 40 after initial CT. For 102 patients who received RT with or without CT, the outcome of primary treatment with RT alone was compared with that of CMT. Five-year OS and PFS was 66% and 61% for RT alone, and 76% and 61%% for CMT, respectively (OS, P = .6433; PFS, P = .8391).

CONCLUSION

RT as primary therapy resulted in good outcome in early-stage disease, and the addition of CT to RT was not accompanied by an improvement in survival.

Weight of evidence: a review of concept and methods

"Weight of evidence" (WOE) is a common term in the published scientific and policy-making literature, most often seen in the context of risk assessment (RA). Its definition, however, is unclear. A systematic review of the scientific literature was undertaken to characterize the concept. For the years 1994 through 2004, PubMed was searched for publications in which "weight of evidence" appeared in the abstract and/or title. Of the 276 papers that met these criteria, 92 were selected for review: 71 papers published in 2003 and 2004 (WOE appeared in abstract/title) and 21 from 1994 through 2002 (WOE appeared in title). WOE has three characteristic uses in this literature: (1) metaphorical, where WOE refers to a collection of studies or to an unspecified methodological approach; (2) methodological, where WOE points to established interpretative methodologies (e.g., systematic narrative review, meta-analysis, causal criteria, and/or quality criteria for toxicological studies) or where WOE means that "all" rather than some subset of the evidence is examined, or rarely, where WOE points to methods using quantitative weights for evidence; and (3) theoretical, where WOE serves as a label for a conceptual framework. Several problems are identified: the frequent lack of definition of the term "weight of evidence," multiple uses of the term and a lack of consensus about its meaning, and the many different kinds of weights, both qualitative and quantitative, which can be used in RA. A practical recommendation emerges: the WOE concept and its associated methods should be fully described when used. A research agenda should examine the advantages of quantitative versus qualitative weighting schemes, how best to improve existing methods, and how best to combine those methods (e.g., epidemiology's causal criteria with toxicology's quality criteria).