Excellent response to very-low-dose radiation (4 Gy) for indolent B-cell lymphomas: is 4 Gy suitable for curable patients?

Radiotherapy plays an important role in managing highly radiosensitive, indolent non-Hodgkin lymphomas, such as follicular lymphoma and marginal zone lymphoma. Although the standard of care for localized indolent non-Hodgkin lymphomas remains 24 Gy, de-escalation to very-low-dose radiotherapy (VLDRT) of 4 Gy further reduces toxicities and duration of treatment. Use of VLDRT outside palliative indications remains controversial; however, we hypothesize that it may be sufficient for most lesions. We present the largest single-institution VLDRT experience of adult patients with follicular lymphoma or marginal zone lymphoma treated between 2005 and 2018 (299 lesions; 250 patients) using modern principles including positron emission tomography staging and involved site radiotherapy. Outcomes include best clinical or radiographic response between 1.5 and 6 months after VLDRT and cumulative incidence of local progression (LP) with death as the only competing risk. After VLDRT, the overall response rate was 90% for all treated sites, with 68% achieving complete response (CR). With a median follow-up of 2.4 years, the 2-year cumulative incidence of LP was 25% for the entire cohort and 9% after first-line treatment with VLDRT for potentially curable, localized disease. Lesion size >6 cm was associated with lower odds of attaining a CR and greater risk of LP. There was no suggestion of inferior outcomes for potentially curable lesions. Given the clinical versatility of VLDRT, we propose to implement a novel, incremental, adaptive involved site radiotherapy strategy in which patients will be treated initially with VLDRT, reserving full-dose treatment for those who are unable to attain a CR.

Involved-site radiotherapy for Helicobacter pylori-independent gastric MALT lymphoma: 26 years of experience with 178 patients.

Treatment options for Helicobacter pylori-independent gastric mucosa-associated lymphoid tissue (MALT) lymphoma (GML) include surgery, immunotherapy, chemotherapy, and radiation therapy (RT). The purpose of this study was to investigate the efficacy and safety of RT and routine endoscopic surveillance, hypothesizing that most patients are curable with RT alone. We queried a single institution database at a tertiary referral cancer center for patients with H pylori-independent GML treated with RT between 1991 and 2017. Response was assessed by follow-up endoscopies (EGDs) starting 10 to 12 weeks post-RT. Computed tomography scans were also part of the follow-up program, and positron emission tomography was added when clinically appropriate. We identified 178 patients (median age, 63 years; range, 25-89 years); 86% had stage I disease, 7% had stage II disease, and 7% had stage IV disease. Median RT dose was 3000 cGy over 20 fractions. Ninety-five percent of patients exhibited complete pathologic response on posttreatment EGD. Two patients experienced grade 3 toxicity, and 2 patients experienced in-field secondary malignancies. Over a median follow-up of 6.2 years, 9.6% experienced local failures, and 11.8% developed distant sites of disease. Five-year and 10-year overall survival were 94% and 79%, respectively, from last date of RT. RT is a highly effective and safe treatment for GML with excellent overall survival and very rare acute or late treatment-related toxicities. Favorable outcomes from this large retrospective sample of patients provide credible and compelling support for RT as standard of care for H pylori-independent GML.

Low grade, indolent lymphomas of the head and neck: Comparative toxicity of standard versus very low dose radiation therapy.

National Comprehensive Cancer Network guidelines recommend radiation therapy (RT) for localized indolent non-Hodgkin lymphomas (iNHL). Many referring physicians avoid RT to the head and neck (HN) due to fears of toxicity. Very low-dose radiation (4 Gy) for select patients produces sustained local control and recently gained popularity. We compared early and late toxicities of standard 24-30 Gy to 4 Gy in patients with HN iNHL. We retrospectively analyzed 266 consecutive patients with HN iNHL receiving RT from 1994 to 2017. Patient characteristics, outcomes, and toxicities were collected from medical records. Early (≤2 months post-RT) and late (>2 months post-RT) toxicities were graded per Common Terminology Criteria for Adverse Events version 4. Grades 1-2 were defined as "low-grade" and 3-4 "high-grade." Toxicity incidence was compared between 4 and >4 Gy, grouped by treated site (orbit, nonorbital head, neck, skin) and early versus late. Median follow-up was 23 months (2-145) and 68 months (2-256) for 4Gy and >4 Gy cohorts, respectively. Median dose for the >4 Gy cohort was 30 Gy (10.5-54 Gy). Early and late toxicity incidences were lower in the 4 Gy cohort compared to >4 Gy across all RT-sites: early toxicity, orbit, 42% versus 96%; nonorbital head, 24% versus 96%; neck, 22% versus 94%; skin, 31% versus 87%; late toxicity, orbit, 20% versus 71%; nonorbital head, 6% versus 66%; neck, 6% versus 57%; skin, 0% versus 46% (4 Gy vs. >4 Gy, respectively). Toxicities among both cohorts were largely low-grade. High-grade early and late toxicities did not occur in the 4 Gy cohort. There was 1 high-grade early toxicity (Grade 3 dry mouth) and 17 high-grade late toxicities (Grade 3 cataracts) in the >4 Gy cohort. RT to HN for iNHL is associated with minimal short- and long-term toxicity and excellent local control among 4 Gy and >4 Gy treatments. In this setting, "toxicity" concerns should not deter oncologists from potentially curative RT. In select patients where toxicity remains a concern, very low dose 4 Gy could be considered.

Salvage Treatment and Survival for Relapsed Follicular Lymphoma Following Primary Radiation Therapy: A Collaborative Study on Behalf of ILROG.

PURPOSE: We previously reported that ∼30% of patients with localized follicular lymphoma (FL) staged by 18F-fluorodeoxyglucose positron emission tomography-computed tomography receiving primary radiation therapy (RT) will relapse within 5 years. We sought to report outcomes for those who relapsed. METHODS AND MATERIALS: We conducted a multicenter, retrospective study of patients aged ≥18 years who received RT ≥ 24 Gy for stage I to II, grade 1 to 3A FL, staged with 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography. Observation was defined as >6 months without treatment from relapse. Overall survival (OS) and freedom from progression (FFP) were estimated with Kaplan-Meier analysis and univariable and multivariable analyses with Cox regression. RESULTS: Of 512 patients with median follow-up of 52 months, 149 (29.1%) developed recurrent lymphoma at a median of 23 months (range, 1-143) after primary RT. Median follow-up was 33 months after relapse. Three-year OS was 91.4% after recurrence. OS was significantly worse for those with relapse ≤12 months from date of diagnosis versus all others-88.7% versus 97.6%, respectively (P = .01)-and remained significantly worse on multivariable analyses (follicular lymphoma international prognostic index-adjusted hazard ratio, 3.61; P = .009). Histology at relapse included 93 indolent (grade 1-3A), 3 FL grade 3B/not otherwise specified, and 18 diffuse large B-cell lymphoma; 35 patients did not undergo biopsy. Of those with follow-up ≥3 months who underwent biopsy (n = 74) or had presumed (n = 23) indolent recurrence, 58 patients (59.8%) were observed, 19 (19.6%) had systemic therapy, 16 (16.5%) had RT, and 4 (4.1%) had systemic therapy + RT. For patients with indolent recurrences that were observed, 3-year FFP or freedom from treatment was 56.6% (median, 48 months). For all patients with biopsied/presumed indolent recurrence receiving salvage treatment (n = 59, including 20 initially observed) 3-year FFP was 73.9%. CONCLUSIONS: Prognosis for patients with relapsed FL after primary radiation therapy is excellent, supporting the role of primary radiation in the management of early stage disease. Patients with localized FL treated with primary RT who experience early relapse (<12 months) have inferior survival compared with those with longer disease-free interval.

Langerhans cell histiocytosis in adults is associated with a high prevalence of hematologic and solid malignancies.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a rare disorder of histiocyte proliferation. Previous case studies suggest a higher prevalence of hematologic and solid malignancies among LCH patients, possibly due to treatment with tumorigenic agents such as etoposide. We report the first large, single-institution experience of adult LCH patients with additional malignancies to study the characteristics of these patients. METHODS: We identified 132 consecutive patients >18 years of age with histologically confirmed LCH at our center between 1990 and 2015. Demographics and detailed oncologic history were recorded to identify patients with additional malignancies. RESULTS: Of 132 adult LCH patients, 42 (32%) patients had an additional malignancy. There were 53 malignancies among the 42 patients, with 31 (58%) preceding LCH diagnosis, 11 concurrent (≤3 months; 21%) with LCH diagnosis, and 11 (21%) after. Median age was 54 years (range 28-89) with a median follow-up of 3.7 years (0.1-22.2) for this cohort. OS at 3 years was 98% in patients with LCH alone and 82% among patients with additional malignancies, with 30 (71%) alive at last follow-up. Solid tumors, lymphomas, and other hematologic malignancies were observed as follows: 39 (74%), 9 (17%), and 5 (9%). CONCLUSION: Our cohort of adult LCH patients demonstrates an unusually high number of additional malignancies. Our study includes predominantly malignancies diagnosed preceding or concurrent with LCH, suggesting a cause of malignancy independent of LCH treatment. Further exploration of the biology of this rare disease may elucidate the mechanism of frequent additional malignancies.

Definitive radiotherapy for localized follicular lymphoma staged by 18F-FDG PET-CT: a collaborative study by ILROG.

Radiotherapy (RT) can be curative in patients with localized follicular lymphoma (FL), with historical series showing a 10-year disease-free survival of 40 to 50%. As 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography with computerized tomography (PET-CT) upstages 10 to 60% of patients compared to CT, we sought to evaluate outcomes in patients staged by PET-CT, to determine if more accurate staging leads to better patient selection and results. We conducted a multicenter retrospective study under the direction of the International Lymphoma Radiation Oncology Group (ILROG). Inclusion criteria were: RT alone for untreated stage I to II FL (grade 1-3A) with dose equivalent ≥24 Gy, staged by PET-CT, age ≥18 years, and follow-up ≥3 months. End points were freedom from progression (FFP), local control, and overall survival (OS). A total of 512 patients treated between 2000 and 2017 at 16 centers were eligible for analysis; median age was 58 years (range, 20-90); 410 patients (80.1%) had stage I disease; median RT dose was 30 Gy (24-52); and median follow-up was 52 months (3.2-174.6). Five-year FFP and OS were 68.9% and 95.7%. For stage I, FFP was 74.1% vs 49.1% for stage II (P < .0001). Eight patients relapsed in-field (1.6%). Four had marginal recurrences (0.8%) resulting in local control rate of 97.6%. On multivariable analysis, stage II (hazard ratio [HR], 2.11; 95% confidence interval [CI], 1.44-3.10) and BCL2 expression (HR, 1.62; 95% CI, 1.07-2.47) were significantly associated with less favorable FFP. Outcome after RT in PET-CT staged patients appears to be better than in earlier series, particularly in stage I disease, suggesting that the curative potential of RT for truly localized FL has been underestimated.

Outcome After Radiation Therapy for Langerhans Cell Histiocytosis Is Dependent on Site of Involvement.

PURPOSE: To characterize the efficacy and safety of radiation therapy in a contemporary Langerhans cell histiocytosis (LCH) cohort and to explore whether there are sites at higher risk for local recurrence. PATIENTS AND METHODS: Between 1995 and 2015 we identified 39 consecutive LCH patients who were treated primarily with radiation therapy. Patients were staged by single/multisystem involvement and established risk organ criteria. In 46 irradiated lesions, clinical and radiologic responses were evaluated at multiple time points after radiation therapy. Patient demographics, treatment, and local failure were compared by site of lesion. RESULTS: Median age at radiation therapy was 35 years (range, 1.5-67 years). Twelve patients had multisystem involvement, and of those, 5 patients had disease in organs considered to be high risk. The following sites were irradiated: bone (31), brain (6), skin (3), lymph node (3), thyroid (2), and nasopharynx (1). Median dose was 11.4 Gy (range, 7.5-50.4 Gy). At a median follow-up of 45 months (range, 6-199 months), local recurrence or progression was noted in 5 of 46 lesions (11%). There were no local failures of the 31 bone lesions evaluated, whereas the 3-year freedom from local failure in the 15 non-bone lesions was 63% (95% confidence interval 32-83%; P=.0008). Local failures occurred in 2 of 3 skin lesions, in 2 of 6 brain lesions, and 1 of 3 lymph node lesions. Deaths were recorded in 5 of 39 patients (13%), all of whom were adults with multisystem disease. CONCLUSION: Radiation therapy is a safe and effective measure for providing local control of LCH involving the bone. Whereas bone lesions are well controlled with low doses of radiation, disease in other tissues, such as the skin and brain, may require higher doses of radiation or additional treatment modalities.

Accelerated Total Lymphoid Irradiation-containing Salvage Regimen for Patients With Refractory and Relapsed Hodgkin Lymphoma: 20 Years of Experience.

PURPOSE: We report the long-term results of integrated accelerated involved field radiation therapy (IFRT) followed by total lymphoid irradiation (TLI) as part of the high-dose salvage regimen followed by autologous bone marrow transplantation or autologous stem cell transplantation in patients with relapsed or refractory Hodgkin lymphoma (HL). METHODS AND MATERIALS: From November 1985 to July 2008, 186 previously unirradiated patients with relapsed or refractory HL underwent salvage therapy on 4 consecutive institutional review board-approved protocols. All patients had biopsy-proven primary refractory or relapsed HL. After standard-dose salvage chemotherapy (SC), accelerated IFRT (18-20 Gy) was given to relapsed or refractory sites, followed by TLI (15-18 Gy) and high-dose chemotherapy. Overall survival (OS) and event-free survival (EFS) were analyzed by Cox analysis and disease-specific survival (DSS) by competing-risk regression. RESULTS: With a median follow-up period of 57 months among survivors, 5- and 10-year OS rates were 68% and 56%, respectively; 5- and 10-year EFS rates were 62% and 56%, respectively; and 5- and 10-year cumulative incidences of HL-related deaths were 21% and 29%, respectively. On multivariate analysis, complete response to SC was independently associated with improved OS and EFS. Primary refractory disease and extranodal disease were independently associated with poor DSS. Eight patients had grade 3 or higher cardiac toxicity, with 3 deaths. Second malignancies developed in 10 patients, 5 of whom died. CONCLUSIONS: Accelerated IFRT followed by TLI and high-dose chemotherapy is an effective, feasible, and safe salvage strategy for patients with relapsed or refractory HL with excellent long-term OS, EFS, and DSS. Complete response to SC is the most important prognostic factor.

Encouraging experience in the treatment of nasal type extra-nodal NK/T-cell lymphoma in a non-Asian population.

Extra-nodal NK/T-cell lymphoma, nasal type (EN-NK/TCL-NT), is rare in the Western world. We launched the current single-institutional retrospective study with Institutional Review Board approval to better understand the disease. 43 EN-NK/TCL-NT patients treated from 1996 to 2014 were analyzed, including 10 (23%) Asians and 33 (76%) non-Asians. 19/26 (73%) early-stage patients received short-course chemotherapy followed by radiotherapy. 14/17 (82%) advanced-stage patients received primary chemotherapy. Complete response rate was significantly higher in the modified-SMILE group than the accelerated-CHOP group (80% vs. 30%, p = 0.015). The 2-year overall survival (OS) and progression-free survival (PFS) were 60% and 40%, respectively. Early-stage disease had significantly higher 2-year OS (87% vs. 21%) and PFS (56% vs.18%) than advanced-stage (p < 0.001). Ethnicity had no prognostic difference. EN-NK/TCL-NT in non-Asians shared similar disease characteristics and treatment outcomes with Asians. Most early-stage patients have achieved durable remissions. Management of advanced-stage disease remains challenging, with frequent progression and high mortality.