Novel insights into the pathogenesis of follicular lymphoma by molecular profiling of localized and systemic disease forms.

Knowledge on the pathogenesis of FL is mainly based on data derived from advanced/systemic stages of FL (sFL) and only small cohorts of localized FL (lFL) have been characterized intensively so far. Comprehensive analysis with profiling of somatic copy number alterations (SCNA) and whole exome sequencing (WES) was performed in 147 lFL and 122 sFL. Putative targets were analyzed for gene and protein expression. Overall, lFL and sFL, as well as BCL2 translocation-positive (BCL2+) and -negative (BCL2-) FL showed overlapping features in SCNA and mutational profiles. Significant differences between lFL and sFL, however, were detected for SCNA frequencies, e.g., in 18q-gains (14% lFL vs. 36% sFL; p = 0.0003). Although rare in lFL, gains in 18q21 were associated with inferior progression-free survival (PFS). The mutational landscape of lFL and sFL included typical genetic lesions. However, ARID1A mutations were significantly more often detected in sFL (29%) compared to lFL (6%, p = 0.0001). In BCL2 + FL mutations in KMT2D, BCL2, ABL2, IGLL5 and ARID1A were enriched, while STAT6 mutations more frequently occurred in BCL2- FL. Although the landscape of lFL and sFL showed overlapping features, molecular profiling revealed novel insights and identified gains in 18q21 as prognostic marker in lFL.

Radiation and Dose-densification of R-CHOP in Primary Mediastinal B-cell Lymphoma: Subgroup Analysis of the UNFOLDER Trial.

UNFOLDER (NCT00278408, EUDRACT 2005-005218-19) is a phase-3 trial in patients with aggressive B-cell lymphoma and intermediate prognosis, including primary mediastinal B-cell lymphoma (PMBCL). In a 2 × 2 factorial design, patients were randomized to 6× R-CHOP-14 or R-CHOP-21 (rituximab, cyclophosphamide, doxorubicin, vincristine, and prediso(lo)ne) and to consolidation radiotherapy to extralymphatic/bulky disease or observation. Response was assessed according to the standardized criteria from 1999, which did not include F-18 fluordesoxyglucose positron emission tomography/computed tomography (FDG-PET) scans. Primary end point was event-free survival (EFS). A subgroup of 131 patients with PMBCLs was included (median age, 34 y; 54% female, 79% elevated lactate dehydrogenase (LDH), 20% LDH >2× upper limit of normal [ULN], and 24% extralymphatic involvement). Eighty-two (R-CHOP-21: 43 and R-CHOP-14: 39) patients were assigned to radiotherapy and 49 (R-CHOP-21: 27, R-CHOP-14: 22) to observation. The 3-year EFS was superior in radiotherapy arm (94% [95% confidence interval (CI), 89-99] versus 78% [95% CI, 66-89]; P = 0.0069), due to a lower rate of partial responses (PRs) (2% versus 10%). PR triggered additional treatment, mostly radiotherapy (n = 5; PR: 4; complete response/unconfirmed complete response: 1). No significant differences were observed in progression-free survival (PFS) (95% [95% CI, 90-100] versus 90% [95% CI, 81-98]; P = 0.25) nor in overall survival (OS) (98% [95% CI, 94-100] versus 96% [95% CI, 90-100]; P = 0.64). Comparing R-CHOP-14 and R-CHOP-21, EFS, PFS, and OS were not different. A prognostic marker for adverse outcome was elevated LDH >2× ULN (EFS: P = 0.016; PFS: P = 0.0049; OS: P = 0.0014). With the limitation of a pre-PET-era trial, the results suggest a benefit of radiotherapy only for patients responding to R-CHOP with PR. PMBCL treated with R-CHOP have a favorable prognosis with a 3-year OS of 97%.

Radiation and Dose-densification of R-CHOP in Aggressive B-cell Lymphoma With Intermediate Prognosis: The UNFOLDER Study.

UNFOLDER (Unfavorable Young Low-Risk Densification of R-Chemo Regimens) is an international phase-3 trial in patients 18-60 years with aggressive B-cell lymphoma and intermediate prognosis defined by age-adjusted International Prognostic Index (aaIPI) of 0 and bulky disease (≥7.5 cm) or aaIPI of 1. In a 2 × 2 factorial design patients were randomized to 6× R-CHOP-14 or 6× R-CHOP-21 (rituximab, cyclophosphamide, doxorubicin, vincristine, and prediso[lo]ne) and to consolidation radiotherapy to extralymphatic and bulky disease or observation. Response was assessed according to the standardized response criteria published in 1999, not including F-18 fluordesoxyglucose positron emission tomography/computed tomography (FDG-PET). Primary endpoint was event-free survival (EFS). A total of 695 of 700 patients were eligible for the intention-to-treat analysis. Totally 467 patients qualified for radiotherapy of whom 305 patients were randomized to receive radiotherapy (R-CHOP-21: 155; R-CHOP-14: 150) and 162 to observation (R-CHOP-21: 81, R-CHOP-14: 81). Two hundred twenty-eight patients not qualifying for radiotherapy were randomized for R-CHOP-14 versus R-CHOP-21. After a median observation of 66 months 3-year EFS was superior in the radiotherapy-arm versus observation-arm (84% versus 68%; P = 0.0012), due to a lower rate of partial responses (PR) (2% versus 11%). PR often triggered additional treatment, mostly radiotherapy. No significant difference was observed in progression-free survival (PFS) (89% versus 81%; P = 0.22) and overall survival (OS) (93% versus 93%; P = 0.51). Comparing R-CHOP-14 and R-CHOP-21 EFS, PFS and OS were not different. Patients randomized to radiotherapy had a superior EFS, largely due to a lower PR rate requiring less additional treatment (NCT00278408, EUDRACT 2005-005218-19).

Molecular Cytogenetic Profiling Reveals Similarities and Differences Between Localized Nodal and Systemic Follicular Lymphomas.

Recently, we have developed novel highly promising gene expression (GE) classifiers discriminating localized nodal (LFL) from systemic follicular lymphoma (SFL) with prognostic impact. However, few data are available in LFL especially concerning hotspot genetic alterations that are associated with the pathogenesis and prognosis of SFL. A total of 144 LFL and 527 SFL, enrolled in prospective clinical trials of the German Low Grade Lymphoma Study Group, were analyzed by fluorescence in situ hybridization to detect deletions in chromosomes 1p, 6q, and 17p as well as BCL2 translocations to determine their impact on clinical outcome of LFL patients. The frequency of chromosomal deletions in 1p and 17p was comparable between LFL and SFL, while 6q deletions and BCL2 translocations more frequently occurred in SFL. A higher proportion of 1p deletions was seen in BCL2-translocation-positive LFL, compared with BCL2-translocation-negative LFL. Deletions in chromosomes 1p, 6q, and 17p predicted clinical outcome of patients with SFL in the entire cohort, while only deletions in chromosome 1p retained its negative prognostic impact in R-CHOP-treated SFL. In contrast, no deletions in one of the investigated genetic loci predicted clinical outcome in LFL. Likewise, the presence or absence of BCL2 translocations had no prognostic impact in LFL. Despite representing a genetic portfolio closely resembling SFL, LFL showed some differences in deletion frequencies. BCL2 translocation and 6q deletion frequency differs between LFL and SFL and might contribute to distinct genetic profiles in LFL and SFL.

Localized- and advanced-stage follicular lymphomas differ in their gene expression profiles.

The genetic background of follicular lymphomas (FLs) diagnosed in advanced clinical stages III/IV, and which are frequently characterized by t(14;18), has been substantially unraveled. Molecular features, as exemplified in the clinicogenetic risk model m7FLIPI, are important tools in risk stratification. In contrast, little information is available concerning localized-stage FL (clinical stages I/II), which accounts for ∼20% of newly diagnosed FL in which the detection rate of t(14;18) is only ∼50%. To investigate the genetic background of localized-stage FL, patient cohorts with advanced-stage FL or localized-stage FL, uniformly treated within phase 3 trials of the German Low-Grade Lymphoma Study Group, were comparatively analyzed. Targeted gene expression (GE) profiling of 184 genes using nCounter technology was performed in 110 localized-stage and 556 advanced-stage FL patients. By penalized Cox regression, a prognostic GE signature could not be identified in patients with advanced-stage FL, consistent with results from global tests and univariate regression. In contrast, it was possible to define robust GE signatures discriminating localized-stage and advanced-stage FL (area under the curve, 0.98) by penalized logistic regression. Of note, 3% of samples harboring an "advanced-stage signature" in the localized-stage cohort exhibited inferior failure-free survival (hazard ratio [HR], 7.1; P = .0003). Likewise, in the advanced-stage cohort, 7% of samples with a "localized-stage signature" had prolonged failure-free survival (HR, 2.3; P = .017) and overall survival (HR, 3.4; P = .072). These data support the concept of a biological difference between localized-stage and advanced-stage FL that might contribute to the superior outcome of localized FL.

Therapy of nodal Follicular Lymphoma (WHO grade 1/2) in clinical stage I/II using response adapted Involved Site Radiotherapy in combination with Obinutuzumab (Gazyvaro) - GAZAI Trial (GAZyvaro and response adapted Involved-site Radiotherapy): a study protocol for a single-arm, non-randomized, open, national, multi-center phase II trial.

BACKGROUND: Large field irradiation had been standard for early-stage follicular lymphoma (FL) for a long time. Although involved field radiotherapy (IF-RT) was recently favored because of the toxicity of large field irradiation, smaller irradiation fields have been accompanied with an increased risk of out-of-field recurrence. The MIR (MabThera® and Involved field Radiation) trial has shown that the combination of IF-RT at a dose of 30-40 Gy with the anti-CD20 antibody rituximab has led to similar efficacy compared with large field irradiation but with markedly reduced side effects. Immune modulating radiation therapy alone using low-dose radiotherapy (LDRT) of 2 × 2 Gy has been shown to be effective in FL. The GAZAI (GAZyvaro and response Adapted Involved-site Radiotherapy) trial aims to prove the efficacy of LDRT in combination with a novel anti-CD20 therapy. METHODS/DESIGN: The GAZAI trial is a non-randomized, open, non-controlled, German, multi-center phase II trial that includes patients with early-stage (I and II) nodular FL (grades 1 and 2) confirmed by central histological review. A maximum of 93 patients will be included in the trial. Patients will receive a combined approach of immunotherapy with the fully humanized anti-CD20 antibody obinutuzumab (Gazyvaro®) and involved site radiotherapy (IS-RT) with 2 × 2 Gy. The primary endpoint of the trial is the rate of metabolic complete response (CR), based on fludeoxyglucose positron emission tomography/computed tomography, after obinutuzumab and 2 × 2 Gy IS-RT in week 18. Secondary endpoints are morphologic CR rate in weeks 7 and 18 and month 6, progression-free survival, toxicity, recurrence patterns, overall survival, and quality of life. Additionally, minimal residual disease response is assessed. The risk for a potentially higher recurrence rate after LDRT will be minimized by additional salvage radiation up to the "full dose" of 40 Gy for patients who have less than a metabolic CR and morphologic partial response/CR, which will be evaluated in week 18, offering a response-adapted approach. DISCUSSION: The goal of this trial is a further reduction of the radiation dose in patients with nodal early-stage FL showing a good response to a combination of LDRT and anti-CD20 immunotherapy and a comparison with the currently published MIR trial. TRIAL REGISTRATION: EudraCT number: 2016-002059-89. ClinicalTrials.gov identifier: NCT03341520 .

Allogeneic haematopoietic cell transplantation offers the chance of cure for patients with transformed follicular lymphoma.

PURPOSE: In patients with follicular lymphoma, secondary transformation to aggressive lymphoma (tFL) implies a poor prognosis. In principle, allogeneic haematopoietic cell transplantation (allo-HCT) offers a chance of cure for tFL but is rarely practiced. Aim of this retrospective multicenter study was to define the actual significance of allo-HCT in treatment of tFL. METHODS: The database of the German Registry for Stem Cell Transplantation (DRST) was screened for patients who underwent allo-HCT for tFL 1998-2008. Confirmation of tFL-diagnosis by local and/or pathologists of the National NHL Board was mandatory for enrolment. Gaps in reported EBMT Minimum Essential Data datasets (MED-A) were filled by local DRST data managers. Relevant HCT outcome variables were evaluated by uni- and multivariate statistical analysis. RESULTS: Median age of enrolled 33 patients was 51 years with a post allo-HCT median follow-up of 7.1 years of surviving patients. At time of HCT 24/33 patients had chemosensitive disease. In 24/33 patients reduced intensity conditioning (RIC) was used. Estimated 1, 2, 5-year overall survival (OS) and event-free survival rates were 49/39/33, and 33/30/24%. Cumulative 100 days non-relapse mortality was 25%. Chemosensitive disease, RIC, and limited chronic GvHD were identified as independent prognostic factors for OS. CONCLUSIONS: Allo-HCT offers the chance of cure for tFL.

Rituximab With Involved Field Irradiation for Early-stage Nodal Follicular Lymphoma: Results of the MIR Study.

The MabThera and Involved field Radiotherapy study investigated efficacy and safety of involved field (IF) radiotherapy in combination with the anti-CD20 antibody Rituximab for early-stage follicular lymphoma (FL) in a prospective, single-arm multicenter phase 2 design. Eighty-five stage I-II FL patients received 8 cycles of Rituximab (375 mg/m2) and IF irradiation (30/40 Gy). The primary endpoint was progression-free survival (PFS) 2 years from treatment start. Secondary endpoints were overall survival (OS), complete response rates, toxicity, quality of life, and minimal residual disease (MRD) response with protocol defined visits up to month 30. For the primary endpoint, PFS at 2 years was 85% for the intention-to-treat set. Long-term data were captured in selected sites and evaluated as post hoc analysis in the per protocol (PP) set: PFS and OS were 78% and 96% at 5 years with a median follow-up of 66 or 78 months, respectively. There were 17/76 recurrences in the PP set, of which 14 were outside the radiation volume only. MRD analyses revealed a clonal marker in 36% of patients at diagnosis. All but 1 marker positive patients experienced a molecular treatment response. There were 13 serious adverse events (4 related to the therapy) during the first 30 months. IF radiotherapy combined with Rituximab is well tolerated and highly efficient with low rates of recurrence in the first years in early-stage FL. The efficacy is comparable with more aggressive therapy approaches without compromising the quality of life and maintains for an extended follow-up of more than 5 years.

Anti-CD20 antibody treatment of non-Hodgkin lymphomas.

The CD20 antigen characteristic for mature B-cell is also expressed on B-cell Non-Hodgkin lymphomas (NHL). It thus presents a possible target for immunotherapy. NHL respond readily to radio- and/or chemotherapy but this standard treatment bears a high risk of relapse. The specific monoclonal anti-CD20-antibody Rituximab, the first to be approved for clinical use, could be shown to improve response rates, response duration, and survival in NHL when combined with standard therapy. This review details the development, clinical application, and future perspectives of anti-CD20-antibody treatment of NHL, thereby proving the efficiency of immunotherapy via targeting of a tumor associated antigen.

Long-term follow-up of pediatric patients receiving total body irradiation before hematopoietic stem cell transplantation and post-transplant survival of >2 years.

BACKGROUND: Total body irradiation (TBI) treatment eradicates malignant cells and suppresses the immune system before hematopoietic stem cell transplantation (HSCT). The radiation dose is limited by its toxicity to healthy organs. Many reports describe long-term sequelae from TBI in adults, but comparable data for pediatric patients are scarce. PROCEDURES: We evaluated late effects of a cohort of survivors after at least 2 years from 106 children treated with TBI and HSCT between 1985 and 2008. Follow-up was available from 39 patients with a mean duration of 8.3 (range 2.0-21.9) years. We examined cardiac, pulmonary and renal function, longitudinal growth, weight development, endocrinological parameters, and gastrointestinal problems. RESULTS: Initial remission status and overall survival were significantly correlated. None of the 39 patients experienced cardiac dysfunction or changes in pulmonal function, but 5 exhibited renal impairment. Gastrointestinal problems were reported by 4 patients, and 10 patients had severe growth impairment. Altogether, our follow-up of pediatric patients who survived TBI-containing conditioning regimens for more than 2 years showed no cardiac morbidity or pulmonary aggravation, but mild renal sequelae and growth impairment. CONCLUSION: The adverse long-term effects of TBI in our cohort of children surviving at least 2 years after TBI and HSCT seem to be within a tolerable range. Future studies are required to investigate whether conditioning regimens lacking TBI result in a better ratio of benefits to overall side effects.

The composition of the microenvironment in follicular lymphoma is associated with the stage of the disease.

The role of regulatory and follicular helper T-cells as prognostic markers in follicular lymphoma was evaluated within the setting of prospective, randomized trials because the previously published results were contradictory. Two hundred sixty-four diagnostic tissue specimens from patients suffering from follicular lymphoma who received therapy within prospective randomized trials of the German Low Grade Lymphoma Study Group were analyzed immunohistochemically for FoxP3 and PD-1 expression to detect regulatory and follicular helper T-cells, respectively. We did not find any correlation between the content of regulatory and follicular helper T-cells and the time to treatment failure or overall survival in patients with advanced stages of follicular lymphoma in need of treatment. However, a perifollicular pattern of regulatory T-cells was associated with a poorer prognosis. The content of regulatory T-cells was positively and the content of follicular helper T-cells inversely correlated with a higher stage of the disease at diagnosis, implying that the microenvironment changes during tumor dissemination. This finding is independent of any therapy administered and needs to be considered when possible biomarkers related to the microenvironment of follicular lymphoma are studied.

Advanced-stage III/IV follicular lymphoma: treatment strategies for individual patients.

BACKGROUND: In patients with advanced-stage III/IV follicular lymphoma (FL), there are many treatment options available. The current challenge is to choose the optimal strategy for the individual patient. METHODS: The literature was reviewed with respect to treatment strategies in patients with advanced FL by screening the PubMed databank. RESULTS: In advanced-stage III/IV FL, median survival may approach 8-10 years. Treatment strategies include a watch-and-wait strategy, chemoimmunotherapy, monotherapy with rituximab, and - as an experimental approach so far - radioimmunotherapy. The use of autologous hematopoietic stem cell transplantation (HSCT) for patients in first remission or chemosensitive relapse prolongs progression-free survival while the effect on overall survival remains unclear compared to standard chemotherapy. However, long-term results are flawed by high relapse rates and risk of secondary malignancies. In patients with relapsed/chemoresistant disease, allogeneic HSCT constitutes the only curative approach but is associated with high treatment-related mortality. In the palliative setting, low-dose involved-field irradiation constitutes an effective treatment option in order to control local symptoms with potential long-lasting response. CONCLUSION: In case of advanced-disease FL, asymptomatic patients can be managed expectantly. In symptomatic patients, chemoimmunotherapy is regarded as standard therapy. In symptomatic elderly patients with relevant comorbidities, rituximab +/- single-agent chemotherapy, or low-dose involved-field radiotherapy might be appropriate. For younger patients with chemoresistant/relapsed disease, allogeneic HSCT might be considered, since advances in supportive care and better patient selection have resulted in improved outcomes.

Nodal follicular lymphoma: the role of radiotherapy for stages I and II.

PURPOSE: To clarify the role of external-beam radiotherapy (RT) in patients with stage I and II nodal follicular lymphoma (FL). METHODS: The literature was reviewed with respect to different treatment strategies in patients with stage I and II nodal FL by screening the PubMed databank. RESULTS: In patients with stage I and II nodal FL, RT alone with different irradiation techniques (involved-field [IFI]/extended-field [EFI]/total nodal [TNI]/total lymphoid irradiation [TLI]) produces excellent local disease control (approximately 95%) resulting in disease-free survival and overall survival (OS) rates of 37-94% and 40-93% at 5-15 years, respectively. The main cause of failure is out-of-field recurrence. In nonrandomized trials, IFI led to higher relapse rates, but larger irradiation volumes failed to show an impact on OS and were associated with increased toxicity. Additional chemotherapy mostly failed to improve treatment results achieved with RT alone. CONCLUSION: Since there is no evidence so far that the prognosis of stage I and II nodal FL can be improved by the use of EFI/TNI/TLI, IFI is recommended internationally. Adequate irradiation doses range between 25-30 Gy to subclinical disease and 36-40 Gy to involved sites. To further improve the curative potential of RT in early-stage FL, novel combined approaches (e.g., RT + immunotherapy with rituximab) are under investigation.

Long-term in vivo effects of cisplatin on gamma-H2AX foci signaling in peripheral lymphocytes of tumor patients after irradiation.

PURPOSE: This study determined the effects of cis-diamminedichloroplatinum(II) on radiation-induced foci formation of gamma-H2AX and Rad51 in lymphocytes. EXPERIMENTAL DESIGN: Twenty-eight cancer patients were irradiated for intrathoracic, pelvic, or head and neck tumors and received simultaneous cisplatin containing chemotherapy. The effect of cisplatin on radiation-induced gamma-H2AX and Rad51 foci as a response to ionizing radiation-induced DNA double-strand breaks was measured in lymphocytes after in vivo and in vitro radiochemotherapy. The role of DNA-dependent protein kinase and ataxia-telangiectasia mutated kinase in gamma-H2AX signaling, the consequences of altered gamma-H2AX foci formation on double-strand break end joining, was studied. RESULTS: Cisplatin decreased the number of induced gamma-H2AX foci in lymphocytes after in vivo or in vitro irradiation by 34% +/- 6% at days 0 to 3 after cisplatin (P < 0.0001) and remained significant until day 6. The variation in this cisplatin effect from patient to patient was larger than the retest error within the same patient (P = 0.01). The cisplatin effect was not accompanied by an inhibition of end joining of double-strand break as analyzed using gel electrophoresis of DNA under neutral conditions. Cisplatin also decreased radiation induced Rad51 foci formation in lymphocytes after stimulation of proliferation with phytohemagglutinin by 47% +/- 6% (P < 0.0001). CONCLUSION: Cisplatin has long-term effects on the early double-strand break response of gamma-H2AX and Rad51 foci formation after ionizing radiation. Inhibition of sensing and processing of double-strand break by gamma-H2AX and Rad51 foci formation are important mechanisms by which cisplatin can alter the radiation response.

Improvement of overall survival in advanced stage mantle cell lymphoma.

PURPOSE: Mantle cell lymphomas (MCLs) represent a clinically aggressive lymphoma subtype with a poor prognosis. To explore a potential progress in outcome a historical comparison was performed using data from the Kiel Lymphoma Study Group (KLSG; 1975 to 1986) and the German Low Grade Lymphoma Study Group (GLSG; 1996 to 2004). PATIENTS AND METHODS: All patients with the histologically confirmed diagnosis of advanced-stage nonblastoid MCL were eligible. To minimize the potential heterogeneity of different risk profiles frequency matching was pursued. In addition, we adjusted for potential confounding variables by multiple Cox regression. RESULTS: A total of 520 patients were assessable, 150 from KLSG and 370 from GLSG studies. The median overall survival was 2.7 years for KLSG patients as compared with 4.8 years for GLSG patients (P < .0001). The 5-year survival rates were 22% in the KLSG group (95% CI, 13% to 31%) as compared with 47% for GLSG treated patients (95% CI, 38% to 55%). The hazard ratio adjusted for performance status, lactate dehydrogenase, and age was 0.44 for GLSG patients (95% CI, 0.32 to 0.59). CONCLUSION: Median overall survival of patients with advanced nonblastoid MCL almost doubled during the past 30 years. Potential reasons for this apparent improvement in overall survival include the application of anthracycline-containing regimens and new approaches, such as antilymphoma antibodies or stem cell transplantation. Advances in general supportive care, new diagnostic tools, and general improvement of life span might have also reinforced this effect. However, our results are questioning the validity of historical comparisons which had been frequently applied in previous trials.

gamma-H2AX foci formation in peripheral blood lymphocytes of tumor patients after local radiotherapy to different sites of the body: dependence on the dose-distribution, irradiated site and time from start of treatment.

PURPOSE: To evaluate the relationship between an estimated integral total body radiation dose delivered and phosphorylated histone H2AX protein (gamma-H2AX) foci formation in peripheral blood lymphocytes of cancer patients. MATERIAL AND METHODS: gamma-H2AX formation was quantified as the mean number of foci per lymphocyte (N(meanH2AX)) and the percentage of lymphocytes with > or =n foci. The integrated total body radiation dose was estimated from the dose volume histogram of patient's body corrected for the proportion of the body scanned by computed tomography for 3D treatment planning. RESULTS: There was a strong linear correlation between the mean number of gamma-H2AX foci per lymphocyte in the peripheral blood sample and integrated total body radiation dose (r = 0.83, p < 0.0001). The slope of the relationship was dependent on the site of body irradiated. In comparison to chest irradiation with a slope of 8.7 +/- 0.8 foci Gy(-1), the slopes for brain, upper leg and pelvic sites were significantly shallower by -4.7, -4.3, and -3.8 Gy(-1), respectively (p < 0.0001), while the slope for upper abdomen irradiation was significantly larger by 9.1 +/- 2.6 Gy(-1) (p = 0.0007). There was a slight time effect since the start of radiotherapy on the slopes of the in vivo dose responses leading to shallower slopes (-1.5 +/- 0.7 Gy(-1), p = 0.03) later (> or =10 day) during radiotherapy. After in vitro irradiation, lymphocytes showed 10.41 +/- 0.12 foci per Gy with no evidence of inter-individual heterogeneity. CONCLUSIONS: gamma-H2AX measurements in peripheral lymphocytes after local radiotherapy allow the estimation of the applied integral body dose. The site and time dependence have to be considered.