Proliferation kinetics of malignant non-Hodgkin's lymphomas related to histopathology of lymph node biopsies

Modelling lymphoma therapy and outcome

Dose and time intensifications of chemotherapy improved the outcome of lymphoma therapy. However, recent study results show that too intense therapies can result in inferior tumour control. We hypothesise that the immune system plays a key role in controlling residual tumour cells after treatment. More intense therapies result in a stronger depletion of immune cells allowing an early re-growth of the tumour.We propose a differential equations model of the dynamics and interactions of tumour and immune cells under chemotherapy. Major model features are an exponential tumour growth, a modulation of the production of effector cells by the presence of the tumour (immunogenicity), and mutual destruction of tumour and immune cells. Chemotherapy causes damage to both, immune and tumour cells. Growth rate, chemosensitivity, immunogenicity, and initial size of the tumour are assumed to be patient-specific, resulting in heterogeneity regarding therapy outcome. Maximum-entropy distributions of these parameters were estimated on the basis of clinical survival data. The resulting model can explain the outcome of five different chemotherapeutic regimens and corresponding hazard-ratios.We conclude that our model explains observed paradox effects in lymphoma therapy by the simple assumption of a relevant anti-tumour effect of the immune system. Heterogeneity of therapy outcomes can be explained by distributions of model parameters, which can be estimated on the basis of clinical survival data. We demonstrate how the model can be used to make predictions regarding yet untested therapy options.

Evaluation of the proliferative index as a prognostic factor in diffuse large cell lymphoma: correlation with the International Index

The reasons for differences in outcome between groups of patients with diffuse large cell lymphoma (DLCL) defined by clinical prognostic factors are largely unknown. Measures of cell proliferation may offer a biological explanation for these differences. This study tested the hypothesis that these survival differences between the groups defined by established prognostic factors were due to the proliferative index. The bromodeoxyuridine labeling index (LI), a measure of the S-phase fraction, was prospectively determined on fresh tumor specimens obtained at initial diagnosis in 80 patients with DLCL seen between 1986-1993 at a single institution. Patients were grouped using prognostic factors that were significant in a univariate analysis as well as the International Index (IPI). The LI in each of these groups was compared to determine whether the differences in outcome between the groups could be explained by differences in the LI. The median LI for all patients was 5.1% (range: 0.1-25%). When the predictive effect of the LI on response and survival was analyzed, the LI did not correlate with complete response or disease-free survival (DFS). There was a trend, however, for patients with a lower LI to have a poorer overall survival (p=0.06). When the patients were analyzed using the International Index (IPI), the mean LI for patients in the low-risk, low-intermediate, high-intermediate and high risk groups was 7.1%, 10.0%, 6.4% and 6.6% respectively (p=0.41). When analyzed separately, there was no significant difference in the LI for any of the patient groups defined by significant prognostic factors. The only difference in the LI was that the median LI in patients with T-cell DLCL was significantly lower than the LI in patients with B-cell DLCL (p=0.001) and these patients had an inferior complete response rate (p=0.001), disease-free survival (p=0.003) and overall survival (p=0.015). In this study, the LI, a measure of lymphoma cell proliferation, was not a significant prognostic factor for response, disease-free survival or overall survival. Furthermore, the LI did not explain the differences in outcome between patient groups defined by the IPI. However, a lower LI seen in patients with T-cell DLCL may account for their poorer response to therapy and inferior survival when compared to patients with B-cell DLCL.

Cell kinetic analysis of non-Hodgkin's lymphomas using in vivo iododeoxyuridine incorporation and flow cytometry

The aim of this study was to analyse dynamic cell proliferation parameters in non-Hodgkin's lymphomas. Sixty-one patients with newly diagnosed or with recurrent disease were given iododeoxyuridine (IdUrd) intravenously near 4 h prior to tumour biopsy. After staining with an IdUrd reactive antibody and propidium iodide, S-phase fraction (SPF), labelling index (LI), S-phase duration time (Ts) and potential tumour doubling time (Tpot) were determined by flow cytometry. Thirty-eight samples, 15 low grade (LGM) and 23 high grade (HGM) malignant lymphomas, were possible to evaluate. Twenty-three cases were excluded due to aneuploidy, insufficient amount of material or technical problems. Tpot values varied between 0.8-32.9 days (mean 7.0 days). HGM lymphomas had shorter mean Tpot times than LGM lymphomas (4.8 versus 10.4 days, p = 0.05). For Ts the range was 4.2-20.1 h (mean 9.1 h), and a difference between the two histological groups was demonstrated with a longer mean Ts for HGM compared with LGM cases (10.0 versus 7.8 h, p = 0.04). Tpot showed a negative correlation with SPF (P = 0.003), and Ts demonstrated a positive correlation to SPF (p = 0.02). The clinical significance of the dynamic cell proliferation parameters studied remains to be clarified, but the interrelationships between Ts/SPF and Ts/morphologic subtype might be factors of interest for future prognostic studies in malignant lymphomas.

The usefulness of cell surface markers in predicting the prognosis of non-Hodgkin's lymphomas

The Working Formulation for classification of non-Hodgkin's lymphomas provides useful prognostic information. Since this scheme was published in 1982, many studies have investigated the prognostic significance of various cell surface markers in lymphoma cases. This article reviews the value of distinguishing T cells from B cells, CD5+ B cells, immunoglobulin light chain types, proliferation antigens such as Ki 67, other markers of B-cell differentiation, and chromosomal anomalies. Each of these contributes some further prognostic significance to that already determined by the Working Formulation.

Prognostic indicators in centroblastic-centrocytic lymphoma

The prognostic importance of ploidy and proliferative index (%S + G2) assessed by flow cytometry, mitotic and centroblast counts, and histological growth pattern were evaluated in biopsy specimens taken before treatment from 60 cases of centroblastic-centrocytic non-Hodgkin's lymphoma. Cases with a high proliferative index (greater than or equal to 18%) or DNA aneuploidy showed significantly poorer survival than those with a low proliferative index (less than 18%). A high mitotic count was also associated with a poor prognosis. On multiple regression analysis the flow cytometric assessments and mitotic counts were significant predictors of survival. Assessments of proliferative activity clearly have prognostic potential in centroblastic-centrocytic lymphoma and may permit more accurate characterisation of individual tumours.

Cell proliferation and DNA content in non-Hodgkin's lymphoma. Flow cytometry in relation to lymphoma classification

Flow cytofluorometric (FCF) DNA analysis was performed on specimens from 154 patients with non-Hodgkin's lymphoma (NHL) and correlated to histopathology according to the Rappaport classification and the Working Formulation of NHL for clinical usage (WF). NHL associated with unfavorable prognosis (UP) had significantly higher proportions of cells in S-phase as compared to the favorable prognosis (FP) group. The proportion of S-phase cells also differed significantly between the low-, intermediate-, and high-grade malignancy groups of the WF. Aneuploidy was significantly more frequent in the UP (41%) than in the FP (15%) group. By stepwise discriminant analysis, the S-phase frequency was a stronger discriminator between prognostic groups than DNA content. Classification by discriminant analysis showed that over 90% of the low grade/FP lymphomas were allocated to the good prognosis group by their S-phase and DNA values. Due to the variation in the proportion of S-phase cells in the intermediate grade and high grade, as well as the UP lymphomas, only approximately 50% of the UP and 60% of the high-grade lymphomas were identified as such by this discriminant model, while almost one half of the intermediate-grade lymphomas were allocated to the low-grade group. The results suggest that S-phase analysis can be of value in distinguishing intermediate- and high-grade lymphomas with high and low proportions of proliferating cells, which may be prognostic importance.

Prognostic significance of DNA-analysis by flow cytometry in non-Hodgkin's lymphoma

DNA analysis by flow cytometry was performed on lymph node cells obtained from 65 untreated patients with non-Hodgkin's lymphoma. According to the Kiel classification 41 cases were of low grade malignancy and 24 cases belonged to the high grade malignancy group. 47 out of 61 evaluable cases were diploid/near-diploid, 12 were aneuploid and 2 cases showed polyploidy. No difference in survival was found between diploid/near-diploid and aneuploid cases. The percentage of S-phase cells was found to be a valuable prognostic parameter. Using a cut point at 4 per cent S-phase cells between low and high S-phase lymphomas a highly significant difference in survival was demonstrated (p = 0.0004). The actuarial survival up to 3 years was about 77 per cent for lymphomas with less than 4 per cent S-phase cells to be compared with 20 per cent for patients with high S-phase (greater than or equal to 4 per cent) lymphomas. Subdivision according to the percentage of S-phase cells seemed to be a better prognostic predictor than morphologic subclassification.

What is known about tumour proliferation rates to choose between accelerated fractionation or hyperfractionation?

Repopulation of surviving clonogenic tumour cells during fractionated radiotherapy is one of the crucial factors determining cure probability in radiotherapy. Clinical and experimental data suggest that repopulation rates vary considerably between different tumours but may be similar to the cell production rates in the untreated tumour. For those tumours which repopulate fast, such as squamous cell carcinomas, bladder cancer and colorectal carcinomas, accelerated fractionation may be indicated.

Monoclonal B cells in peripheral blood in non-Hodgkin's lymphoma. Correlation with clinical features and DNA content

Peripheral blood from 69 patients with non-Hodgkin's lymphoma was examined with respect to B and T cell markers. Evidence for monoclonal B cell was found in 29 cases, 8 of 'high grade' and 21 of 'low grade' malignancy according to the Kiel classification. 17 out of the 29 patients had a normal lymphocyte count. Using conventional staging methods 4 cases of the 29 were in stages II and III, all others in stage IV. The proportion of S-phase cells in peripheral blood, determined by flow cytometry, was found to be elevated in cases with a monoclonal cell population. It is concluded that surface marker analysis of blood cells may be valuable as a diagnostic tool, as an indicator of prognosis and perhaps for the staging procedure of malignant lymphomas.

Determination of growth kinetics in a renal sarcoma of the rat by double labeling with 14C- and 3H-thymidine

An in vitro double-labeling technique for determination of kinetic growth parameters was tested; 13 renal sarcomas of rats were incubated after excision under standardized conditions with 14C- and 3H-thymidine successively. Another ten tumors were evaluated after in vivo double injection of 14C and 3H-thymidine into sarcoma-bearing animals. In both groups histoautoradiography was performed using a simple stripping-film method. Results including labeling indices, mitotic indices, length of DNA-synthesis phase and cell-production rate obtained by both methods were in excellent agreement. All values fitted those determined in earlier experiments using a continuous labeling and a fraction-labeled-mitoses method in vivo. Theoretical considerations on the calculation of kinetic parameters by double labeling have been added. The experimental results found in this study represent a base for evaluation of biopsies from human tumors.

J-chain-producing immunoblastic lymphoma in a case of Richter's syndrome. Immunohistochemical evidence for a gradual malignant transformation of a single B-cell clone and flow cytophotometric data

A 66-year old male with Richter's syndrome died 52 month after diagnosis of chronic lymphocytic leukaemia (CLL). The clinical course was characterized by a marked IgM hypoglobulinaemia which paralleled a chronically relapsing Herpes simplex infection. Autopsy showed a large retroperitoneal and intraabdominal tumour mass and well defined supradiaphragmatic lymphomas. Histological examination revealed a composite tumour consisting of CLL B-cell type (B-CLL) and immunoblastic malignant lymphoma of B-cell type (B-IbL). The lymphocytes bear mu-chains on their surface and to a lesser extend within their cytoplasm, the obviously defective immunoblasts produce J chains exclusively. Flow cytophotometric data seem to indicate an identical diploid stem line of the two tumours. The majority of the cells are in G0/1 phase. The CLL rarely produces mitoses, however, the IbL has a mitotic rate of 7% and a considerable proportion (33%) of cells in the phase of DNA-synthesis. This is the fourth malignant lymphoma and the second immunoblastic lymphoma to be reported that produces J chain in the absence of immunoglobulin.