A diachronic-comparative analysis for the identification of the most powerful prognostic index for localized diffuse large B-cell lymphoma.

BACKGROUND: In the rituximab era, the conventional International Prognostic index (IPI) lost at least in part its predictive power, while the National Comprehensive Cancer Network-IPI (NCCN-IPI) seems to be a new and valid prognosticator. However, it has not yet been evaluated in patients with localized disease and it has not been compared with the modified IPI (mIPI) of the pre-rituximab era. In order to evaluate the different prognosticators and to assess the importance of rituximab and radiotherapy (RT), we carried out the so far largest retrospective analysis of patients with localized diffuse large B-cell lymphoma (DLBCL). PATIENTS AND METHODS: We retrospectively assessed clinical and therapeutical data of 1405 patients treated in from 1987 to 2012 in 10 cancer centers in Italy and 1 in Austria. RESULTS: All patients underwent an anthracycline containing polychemotherapy and 254 additional rituximab. The median follow-up was 5.7 years (range 0.1-23 years). The 5-year overall survival (OS) was 75%, being significantly superior in those who underwent additional rituximab, while RT consolidation did not improve the outcome of those who received immunochemotherapy. Patients with extranodal disease benefited from the addition of rituximab, while RT did not improve OS of the immunochemotherapy subgroup. In the pre-rituximab era, the mIPI showed a better performance than the others. In rituximab-treated patients, the NCCN-IPI had the highest discriminant value and the 5-years OS varied significantly (P < 0.001) between the three risk groups and was 98% in low-risk patients, 82% in those with a low-intermediate risk and 57% among high-intermediate and high-risk cases. CONCLUSIONS: The NCCN-IPI is so far the best prognosticator for patients with localized DLBCL who underwent R-CHOP(-like). The addition of rituximab is indispensable regardless of the risk category and site of involvement, while the addition of RT should be reserved to those cases who are ineligible to rituximab.

Early-stage diffuse large B cell lymphoma of the head and neck: clinico-biological characterization and 18 year follow-up of 488 patients (IELSG 23 study).

It is known that extranodal head and neck diffuse large B cell lymphomas (eHN-DLBCL) can affect various anatomical structures what is not well-known, however, is whether they differ in terms of clinical presentation and outcome. Clinical data of the multi-institutional series, the largest of its kind as yet, has been analysed with the aim of answering these open questions and providing long-term follow-up information. Data from 488 patients affected by stage I/II eHN-DLBCL was collected: 300 of the Waldeyer's Ring (WR), 38 of the parotid and salivary glands (PSG), 48 of the thyroid gland (TG), 53 of the nasal cavity and paranasal sinuses (NPS), 24 of the palate and oral cavity (POC) and 25 with more than one involved site. Different eHN-DLBCL arising have distinct characteristics at presentation. The intermediate high risk-modified IPI was 67 % in TG, 44 % in WR, 38 % in PSG and POC and 20 % in MS. The worst 5-year survival rate had TG-DLBCL (61 %) due to the 61 % of patients with a mIPI >1. The addition of radiotherapy (cRT) to remitters did not translate into a survival advantage (5-year disease-free survival of 67 % in the cRT group vs. 70 % in the other). Three of four central nervous system recurrences occurred in NPS-DLBCL. Survival of HN-DLBCL was inferior to nodal DLBCL. This study showed that eHN-DLBCL remitters have an inferior survival when compared to nodal DLBCL, and that the addition of cRT does not provide a survival advantage. Since the standard of care nowadays is chemo-immunotherapy, survival of these patients might have been improved.

Healthcare costs of multiple myeloma: an Italian study.

Few economic evaluations are currently available on multiple myeloma (MM) and they address treatment-related rather than disease-related costs. We estimated resource utilisation and costs associated with MM in an Italian haematology department. This was a single-centre observational study which followed retrospectively for 2 years 90 patients with MM stages II-III. To investigate the association between costs and age as a prognostic factor for treatment eligibility, patients were classified in two age groups (under 65 or >65). The annual average cost per patient was very similar in the two subgroups. Drugs and hospitalisations were the largest cost components. Differences between the two age groups were significant only for drugs, hospital admissions and day hospital (DH) days. Autologous stem-cell transplantation (ASCT) accounted for more than 80% of the non-pharmacological therapy costs, being nearly double in the younger patients. Cost of elderly patients is comparable with that of younger ones who generally receive expensive procedures such as ASCT. The higher hospital costs of younger patients were counterbalanced by supportive pharmaceutical care and DH days for older patients, mainly in the group treated with new immunomodulatory agents. Further multi-centre studies on larger samples of patients are needed.

Long-term follow-up of patients with peripheral T-cell lymphomas treated up-front with high-dose chemotherapy followed by autologous stem cell transplantation.

We report the results of two prospective phase II studies investigating the role of high-dose sequential chemotherapy, followed by autologous stem cell transplantation (ASCT) in 62 patients with advanced stage peripheral T-cell lymphomas (PTCLs) at diagnosis. Conditioning regimen consisted of mitoxantrone (60 mg/m2) and melphalan (180 mg/m2) or carmustine, etoposide, Ara-C and melphalan followed by peripheral blood stem cell autografting. In an intent-to-treat analysis, 46 out of 62 patients (74%) completed the whole programme, whereas 16 patients did not undergo ASCT, mainly because of disease progression. At a median follow-up of 76 months, the estimated 12-year overall (OS), disease-free and event-free survival (EFS) were 34, 55 and 30%, respectively. OS and EFS were significantly better in patients with anaplastic lymphoma-kinase (ALK)-positive anaplastic large-cell lymphoma (ALCL), as compared with the remaining PTCL. Multivariate analysis showed that patients attaining complete remission (CR) before ASCT had a statistically significant benefit in terms of OS and EFS (P<0.0001). Overall treatment-related mortality rate was 4.8%. In conclusion, our findings indicate (1) up-front high-dose therapy and ASCT are feasible, but could induce a high rate of long-term CR only in patients with ALK-positive ALCL and (2) the achievement of CR before autografting is a strong predictor of better survival.

PO-03 - Khorana score and histotype predict the incidence of early venous thromboembolism (VTE) in Non Hodgkin Lymphoma (NHL). A pooled data analysis of twelve clinical trials of Fondazione Italiana Linfomi (FIL).

BACKGROUND: Recent studies show that the risk of VTE in NHL pts is similar to that observed in high risk solid tumors (i.e. pancreatic, ovarian cancer). VTE in NHL occurs in most cases within three months from diagnosis and can have substantial impact on treatment delivery and outcome as well as on quality of life. However few data are available on potential predictors. AIMS: To better clarify the epidemiology of early (within six months from treatment start) VTE in NHL we conducted a pooled data analysis of 12 clinical trials from FIL. Our analysis included basic demographic features, lymphoma-related characteristics as well the Khorana score (based on histology, BMI, platelets WBC and HB counts) which is extensively used in solid tumors to predict VTE risk. PATIENTS AND METHODS: From Jan. 2010 to Dec. 2014, all pts with B-cell NHL enrolled in prospective clinical trials from FIL for frontline treatment were included. For 9 studies study period included the entire trial population was included. The analyses were conducted based on CRFs as well as pharmacovigilance reports. VTE definition and grading was stated according to standard criteria of toxicity (CTCAE V4.0). Cumulative incidence of VTE from the study enrollment was estimated using the method described by Gooley et al. accounting for death from any causes as a competing risk. The Fine & Gray survival model was used to identify predictors of VTE among NHL pts. Factors predicting the grade of VTE were investigated using an ordinal logistic regression model. This pooled data analysis was approved by local IRB. RESULTS: Overall, 1,717 patients belonging to 12 studies were evaluated. Eight were phase I/II or II (25% of pts) and 4 phase III (75% of pts). M/F ratio was 1.41, Median age was 57, (IQ range (IQR) 49-66). Histologies were: DLCL-B 34%, FL 41%, MCL 18%, other 6%. Median BMI was 25 (IQR 22-28). Median Hb, WBC and platelets counts were 13g/dl) (IQR 11.5-14.2), 7.1*10^(9)/l (IQR 5.6-10.3), 224*10^(9)/l (IQR 169-298), respectively. 1189 pts were evaluable Khorana score: 58% low risk, 30% intermediate risk, 12% were high risk. Human erythropoetin support was given to 9% of patients. All pts received Rituximab. Planned therapeutic programs included ASCT in 27% of pts, conventional chemotherapy in 67% a conventional chemotherapy plus lenalidomide in 6%. Overall 59 any grade VTE episodes occurred in 51 pts (2.9%), including 21 grade III-IV VTE (18 pts). None was fatal. Median time from study enrolment to VTE was 63 days (IQR: 35-110). Considering death as a competitive event the 6 months cumulative incidence of VTE was 2,2% in low risk Khorana score, 4.5% (95%IC: 2.3-6.7) in intermediate and 6.6% (95%IC: 2.4-10.8) in high risk (p=0.012) (figure 1). Khorana score was predictive also for grade III-IV events as they were 0,7% (95% CI:0.1-1.4) in low risk and 2.0% (95% CI:0.8-3.3) in intermediate-high risk (p=0.048). The results were similar also after excluding lenalidomide containing studies. The Fine and Gray multivariate analyses, adjusted for age and stage, showed that Khorana score (intermediate risk adjHR=1.96; 95%IC: 0.84-4.56 and high risk adjHR=3.81; 95%IC: 1.51-9.58) and DLCL-B histotype (adjHR=2.58; 95% CI: 1.01-6.55) were independently associated to an increased risk of VTE. Moreover an ordinal logistical regression model indicated that the increase of one point in the Khorana score resulted in an increased risk of VTE (OR=1.85; 95% CI: 1.23-2.79). CONCLUSIONS: Our results suggest that DLCL-B histotype and Khorana score are predictors of VTE in NHL. The latter might become a simple and effective tool to assess the risk of VTE in NHL. Prospective validation including also patients not eligible for clinical trials is needed.

Incidence and risk factors for thrombotic complications in a historical cohort of 100 patients with essential thrombocythemia.

The purpose of this study was to determine which factors were associated with an increased risk of thrombo-hemorrhagic complications in a historical cohort of 100 consecutive and unselected patients with essential thrombocythemia (ET) in whom busulfan treatment was given when platelets were more than 1,000 x 10(9)/L and/or a major thrombotic or hemorrhagic event occurred. The incidence of major hemorrhagic complications was very low (0.33%/person-time at risk [pt-yr]) in comparison with that of thrombotic episodes (6.6%/pt-yr). In an adequate and appropriate control historical group of 200 patients, no severe hemorrhages were recorded and the incidence of thrombotic events was 1.2% pt-yr. Thus, the analysis of risk factors was restricted to this latter group of events. Age, a previous thrombotic event, and long duration of thrombocytosis were identified as major risk factors for thrombosis, while smoking, diabetes mellitus, hyperlipidemia, and hypertension did not influence the rate of thrombotic episodes.

Granulocyte colony-stimulating factor following peripheral-blood progenitor-cell transplant in non-Hodgkin's lymphoma.

PURPOSE: To compare the hematologic recovery after high-dose chemotherapy and circulating peripheral-blood progenitor-cell (PBPC) transplant between patients who received recombinant human granulocyte colony-stimulating factor (G-CSF) (treated group) and those who did not (control group). PATIENTS AND METHODS: From December 1992 through June 1994, two sequential and consecutive cohorts of 20 patients each with histologically proven non-Hodgkin's lymphoma (NHL) received high-dose chemotherapy (carmustine [BCNU], cytarabine [Ara-C], etoposide and melphalan [BEAM]) followed by PBPC transplant. The first 20 patients were treated with G-CSF (5 micrograms/kg/d) after PBPC administration. Since the time of platelet and leukocyte recovery in this group was short (< 15 days), with a narrow standard deviation from the mean value, the last 20 patients were not given G-CSF. Hematologic recovery, number of febrile days, rate of documented infections, number of hospital days, duration of gastrointestinal complications, platelet and RBC transfusions, and antibiotic requirements were compared in the two groups. RESULTS: The two groups of patients were comparable according to disease status, histology, stage, bulky disease bone marrow involvement, elevated lactate dehydrogenase (LDH) level, and median number of infused CD34+ cells and colony-forming units granulocyte-macrophage (CFU-GM). The median time to reach 0.5 x 10(9)/L and 1.0 x 10(9)/L neutrophils was 2 days shorter in G-CSF group, but this difference was not statistically significant. The median times to reach 20 x 10(9)/L and 50 x 10(9)/L platelets were, respectively, 10 and 14 days in the G-CSF group and 11 and 16 days in the control group, but again this was not statistically significant. Moreover, when considering clinically relevant end points including the number of documented infections and antibiotic requirements, platelet transfusions, gastrointestinal toxicity, and days of hospitalization, no differences were demonstrated between the two groups. CONCLUSIONS: Provided an optimal dose of circulating progenitors is infused, NHL patients transplanted with PBPC do not benefit by the administration of hematopoietic growth factors.

Patterns of outcome and prognostic factors in primary large-cell lymphoma of the testis in a survey by the International Extranodal Lymphoma Study Group.

PURPOSE: To determine clinical features and patterns of outcome of primary testicular diffuse large B-cell lymphomas (DLCL). PATIENTS AND METHODS: A retrospective international survey of 373 patients with primary testicular DLCL. RESULTS: Most patients presented with localized disease (stage I to II), and the median age at diagnosis was 66 years (range, 19 to 91 years). Anthracycline-based chemotherapy was administered to 255 patients (68%), and prophylactic intrathecal chemotherapy was given to 68 patients (18%); 133 patients (36%) received prophylactic scrotal radiotherapy. Median overall survival was 4.8 years, and median progression-free survival was 4 years. The survival curves showed no clear evidence of a substantial proportion of cured patients. A favorable international prognostic index score (IPI), no B-symptoms, the use of anthracyclines, and prophylactic scrotal radiotherapy were significantly associated with longer survival at multivariate analysis. However, even for patients with stage I disease and good-risk IPI, the outcome seems worse than what was reported for DLCL at other sites. At a median follow-up of 7.6 years, 195 patients (52%) had relapsed. Extranodal recurrence was reported in 140 cases. Relapses in CNS were detected in 56 patients (15%) up to 10 years after presentation. A continuous risk of recurrence in the contralateral testis was seen in patients not receiving scrotal radiotherapy. CONCLUSION: Testicular DLCL is characterized by a particularly high risk of extranodal relapse even in cases with localized disease at diagnosis. Anthracycline-based chemotherapy, CNS prophylaxis, and contralateral testicular irradiation seem to improve the outcome. Their efficacy is under evaluation in a prospective clinical trial.

G-CSF-mobilized peripheral blood progenitor cells for allogeneic transplantation of resistant or relapsing acute leukemias.

Peripheral blood progenitor cells (PBPC) were mobilized by G-CSF in normal HLA identical siblings and used for allogeneic transplantation in eight patients with refractory or relapsed acute leukemias. G-CSF administration was well tolerated and no significant side-effects were registered. The number of circulating WBC peaked at day 5 after G-CSF (range: 22.6-74.6 x 10(9)/l) with a median of 65 CD34+ cells/microl (38-155). As a consequence of leukaphereses, platelets progressively decreased, reaching the nadir after the last procedure (84-205 x 10(9)/l). A mean of two aphereses (1-3) were performed between day +4 and +7 during which 10 liters of blood were processed each time by a cell separator. Conditioning regimens were: fractionated total body irradiation (FTBI) plus either HDAra-C (2 g/m2 x 2/day for 6 days) (n=5) or melphalan (110 mg/m2) (n= 1) and busulfan (4 mg/kg/day for 4 days) and melphalan (110 mg/m2) in two patients relapsed after a previous FTBI-based allogeneic or autologous BMT. At transplantation, a median of 6.9 x 10(6) CD34+ cells/kg (4.2-16.5) and 279 x 10(6) CD3+ cells/kg (161-786) were infused. Engraftment of both neutrophils (> or v=1.5 x 10(9)/l) and platelets (> or v=20 x 10(9)/l) was observed in all patients after a median time of 18 days (range: 11-20 and 10-26, respectively). The evaluation of engraftment after transplantation was accomplished by PCR analysis of four hypervariable genomic regions (VNTR) (ApoB, ApoC2, YNZ-22, and MCT 118) which allowed to demonstrate the condition of donor chimaera in all patients after transplantation. As far as the clinical outcome, two patients died of interstitial pneumonitis at day +243 and +69 and two patients died at day +62 and +152 of pulmonary aspergillosis. Four patients remain alive in remission between day +88 and +287 with grade 0-l GVHD. Allogeneic PBPC transplantation is associated with a complete hematologic recovery and despite the infusion of a large amount of mature CD3+ lymphocytes, apparently acute GVHD is not worse than expected after transplantation of bone marrow progenitors.

Aspirin and risk of bleeding in patients with thrombocythemia.

Thirty-two patients with thrombocythemia associated with myeloproliferative syndromes were selected on the basis of normal bleeding time and absence of hemorrhagic or thrombotic history. Twenty-five control subjects were studied simultaneously. They were all given a single intravenous infusion of 500 mg of aspirin (lysine acetylsalicylate), and bleeding time was measured two hours later. Both in the control group and in the patient group, aspirin significantly prolonged the bleeding time, but the average prolongation was significantly more pronounced in the patients. In comparison with the control subjects, the patients had a statistically significant reduction of platelet serotonin content and no difference in the production of platelet lipoxygenase derivative 12-HETE or plasma von Willebrand factor properties. Fourteen patients had abnormal platelet aggregation in response to adenosine diphosphate, adrenaline (epinephrine), or collagen. In six of them, all with very low serotonin content, the bleeding time was prolonged above the upper limit of the post-aspirin values in the control group. Thus, cyclooxygenase inhibition by aspirin unmasked a bleeding tendency in patients with a severe reduction in platelet dense bodies content. These findings might be relevant in relation to the use of antiplatelet drugs.

Hemostatic complications in young patients with essential thrombocythemia.

PURPOSE: The purpose of this study was to determine the incidence of hemostastic complications in young patients with essential thrombocythemia (ET). PATIENTS AND METHODS: The clinical course of 44 patients under the age of 45 with the diagnosis of ET was reviewed in a retrospective manner. Patients were collected from three medical centers in the United States and Italy: the Brigham and Women's Hospital and the Harvard Community Health Plan, Boston, Massachusetts, and the Ospedali Riuniti di Bergamo, Bergamo, Italy. RESULTS: The overall incidence of hemorrhage or thrombosis, or both, in this group of patients was 39% (17 of 44), with serious complications occurring in 23% (10 of 44). Two patients died of thrombotic events. Neither the presence of symptoms at diagnosis nor any single laboratory parameter proved predictive of clinical sequelae. Treatment with antiplatelet drugs or platelet-lowering agents was not protective. CONCLUSION: We conclude that ET in young patients may result in serious and life-threatening hemostatic problems and consequently that young age is not a favorable prognostic factor in this disease.

Platelet activation in myeloproliferative disorders.

Beta-thromboglobulin (beta-TG) and platelet factor four (PF4) are specific platelet proteins released when a process of platelet activation occurs. The present study was undertaken in order to measure beta-TG and PF4 both as absolute plasma value and ratio to platelet number in 69 patients with myeloproliferative disorders (MD). The aim was to establish whether the increase of the two proteins could depend on platelet number or indicated an "in vivo" platelet activation. In 74% of patients beta-TG was found elevated and PF4 was high in 68% of cases. However in 34.7% and in 31.9% of cases respectively, the elevation of the two platelet markers was correlated to platelet number and the ratio was normal. Only in about one third of cases an "in vivo" platelet activation could be admitted and this finding provides a more rational use of antiaggregating agents.

Abnormal aggregation and increased size of platelets in myeloproliferative disorders.

Platelet aggregation is frequently impaired in myeloproliferative disorders (MPD). The presence of spontaneous platelet aggregation (SPA) or alterations of the aggregation pattern after ADP, epinephrine and collagen have been a frequent feature in the series of 52 patients here presented. The occurrence of SPA was not related to the findings obtained with the aggregating agents or to the number of circulating platelets. The aggregation results did not correlate with the number of megathrombocytes. The presence of platelet abnormalities, not completely corrected after busulfan therapy, and the increased size of platelets should aid in diagnosis of myeloproliferative disorders.

Effect of aspirin on platelet 5-hydroxytryptamine and beta-thromboglobulin plasma levels in patients with myeloproliferative diseases.

14 patients with myeloproliferative diseases (MD) showed low 5-hydroxytryptamine (5-HT) platelet content and high beta-thromboglobulin (beta-TG) plasma levels. This pattern could support the view that MD platelets undergo "in vivo" degranulation. A single dose of aspirin was unable to induce modifications of platelet 5-HT and plasma beta-TG, whereas 6 out of 14 patients treated over 7 days period with the drug showed a decrease but not normalization in their beta-TG levels. No modification of platelet 5-HT was obtained suggesting that the cause of dense bodies deficiency may lie in the production of abnormal platelets and not be related to "in vivo" degranulation.

Prolonged bleeding time in patients with lupus anticoagulant.

Platelet adhesion to collagen under flow conditions was studied in 18 patients with lupus anticoagulant, seven of which showed a prolonged bleeding time in the presence of a normal platelet count. The effect of patient plasma, IgG and purified anticardiolipin antibodies on platelet adhesion was also examined. We found a significant reduction of platelet adhesion in patients with lupus anticoagulant, which was more evident in patients with prolonged bleeding time. This platelet adhesion defect could be attributed to a plasma factor. In fact, patients' platelets regained normal adhesion when mixed with normal plasma, whereas controls' platelets showed abnormal adhesion in the presence of patient plasma. A causative role of antiphospholipid antibodies was demonstrated in experiments using purified immunoglobulins and anticardiolipin antibodies.

Thrombotic and hemorrhagic complications in patients with mechanical heart valve prosthesis attending an anticoagulation clinic.

This study evaluated the advantage of an anticoagulation clinic in terms of the improvement of the clinical quality of oral anticoagulation (i.e. prevention of thromboembolism and low rate of hemorrhagic complications). The incidence of thromboembolic events and major hemorrhagic complications was assessed in a series of 271 patients on oral anticoagulation for mechanical heart valve prosthesis before and after their enrollment in our anticoagulation clinic from January 1987 to December 1990. Risk factors for hemostatic events were also analyzed. The incidence of major hemostatic complications was significantly lower when patients attended the clinic: 1.0 vs 4.9%/pt-yr for hemorrhage and 0.6 vs 6.6%/pt-yr for thrombosis. This depended on three main factors: better dose regulation of warfarin, continuous patient education and early identification of clinical conditions potentially at risk for thrombosis and hemorrhage. Only previous hemorrhagic or thromboembolic events were recognized as major risk factors for hemostatic complications. In conclusion, our study shows that an anticoagulation clinic offers a real advantage to patients with mechanical heart valve prosthesis in terms of prevention of thromboembolic events and hemorrhagic complications.

Recombinant versus high-sensitivity conventional thromboplastin: a randomized clinical study in patients on oral anticoagulation.

A prospective, randomized, double-blind clinical trial was carried out in a single center to compare the clinical and laboratory quality of oral anticoagulant therapy monitored with recombinant tissue factor (RTF) or with a sensitive, human-derived, conventional thromboplastin (CT) in the PT test. Seven hundred and fifty-seven consecutive patients receiving oral anticoagulation for various indications were randomized to RTF (n = 379) or CT (n = 368) for 6 months. Total follow-up was 167 and 153 patient-years for RTF and TP groups respectively. Fifty-six bleeding events were observed: 31 in the RTF group and 25 in the TP group. The incidence of bleeding was 18.5 and 16.5% pt-yrs for RTF and TP patients respectively (n.s.). The event-free follow-up curves were not significantly different between the two groups. The laboratory quality of oral anticoagulation was evaluated with the "last check in file" method: therapeutic INR was found in the same proportion of RTF and TP patients (70.2% vs 68.8%). Our study shows that RTF is as effective as a sensitive, conventional thromboplastin for monitoring oral anticoagulation.

Increased response to arachidonic acid and U-46619 and resistance to inhibitory prostaglandins in patients with chronic myeloproliferative disorders.

In patients with myeloproliferative disorders (MPD) a group of related diseases of the bone marrow stem cell and recurrent haemorrhagic and/or thrombotic complications, the production of aggregating prostaglandins (PGs) may be normal or slightly reduced, while PGI2 production is normal. However, MPD platelet sensitivity to antiaggregatory PGs is still unknown. We studied the potency of PGD2, PGI2 and PGE1 as inhibitors of platelet aggregation induced by threshold aggregating concentrations of arachidonic acid and U-46619-analogue of the cyclic endoperoxide PGH2 in 20 patients with MPD in comparison with healthy controls, with the aim of evaluating the sensitivity of MPD platelets to antiaggregatory PGs. In these patients platelet prostanoid metabolism was normal. However, the functional response of platelets to aggregating and antiaggregating prostanoids was shifted towards potentially increased platelet aggregation response. These findings could have a clinical relevance in view of the haemostatic and thrombotic complications so frequent in MPD.

Increased thromboxane biosynthesis in essential thrombocythemia.

In order to investigate the in vivo thromboxane (TX) biosynthesis in essential thrombocythemia (ET), we measured the urinary excretion of the major enzymatic metabolites of TXB2, 11-dehydro-TXB2 and 2,3-dinor-TXB2 in 40 ET patients as well as in 26 gender- and age-matched controls. Urinary 11-dehydro-TXB2 was significantly higher (p < 0.001) in thrombocythemic patients (4,063 +/- 3,408 pg/mg creatinine; mean +/- SD) than in controls (504 +/- 267 pg/mg creatinine), with 34 patients (85%) having 11-dehydro-TXB2 > 2 SD above the control mean. Patients with platelet number < 1,000 x 10 (9)/1 (n = 25) had significantly higher (p < 0.05) 11-dehydro-TXB2 excretion than patients with higher platelet count (4,765 +/- 3,870 pg/mg creatinine, n = 25, versus 2,279 +/- 1,874 pg/mg creatinine, n = 15). Average excretion values of patients aging > 55 was significantly higher than in the younger group (4,784 +/- 3,948 pg/mg creatinine, n = 24, versus 2,405 +/- 1,885 pg/mg creatinine, n = 16, p < 0.05). Low-dose aspirin (50 mg/d for 7 days) largely suppressed 11-dehydro-TXB2 excretion in 7 thrombocythemic patients, thus suggesting that platelets were the main source of enhanced TXA2 biosynthesis. The platelet count-corrected 11-dehydro-TXB2 excretion was positively correlated with age (r = 0.325, n = 40, p < 0.05) and inversely correlated with platelet count (r = -0.381, n = 40, p < 0.05). In addition 11 out of 13 (85%) patients having increased count-corrected 11-dehydro-TXB2 excretion, belonged to the subgroup with age > 55 and platelet count < 1,000 x 10(9)/1. We conclude that in essential thrombocythemia: 1) enhanced 11-dehydro-TXB2 excretion largely reflects platelet activation in vivo; 2) age as well as platelet count appear to influence the determinants of platelet activation in this setting, and can help in assessing the thrombotic risk and therapeutic strategy in individual patients.