[1998 oncologic highlights: difficult choices--no inferior quality].
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Biomedical subjects
Publications and source records attributed to M F Fey.
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Aberrant FHIT mRNA transcripts are present in malignant and normal haematopoiesis, but absence of FHIT protein is restricted to leukaemia Alterations of the recently cloned fragile histidine triad (FHIT) gene at chromosome 3p14.2 are frequent in a variety of solid tumours and cancer cell lines. Based on these findings, FHIT has been proposed as a putative tumour-suppressor gene. We evaluated the mRNA expression of the FHIT gene in samples from 55 patients with various haematological malignancies (21 AML, 8 CML, 10 CLL, seven low-grade and nine high-grade Non-Hodgkin's lymphomas), in a panel of 16 leukaemia cell lines, in normal mature haematopoietic cells of both myeloid and lymphoid lineage, as well as in CD34+ haematopoietic progenitor cells. Aberrant FHIT mRNA transcripts were observed in 14/16 (88%) leukaemia cell lines, 43/55 (78%) primary haematological neoplasms, but also in 17/22 (77%) normal controls. 1/16 (6%) cell lines and 7/55 (13%) neoplasms did not express any FHIT mRNA. cDNA sequencing revealed exonic deletions, small DNA insertions and combinations of both. Analysis of genomic DNA showed gene deletions in two myeloid leukaemia cell lines. In contrast to all normal types of haematopoietic cells, FHIT protein was clearly reduced or absent in 8/18 (44%) neoplastic samples tested. Our data indicate that whilst aberrant FHIT mRNA transcripts are seen both in normal and malignant cells, lack of FHIT protein is restricted to leukaemia. Absent FHIT protein expression might contribute to leukaemogenesis.
We report on a patient with recurrent T-cell-rich B-cell lymphoma (TCRBCL), initially misdiagnosed as a lymphocyte-rich Hodgkin's disease. This case exemplifies the diagnostic problems of TCRBCL and the need for immunophenotypic analysis to differentiate TCRBCL from Hodgkin's disease, nodular paragranuloma and peripheral T-cell lymphoma. A rather unusual aspect is the long disease-free interval between the excision of the node in and the late relapse in 1996. The significance of the abundant T-cell infiltration in this B-cell neoplasm will be discussed and the concepts concerning antitumor response will be reviewed. Based on epidemiological data and the clinical behaviour TCRBCL does not seem to represent a distinctive pathological entity.
PURPOSE: We determine the efficacy and safety of 2 cycles of adjuvant chemotherapy after orchiectomy in patients with high risk clinical stage I nonseminomatous germ cell tumor of the testis as an alternative to retroperitoneal lymphadenectomy or watchful waiting. MATERIALS AND METHODS: A total of 60 consecutive patients with clinical stage I nonseminomatous germ cell tumor of the testis and 1 or more risk factors were entered into this prospective study. Criteria for high risk were embryonal cell carcinoma, tumor invasion of blood or lymph vessels, or tumor stage pT2 or greater. Chemotherapy consisted of 2 cycles of cisplatin, vinblastine and bleomycin or bleomycin, etoposide and cisplatin. RESULTS: Of the 60 patients 1 refused chemotherapy and 1 was lost to followup 1.5 years after treatment. The remaining 58 patients have been followed for a median of 93 months (range 32 to 146). World Health Organization grade 4 toxicity was observed in 9 of the 116 chemotherapy cycles, and consisted mainly of transient neutropenia and thrombocytopenia. No significant long-term sequelae were detected. There was 1 relapse after 22 months in a patient with adult teratoma in the ipsilateral region of the iliac vessels who remained disease-free 85 months after surgical excision of the lesion. Another patient had a seminoma in the contralateral testicle with interaortocaval lymph node metastases 7.5 years after adjuvant chemotherapy. The remaining 56 men are without relapse or contralateral tumor to date. CONCLUSIONS: We recommend adjuvant chemotherapy as an efficient therapeutic alternative to retroperitoneal lymphadenectomy for high risk nonseminomatous germ cell tumor of the testis.
The CDKN2 locus expresses two different mRNA transcripts, designated alpha and beta. The protein product of the alpha transcript is the cell cycle inhibitor and tumour suppressor p16INK4a. The beta transcript is translated in an alternate reading frame (ARF) and in humans encodes a 15 kDa protein (p19ARF). Immunohistochemical and Western analysis of p16INK4a has shown that the protein is downregulated in a significant number of tumours, but less is known on the expression of the p19ARF. We have examined the expression of p16INK4a and p19ARF in resectable non-small cell lung cancer (NSCLC) by immunostaining (n=49) and multiplex RT-PCR (n=28). In order to investigate the mechanism responsible for p16INK4a downregulation, exon 1alpha methylation was analysed in a PCR-based assay. Of 49 tumours examined by immunostaining, 24 and 20 tumours expressed p16INK4a and p19ARF at nil to low levels, respectively. p19ARF was localized primarily to the nuclei of tumour cells, but was also seen to varying degrees in nuclei of lymphocytes, chondrocytes, fibroblasts, and epithelial cells. No tumour with normal p16INK4a had decreased p19ARF expression. Among 16 tumours with nil to low p16INK4a expression, 11 tumours exhibited full methylation of at least one site within exon 1alpha and these tumours showed normal p19ARF expression. In contrast, no methylation of exon 1alpha was observed in five tumours which also lacked p19ARF. In normal lung, p16INK4a and p19ARF were not expressed at detectable levels, the multiplex RT-PCR results were balanced, and sites within exon 1alpha were strongly methylated. In tumours, imbalanced multiplex RT-PCR data (p16INK4a<p19ARF) predicted methylation of exon 1alpha (P=0.0006) as well as downregulation of p16INK4a. p19ARF downregulation was inversely correlated with p53 overexpression (P=0.025), whilst negative immunostaining for p16INK4a was inversely correlated with pRb down-regulation (P=0.003) and directly correlated with p53 overexpression as assessed by immunostaining (P=0.015). Our results show that: (1) p16INK4a and p19ARF expression are altered in almost half of resectable NSCLC; (2) methylation within exon 1alpha is a frequent, but not the only mechanism of p16INK4a downregulation; and that (3) the inverse association of p19ARF and p53 alteration is consistent with a linked pathway.
BACKGROUND: Axillary lymph node status is an important determinant of prognosis in breast cancer. However, lymphadenectomy does not benefit half of the patients in whom axillary nodes are free of disease. Sentinel lymph node biopsy is a new technique which allows accurate staging of breast carcinoma without performing total axillary dissection. We describe our experience with the introduction of sentinel lymphadenectomy. METHODS: Thirty-seven sentinel lymphadenectomies were performed in 35 patients referred to the Department of Obstetrics and Gynaecology of the University of Berne between December 1997 and June 1998. Mapping procedures were performed using a combination of vital blue dye with preoperative lymphscintigraphy with 99mTechnetium-labelled colloidal albumin and intraoperative use of a gamma probe. Complete axillary lymphadenectomy was then performed in 34 patients. RESULTS: One or more lymph nodes were identified in 33 of 37 procedures (89%). With the combination of both localisation techniques the sentinel nodes were identified in all (100%) of the last 19 patients. Sentinel and non-sentinel lymph nodes were always concordant. In this series the negative predictive value is 100% (95% confidence interval: 87.7%-100%). Metastases were found in the sentinel node in 11 of 30 patients (37%). From these 11 patients, 3 (27%) had micrometastases. CONCLUSIONS: Histopathologic examination of the sentinel lymph node accurately predicts the axillary lymph-node status. Patients with sentinel nodes free of metastases could avoid the unnecessary peri- and postoperative complications of complete axillary dissection. Further studies are needed to assess whether the improved diagnosis of micrometastases by sentinel lymphadenectomy influences the long-term prognosis of breast cancer.
In normal cells the cell cycle, cell proliferation and differentiation are precisely regulated by a variety of different players. These include cyclins, which help to drive cells into mitosis, as well as cyclin-dependent kinase inhibitors which may be viewed as cell cycle brakes. Alterations in such genes and their products are frequent in human cancer. Overexpression of cyclins has been identified in lymphoma and in non-small cell lung cancer. Mutations in cyclin-dependent kinase inhibitors, such as the p16 gene, are particularly frequent in human cancer cell lines. Tumor suppressor genes, including the retinoblastoma gene and the p53 gene, are also crucial in this context, and their inactivation through gene mutations in cancer is frequent. Assessing alterations of genes associated with cell cycle regulation in malignancy or their protein products is of clinical interest. Molecular and immunological techniques to identify such alterations may provide unique markers of prognostic and predictive value in cancer. In addition, the technology is being developed for the treatment of such genetic alteration in cancer cells at the molecular-genetic level. Protocols introducing the wild-type p53 gene in tumors with p53 inactivations are on the way and clinical trials, although very preliminary, seem to be opening up completely new avenues for cancer treatment. Investigating cell cycle alterations in cancer is no longer the exclusive province of experimental research, but has rapidly developed into an area of unique clinical relevance.
PURPOSE: A wide variety of fluorouracil (FU)-plus-leucovorin (LV) dose schedules are in clinical use for the treatment of advanced colorectal cancer. Only the monthly low-dose LV-plus-FU regimen, as used by the North Central Cancer Treatment Group, has demonstrated a lasting survival benefit as opposed to FU alone (J Clin Oncol 1989; 7: 1407-1417). The Swiss Cancer Group adopted this regimen for a confirmatory phase III trial but used the same dose-intensity of fluorouracil in both treatment arms. PATIENTS AND METHODS: Patients with inoperable or metastatic colorectal cancer were randomized to receive monthly FU 400 mg/m2/day plus LV 20 mg/m2/day as intravenous push daily for five days, or FU alone. RESULTS: Three hundred nine of the 310 patients randomized were eligible and included in the analysis. The objective response rate for patients with measurable disease was 9% with FU alone and 22% with FU-plus-LV (P = 0.0001). The median progression-free survival was 3.9 versus 6.2 months (P = 0.003) and the overall survival 10 versus 12.4 months (P = 0.02). The major prognostic factors for survival were performance status, weight loss, and disease symptoms. WHO > 2 toxicity, consisting of stomatitis (P = 0.001), diarrhea (P = 0.001), and nausea (P = 0.001), was more pronounced for FU-plus-LV, without fatal events. CONCLUSIONS: This is the largest published randomized trial to compare FU-plus-LV to FU alone in advanced colorectal cancer. It confirms the survival benefit obtained from biomodulating monthly FU with low-dose LV. The toxic effects of FU-plus-LV were acceptable to most patients, and they responded well to FU dose reductions. In the absence of an ideal dose-intense FU monotherapy regimen, monthly FU with low-dose LV provides a simple and economical means by which to achieve adequate FU efficacy in the treatment of advanced colorectal cancer.
PURPOSE: To study the efficacy and the safety of cladribine (2-chlorodeoxyadenosine, 2-CDA) administered as 24-hour infusions or as subcutaneous bolus injections at two different doses to patients with relapsing or refractory chronic lymphocytic leukaemia (CLL). PATIENTS AND METHODS: In this non randomised 2-cohort study, 20 patients with pretreated CLL received cladribine at a dose of 0.7 mg/kg/cycle as continuous i.v. infusions over seven days (group 1) and 35 patients were treated at a reduced dose of 0.5 mg/kg/cycle given as s.c. bolus injections for five days (group 2). After two cycles of four week duration, response was assessed. In the case of progressive disease, therapy was discontinued, otherwise a maximum of four additional cycles were administered until best response. RESULTS: A total of 130 cycles were administered (group 1: 41, group 2: 89). Patient characteristics in both groups were comparable. The median dose intensities were 0.172 mg/kg per week and 0.123 mg/kg per week for groups 1 and 2, respectively (P < or = 0.0001). The overall response rate for all 55 patients was 38% (95% confidence interval (95% CI): 25%-52%), with 5% CR and 33% PR. Response was similar in both patient groups (35% in group 1, 40% in group 2). No association between cladribine dose intensity and response rate was found, and there was no difference between patients relapsing after or refractory to previous therapies (11 of 24 vs. 10 of 31). Median remission duration was six months in both groups. Toxicity, in particular infections (all WHO grades, 34% in group 1 versus 7% in group 2) and myelosuppression (grade 1-4 neutropenia, 72% versus 41% of cladribine cycles) were statistically significantly more frequent in group 1. CONCLUSION: Cladribine is active in heavily pretreated patients with chronic lymphocytic leukaemias. Dose reduction by 29% led to similar response and remission duration, but to a significant decrease of myelotoxicity and risk of infection. Cladribine administered as s.c. bolus injections at 0.5 mg/kg per cycle is safe and this dose level should not be exceeded in this patient population.
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PURPOSE: To study the efficacy and the safety of cladribine (2-chlorodeoxyadenosine [2-CDA]) administered at two different dosages. PATIENTS AND METHODS: In this two-cohort study, patients with low-grade refractory/relapsing non-Hodgkin's lymphoma (NHL) received 2-CDA at a dose of 0.7 mg/kg per cycle as a continuous intravenous (i.v.) infusion (group 1, n = 44) or at a reduced dose of 0.5 mg/kg per cycle as a subcutaneous (s.c.) bolus injection (group 2, n = 60). Three 2-CDA cycles at > or = 4-week intervals were planned, then treatment could be pursued until six cycles. RESULTS: A total of 300 cycles were administered (group 1, 114 cycles; group 2, 186). Patient characteristics in both groups were comparable. The median dose-intensities were 0.17 mg/kg/wk and 0.13 mg/kg/wk for groups 1 and 2, respectively (P < or = .0001). The overall response rate for all 104 patients was 54% (95% confidence interval [CI], 45% to 66%; 15% complete response [CR] and 39% partial response [PR]). Response was similar in both patient groups (57% in group 1 and 53% in group 2; P = .72), and no association between 2-CDA dose-intensity and response rate was found (P = .35). Median remission duration was 7 and 12 months in groups 1 and 2, respectively (P = .21). Toxicity, in particular opportunistic infections (> or = grade 2, 30% in group 1 v 7% in group 2; P = .003) and myelosuppression (> or = grade 3 neutropenia, 33% v 8% of 2-CDA cycles, P < .0001), were more frequent in group 1. Multiple logistic regression analysis showed that the infection risk (grade > or = 2) was decreased by 81% with 2-CDA dose reduction in group 2 after adjusting for number of pretreatment regimens and time since diagnosis (P = .01). CONCLUSION: When administered as a s.c. bolus injection, 2-CDA at 0.5 mg/kg per cycle is safe and this dose level should not be exceeded in this patient population.
Many cases of early breast cancer appear to be restricted to the breast and perhaps the axillary lymph nodes, but may relapse if given local treatment only. This fact points to the presence of occult micrometastases present at diagnosis. Fisher was among the first to pinpoint this problem, and to establish the concept of adjuvant systemic treatment in early operable breast cancer. The pioneering work of Fisher, Bonadonna and others has now largely been confirmed in many prospective trials. Adjuvant systemic treatment works in terms of improving disease-free and overall survival of women with breast cancer. Postmenopausal women benefit from tamoxifen supplemented by chemotherapy given according to specific risk profiles. Chemotherapy is the treatment basis in premenopausal women, but hormonal manipulation (either tamoxifen or derivatives thereof, or cessation of ovarian function) may perhaps also offer benefit. Dose intensity of chemotherapy has been shown to be important in breast cancer. Thus, high dose chemotherapy protocols with reinfusion of peripheral blood haematopoietic stem cells are being evaluated in prospective trials. It seems important to await the mature results of these trials before this potentially very effective but extremely toxic and expensive treatment is being offered on a routine basis. Examined under the stringent criteria of evidence-based medicine, the literature on adjuvant systemic treatment of breast cancer has certainly stood the test of time. It would, however, seem prudent not to abandon the tradition of clinical studies, and to continue to accrue women with this frequent disorder in clinical trials. Sadly, this possibility is rather neglected by many clinicians working outside large university and other hospital centers, and these colleagues would be kindly invited to participate actively in trials offered by collaborative groups such as the IBCSG.
BACKGROUND: We assessed the frequency and molecular basis of p53 mutations in clinically localized prostatic adenocarcinoma. METHODS: Prostate specimens were examined from 100 patients with clinically localized prostatic adenocarcinoma and 13 patients with benign prostatic hyperplasia (BPH). Mutations producing nuclear accumulation of p53 were detected immunohistochemically. Exon-specific mutations were analyzed by polymerase chain reaction amplification and single strand conformation polymorphism (PCR-SSCP) and sequenced. RESULTS: p53 accumulation was detected in 5 tumors using antibody DO-1, and in 4 of these using antibody PAb 1801, but not in BPH. PCR-SSCP detected mutations in all 5 tumors, with alterations in exon 5 for 1 tumor, exon 6 for 3 tumors, and exon 7 for 1 tumor. An exon 6 mutation was also found in a tumor with no anti-p53 staining. CONCLUSIONS: p53 mutations are uncommon in clinically localized prostatic adenocarcinoma and absent from BPH. 5 of the 6 mutations were derived from locally invasive, prostate carcinomas, supporting the hypothesis that mutation of p53 is a late event in prostate carcinoma progression.
Assessment of clonality of cellular proliferations is important in experimental and clinical cancer research. X-chromosome inactivation studies are widely used to assess clonality, but most assays require relatively large amounts of high molecular weight DNA. Two PCR-based strategies, the phosphoglycerate kinase (PGK) and the human androgen receptor (HUMARA) clonality assays allow studies of small tissue samples. The HUMARA assay was adapted to non-radioactive analysis taking advantage of an automated sequencer providing high resolution of alleles and immediate quantitation. This assay was validated by comparison with X-inactivation patterns obtained by Southern analysis with the probes M27 beta and PGK. Fifteen gastrointestinal carcinomas, 25 benign goiter nodules and normal peripheral leukocytes of 27 individuals (12 who were under 15 years and 15 over 80 years) were analysed. Furthermore, DNA extracted from formalin-fixed paraffin-embedded tissue (FPT) was analysed with the two PCR-based methods and compared with X-inactivation patterns determined by Southern analysis of high molecular weight (HMW) DNA. This modified HUMARA assay is reliable in most patients; as with other clonality assays, constitutive skewing in normal tissue precludes clonal analysis in some individuals. Extremely skewed X-inactivation patterns were found in normal peripheral leukocytes of 7 out of 15 old females (over 80 years) and in 1 of 12 of the young females tested (under 15 years). Comparison of results obtained with HMW and FPT DNA yielded consistent results for the HUMARA assay whereas the PGK PCR assay was much less reliable. The HUMARA assay thus permits studies of selected areas of tissue sections without significant stromal components, allowing correlation of histological and genotype findings in fresh and archival specimens.
MTS1, a tumor suppressor gene located on chromosome 9p21, has been shown to be altered in a number of human tumor cell lines, primary solid tumors, and leukemias. In this study we found low expression of MTS1 in lymphocytes from seven of nine healthy donors, but in none of eight granulocyte samples from the same controls, suggesting a physiological role of MTS1 in peripheral blood cells capable of proliferation, but not in end-stage differentiated cells. We detected MTS1 mRNA expression in 38 of 57 patients (66%) with acute myelogenous leukemia (AML) treated in a standardized clinical protocol. No deletion of the MTS1 gene was found in any of the AML samples tested. There was no significant association between expression of MTS1 and response to therapy, progression-free, or overall survival. Except for a negative correlation between MTS1 level and leukocyte count at diagnosis (p = 0.03), there was also no association with any of the known prognostic parameters in AML. We conclude that MTS1 shows a significantly higher expression in leukemic than in normal peripheral blood cells, that deletion of MTS1 is not a frequent event in AML, and that its expression is not significantly correlated with outcome of the disease.
The aim of the study was to compare efficacy and tolerability of the new aromatase inhibitor formestane (Lentaron) with megestrol acetate (Megestat) (MGA) in postmenopausal patients with advanced breast cancer. 179 patients were randomised to receive either 250 mg formestane intramuscularly biweekly or MGA 160 mg orally daily. 51% of the patients had received tamoxifen as adjuvant treatment; 73% of the patients had positive and 16% unknown oestrogen receptor values. The response rate was 17% in both treatment arms (95% confidence interval 10-26% for formestane and 10-27% for MGA). Disease stabilisation > or = 6 months was seen in 25% of the formestane and 22% of the MGA patients. Time to treatment failure was 120 days in the formestane arm and 111 days in the MGA arm. There was no significant difference between the treatments with regard to response rate and time to treatment failure. Overall toxicity was similar in both arms, but weight gain > 3 kg (P = 0.081) and severe cardiovascular toxicity (P = 0.044) were more frequently observed with MGA, e.g. deep vein thrombosis 0/90 formestane versus 5/81 MGA cases (P = 0.022). Formestane was associated with worsening of hot flushes/sleeping problems (P = 0.051) and mild leucopenia (P = 0.004). In our study, formestane and MGA showed similar antineoplastic activity as second-line hormonal treatment for advanced breast cancer. Both drugs have a specific toxicity profile. MGA was associated with significantly more severe cardiovascular toxicity and weight increase than formestane.
PURPOSE: It has been postulated that breast cancer surgery performed during the follicular phase of the menstrual cycle is associated with poorer outcome. PATIENTS AND METHODS: We tested this hypothesis by evaluating disease-free survival (DFS) for 1033 premenopausal patients who received definitive surgery either during the follicular phase (n = 358) or the luteal phase (n = 675). All patients were enrolled in a randomized trial conducted between July 1986 and April 1993. All had node positive breast cancer and randomization was stratified by estrogen receptor (ER) status. All patients received at least three cycles of adjuvant cyclophosphamide, methotrexate, and 5-fluorouracil (CMF). The median follow-up was 60 months. RESULTS: Patients who underwent definitive surgery for breast cancer in the follicular phase had a slightly worse disease-free survival than those operated on during the luteal phase (five-year DFS percentage: 53% versus 58%; hazard ratio, 1.13; 95% confidence interval (CI), 0.94-1.38; P = 0.20). The effect was significantly greater for the subpopulation of 300 patients with ER-negative primaries (P = 0.02 interaction effect; five-year DFS percentages 42% vs. 59%; hazard ratio 1.60; 95% CI, 1.12-2.25; P = 0.008). The effect of timing of surgery diminished for analyses based on lesser surgical procedures, e.g., excisional biopsies. In particular, no effect of timing was observed for fine needle aspiration procedures. CONCLUSIONS: Surgical procedures which are more extensive than a fine needle aspiration biopsy might be associated with worse prognosis if conducted during the follicular phase of the menstrual cycle. This phenomenon was seen predominantly for high risk breast cancer with low levels or no estrogen receptors in the primary tumor.
BACKGROUND: Intensification of post-remission therapy improves the cure rate of acute myeloid leukemia (AML) but is often accompanied by unacceptable toxicity. From 1985 to 1992 the Swiss Group for Clinical Cancer Research (SAKK) performed a randomized phase III trial to evaluate the effectiveness of one single postremission course of high-dose cytarabine (HDAC) in terms of leukaemia-free and overall survival in adults with de novo AML. PATIENTS AND METHODS: Adult (15-65 years) AML patients in remission after two induction courses were randomly assigned to one consolidation course either with standard (SDAC: 100 mg/sqm 24 hours infusion over seven days) or with high-dose cytarabine (HDAC: 3000 mg/sqm every 12 hours as one-hour-infusion for six days). In addition, both arms included daunorubicin (45 mg/sqm daily on days 1 to 3). Thereafter, patients were observed without maintenance until relapse. RESULTS: After two induction courses 208/276 eligible patients achieved remission (CR: 169, 61%, PR: 39, 14%), 41 were resistant (15%) and 20 died early (7%). Seventy-one patients in remission were not randomized. One hundred thirty-seven were randomized in CR/PR (67 SDAC, 70 HDAC). 4/70 patients randomized to HDAC did not receive it. Treatment-related mortality in HDAC was 1.4% (1/66). WHO grade 3-4 toxicities occurred in 14/67 SDAC and in 38/66 HDAC patients (P < 0.0001). The median event free survival was 10.8 (SDAC) vs. 12.2 months (HDAC; P = 0.18). The median overall survival was 24.6 (SDAC) vs. 32.6 months (HDAC; P = 0.07). Although statistically uncertain, HDAC reduced the hazard of progression (hazard ratio: 0.69, P = 0.08) and of death (hazard ratio: 0.70, P = 0.13). For 112 patients stratified as CR the estimated four-year disease-free survival was 25% (+/-6%) with SDAC and 37% (+/-6%) with HDAC (P = 0.09). The overall survival rates at four years were 38% (+7%) and 48% (+7%), respectively (P = 0.10). In multivariate analysis HDAC significantly reduced the hazard of relapse by 39% compared to SDAC (hazard ratio = 0.61, 95% CI: 0.37-0.99; P = 0.049). CONCLUSIONS: We conclude that early consolidation of adult AML in CR with a single course of HDAC is superior in terms of outcome to one cycle of SDAC. The results of our intensive, single course HDAC group compare favourably with less intensive, repetitive HDAC cycles, suggesting that Ara-C dose intensity may be more important than total dosage. In addition, our treatment strategy is much less toxic and less expensive.