Why do some patients with > 80% stenosis of the internal carotid artery not undergo surgery? A retrospective review

BACKGROUND

Carotid endarterectomy is known to benefit both symptomatic and asymptomatic patients with high-grade internal carotid artery stenosis. Duplex scanning is the 'gold standard' for non-invasive preoperative investigation of carotid artery stenosis. The aim of the present study was to analyse the indications for duplex scanning and to identify other factors that influenced the management of patients with high-grade stenosis who did not undergo carotid endarterectomy.

METHODS

A total of 271 patients was observed to have > 80% stenosis of the internal carotid artery on duplex scanning during the period of review. Of these patients, 85 did not undergo carotid endarterectomy. The vascular laboratory database and hospital records of these patients were retrospectively reviewed.

RESULTS

The indications for requesting a carotid duplex scan in the 85 patients were transient ischaemic attack (22%), stroke (25%), symptomatic bruit (7%), asymptomatic bruit (12%), and stroke and symptomatic bruit combined (7%). Falls and preoperative carotid assessment prior to coronary surgery were the commonest indications in the remaining patients. The main risk factors were cardiac (68%), hypertension (60%), respiratory (21%), diabetes (25%), peripheral vascular disease (19%), neoplasm (16%) and renal disease (16%). Twenty-five per cent of the patients were over 80 years of age.

CONCLUSION

In the present study risk factors associated with increased perioperative morbidity and mortality were the commonest explanation for patients with high-grade stenosis of the internal carotid artery not undergoing surgery. These patients would generally not meet the inclusion criteria for the major carotid endarterectomy trials.

Treatment of patients with ovarian carcinoma with pegylated liposomal doxorubicin: analysis of toxicities and predictors of outcome

BACKGROUND

Pegylated liposomal doxorubicin is a new formulation with activity against epithelial ovarian carcinoma (EOC). The authors sought to determine patient characteristics that may predict for response to this treatment and favorable time to failure as well as survival.

METHODS

Eight patients in a Phase I study and 44 patients in two consecutive Phase II studies who were treated with pegylated liposomal doxorubicin (40-60 mg/m2 every 3 weeks for the first two cycles and 40 mg/m2 every 4 weeks thereafter) after failing initial platinum-based chemotherapies for ovarian carcinoma were analyzed. Associations were sought for response, time to failure (TTF), and survival after the treatment and various pretreatment characteristics.

RESULTS

Treatment with pegylated liposomal doxorubicin yielded 23% objective responses in measurable disease and 31% overall responses, including serum CA 125-defined responses. The median TTF was 5.2 months (95% confidence interval, 4.1-6.9 months) in all patients, and the median response duration in all responders was 13.2 months (95% confidence interval, 11.9-18.5 months). The overall median survival was 15 months (95% confidence interval, 11-40 months). The main predictive factors were tumor size and baseline hemoglobin level for TTF, and these plus Karnofsky performance status were the main predictive factors for survival.

CONCLUSIONS

Pegylated liposomal doxorubicin is an effective drug when it is given as secondary therapy to patients with EOC. Lack of bulky disease is the major predictor for a favorable response, TTF, and survival. The role of this treatment in combination with other effective drugs should be explored in both previously treated and untreated patients with ovarian carcinoma.

In vivo drug-drug interaction studies--a survey of all new molecular entities approved from 1987 to 1997

Ninety-eight new molecular entities applications approved between 1987 to 1991 (period I) and 193 applications for new molecular entities between 1992 to 1997 (period II) were surveyed for drug-drug interaction studies. In period I (used as a comparator), 32 applications contained drug-drug interaction studies for a total of 117 studies. In period II, 106 applications reported drug-drug interaction studies, and the number of studies per new molecular entity ranged from 0 to 15. Most studies (77%) were performed in healthy subjects, with 44% using crossover designs, 7% using parallel designs, and the remaining using fixed sequence designs. The most common dosing scheme for new molecular entities/interacting drug was multiple dose (47%), whereas single dose/multiple dose was used in 31% of studies, and single dose/single dose was used in 18% of studies. Of the 540 drug-drug interaction studies submitted in period II, 80 (15%) resulted in clinically significant labeling statements. Submissions for new molecular entities to the Center for Drug Evaluation and Research divisions most likely to include drug-drug interaction studies were neuropharmacology, cardiorenal, antiviral, and antiinfective drugs. Some drug classes such as oncology drug products and radioimaging products were least likely to include drug-drug interaction studies in their submissions. We conclude that the use of drug-drug interaction studies in the drug development process has increased between the two periods.

Phase II study of liposomal doxorubicin in advanced gynecologic cancers

OBJECTIVE

Pegylated liposomal doxorubicin (Doxil) may have enhanced therapeutic efficacy and reduced toxicity compared with the parent compound. This phase II study further evaluates the activity of Doxil in patients with ovarian cancer and explores activity in other gynecologic cancers.

METHODS

Sixty-three patients were treated with Doxil 50 mg/m(2) infused over 1 h; 44 were evaluable. Forty-eight had epithelial ovarian cancer and all received prior treatment with cisplatin and paclitaxel: 27 received two to six prior regimens, 44 were platinum resistant, 21 patients had measurable disease, and 27 had evaluable disease only.

RESULTS

The overall survival of these patients was 10 months (range, 0.25-33); progression-free survival was 3 months (range, 0.25-18). The response rate among those with measurable disease was 19%, with a median duration of 4.5 months (range, 3-12). The response rate of 22 patients with elevated CA-125 was 59%; median duration was 3.5 months (range, 1-12). Also, 27% achieved prolonged stabilization of disease for a median of 7 months (range, 5-18). Overall, treatment was well tolerated in this heavily pretreated population. Grade 3 and 4 toxic effects were: 5 grade 3 stomatitis, 3 grade 3 skin, 1 each grade 4 neutropenia and thrombocytopenia, 5 admits for infection, and no neutropenic fever; nausea and vomiting were uncommon in 204 cycles to ovarian cancer patients.

CONCLUSION

This study demonstrates the activity of Doxil in heavily pretreated patients with ovarian cancer and poor prognostic features and confirms the prolonged responses and favorable toxicity profile. Encouraging findings were also observed in the patients with nonovarian gynecologic cancers.

Report of the international consensus development conference on female sexual dysfunction: definitions and classifications

PURPOSE

Female sexual dysfunction is highly prevalent but not well defined or understood. We evaluated and revised existing definitions and classifications of female sexual dysfunction.

MATERIALS AND METHODS

An interdisciplinary consensus conference panel consisting of 19 experts in female sexual dysfunction selected from 5 countries was convened by the Sexual Function Health Council of the American Foundation for Urologic Disease. A modified Delphi method was used to develop consensus definitions and classifications, and build on the existing framework of the International Classification of Diseases-10 and DSM-IV: Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association, which were limited to consideration of psychiatric disorders.

RESULTS

Classifications were expanded to include psychogenic and organic causes of desire, arousal, orgasm and sexual pain disorders. An essential element of the new diagnostic system is the "personal distress" criterion. In particular, new definitions of sexual arousal and hypoactive sexual desire disorders were developed, and a new category of noncoital sexual pain disorder was added. In addition, a new subtyping system for clinical diagnosis was devised. Guidelines for clinical end points and outcomes were proposed, and important research goals and priorities were identified.

CONCLUSIONS

We recommend use of the new female sexual dysfunction diagnostic and classification system based on physiological as well as psychological pathophysiologies, and a personal distress criterion for most diagnostic categories.

Significance of the nitric oxide cascade in erectile function

In recent years, a significant body of experimental evidence has accumulated implicating nitric oxide as the central component of a novel signal transduction system that functions in the penis to mediate penile erection. The involvement of nitric oxide in erection physiology appears to be quite complex, involving multiple regulatory interactions: this gaseous molecule has been found to trigger several biochemical events that elicit erectile tissue responses, while a host of modulatory factors have been identified that influence its release and action in erectile tissue. Ongoing investigations in nitric oxide biology in other organ systems also suggest mechanisms which, while yet to be fully established in the penis, may operate significantly to determine the role of nitric oxide in this organ. Further elucidation of cellular and molecular interactions involving nitric oxide effects in the penis can be expected to reveal diverse targets that may serve as a basis for novel pharmacotherapeutic strategies for the future management of erectile dysfunction.

Caring for people with HIV in Zambia: are traditional healers and formal health workers willing to work together?

This study of traditional healers and formal health workers determined their knowledge and practices in the field of HIV/AIDS and examined their training needs and attitudes to collaboration, in preparation for planning joint training workshops. Several misconceptions concerning symptoms and transmission of HIV disease were found in both groups, particularly among traditional healers. Twenty healers (51%) and four formal health workers (15%) claimed a cure existed for AIDS. The majority of traditional healers interviewed expressed difficulties discussing a diagnosis of HIV directly with patients, mainly due to fear of the patient becoming depressed and suicidal. Most interviewees wanted more training--the majority of traditional healers in recognizing symptoms of HIV/AIDS and their treatment, and the majority of formal health workers in HIV counselling. Most were interested in supplying condoms. Almost all healers and half of the formal health workers were keen to collaborate in training and patient care. The study indicates that there is willingness amongst Zambian traditional healers and formal health workers to collaborate in training and patient care in the field of HIV/AIDS. As well as covering symptoms, transmission and prevention of HIV/AIDS, training should aim to increase ability to openly discuss HIV with patients, which many traditional healers and some formal health workers find difficult. Involving traditional healers in supplying condoms may improve acceptability and availability, particularly in rural areas.

In vitro metabolic interaction studies: experience of the Food and Drug Administration

A total of 194 new molecular entities approved by the Food and Drug Administration between 1992 and 1997 were surveyed to determine the role of in vitro metabolic interactions in the conduct of drug-drug interaction studies and to examine the methods used in these studies. Approximately 30% of the submissions were found to have in vitro metabolism-based interaction studies, most of which were inhibitory in nature. Chemical inhibition was the most commonly used approach in studying drug interactions in vitro. In this article, an attempt to assess the quality of the chemical inhibition approach was made. Four areas were found to be often overlooked: (1) incubation time and concentrations of the drug, (2) the difference between inhibition constant (k(i)) and 50% inhibitory concentration (IC50) values, (3) the substrate-dependent inhibition potential, and (4) the metabolic genotype or phenotype of the liver donor. We discuss the pitfalls in estimating drug interactions when these four areas are overlooked.

Identification of the t(15;17) in AML FAB types other than M3: evaluation of the role of molecular screening for the PML/RARalpha rearrangement in newly diagnosed AML. The Medical Research Council (MRC) Adult Leukaemia Working Party

Acute promyelocytic leukaemia (APL) is characterized by the t(15;17) leading to the formation of PML-RARalpha and RARalpha-PML fusion genes; this rearrangement has been considered both diagnostic for, and restricted to, this subtype of acute myeloid leukaemia (AML FAB M3). We describe two cases of AML with the t(15;17) associated with a PML/RARalpha rearrangement which lacked typical APL morphology, classified as FAB M1 and M2 respectively. In both cases morphological review revealed small populations of cells which exhibited some features associated with APL. In the case classified as M1, PML immunofluorescence studies revealed the classic microparticulate nuclear staining pattern as observed in typical cases of APL with the t(15;17). Similarly, blasts from this case were found to be sensitive to ATRA in vitro as determined by NBT reduction test and by normalization of the PML nuclear body staining pattern. To determine the frequency of PML/RARalpha rearrangements in FAB subtypes other than M3, 530 patients from the MRC AML trials were screened using nested RT-PCR. Only one individual, initially classified as M5 with a normal karyotype, was found to have a PML/RARalpha rearrangement. The diagnosis was revised to M3 variant on subsequent morphological review. In conclusion, this study demonstrates that, in rare cases, the t(15;17) is not restricted to patients with M3 morphology as defined by current FAB criteria. Therefore, although we consider cytogenetic analysis of newly diagnosed cases of AML to be mandatory, our data suggests that routine molecular screening for PML/RARalpha rearrangements is not justified and should be reserved for those cases displaying features which may be suspicious of APL even if such cells comprise only a minority of the total population.

The importance of diagnostic cytogenetics on outcome in AML: analysis of 1,612 patients entered into the MRC AML 10 trial. The Medical Research Council Adult and Children's Leukaemia Working Parties

Cytogenetics is considered one of the most valuable prognostic determinants in acute myeloid leukemia (AML). However, many studies on which this assertion is based were limited by relatively small sample sizes or varying treatment approach, leading to conflicting data regarding the prognostic implications of specific cytogenetic abnormalities. The Medical Research Council (MRC) AML 10 trial, which included children and adults up to 55 years of age, not only affords the opportunity to determine the independent prognostic significance of pretreatment cytogenetics in the context of large patient groups receiving comparable therapy, but also to address their impact on the outcome of subsequent transplantation procedures performed in first complete remission (CR). On the basis of response to induction treatment, relapse risk, and overall survival, three prognostic groups could be defined by cytogenetic abnormalities detected at presentation in comparison with the outcome of patients with normal karyotype. AML associated with t(8;21), t(15;17) or inv(16) predicted a relatively favorable outcome. Whereas in patients lacking these favorable changes, the presence of a complex karyotype, -5, del(5q), -7, or abnormalities of 3q defined a group with relatively poor prognosis. The remaining group of patients including those with 11q23 abnormalities, +8, +21, +22, del(9q), del(7q) or other miscellaneous structural or numerical defects not encompassed by the favorable or adverse risk groups were found to have an intermediate prognosis. The presence of additional cytogenetic abnormalities did not modify the outcome of patients with favorable cytogenetics. Subgroup analysis demonstrated that the three cytogenetically defined prognostic groups retained their predictive value in the context of secondary as well as de novo AML, within the pediatric age group and furthermore were found to be a key determinant of outcome from autologous or allogeneic bone marrow transplantation (BMT) in first CR. This study highlights the importance of diagnostic cytogenetics as an independent prognostic factor in AML, providing the framework for a stratified treatment approach of this disease, which has been adopted in the current MRC AML 12 trial.

Characterization of cryptic rearrangements and variant translocations in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is typified by the reciprocal translocation, t(15; 17)(q22; q21), leading to the formation of PML-RARalpha and RARalpha-PML fusion genes. We have characterized 7 cases of morphologic APL found to lack the t(15; 17) on conventional cytogenetic assessment. In 6 of 7 cases, cryptic PML-RARalpha rearrangements were identified by reverse transcriptase-polymerase chain reaction and fluorescent in situ hybridization (FISH); whereas, in the remaining patient, APL was associated with the variant translocation, t(11; 17)(q23; q12-21), leading to the formation of PLZF-RARalpha and RARalpha-PLZF fusion genes. In each of the cases with cryptic PML-RARalpha rearrangements, PML-RARalpha transcripts were detected in the absence of RARalpha-PML, consistent with the concept that PML-RARalpha is the critical oncogenic fusion protein. In 4 of these cases with evaluable metaphase spreads, the occurrence of a nonreciprocal translocation was confirmed by FISH with sole formation of the PML-RARalpha fusion gene; in 3 cases with morphologically normal chromosomes 15 and 17, RARalpha was inserted into PML on 15q, whereas in the remaining patient the PML-RARalpha fusion arose due to insertion of 15q-derived material including PML into RARalpha on 17q. Immunofluorescence studies were performed using antibodies raised against PML and PIC 1, a ubiquitin-homology domain protein previously identified as an interaction partner of PML. In acute myeloid leukemia (AML) of subtypes other than M3, PIC 1 was localized to the nuclear membrane and colocalized with PML within discrete nuclear bodies. In APL cases with cryptic PML-RARalpha rearrangements, the characteristic microparticulate pattern of PML staining was detected with partial colocalization with PIC 1, indicative of disruption of the nuclear bodies; whereas in t(11; 17)-associated APL, PML and PIC 1 remained colocalized within discrete nuclear bodies, as observed in non-APL cases. Although deregulation of the putative growth suppressor PML and delocalization of other nuclear body constituents have been advocated to play a key role in the development of t(15; 17)-associated APL, the present study shows that disruption of PML nuclear bodies per se is not a prerequisite for the pathogenesis of APL.

Allelic loss of the FMS gene in acute myeloid leukaemia

The FMS proto-oncogene encodes for the colony stimulating factor-1 receptor expressed on monocytes and B lymphocytes within the peripheral blood system. Allelic loss of the FMS gene occurs in patients with refractory anaemia and the 5q- syndrome associated with the myelodysplastic syndromes. To determine the frequency of FMS gene loss in patients with myeloid malignancy, 50 DNA samples from patients with acute myeloid leukaemia (AML) and 30 samples from haematologically normal samples were analysed using a quantitative Southern blotting technique. Allelic loss of one allele (hemizygous) was detected in five of 18 samples of AM-M4 and eight of 27 samples of AML M1, M2 and M3. In addition, loss of both FMS alleles (homozygous) was demonstrated in three of 18 samples of AML M4 and 0127 samples of AML M1, M2 and M3. One patient with AML M5 and one with AML M6 were assessed although no allelic loss of FMS was detected. Three samples from patients with secondary AML were also analysed and hemizygous loss was detected in one case. Homozygous or hemizygous loss of FMS was not detected in any of 30 DNA samples isolated from haematologically normal individuals. These data indicate that loss of the FMS gene is common in AML, with an increased frequency in those patients with AML subtype M4.

What happens subsequently in AML when cytogenetic abnormalities persist at bone marrow harvest? Results of the 10th UK MRC AML trial. Medical Research Council Leukaemia Working Parties

Cytogenetic analysis performed at diagnosis is widely recognised to provide one of the most valuable prognostic indicators in AML. Yet any role for this technique in residual disease assessment, particularly in the context of subsequent transplantation procedures has been incompletely explored. The present study considers the outcome of 190 patients drawn from the UK MRC AML 10 trial in whom cytogenetics were assessed whilst in morphological CR at the time of bone marrow harvest. Cytogenetics at this stage were abnormal in 19 patients (10%). In 11/19 patients, the abnormalities detected reflected the acquisition of new clonal (3/11) or nonclonal changes (8/11) that were not identified at diagnosis; comparison of this group to patients with normal cytogenetics at harvest provided no evidence that such acquired changes are of prognostic significance. In 8/19 patients, abnormalities detected were indicative of persistence of the disease-related clone in harvested marrow. Two of these patients died of sepsis during consolidation therapy. Two received ABMT in first morphological CR: one patient with AML associated with a favourable karyotype (+8,inv(16)) remains in CR, 5.5 years post-transplant, whereas the other with cytogenetic abnormalities considered to confer a poor prognosis (inv(3q),-7), relapsed within 5 months of ABMT. All four of the remaining patients with cytogenetic evidence of persistent disease who were not transplanted in first CR, relapsed within 6.5 months of harvest. Therefore, among 101 of 190 patients with AML characterised by abnormal karyotype at diagnosis, persistence of the disease-related clone in eight patients (8%), revealed by conventional cytogenetic assessment at bone marrow harvest whilst in morphological remission, was found to predict a poor prognosis. Nevertheless, transplantation procedures using marrow which is obviously contaminated with the original leukaemic clone may occasionally still be associated with long-term survival.

Phase II study of liposomal doxorubicin in refractory ovarian cancer: antitumor activity and toxicity modification by liposomal encapsulation

PURPOSE

A phase II study of liposomal doxorubicin was conducted in patients with ovarian cancer who failed to respond to platinum- and paclitaxel-based regimens. Liposomal doxorubicin was selected as a result of its superior activity against ovarian cancer xenografts relative to free doxorubicin and activity in refractory ovarian cancer patients that was noted during the phase I study.

PATIENTS AND METHODS

Thirty-five consecutive patients were accrued in two institutions (22 in one and 13 in the other). All had progressive disease after either cisplatin or carboplatin and paclitaxel, or at least one platinum-based and one paclitaxel-based regimen. Patients received intravenous (I.V.) liposomal doxorubicin 50 mg/m2 every 3 weeks with a dose reduction to 40 mg/m2 in the event of grade 3 or 4 toxicities, or a lengthening of the interval to 4 weeks (and occasionally to 5 weeks) with persistence of grade 1 or 2 toxicities beyond 3 weeks.

RESULTS

Nine clinical responses (one complete response [CR], eight partial responses [PRs]) were observed in 35 patients (25.7%), with seven of these having been confirmed by two consecutive computed tomographic (CT) measurements. The median progression-free survival was 5.7 months with an overall survival of 1.5 to 24+ months (median, 11 months). Although 13 patients experienced grade 3 or 4 nonhematologic skin and mucosal toxicities (either hand-foot syndrome or stomatitis), with dose modifications, the treatment was very well tolerated. Nausea that was clearly attributable to the drug, hair loss, extravasation necrosis, or decreases in ejection fraction did not occur.

CONCLUSION

Liposomal doxorubicin has substantial activity against ovarian cancer refractory to platinum and paclitaxel. The responses achieved with liposomal doxorubicin were durable and maintained with minimal toxicity. This liposomal formulation should be evaluated further in combination with other drugs in less refractory patients.

Influence of genetic predisposition to thrombosis on natural history of acute promyelocytic leukaemia. MRC Adult Leukaemia Working Party

There is currently no means of identifying the subgroup of APL patients who will succumb to haemorrhagic or thrombotic complications. We have investigated factor V Leiden and thermolabile methylene tetrahydrofolate reductase (MTHFR) to determine whether these are of predictive value for thrombosis in the context of APL. Of 48 patients drawn from the MRC ATRA trial, two were heterozygous for factor V Leiden (allele frequency 2.1%). 10 homozygotes and 17 heterozygotes for thermolabile MTHFR were identified (allele frequency 38.5%). Amongst these patients, one thrombosis occurred (thermolabile MTHFR heterozygote). In the group with no identified increased thrombotic risk, three episodes were recorded. This approach failed to predict thrombotic events in APL, although the exact implications of specific genotypes remain to be established by larger studies.

Variation in measurement of ankle-brachial pressure index in routine clinical practice

PURPOSE

The purpose of this study was to determine the variation in ankle-brachial pressure index (ABPI) measurements in routine clinical practice.

METHODS

Analysis was done of preoperative and postoperative ABPIs in 130 limbs contralateral to those undergoing femoral bypass grafting in 123 patients over a 15-month period.

RESULTS

The mean initial ABPI was 0.72 (range 0.22 to 1.10). The range of observed differences between the preoperative and postoperative ABPIs was from -0.33 to +0.25. The mean (+/-SD) difference between the first and second ABPIs was 0.00 (+/-0.11). The 95% confidence limits of the difference were -0.21 to 0.21. There was no trend for the size or direction of the difference in ABPI to vary according to the mean ABPI, brachial blood pressure, or time between tests.

CONCLUSIONS

ABPI is routinely used as an objective measure of peripheral vascular disease. The variation observed in this study is comparable with values obtained in reproducibility studies and is greater than that accepted in clinical practice. The difference between an ABPI measurement and the actual ABPI and the difference between repeat single measurements are not the same and should be distinguished. Vascular laboratories should determine the accuracy of ABPI measurement on a local basis to guarantee and maintain quality assurance.

Establishing the presence of the t(15;17) in suspected acute promyelocytic leukaemia: cytogenetic, molecular and PML immunofluorescence assessment of patients entered into the M.R.C. ATRA trial. M.R.C. Adult Leukaemia Working Party

Detection of the t(15;17) or its molecular consequence, the PML-RAR alpha rearrangement, is critical for meaningful analysis of clinical trials involving patients with suspected acute promyelocytic leukaemia (APL). Its presence remains the best predictor of a favourable response to retinoids, such as ATRA, which in combination with chemotherapy confer significant improvements in disease-free survival. We have evaluated the relative efficacy of RT-PCR, cytogenetics and PML immunofluorescence staining to identify the existence of the translocation in 100 patients entered into the Medical Research Council (M.R.C.) ATRA trial. RT-PCR successfully identified PML-RAR alpha rearrangements in 93/100 patients, including 65 where only peripheral blood or post-induction marrow samples were available for analysis and in 12 patients in whom cytogenetic assessment failed to demonstrate t(15;17) due to poor-quality metaphases (10/12) or as a reflection of cryptic PML-RAR alpha rearrangements (2/12). Parallel employment of the RAR alpha-PML assay confirmed expression of del(17q)-derived transcripts in 81% and permitted determination of the PML breakpoint (a potential independent prognostic variable) in all 93 cases. Sequencing of RT-PCR products derived from 50 patients with 3' PML breakpoints revealed five bcr 2 cases, including a novel exon 5 breakpoint. 35/81 (43%) patients with cytogenetic evidence of t(15;17) possessed additional karyotypic abnormalities. In four patients with available buffy coat smears, lack of cytogenetic or molecular evidence of the t(15;17) was confirmed by a wild-type PML immunofluorescence nuclear staining pattern, in contrast to the characteristic microparticulate distribution detected in 14 patients with RT-PCR evidence of the rearrangement. However, although PML immunofluorescence staining is suitable for rapid determination of patients likely to benefit from ATRA, this approach does not obviate the need for cytogenetic and RT-PCR analysis of all patients entered into APL clinical trials, because both techniques provide additional information which may prove to be of independent prognostic significance.