Processing two-dimensional X-ray diffraction and small-angle scattering data in DAWN 2.

A software package for the calibration and processing of powder X-ray diffraction and small-angle X-ray scattering data is presented. It provides a multitude of data processing and visualization tools as well as a command-line scripting interface for on-the-fly processing and the incorporation of complex data treatment tasks. Customizable processing chains permit the execution of many data processing steps to convert a single image or a batch of raw two-dimensional data into meaningful data and one-dimensional diffractograms. The processed data files contain the full data provenance of each process applied to the data. The calibration routines can run automatically even for high energies and also for large detector tilt angles. Some of the functionalities are highlighted by specific use cases.

Survival follow-up and ipilimumab retreatment of patients with advanced melanoma who received ipilimumab in prior phase II studies.

BACKGROUND: This report provides a survival update at a follow-up of >5 years (5.5-6 years) for patients with advanced melanoma who previously received ipilimumab in phase II clinical trials. Safety and efficacy data following ipilimumab retreatment are also reported. PATIENTS AND METHODS: Patients who previously received ipilimumab 0.3, 3, or 10 mg/kg in one of six phase II trials (CA184-004, CA184-007, CA184-008, CA184-022, MDX010-08, and MDX010-15) were eligible to enroll in the companion study, CA184-025. Upon enrollment, patients initially received ipilimumab retreatment, extended maintenance therapy, or were followed for survival only. Overall survival (OS) rates were evaluated in patients from studies CA184-004, CA184-007, CA184-008, and CA184-022. Safety and best overall response during ipilimumab retreatment at 10 mg/kg were assessed in study CA184-025. RESULTS: Five-year OS rates for previously treated patients who received ipilimumab induction at 0.3, 3, or 10 mg/kg were 12.3%, 12.3%-16.5%, and 15.5%-28.4%, respectively. Five-year OS rates for treatment-naive patients who received ipilimumab induction at 3 or 10 mg/kg were 26.8% and 21.4%-49.5%, respectively. Little to no change in OS was observed from year 5 up to year 6. The objective response rate among retreated patients was 23%. Grade 3/4 immune-related adverse events occurred in 25%, 5.9%, and 13.2% of retreated patients who initially received ipilimumab 0.3, 3, and 10 mg/kg, with the most common being observed in the skin (4.2%, 2.9%, 3.8%) and gastrointestinal tract (12.5%, 2.9%, 3.8%), respectively. CONCLUSIONS: At a follow-up of 5-6 years, ipilimumab continues to demonstrate durable, long-term survival in a proportion of patients with advanced melanoma. In some patients, ipilimumab retreatment can re-establish disease control with a safety profile that is comparable with that observed during ipilimumab induction. Further studies are needed to determine the contribution of ipilimumab retreatment to OS. CLINICALTRIALSGOV: NCT00162123.

Efficacy and safety of ipilimumab monotherapy in patients with pretreated advanced melanoma: a multicenter single-arm phase II study.

BACKGROUND: This phase II study evaluated the safety and activity of ipilimumab, a fully human mAb that blocks cytotoxic T-lymphocyte antigen-4, in patients with advanced melanoma. PATIENTS AND METHODS: Patients with previously treated, unresectable stage III/stage IV melanoma received 10 mg/kg ipilimumab every 3 weeks for four cycles (induction) followed by maintenance therapy every 3 months. The primary end point was best overall response rate (BORR) using modified World Health Organization (WHO) criteria. We also carried out an exploratory analysis of proposed immune-related response criteria (irRC). RESULTS: BORR was 5.8% with a disease control rate (DCR) of 27% (N = 155). One- and 2-year survival rates (95% confidence interval) were 47.2% (39.5% to 55.1%) and 32.8% (25.4% to 40.5%), respectively, with a median overall survival of 10.2 months (7.6-16.3). Of 43 patients with disease progression by modified WHO criteria, 12 had disease control by irRC (8% of all treated patients), resulting in a total DCR of 35%. Adverse events (AEs) were largely immune related, occurring mainly in the skin and gastrointestinal tract, with 19% grade 3 and 3.2% grade 4. Immune-related AEs were manageable and generally reversible with corticosteroids. CONCLUSION: Ipilimumab demonstrated clinical activity with encouraging long-term survival in a previously treated advanced melanoma population.

Experimental simulation of cat electromyogram: evidence for algebraic summation of motor-unit action-potential trains.

Prompted by the observation that the slope of the relationship between average rectified electromyography (EMG) and the ensemble activation rate of a pool of motor units progressively decreased (showing a downward nonlinearity), an experimental study was carried out to test the widely held notion that the EMG is the simple algebraic sum of motor-unit action-potential trains. The experiments were performed on the cat soleus muscle under isometric conditions, using electrical stimulation of alpha-motor axons isolated in ventral root filaments. The EMG signals were simulated experimentally under conditions where the activation of nearly the entire pool of motor units or of subsets of motor units was completely controlled by the experimenter. Sets of individual motor units or of small groups of motor units were stimulated independently, using stimulation profiles that were strictly repeatable between trials. This permitted a rigorous quantitative comparison of EMGs that were recorded during combined activation of multiple motor filaments with EMGs that were synthesized from the algebraic summation of motor unit action potential trains generated by individual nerve filaments. These were recorded separately by individually stimulating the same filaments with the same activation profiles that were employed during combined stimulation. During combined activation of up to 10 motor filaments, experimentally recorded and computationally synthesized EMGs were virtually identical. This indicates that EMG signals indeed are the outcome of the simple algebraic summation of motor-unit action-potential trains generated by concurrently active motor units. For both recorded and synthesized EMGs, it was confirmed that EMG magnitude increased nonlinearly with the ensemble activation rate of a pool of motor units. The nonlinearity was largely abolished when EMG magnitude was estimated as the sum of rectified, instead of raw, motor-unit action-potential trains. This suggests that the downward nonlinearity in the EMG-ensemble activation rate relation is due to signal cancellation arising from the perfectly linear summation of positive and negative components of action-potential waveforms. The findings provide a much needed post hoc validation of the concept of EMG generation by strict algebraic summation of motor unit action potentials that is generally relied on in theoretical modeling studies of EMG and in EMG decomposition algorithms.

Molecular detection of metastatic melanoma cells in cerebrospinal fluid in melanoma patients.

Melanoma frequently metastasizes to the central nervous system (CNS). The diagnosis of CNS metastases typically is made following the onset of clinical symptoms. Thus, more sensitive diagnostic approaches are needed to identify subclinical CNS metastases. Currently, standard cytologic analysis of the cerebrospinal fluid (CSF) is limited by its poor sensitivity. A more sensitive assay was therefore developed using multiple reverse transcriptase-polymerase chain reaction (RT-PCR) markers. CSF was collected and assessed by RT-PCR for three known melanoma-associated markers (MAGE-3, MART-1, and tyrosinase) to detect occult metastatic melanoma cells in the CSF of 37 American Joint Committee on Cancer (AJCC) stage IV melanoma patients. Cytologic analysis of CSF was performed on all patients, and immunohistochemistry (IHC) analysis was performed on 33 CSF samples using anti-S100 and anti-HMB-45 antibodies. Only one patient (3%) had tumor-positive CSF cytology and IHC upon entry into the study, whereas 12 patients (32%) were positive for at least one RT-PCR marker. The correlation between CSF RT-PCR positivity of MART-1 and/or MAGE-3 and the development of CNS metastases at 3 mo was significant (p = 0.04). Fifteen of 37 patients (41%) had either positive MRI and/or positive RT-PCR results. Multimarker RT-PCR is more informative and sensitive than cytology/IHC in assessing the CSF of melanoma patients.

High-dose tamoxifen added to concurrent biochemotherapy with decrescendo interleukin-2 in patients with metastatic melanoma.

BACKGROUND: In vitro cell culture data and preclinical models suggest that tamoxifen modulates tumor cell sensitivity to a wide range of therapeutic agents. In the current study, the authors examined whether high-dose tamoxifen (HDT) improved the overall and complete response in patients with metastatic melanoma who were treated with concurrent biochemotherapy. METHODS: Forty-nine patients were treated with a biochemotherapy regimen of dacarbazine, vinblastine, cisplatin, decrescendo interleukin-2, interferon-alpha-2b, and tamoxifen. The study had a 2-step design, beginning with a tamoxifen dose escalation from 40 mg to 320 mg (17 subjects) to evaluate safety and tolerability, followed by Phase II accrual of 32 patients to HDT (320 mg) to assess clinical efficacy. Efficacy was compared with a similar modified biochemotherapy regimen with low-dose tamoxifen (LDT). Pharmacokinetic studies were performed to determine in vivo tamoxifen levels. RESULTS: Tamoxifen dose escalation was completed without any reported dose-limiting toxicity. The overall response rate in the HDT group was 50% (95% confidence interval, 33.2%-66.8%), with a complete response rate of 6% and a median survival of 9.5 months. The overall response rate was not improved and the complete response and survival appeared inferior compared with that of patients recently treated with concurrent biochemotherapy and LDT. Serum tamoxifen levels were found to correlate with the dose administered, with a mean of 0.9 microM at the 40-mg dose to 4.6 microM at the 320-mg dose. Ultrafiltered protein-free sera demonstrated low (< 0.01 microM) concentrations of tamoxifen. CONCLUSIONS: The addition of HDT to a regimen of concurrent biochemotherapy did not appear to improve response rates or overall survival, despite reaching the targeted plasma concentration. Unknown drug interactions or high protein binding of tamoxifen may account for the lack of clinical effectiveness.

A new method for experimental simulation of EMG using multi-channel independent stimulation of small groups of motor units.

The experimental simulation method was based upon the separate activation of up to 10 small groups of motor units (MU) in an acute nerve-muscle preparation. The investigator was able to precisely control and systematically alter the features of MU pool activation strategies. No implicit assumptions were made regarding MU properties. The purpose of this study was to evaluate the validity of this method. Three criteria were formulated and found to be satisfied: First, in the time domain, visual and audio displays of simulated EMG were indistinguishable from physiological EMG. Secondly, in the frequency domain, power spectra of simulated EMG revealed the typical features of EMG recorded during voluntary activation in the cat. Thirdly, the well-known monotonic relationship between EMG magnitude and force was readily reproduced, although strictly linear relations were not found. In addition, the relationship between the pool's ensemble activation rate and EMG magnitude showed distinct gain compression, mostly attributable to signal cancellation.

Intrathecal treatment of neoplastic meningitis due to breast cancer with a slow-release formulation of cytarabine.

DepoCyte is a slow-release formulation of cytarabine designed for intrathecal administration. The goal of this multi-centre cohort study was to determine the safety and efficacy of DepoCyte for the intrathecal treatment of neoplastic meningitis due to breast cancer. DepoCyte 50 mg was injected once every 2 weeks for one month of induction therapy; responding patients were treated with an additional 3 months of consolidation therapy. All patients had metastatic breast cancer and a positive CSF cytology or neurologic findings characteristic of neoplastic meningitis. The median number of DepoCyte doses was 3, and 85% of patients completed the planned 1 month induction. Median follow up is currently 19 months. The primary endpoint was response, defined as conversion of the CSF cytology from positive to negative at all sites known to be positive, and the absence of neurologic progression at the time the cytologic conversion was documented. The response rate among the 43 evaluable patients was 28% (CI 95%: 14-41%); the intent-to-treat response rate was 21% (CI 95%: 12-34%). Median time to neurologic progression was 49 days (range 1-515(+)); median survival was 88 days (range 1-515(+)), and 1 year survival is projected to be 19%. The major adverse events were headache and arachnoiditis. When drug-related, these were largely of low grade, transient and reversible. Headache occurred on 11% of cycles; 90% were grade 1 or 2. Arachnoiditis occurred on 19% of cycles; 88% were grade 1 or 2. DepoCyte demonstrated activity in neoplastic meningitis due to breast cancer that is comparable to results reported with conventional intrathecal agents. However, this activity was achieved with one fourth as many intrathecal injections as typically required in conventional therapy. The every 2 week dose schedule is a major advantage for both patients and physicians.

The clinical utility of multimarker RT-PCR in the detection of occult metastasis in patients with melanoma.

Cutaneous melanoma is characterized by a high propensity for metastasis. Currently, surgical intervention remains the mainstay of therapy. This approach has proven most beneficial when the diagnosis is of early stage primary lesions. Likewise, patients undergoing resection for a solitary site of metastasis have shown a survival advantage. Identification of metastatic disease depends predominantly on radiographic techniques requiring the presence of significant tumor burdens for successful imaging. However, at that time, the role of surgery and/or biochemotherapy may be of limited value. Techniques to identify minimal disease states may permit more accurate assessment of prognosis. The detection of occult tumor cells by RT-PCR in the blood, lymph nodes, and bone marrow of melanoma patients provides one such approach to monitor tumor progression. Single-marker RT-PCR has been used as one such approach but is noted to have limitations in sensitivity and specificity based on the heterogeneity of tumor marker expression among tumors as well as within an individual tumor lesion or among multiple lesions in individual patients. We employed a multimarker reverse transcriptase polymerase chain reaction assay that demonstrates improved sensitivity over a single-marker approach. Currently, the consequences of detecting systemic subclinical metastasis remain unknown pending longer-term follow-up. The detection of occult melanoma cells using molecular techniques in conjunction with known clinicopathologic prognostic factors may provided a novel and efficient approach in monitoring tumor progression and further identify high-risk patients diagnosed early in the disease course.

Measuring dimensions: the regulation of size and shape.

Over many years evidence has accumulated that plants and animals can regulate growth with reference to overall size rather than cell number. Thus, organs and organisms grow until they reach their characteristic size and shape and then they stop - they can even compensate for experimental manipulations that change, over several fold, cell number or average cell size. If the cell size is altered, the organism responds with a change in cell number and vice versa. We look at the Drosophila wing in more detail: here, both extracellular and intracellular regulators have been identified that link cell growth, division and cell survival to final organ size. We discuss a hypothesis that the local steepness of a morphogen gradient is a measure of length in one axis, a measure that is used to determine whether there will be net growth or not.

Advantages of concurrent biochemotherapy modified by decrescendo interleukin-2, granulocyte colony-stimulating factor, and tamoxifen for patients with metastatic melanoma.

PURPOSE: Concurrent biochemotherapy results in high response rates but also significant toxicity in patients with metastatic melanoma. We attempted to improve its efficacy and decrease its toxicity by using decrescendo dosing of interleukin-2 (IL-2), posttreatment granulocyte colony-stimulating factor (G-CSF), and low-dose tamoxifen. PATIENTS AND METHODS: Forty-five patients with poor prognosis metastatic melanoma were treated at a community hospital inpatient oncology unit affiliated with the John Wayne Cancer Institute (Santa Monica, CA) between July 1995 and September 1997. A 5-day modified concurrent biochemotherapy regimen of dacarbazine, vinblastine, cisplatin, decrescendo IL-2, interferon alfa-2b, and tamoxifen was repeated at 21-day intervals. G-CSF was administered beginning on day 6 for 7 to 10 days. RESULTS: The overall response rate was 57% (95% confidence interval, 42% to 72%), the complete response rate was 23%, and the partial response rate was 34%. Complete remissions were achieved in an additional 11% of patients by surgical resection of residual disease after biochemotherapy. The median time to progression was 6.3 months and the median duration of survival was 11.4 months. At a maximum follow-up of 36 months (range, 10 to 36 months), 32% of patients are alive and 14% remain free of disease. Decrescendo IL-2 dosing and administration of G-CSF seemed to reduce toxicity, length of hospital stay, and readmission rates. No patient required intensive care unit monitoring, and there were no treatment-related deaths. CONCLUSION: The data from this study indicate that the modified concurrent biochemotherapy regimen reduces the toxicity of concurrent biochemotherapy with no apparent decrease in response rate in patients with poor prognosis metastatic melanoma.

Evaluation of the genotoxicity of 2,4-dichlorophenoxyacetic acid and its derivatives in mammalian cell cultures.

2,4-dichlorophenoxyacetic acid and its derivatives (collectively known as 2,4-D) are herbicides used to control a wide variety of broadleaf and woody plants. The genetic toxicity of an ester (2,4-D 2-butoxyethylester) and two salts (2,4-D isopropylamine and 2,4-D triisopropanolamine) was investigated in cultured mammalian cells. The end points used were the induction of chromosomal aberrations in primary cultures of rat lymphocytes and forward mutations at the HGPRT locus of Chinese hamster ovary cells. There was no evidence of genotoxicity for the test materials in the experimental systems used. These results were consistent with the general lack of genotoxic potential for 2,4-D in a number of other test systems.

Gamma knife radiosurgery for metastatic melanoma: an analysis of survival, outcome, and complications.

OBJECTIVE: Although the mainstays for treatment of metastatic brain disease have been surgery and/or external beam radiation therapy, an increasing number of patients are being referred for stereotactic radiosurgery as the primary intervention for their intracranial pathological abnormalities. The lack of efficacy and cognitive and behavioral consequences of whole brain irradiation have prompted clinicians to select patients for alternative therapies. This study analyzes the effectiveness of Leksell gamma unit therapy for metastatic melanoma to the brain. METHODS: We present our experience with 59 Leksell gamma unit treatment sessions in 45 consecutive patients who presented with metastatic melanoma to the brain. Five of these procedures were performed as salvage therapy for patients who needed second radiosurgical treatment for new lesions that were remote from the previous targets and were not included in the overall analyses. RESULTS: The population included 78% male patients. The mean patient age was 53 years (age range, 24-80 yr). The mean time from diagnosis of primary melanoma to discovery of brain metastasis was 43 months (median, 27.5 mo; range, 1-180 mo). At the time of diagnosis of brain disease, 35.5% of the patients (16 of 45 patients) had neurological symptoms, 77.7% (35 of 45 patients) had known visceral metastases, and 11.1% (5 of 45 patients) had seizure disorders. Eighty-six percent of the lesions (80 of 93 lesions) were cortical, 12% (11 of 93 lesions) were cerebellar, 1% (1 of 93 lesions) were pontine, and 1% (1 of 93 lesions) were thalamic. Fifty-seven percent of the sessions (31 of 54 sessions) were performed for a single lesion, 24.1% (13 of 54 sessions) for two lesions, 9.2% (5 of 54 sessions) for three lesions, 7.4% (4 of 54 sessions) for four lesions, and 1.8% (1 of 54 sessions) for five lesions. The mean treatment volume was 5.6 cc, with a mean prescription of 21.6 Gy to the 56.0% mean isodose line. The median survival time of the patients in our population, using Kaplan-Meier curves, was 43 months from the time of diagnosis of primary melanoma (range, 3-180 mo) and 8 months (range, 1-20 mo) from the time of gamma knife treatment. Complications included seizures within 24 hours of the procedure in four patients, with transient nausea and vomiting in three patients, transient worsening of preprocedure paresis responsive to steroids in three patients, and increased confusion in one patient. All 45 patients were located for follow-up (mean follow-up duration, 1 yr). After gamma knife treatment, 78% of the patients (35 of 45 patients) experienced either improved or stable neurological symptomatology before death or at the time of the latest follow-up examination. There were 26 deaths (58%). The cause of death was determined to be neurological in only 2 of 45 patients (7.7%). Follow-up magnetic resonance images revealed a 97% local tumor control rate of gamma knife-treated lesions, with 28% radiographic disappearance (9 of 32 cases). Six patients developed new lesions remote from radiosurgical targets and underwent second procedures. CONCLUSION: Although metastatic melanoma to the brain continues to have a foreboding prognosis for long-term survival, gamma knife radiosurgery seems to be a relatively safe, noninvasive, palliative therapy, halting or reversing neurological progression in 77.8% of treated patients (35 of 45 patients). The survival rate matches or exceeds those previously reported for surgery and other forms of radiotherapy. Only 7.7% of the patients in our study population who died as a result of metastatic melanoma (2 of 26 patients) died as a result of neurological disease. The routine use of therapeutic level antiseizure medication is emphasized, considering the findings of our review.

Relationship between cancer patients' predictions of prognosis and their treatment preferences.

CONTEXT: Previous studies have documented that cancer patients tend to overestimate the probability of long-term survival. If patient preferences about the trade-offs between the risks and benefits associated with alternative treatment strategies are based on inaccurate perceptions of prognosis, then treatment choices may not reflect each patient's true values. OBJECTIVE: To test the hypothesis that among terminally ill cancer patients an accurate understanding of prognosis is associated with a preference for therapy that focuses on comfort over attempts at life extension. DESIGN: Prospective cohort study. SETTING: Five teaching hospitals in the United States. PATIENTS: A total of 917 adults hospitalized with stage III or IV non-small cell lung cancer or colon cancer metastatic to liver in phases 1 and 2 of the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT). MAIN OUTCOME MEASURES: Proportion of patients favoring life-extending therapy over therapy focusing on relief of pain and discomfort, patient and physician estimates of the probability of 6-month survival, and actual 6-month survival. RESULTS: Patients who thought they were going to live for at least 6 months were more likely (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.8-3.7) to favor life-extending therapy over comfort care compared with patients who thought there was at least a 10% chance that they would not live 6 months. This OR was highest (8.5; 95% CI, 3.0-24.0) among patients who estimated their 6-month survival probability at greater than 90% but whose physicians estimated it at 10% or less. Patients overestimated their chances of surviving 6 months, while physicians estimated prognosis quite accurately. Patients who preferred life-extending therapy were more likely to undergo aggressive treatment, but controlling for known prognostic factors, their 6-month survival was no better. CONCLUSIONS: Patients with metastatic colon and lung cancer overestimate their survival probabilities and these estimates may influence their preferences about medical therapies.

Dominant lethal test with rats exposed to 1,3-dichloropropene by inhalation.

The potential of 1,3-dichloropropene (1,3-DCP) to induce dominant lethal mutations in the germ cells of male CD rats following inhalation exposure was investigated. Groups of 11-week-old males (30 animals/group) were exposed to 1,3-DCP vapors by inhalation at targeted concentrations of 0 (negative control), 10, 60, and 150 ppm for 10 weeks (6 hr/day, 7 days/week). An additional group of 30 males (designated the pairfed group) was kept on dietary restriction for 10 weeks. This group served as a control for any effects of decreased feed consumption and the associated body weight loss on the dominant lethal indices in the males exposed to 1,3-DCP. At the termination of the exposures, each male was cohoused with naive adult virgin CD females for two consecutive mating trials (1 week/trial, 2 females/male). Females were necropsied 13 days after the conclusion of each weekly mating trial and the number of corpora lutea, live implantations, and resorptions were determined. There were no statistically significant increases in either the pre- or postimplantation embryonic/fetal loss in females mated with 1,3-DCP-exposed males relative to controls at any weekly mating period. Based on these results, it can be concluded that 1,3-DCP is not mutagenic to the male germ cells of CD rats at exposure levels < or = 150 ppm, the highest concentration tested.

Der(16)t(1;16)(q21;q13) as a secondary structural aberration in yet a third sarcoma, extraskeletal myxoid chondrosarcoma.

Cytogenetic analysis of an extraskeletal myxoid chondrosarcoma revealed a der(16)t(1;16)(q21;q13) in addition to the t(9;22)(q22;12) described as characteristic for this chondrosarcoma clinicohistopathologic subtype. An identical der(16) has been identified as the most common secondary structural aberration in Ewing's sarcoma and alveolar rhabdomyosarcoma.

Use of confidence intervals and sample size calculations in health economic studies.

OBJECTIVE: To discuss the calculation and application of confidence intervals in pharmacoeconomic studies. DATA SYNTHESIS: The increasing frequency with which pharmacoeconomic evaluations are made within clinical trials makes it possible to obtain information on the outputs and costs of an intervention in each patient of a sample under study. This allows the same statistical principles commonly used in clinical trials to be applied to cost or cost-effectiveness data. The methodology described in this article would allow expression of cost-effectiveness ratios in the form of confidence intervals. The calculation of the cost-effectiveness ratio by means of a confidence interval may have important practical consequences, both in decision-making on the choice of 1 intervention versus another and in calculating the size of the sample necessary to identify statistically significant differences, from both clinical and economic points of view. CONCLUSIONS: The complementary use of confidence intervals and sensitivity analysis makes it possible to measure uncertainty related and unrelated to variability in sample data, allowing the decision to adopt 1 technology or another to be based on the most objective information available. Although several ethical and methodologic concerns remain to be addressed, this methodology may contribute to improving the more rational and efficient use of drugs.

Internal pilot studies for estimating sample size.

We develop the idea of using data from the first 'few' patients entered in a clinical trial to estimate the final trial size needed to have specified power for rejecting H0 in favour of H1 if a real difference exists. When comparing means derived from Normally distributed data, there is no important effect on test size, power or expected trial size, provided that a minimum of about 20 degrees of freedom are used to estimate residual variance. Relative advantages and disadvantages of using larger internal pilot studies are presented. These revolve around crude expectations of the final study size, recruitment rate, duration of follow-up and practical constraints on the ability to prevent the circulation of unblinded randomization codes to investigators and those involved in editing and checking data.