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J Crowley

Publications and source records attributed to J Crowley.

At least 37 records · Page 2Linked to original sources
PubMed1999

Estimation of failure probabilities in the presence of competing risks: new representations of old estimators.

A topic that has received attention in both the statistical and medical literature is the estimation of the probability of failure for endpoints that are subject to competing risks. Despite this, it is not uncommon to see the complement of the Kaplan-Meier estimate used in this setting and interpreted as the probability of failure. If one desires an estimate that can be interpreted in this way, however, the cumulative incidence estimate is the appropriate tool to use in such situations. We believe the more commonly seen representations of the Kaplan-Meier estimate and the cumulative incidence estimate do not lend themselves to easy explanation and understanding of this interpretation. We present, therefore, a representation of each estimate in a manner not ordinarily seen, each representation utilizing the concept of censored observations being 'redistributed to the right.' We feel these allow a more intuitive understanding of each estimate and therefore an appreciation of why the Kaplan-Meier method is inappropriate for estimation purposes in the presence of competing risks, while the cumulative incidence estimate is appropriate.

Confounding Factors, Epidemiologic↗
PubMed1999

Total therapy with tandem transplants for newly diagnosed multiple myeloma.

Between August 1990 and August 1995, 231 patients (median age 51, 53% Durie-Salmon stage III, median serum beta-2-microglobulin 3.1 g/L, median C-reactive protein 4 g/L) with symptomatic multiple myeloma were enrolled in a program that used a series of induction regimens and two cycles of high-dose therapy ("Total Therapy"). Remission induction utilized non-cross-resistant regimens (vincristine-doxorubicin-dexamethasone [VAD], high-dose cyclophosphamide and granulocyte-macrophage colony-stimulating factor with peripheral blood stem cell collection, and etoposide-dexamethasone-cytarabine-cisplatin). The first high-dose treatment comprised melphalan 200 mg/m2 and was repeated if complete (CR) or partial (PR) remission was maintained after the first transplant; in case of less than PR, total body irradiation or cyclophosphamide was added. Interferon--2b maintenance was used after the second autotransplant. Fourteen patients with HLA-compatible donors underwent an allograft as their second high-dose therapy cycle. Eighty-eight percent completed induction therapy whereas first and second transplants were performed in 84% and 71% (the majority within 8 and 15 months, respectively). Eight patients (3%) died of toxicity during induction, and 2 (1%) and 6 (4%) during the two transplants. True CR and at least a PR (PR plus CR) were obtained in 5% (34%) after VAD, 15% (65%) at the end of induction, and 26% (75%) after the first and 41% (83%) after the second transplants (intent-to-treat). Median overall (OS) and event-free (EFS) survival durations were 68 and 43 months, respectively. Actuarial 5-year OS and EFS rates were 58% and 42%, respectively. The median time to disease progression or relapse was 52 months. Among the 94 patients achieving CR, the median CR duration was 50 months. On multivariate analysis, superior EFS and OS were observed in the absence of unfavorable karyotypes (11q breakpoint abnormalities, -13 or 13-q) and with low beta-2-microglobulin at diagnosis. CR duration was significantly longer with early onset of CR and favorable karyotypes. Time-dependent covariate analysis suggested that timely application of a second transplant extended both EFS and OS significantly, independent of cytogenetics and beta-2-microglobulin. Total Therapy represents a comprehensive treatment approach for newly diagnosed myeloma patients, using multi-regimen induction and tandem transplantation followed by interferon maintenance. As a result, the proportion of patients attaining CR increased progressively with continuing therapy. This observation is particularly important because CR is a sine qua non for long-term disease control and, eventually, cure.

Adult↗
PubMed1999

Treatment of poor-prognosis extensive disease small-cell lung cancer with an all-oral regimen of etoposide and cyclophosphamide - a Southwest Oncology Group clinical and pharmacokinetic study.

PURPOSE: An all-oral regimen of etoposide and cyclophosphamide was developed for use in poor-prognosis extensive disease small-cell lung cancer. Limited pharmacokinetic sampling was used to derive a pharmacodynamic model predictive of myelosuppression early in the course of therapy. PATIENTS AND METHODS: Eligible patients were chemotherapy-naive and had extensive disease small-cell lung cancer with either SWOG performance status 2 or serum albumin <3.5 g/dl. The first cohort (n = 18) received etoposide orally at 50 mg daily and cyclophosphamide orally at 50 mg daily days 1-14 every 28 days. Due to good hematologic tolerance, the second cohort (n = 39) received both agents orally at 50 mg twice daily days 1-14 every 28 days. Plasma etoposide levels were determined in samples drawn at baseline, and at 1 h, 2 h, and 23.5 h (trough) after the first dose. Linear regression analysis was used to determine pharmacokinetic and demographic parameters predictive of myelosuppression. RESULTS: A total of 173 treatment cycles were delivered. Patients on the daily regimen had a 22% response rate (complete and partial), a 22% unconfirmed response rate, and a 5-month median survival, while patients on the twice-daily regimen had a 28% response rate (complete and partial), a 13% unconfirmed response rate, and a 7-month median survival. Granulocytopenia and alopecia were the most common toxicities seen. Significant granulocytopenia could be predicted for the twice-daily regimen according to the formula ln(AGC nadir)=7.80 - 1.88(trough), with an increased incidence of granulocytopenia if the etoposide trough value was >/=1.49 microg/ml. CONCLUSION: Oral etoposide and oral cyclophosphamide given days 1-14 every 28 days is well tolerated and results in an acceptable response rate and median survival in poor-prognosis (poor performance status or low serum albumin) extensive disease small-cell lung cancer. A trough etoposide level obtained within 24 h of starting therapy can predict severe granulocytopenia.

Administration, Oral↗
PubMed1999

Adaptive regression splines in the Cox model.

We develop a method for constructing adaptive regression spline models for the exploration of survival data. The method combines Cox's (1972, Journal of the Royal Statistical Society, Series B 34, 187-200) regression model with a weighted least-squares version of the multivariate adaptive regressi on spline (MARS) technique of Friedman (1991, Annals of Statistics 19, 1-141) to adaptively select the knots and covariates. The new technique can automatically fit models with terms that represent nonlinear effects and interactions among covariates. Applications based on simulated data and data from a clinical trial for myeloma are presented. Results from the myeloma application identified several important prognostic variables, including a possible nonmonotone relationship with survival in one laboratory variable. Results are compared to those from the adaptive hazard regression (HARE) method of Kooperberg, Stone, and Truong (1995, Journal of the American Statistical Association 90, 78-94).

Biometry↗
PubMed1998

A Southwest Oncology Group and Cancer and Leukemia Group B phase II study of doxorubicin, dacarbazine, ifosfamide, and mesna in adults with advanced osteosarcoma, Ewing's sarcoma, and rhabdomyosarcoma.

BACKGROUND: Ewing's sarcomas, osteosarcomas, and rhabdomyosarcomas are significantly more responsive to chemotherapy than other sarcomas. Adjuvant chemotherapy is used routinely based on data from randomized trials. Although a percentage of children with locally advanced or metastatic tumors remain curable, few data exist regarding the tumor's natural history or response and survival in adults. METHODS: This Phase II study evaluated doxorubicin, dacarbazine, ifosfamide, and mesna (MAID) in adults with inoperable or metastatic Ewing's sarcoma, rhabdomyosarcoma, or osteosarcoma. RESULTS: Between 1987-1991, 81 patients were entered; 69 patients were eligible. One patient died of neutropenic infection. Ten patients (14%) responded completely and 34 patients (49%) had a complete or partial response. Response rates were significantly higher for patients with Ewing's sarcoma and rhabdomyosarcoma than for those with osteosarcoma (77%, 64%, and 26%, respectively; P < 0.005). Although there were no significant differences in progression free survival by histology, survival for patients with Ewing's sarcoma was significantly longer than for patients with osteosarcoma (P = 0.004.) At the time of last follow-up, 7 patients (10%) were alive without progression: 3 with Ewing's sarcoma, 1 with osteosarcoma, and 3 with rhabdomyosarcoma. CONCLUSIONS: MAID chemotherapy is an active regimen in adults with advanced or metastatic Ewing's sarcoma and rhabdomyosarcoma. Although there was no direct comparison with a doxorubicin and cisplatin-based regimen, the response rate and survival in patients with osteosarcoma suggest that doxorubicin and cisplatin-based chemotherapy would remain the accepted initial chemotherapy regimen. For patients with rhabdomyosarcoma and Ewing's sarcoma, 10-20% of patients remained disease free at 5 years.

Adolescent↗
PubMed1998

Long-term follow-up after high-dose therapy for high-risk multiple myeloma.

Between 1985 and 1990, 133 patients with advanced multiple myeloma (MM) (74% resistance; 41% resistant relapse, RR) were treated with five high-dose therapy (HDT) regimens including: melphalan < or =100 mg/m2 (MEL 100) (46 patients); MEL 100 plus GM-CSF (24 patients); MEL 140 plus autologous bone marrow transplantation (ABMT) (eight patients); MEL 140 plus TBI 850 cGy plus ABMT (37 patients); and thiotepa 750 mg/m2 (THIO 750) + TBI 850 cGy plus ABMT (18 patients). The median follow-up of alive patients as of December 1997 was 9 years. Overall, 17% experienced treatment-related mortality within 60 days (TRM) and 12% achieved stringently defined complete remission (CR) with a median duration of 16 months; four of 16 patients (25%) remain in CR at 10 years. The median durations of event-free survival (EFS)/overall survival (OS) were 6/15 months. Superior EFS/OS were noted with MEL 100 plus GM-CSF and the two TBI-containing regimens (9/24 months among 79 patients) compared to the remaining 54 patients receiving MEL < or =100 or MEL 140 plus ABMT (3/5 months) (P = 0.0001/0.0001, respectively). Multivariate regression analyses (MVA) were performed so that, despite patient heterogeneity among the five treatment groups, potentially relevant disease, host, treatment, and supportive care variables could be identified that were associated with TRM, CR, EFS and OS. TRM was higher with creatinine >2.0 mg/dl, absence of ABMT/GM-CSF support and age >50 years; CR was superior with TBI-containing regimens and < or =12 months of prior therapy; EFS and OS both were longer with B2M < or =2.5 mg/l, age < or =50 years, absence of RR and with ABMT/GM-CSF support. In the presence of >2 favorable variables (32 % of patients), median EFS/OS durations of 18/48 months were observed which progressively declined with 2 and <2 favorable parameters to 6/11 months (28% of patients) to 3/5 months (40% of patients) (P = 0.0001/0.0001). At 10 years, 10 and 20% of patients with >2 favorable variables were event-free and alive, which was also true for the 37 patients receiving MEL 140 plus TBI. To appreciate possible long-term contributions of supportive care or treatment intensity, landmark analyses performed at 1, 2, 4 and 6 months revealed virtually identical ranking orders of prognostically favorable variables to those seen pre-HDT; once supportive care was accounted for, regimen intensity with added TBI did not emerge as an independent favorable feature.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Salvage autologous or allogeneic transplantation for multiple myeloma refractory to or relapsing after a first-line autograft?

Forty-two patients allografted for multiple myeloma after not having attained at least a partial remission (n = 19) or after having experienced disease progression (n = 23) following one autograft were compared with 42 pair-matched controls who underwent salvage autotransplantation under identical conditions. Autografted controls were matched closely for albumin, C-reactive protein, creatinine, disease sensitivity, duration of standard therapy prior to the first transplant, Ig isotype, karyotype, LDH, and response to the first transplant, but, in comparison to allografted patients, were older, had higher beta2-microglobulin, and had a shorter interval between the two transplants. The complete remission rate was 41% after allogeneic and 33% after autologous transplantation (P = NS). The 3-year probability of event-free survival was comparable for the two groups (25 +/- 8% after autografting and 20 +/- 8% after allografting). The 3-year probability of survival was significantly higher after autologous transplantation (54 +/- 8% vs 29 +/- 9%; P = 0.01). Twenty-one patients in the autograft group were alive 11-59 months (median 32) following the second transplant, while 15 patients in the allograft group were alive at 10-53 months (median 20). The 3-year probability of disease progression was significantly lower after allogeneic transplantation (31 +/- 10% vs 72 +/- 9%, P = 0.03). The 1-year probability of transplant-related mortality was significantly higher after allografting (43 +/- 8% vs 10 +/- 5%; P = 0.0001). We conclude that while autografting appears to be superior to allografting for salvage therapy of myeloma persisting or relapsing after one previous autotransplant in terms of overall survival, event-free survival is comparable due to significantly lower disease progression after allografting. Reduction in allograft-related toxicity can potentially improve the results of allogeneic transplantation significantly.

Adult↗
PubMed1998

Increased plasma gln and Leu Ra and inappropriately low muscle protein synthesis rate in AIDS wasting.

Muscle protein wasting occurs in human immunodeficiency virus (HIV)-infected individuals and is often the initial indication of acquired immunodeficiency syndrome (AIDS). Little is known about the alterations in muscle protein metabolism that occur with HIV infection. Nine subjects with AIDS wasting (CD4 < 200/mm3), chronic stable opportunistic infections (OI), and >/=10% weight loss, fourteen HIV-infected men and one woman (CD4 > 200/mm3) without wasting or OI (asymptomatic), and six HIV-seronegative lean men (control) received a constant intravenous infusion of [1-13C]leucine (Leu) and [2-15N]glutamine (Gln). Plasma Leu and Gln rate of appearance (Ra), whole body Leu turnover, disposal and oxidation rates, and [13C]Leu incorporation rate into mixed muscle protein were assessed. Total body muscle mass/fat-free mass was greater in controls (53%) than in AIDS wasting (43%; P = 0.04). Fasting whole body proteolysis and synthesis rates were increased above control in the HIV+ asymptomatic group and in the AIDS-wasting group (P = 0. 009). Whole body Leu oxidation rate was greater in the HIV+ asymptomatic group than in the control and AIDS-wasting groups (P < 0.05). Fasting mixed muscle protein synthesis rate was increased in the asymptomatic subjects (0.048%/h; P = 0.01) but was similar in AIDS-wasting and control subjects (0.035 vs. 0.037%/h). Plasma Gln Ra was increased in AIDS-wasting subjects but was similar in control and HIV+ asymptomatic subjects (P < 0.001). These findings suggest that AIDS wasting results from 1) a preferential reduction in muscle protein, 2) a failure to sustain an elevated rate of mixed muscle protein synthesis while whole body protein synthesis is increased, and 3) a significant increase in Gln release into the circulation, probably from muscle. Several interesting explanations for the increased Gln Ra in AIDS wasting exist.

CD4 Lymphocyte Count↗
PubMed1998

Survival in renal vascular disease.

Renal artery stenosis (RAS) is a relatively uncommon but important potentially reversible cause of renal failure. Little is known about the natural history of ischemic renal disease secondary to RAS. In previous reports, these researchers examined the incidence and risk factors associated with RAS. The study presented here investigates the long-term follow-up of these patients, specifically the effect of RAS on 4-yr, all-cause mortality in a group of 1235 patients undergoing diagnostic cardiac catheterization and abdominal aortography. A total of 1235 consecutive patients undergoing cardiac catheterization also underwent an abdominal flush aortogram. Significant RAS was considered present if one or more renal artery had 50% or greater narrowing in luminal diameter. Four-year unadjusted survival for patients with RAS was 65% compared with 86% for patients undergoing catheterization without significant RAS. Factors associated with decreased 4-yr survival included increased age, increased serum creatinine, presence of RAS, peripheral vascular disease, congestive heart failure, diabetes, hypertension, and reduced ejection fraction. Using the Cox proportional hazards model, the factors associated with decreased 4-yr survival were the presence of significant RAS, reduced ejection fraction, elevated serum creatinine, and symptoms of congestive heart failure. These observations indicate that the presence of significant RAS is a strong independent predictor of 4-yr survival in this patient population.

Age Distribution↗
PubMed1997

Chemoprevention of prostate cancer: the Prostate Cancer Prevention Trial.

BACKGROUND: A variety of innovative approaches to the prevention of prostate cancer are now available, including selenium, alpha tocopherol, dietary interventions, and vitamin D. Perhaps the most promising opportunity is based upon considerable evidence that cumulative androgen exposure of the prostate contributes to the age-related risk of prostate cancer. METHODS: The Prostate Cancer Prevention Trial has completed randomization of over 18,000 healthy men to either finasteride or placebo. CONCLUSIONS: While the primary objective of this study is to determine whether finasteride can reduce the period prevalence of prostate cancer over a 7-year period, the biologic and data resources of this study will provide multiple opportunities to better understand this most common cancer in U.S. men.

Aged↗
PubMed1997

Superiority of tandem autologous transplantation over standard therapy for previously untreated multiple myeloma.

Virtually no progress has been made during more than 2 decades of clinical trials for multiple myeloma (MM) involving standard therapy (ST). Recent studies suggest that dose intensification requiring hematopoietic stem cell support results in higher complete response (CR) rates and extended disease control. "Total Therapy" (TT) consisting of noncross-resistant induction regimens, followed by a double autotransplant (AT) procedure, was administered to 123 untreated patients with symptomatic MM. Upon hematologic recovery, interferon (IFN) maintenance (3 million units [MU]/m2 subcutaneously thrice weekly) was given until disease recurrence/progression. Results were compared with the outcome of untreated patients receiving ST according to Southwest Oncology Group (SWOG) trials. One hundred sixteen pair mates were selected from both TT and among 1,123 patients to match for the major prognostic features. TT induced CR in 40% of all 123 patients (intent-to-treat). By 12 months, 7% had died, including 4% from treatment-related complications. With a median follow-up of 31 months, median durations of event-free survival (EFS) and overall survival (OS) are 49 and 62+ months, respectively. Abnormalities of chromosomes 11q and 13 were associated with inferior outcome, whereas CR within 6 months after induction was a favorable prognostic feature for both EFS and OS. In comparison to ST, TT induced higher PR rates (85% v 52%, P < .0001) (CR rates not available on SWOG trials) and extended EFS (49 v 22 months, P = .0001) and OS (62+ v 48 months, P = .01). Compared to ST, dose intensification with double AT markedly augments tumor cytoreduction, effecting not only higher CR rates but also significantly extending EFS and OS in previously untreated patients with MM.

Aged↗
PubMed1997

Feasibility and cost-effectiveness of outpatient autotransplants in multiple myeloma.

This report summarizes 2 years experience in performing 336 autotransplant procedures in 251 consecutive patients with multiple myeloma, using high-dose melphalan at 200 mg/m2 in the context of a tandem transplant program. A total of 91 patients received 118 transplants as outpatients while the remaining 160 patients received 218 transplants as inpatients. Outpatients were more often younger, with better stem cell products, normal serum albumin and beta-2-microglobulin levels as well as chemotherapy-sensitive disease compared to inpatients. There were no differences in hematopoietic recovery and non-hematologic toxicities between outpatient and inpatient transplant recipients. Post-transplant febrile neutropenia and most other post-transplant toxicities were managed successfully in an ambulatory setting. Although liberal criteria were developed for hospitalization of outpatients, including clinical parameters as well as patient desire and physician/nurse judgement, only 21% of outpatients required admission after transplantation. Median hospital stay for these outpatients was 9 days, while inpatients were hospitalized for a median of 15 days (P = 0.0001). After adjusting for differences in disease and host features, our study showed outpatient management resulted in significant financial savings due to lower pharmacy (42%), hospitalization (50%) and pathology/laboratory charges (36%). We conclude that outpatient transplants should facilitate access to myeloablative therapy, thereby improving complete remission rates and survival of myeloma patients.

Adult↗
PubMed1997

Purification and characterization of the Escherichia coli K1 neuB gene product N-acetylneuraminic acid synthetase.

Escherichia coli K1 produces a capsular polysaccharide of alpha(2-8) poly-N-acetylneuraminic acid. This polysaccharide is an essential virulence factor of these neuropathogenic bacteria. The genes necessary for the synthesis of neuNAc were localized to a plasmid containing the neuBAC genes of the K1 gene cluster. Cells harboring the neuB+ allele in an aldolase (nanA-) negative background produce neuNAc in vivo. Enzymatic synthesis of neuNAc could be demonstrated in extracts of cells harboring an expression plasmid (pNEUB) containing the neuB gene alone. NeuNAc synthetase was purified to homogeneity from extracts of cells harboring pNEUB. The molecular weight of the purified enzyme is 40 kDa, similar to that predicted by the nucleotide sequence of the neuB gene. The amino terminal sequence of the purified protein matches that predicted by the nucleotide sequence of the neuB gene. NeuNAc synthetase catalyzes the formation of neuNAc as indicated by its coupling to the CMP-neuNAc synthetase reaction. The enzyme condenses manNAc and PEP with the release of phosphate. The E. coli neuNAc synthetase is specific for manNAc and PEP, unlike rat liver enzyme that utilizes N-acetylmannosamine-6-phosphate to form neuNAc-9-PO4. This represents the first report of a purification of a sialic acid synthetase from either a eukaryotic or prokaryotic source to homogeneity. These experiments clearly demonstrate an aldolase-independent sialic acid synthetase activity in E. coli K1.

Amino Acid Sequence↗
PubMed1996

Autotransplants in multiple myeloma: what have we learned?

Of 496 consecutive patients with multiple myeloma (MM) enrolled in clinical trials of tandem transplants with peripheral blood stem cells support, 470 (95%) completed the first autotransplant with melphalan 200 mg/m2 (MEL 200) and 363 (73%) completed the second transplant with either MEL 200 (40%), MEL 140 mg/m2 (MEL 140) with total-body irradiation (17%), or a combination of alkylating agents (16%), depending on the response status prior to the second transplant; 31 patients up to age 60 years received an allograft as the second transplant. The median interval from first to second transplant was 5 months. Treatment-related mortality during the first year after transplantation was 7%, and complete remission (CR) was obtained in 36%; the median durations of event-free survival (EFS) and overall survival (OS) after transplant were 26 and 41 months, respectively. Low beta 2-microglobulin ([B2M] < or = 2.5 mg/L) and C-reactive protein ([CRP] < or = 0.4 mg/dL) were the most significant standard parameters associated with both prolonged EFS and OS. Median OS exceeded 5.5 years in the one third of patients with both low B2M and CRP. When cytogenetics were included in the analysis, the presence of 11q abnormalities and/or complete or partial deletion of chromosome 13 ("unfavorable karyotype") became a dominant negative feature for both EFS and OS. In addition to these pretransplant parameters, attainment of CR and application of two transplants within 6 months both significantly extended EFS and OS. The group of patients (7%) with high B2M and CRP with either IgA isotype or unfavorable karyotype had the worst prognosis (EFS, < or = 10 months; median OS, < or = 12 months) and will require novel therapy. We conclude that tandem transplants are feasible in the majority of patients up to age 70 years, effecting CR in one third of all patients. Median OS was greater than 5.5 years, regardless of pretransplant features, if the first transplant was applied within 12 months of initial treatment and the second transplant no more than 6 months later.

Adult↗