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Biomedical subjects

R Macklis

Publications and source records attributed to R Macklis.

10 recordsLinked to original sources
PubMed2001

Treatment with nephrectomy only for small, stage I/favorable histology Wilms' tumor: a report from the National Wilms' Tumor Study Group.

PURPOSE: Children younger than 24 months with small (< 550 g), favorable histology (FH) Wilms tumors (WTs) were shown in a pilot study to have an excellent prognosis when treated with nephrectomy only. PATIENTS AND METHODS: A study of nephrectomy only for the treatment of selected children with FH WT was undertaken. Stringent stopping rules were designed to insure closure of the study if the true 2-year relapse-free survival rate was 90% or lower. RESULTS: Seventy-five previously untreated children younger than 24 months with stage I/FH WTs for which the surgical specimen weighed less than 550 g were treated with nephrectomy only. Three patients developed metachronous, contralateral WT 1.1, 1.4, and 2.3 years after nephrectomy, and eight patients relapsed 0.3 to 1.05 years after diagnosis (median, 0.4 years; mean, 0.51 years). The sites of relapse were lung (n = 5) and operative bed (n = 3). The 2-year disease-free (relapse and metachronous contralateral WT) survival rate was 86.5%. The 2-year survival rate is 100% with a median follow-up of 2.84 years. The 2-year disease-free survival rate (excluding metachronous contralateral WT) was 89.2%, and the 2-year cumulative risk of metachronous contralateral WT was 3.1%. CONCLUSION: Children younger than 24 months treated with nephrectomy only for a stage I/FH WT that weighed less than 550 g had a risk of relapse, including the development of metachronous contralateral WT, of 13.5% 2 years after diagnosis. All patients who experienced relapse on this trial are alive at this time. This approach will be re-evaluated in a clinical trial using a less conservative stopping rule.

Disease-Free Survival↗
PubMed1999

A mobile shield to reduce scatter radiation to the contralateral breast during radiotherapy for breast cancer: preclinical results.

PURPOSE: To design a practical breast shield and to investigate its efficacy in reducing scattered radiation to the contralateral breast of patients undergoing radiation therapy for breast cancer. METHODS AND MATERIALS: We constructed a mobile shield consisting of (a) a mobile base and a counterweight; (b) a vertical column adjustable in height and a diagonal arm adjustable in angle; (c) a curved, 2.5-cm thick lead sheet with a 1-cm thick polystyrene liner for blocking scattered radiation; and (d) diode detectors to verify that the edge of the lead sheet is not in the useful beam in addition to the use of the field light. Measurements were performed with thermoluminescent dosimeters on 10 patients without the shield and on an anthropomorphic phantom with a pair of wax breasts with and without the shield. All of the patients were treated with 6-MV photons (Varian 6/100). The scattered radiation from the medial and lateral fields was measured separately. RESULTS: The contribution of the medial field to the total scattered dose was 70% to 75%, whether a medial wedge was used or not. However, without a medial wedge, the scattered dose was reduced by nearly 33% at 3 to 9 cm away from the medial border. In the anthropomorphic phantom study with wax breast, the mobile shield reduced the medial field contribution to the total scatter dose to less than the contribution from the lateral field without a shield. With a prescribed dose of 50 Gy and a medial wedge, the median scatter dose to the contralateral breast from 6 patients was 5.3 Gy; without a medial wedge, it was 3.8 Gy from 4 patients at 6 cm from the medial border. In the phantom study, with the shield the total dose to the contralateral breast was 1.0 Gy at 6 cm from the medial border with a same prescribed dose. CONCLUSION: The mobile shield reduced the scatter dose to the contralateral breast from the linear accelerator (Varian 6/100, 6-MV photons) by a factor of 3 to 4. The shield greatly reduced the scattered dose in the wax phantom. Equivalent reductions in patients may be clinically significant by reducing the risk of radiation-induced breast cancer in the contralateral breast of woman undergoing radiation therapy for breast cancer. The shield is safe and easy to adjust to each patient.

Breast↗
PubMed1997

Family history of prostate cancer in patients with localized prostate cancer: an independent predictor of treatment outcome.

PURPOSE: To determine if familial prostate cancer patients have a less favorable prognosis than patients with sporadic prostate cancer after treatment for localized disease with either radiotherapy (RT) or radical prostatectomy (RP). PATIENTS AND METHODS: One thousand thirty-eight patients treated with either RT (n = 583) or RP (n = 455) were included in this analysis. These patients were noted as having a positive family history if they confirmed the diagnosis of prostate cancer in a first-degree relative. The outcome of interest was biochemical relapse-free survival (bRFS). We used proportional hazards to analyze the effect of the presence of family history and other potential confounding variables (ie, age, treatment modality, stage, biopsy Gleason sum [GS], and initial prostate-specific antigen [iPSA] levels) on treatment outcome. RESULTS: Eleven percent of all patients had a positive family history. The 5-year bRFS rates for patients with negative and positive family histories were 52% and 29%, respectively (P < .001). The potential confounders with bRFS rates were iPSA levels, biopsy GS, and clinical tumor stage; treatment modality and age did not appear to be associated with outcome. After adjusting for potential confounders, family history of prostate cancer remained strongly associated with biochemical failure. CONCLUSION: This is the first study to demonstrate that the presence of a family history of prostate cancer correlates with treatment outcome in a large unselected series of patients. Our findings suggest that familial prostate cancer may have a more aggressive course than nonfamilial prostate cancer, and that clinical and/or pathologic parameters may not adequately predict this course.

Aged↗
PubMed1995

Accommodating modern cancer treatment procedures in an outpatient facility.

The aging of the American population, the recent increasing prevalence of smoking in females, and the decline in heart disease mortality are setting the stage for cancer to be the most common cause of death in the United States by the year 2000. The technology exists today to increase survival rates from 50% to 75%, but this continuing care will increase cancer-related expenditures to 20% of the nation's total health care expenditures. Many advances in cancer diagnosis and treatment offer promise for less invasive procedures, and some new interventions focus on prevention or early detection of limited disease in ambulatory patients. The likelihood and the length of hospital admissions are declining, and the proportion of care delivered in an inpatient setting is expected to represent less than 10% of total cancer patient care. While the delivery of care shifts to the outpatient setting, the need for a continuum of care, interdisciplinary collaboration, and access to regional centers for technology and research is likely to encourage the formation of systems that combine a tertiary care hub and a network of community-based ambulatory centers.

Ambulatory Care Facilities↗
PubMed1979

Sequence of the 16 S-23 s spacer region in two ribosomal RNA operons of Escherichia coli.

The transducing phages lambdadaroE and lambdadilv5, which carry the Escherichia coli ribosomal RNA operons rrnD and rrnX, respectively, have been mapped with the restriction endonucleases BamHI, EcoRI, HindIII, and Sma I. Using hybridization techniques, we have located the ribosomal RNA genes on these phage DNAs. The DNA sequence of the 437-base-pair 16 S-23 S ribosomal RNA intergenic spacer in the two rRNA operons rrnD and rrnX has been determined. The nucleotides examined exhibit only one base pair change between rrnD and rrnX. Both spacer regions contain the genes for tRNA1Ile and tRNA1BAla; the gene sequences are identical with the previously deduced tRNA sequences and are clustered within the first 60% of the spacer DNA. The most striking feature of the 16 S-23 S intergenic region in these two operons is the disparity in G-C content between the tRNA gene sequences (60% G-C) and the remaining spacer DNA (37% G-C). Spacer sequences are known to be involved in the processing of the ribosomal RNA transcript by RNase III and RNase P. In addition, we report the sequence of the first 108 base pairs of the 23 S rRNA gene.

Base Sequence↗
PubMedDate not supplied

External beam radiotherapy versus radical prostatectomy for clinical stage T1-2 prostate cancer: therapeutic implications of stratification by pretreatment PSA levels and biopsy Gleason scores.

PURPOSE: Prostate-specific antigen (PSA) has affected the management of prostate cancer by allowing better case selection. The comparison between the two definitive treatment modalities, radiotherapy (RT) and radical prostatectomy (RP), can now be made accurately with respect to case selection and treatment outcome. PATIENTS AND METHODS: The charts of 787 patients with prostate carcinoma who were treated with either RP alone or RT alone between 1987 and 1993 were reviewed. Patients with stage T3 disease, without pretreatment PSA levels or biopsy Gleason scores (GS), with synchronous bladder cancers or receiving adjuvant therapy, were excluded. Patients with less than 2 years' follow-up were also excluded. Of the remaining 551 patients, 253 were treated with RT and 298 with RP. The median pretreatment PSA level for RP patients was 8.1 versus 12.1 for the RT patients. The median radiation dose was 68.4 Gy. Positive margins were reported in 49% after RP. The median follow-up time was 42 months (range: 24 to 108). RESULTS: For the 551 patients, the 5-year biochemical relapse-free survival (bRFS) rate was 53%, with biochemical relapse being defined as either a detectable PSA level after RP, or two consecutive rising PSA levels after RT. All clinical relapses were associated with rising PSA levels. The 5-year bRFS rates for RT versus RP were 43% versus 57%, respectively. Multivariate time-to-failure analysis using the proportional hazards model for clinical parameters showed pretreatment PSA level and biopsy Gleason scores to be the only independent predictors of relapse. Clinical stage and treatment modality were not independent predictors of failure. Using PSA and GS, two risk groups were defined: low risk (PSA < or = 10.0 and GS < or = 6) and high risk (PSA > 10.0 or GS > or = 7). The 5-year RFS rates for the low-versus high-risk groups were 81% versus 34%, respectively. Forty-eight percent of RP patients were low-risk cases versus 33% of RT patients. The rate of surgical margin involvement in RP patients was 39% in the low-risk group versus 59% in the high-risk group. For low-risk patients, the 5-year RFS rates for patients treated with RT versus RP were 81% versus 80%, respectively. In this subgroup, the bRFS rates for patients with negative margins were identical to the bRFS rates of patients treated with radiotherapy. However, patients with positive surgical margins fared significantly worse. For high-risk patients, the 5-year RFS rates for patients treated with RT versus RP were 26% versus 37%, respectively. In this subgroup, there was a definite advantage to surgery if negative margins were achieved: 5-year bRFS 62%, compared to 26% for RT and 21% for surgery with positive margins. CONCLUSIONS: By using biochemical failure as an endpoint, more failures are documented after RP or RT than previously suspected. However, case selection using pretreatment PSA levels and biopsy GS can result in large differences in control rates. Significantly more high-risk patients are treated with RT. By stratifying cases using PSA and biopsy GS, treatment outcome is equivalent after either radiotherapy or surgery. Further follow-up is needed to confirm these findings after 5 years. For low-risk cases, there is no difference between radiotherapy and surgery, even when negative margins are achieved. Positive surgical margins predict for poor outcome even in low-risk cases. Standard radiotherapy alone should not be used for lesions with aggressive features. The outcome in high-risk cases is better with surgery if negative margins are achieved. For such high-risk patients, several new treatment approaches are currently being investigated with either high-dose conformal radiotherapy with or without androgen blockade, or neoadjuvant androgen blockade or radical prostatectomy.

Adult↗