Search NASA⌕ Search

SEARCH · Search NASA

Results for “Multivariate Analysis”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10

Merkel Cell Carcinoma: 27-Year Experience at the Peter MacCallum Cancer Centre

Purpose: To retrospectively evaluate the treatment outcome of patients with Merkel cell carcinoma after local and/or regional treatment. Methods and Materials: Patients presenting to our center between January 1980 and July 2006 with Merkel cell carcinoma and without distant metastases were reviewed. The primary endpoint was locoregional control. Secondary endpoints were distant recurrence, survival and treatment toxicity. Results: A total of 176 patients were identified. The median age was 79 years. The median follow-up was 2.2 years for all patients and 3.9 years for those alive at the last follow-up visit. The most common primary site was the head and neck (56%), and 62 patients(35%) had regional disease at presentation. The initial surgery to the primary tumor involved (wide) local excision in 140 patients and biopsy only in 28 patients (8 patients had no identifiable primary tumor); 33 patients underwent nodal surgery. Of the 176 patients, 165 (94%) underwent radiotherapy (RT) and 29 of them also underwent concurrent chemotherapy. The median radiation dose was 50 Gy (range, 18-60). Locoregional recurrence developed in 33 patients(19%), with a median interval to recurrence of 8 months. Distant metastases developed in 43 patients(24%). Age, primary tumor size, and RT (no RT vs. <45 Gy vs. {>=}45 Gy) were predictive of locoregional control on univariate analysis. However, only RT remained significant on multivariate analysis. The estimated 5-year actuarial rate for locoregional control, progression-free survival, and overall survival was 76%, 60%, and 45%, respectively. Conclusion: The locoregional control rate for Merkel cell carcinoma in our study was comparable to those from other series using combined modality treatment with RT an integral part of treatment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

The Role of the Neo-Bioscore Staging System in Guiding the Optimal Strategies for Regional Nodal Irradiation Following Neoadjuvant Treatment in Breast Cancer Patients with cN1 and ypN0–1

Background: The role of regional nodal irradiation (RNI) in patients with cN1 breast cancer following neoadjuvant treatment (NAT) is still controversial. The Neo-Bioscore staging system has shown promising prospect in assessing individual prognosis after NAT, and we sought to evaluate the role of Neo-Bioscore in guiding RNI following NAT. Methods: Medical records of 163 women with cN1 and ypN0–1 disease treated with NAT between 2009 and 2014 were retrospectively reviewed and a Neo-Bioscore was assigned to each patient. Survivals were calculated using the Kaplan–Meier method and compared with the log-rank test. Multivariate analysis was used to identify independent predictors by using Cox proportional hazards models. Results: The median follow-up after surgery was 59.4 months. Of all 163 patients, 119 received RNI. At surgery, 36 patients (22.1%) had pathological complete response (pCR), while 89 patients (54.6%) achieved ypN0. In the whole cohort, RNI significantly improved distant metastasis-free survival (DMFS) on multivariable analysis. In the subgroup of patients with a Neo-Bioscore of 1–3, RNI significantly improved the 5-year DMFS rate of 97.0% versus 76.9% (p = 0.002), 5-year regional node recurrence-free survival rate of 95.5% versus 76.9% (p = 0.007), and 5-year overall survival rate of 100% versus 89.2% (p = 0.005). No significant difference in outcomes was found between the RNI and non-RNI groups in patients with a score of 4–6. Conclusions: In patients with cN1 and ypN0–1, RNI was found to significantly improve DMFS following NAT. Patients with a Neo-Bioscore of 1–3 are more likely to benefit from RNI, however a large prospective study is needed to confirm this finding.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Role of Postmastectomy Radiotherapy After Neoadjuvant Chemotherapy in Breast Cancer Patients: A Study from the Japanese Breast Cancer Registry

Background: The role of postmastectomy radiotherapy (PMRT) in breast cancer patients receiving neoadjuvant chemotherapy (NAC) is controversial. We aimed to evaluate the effectiveness of radiotherapy in patients treated with NAC and mastectomy in the Japanese Breast Cancer Registry. Methods: We enrolled patients who received NAC and mastectomy for cT1–4 cN0–2 M0 breast cancer. We evaluated the association between radiotherapy and outcomes, locoregional recurrence (LRR), distant disease-free survival (DDFS), and overall survival (OS) based on ypN status by multivariable analysis. Results: Of the 145,530 patients, we identified 3226 who met the inclusion criteria. Among ypN1 patients, no differences were found in LRR, DDFS, or OS between groups with and without radiotherapy (p = 0.72, p = 0.29, and p = 0.36, respectively). Radiotherapy was associated with improved LRR-free survival (p < 0.001), DDFS (p = 0.01), and OS (p < 0.001) in patients with ypN2–3. Multivariable analysis demonstrated that use of radiotherapy was independently associated with improved LRR [hazard ratio (HR) 0.61, 95% confidence interval (CI) 0.45–0.82, p = 0.001] and OS [HR 0.69, 95% CI 0.53–0.89, p = 0.004) for ypN2–3 patients only. The association between radiotherapy and OS was not statistically significant among ypN0 (p = 0.22) and ypN1 patients (p = 0.51). Conclusions: The results from this nationwide database study did not show significant associations between PMRT and improved survival among ypN0 and ypN1 patients. Radiotherapy may be beneficial only for ypN2–3 breast cancer patients who receive NAC and mastectomy in the modern era.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

pN0(i+) Breast Cancer: Treatment Patterns, Locoregional Recurrence, and Survival Outcomes

Purpose: To examine treatment patterns, recurrence, and survival outcomes in patients with pN0(i+) breast cancer. Methods and Materials: Subjects were 5999 women with AJCC (6th edition) pT1-3, pN0-N1a, M0 breast cancer diagnosed between 2003 and 2006. Of these, 4342 (72%) had pN0, 96 (2%) had pN0(i+), 349 (6%) had pNmic (micrometastases >0.2 mm to ≤2 mm), and 1212 (20%) had pN1a (1-3 positive macroscopic nodes) disease. Treatment characteristics and 5-year Kaplan-Meier local recurrence, regional recurrence (RR), locoregional recurrence (LRR), and overall survival were compared between nodal subgroups. Multivariable analysis was performed using Cox regression modeling. A 1:3 case-match analysis examined outcomes in pN0(i+) cases compared with pN0 controls matched for similar tumor and treatment characteristics. Results: Median follow-up was 4.8 years. Adjuvant systemic therapy use increased with nodal stage: 81%, 92%, 95%, and 94% in pN0, pN0(i+), pNmic, and pN1a disease, respectively (P<.001). Nodal radiation therapy (RT) use also increased with nodal stage: 1.7% in pN0, 27% in pN0(i+), 33% in pNmic, and 63% in pN1a cohorts (P<.001). Five-year Kaplan-Meier outcomes in pN0 versus pN0(i+) cases were as follows: local recurrence 1.7% versus 3.7% (P=.20), RR 0.5% versus 2.2% (P=.02), and LRR 2.1% versus 5.8% (P=.02). There were no RR events in 26 patients with pN0(i+) disease who received nodal RT and 2 RR events in 70 patients who did not receive nodal RT. On multivariable analysis, pN0(i+) was not associated with worse locoregional control or survival. On case-match analysis, LRR and overall survival were similar between pN0(i+) and matched pN0 counterparts. Conclusions: Nodal involvement with isolated tumor cells is not a significant prognostic factor for LRR or survival in this study's multivariable and case-match analyses. These data do not support the routine use of nodal RT in the setting of pN0(i+) disease. Prospective studies are needed to define optimal locoregional management for women with pN0(i+) breast cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Incidence of Second Malignancies in Prostate Cancer Patients Treated With Low-Dose-Rate Brachytherapy and Radical Prostatectomy

Purpose: To compare the second malignancy incidence in prostate cancer patients treated with brachytherapy (BT) relative to radical prostatectomy (RP) and to compare both groups with the cancer incidence in the general population. Methods and Materials: From 1998 to 2010, 2418 patients were treated with Iodine 125 prostate BT monotherapy at the British Columbia Cancer Agency, and 4015 referred patients were treated with RP. Cancer incidence was compared with the age-matched general population using standardized incidence ratios (SIRs). Pelvic malignancies included invasive and noninvasive bladder cancer and rectal cancer. Cox multivariable analysis was performed with adjustment for covariates to determine whether treatment (RP vs BT) was associated with second malignancy risk. Results: The median age at BT was 66 years and at RP 62 years. The SIR comparing BT patients with the general population was 1.06 (95% confidence interval [CI] 0.91-1.22) for second malignancy and was 1.53 (95% CI 1.12-2.04) for pelvic malignancy. The SIR comparing RP patients with the general population was 1.11 (95% CI 0.98-1.25) for second malignancy and was 1.11 (95% CI 0.82-1.48) for pelvic malignancy. On multivariable analysis, older age (hazard ratio [HR] 1.05) and smoking (HR 1.65) were associated with increased second malignancy risk (P<.0001). Radical prostatectomy was not associated with a decreased second malignancy risk relative to BT (HR 0.90, P=.43), even when excluding patients who received postprostatectomy external beam radiation therapy (HR 1.13, P=.25). Older age (HR 1.09, P<.0001) and smoking (HR 2.17, P=.0009) were associated with increased pelvic malignancy risk. Radical prostatectomy was not associated with a decreased pelvic malignancy risk compared with BT (HR 0.57, P=.082), even when excluding postprostatectomy external beam radiation therapy patients (HR 0.87, P=.56). Conclusions: After adjustment for covariates, BT patients did not have an increased second malignancy risk compared with RP patients. Further follow-up of this cohort is needed given the potential latency of radiation-induced malignancies.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Predictors of IMRT and Conformal Radiotherapy Use in Head and Neck Squamous Cell Carcinoma: A SEER-Medicare Analysis

Purpose: The extent to which new techniques for the delivery of radiotherapy for head and neck squamous cell carcinoma (HNSCC) have diffused into clinical practice is unclear, including the use of 3-dimensional conformal RT (3D-RT) and intensity-modulated radiation therapy (IMRT). Methods and Materials: Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database, we identified 2,495 Medicare patients with Stage I-IVB HNSCC diagnosed at age 65 years or older between 2000 and 2005 and treated with either definitive (80%) or adjuvant (20%) radiotherapy. Our primary aim was to analyze the trends and predictors of IMRT use over this time, and the secondary aim was a similar description of the trends and predictors of conformal radiotherapy (CRT) use, defined as treatment with either 3D-RT or IMRT. Results: Three hundred sixty-four (15%) patients were treated with IMRT, and 1,190 patients (48%) were treated with 3D-RT. Claims for IMRT and CRT rose from 0% to 33% and 39% to 86%, respectively, between 2000 and 2005. On multivariable analysis, IMRT use was associated with SEER region (West 18%; Northeast 11%; South 12%; Midwest 13%), advanced stage (advanced, 21%; early, 9%), non-larynx site (non-larynx, 23%; larynx, 7%), higher median census tract income (highest vs. lowest quartile, 18% vs. 10%), treatment year (2003-2005, 31%; 2000-2002, 6%), use of chemotherapy (26% with; 9% without), and higher radiation oncologist treatment volume (highest vs. lowest tertile, 23% vs. 8%). With CRT as the outcome, only SEER region, treatment year, use of chemotherapy, and increasing radiation oncologist HNSCC volume were significant on multivariable analysis. Conclusions: The use of IMRT and CRT by Medicare beneficiaries with HNSCC rose significantly between 2000 and 2005 and was associated with both clinical and non-clinical factors, with treatment era and radiation oncologist HNSCC treatment volume serving as the strongest predictors of IMRT use.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Measurement of the Inclusive $t\bar{t}$ Production Cross Section in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV and Determination of the Top Quark Pole Mass

The inclusive cross section of top quark-antiquark pairs produced in pp¯ collisions at s=1.96 TeV is measured in the lepton+jets and dilepton decay channels. The data sample corresponds to 9.7 fb-1 of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of σtt¯=7.26±0.13(stat)-0.50+0.57(syst) pb which is consistent with standard model predictions. We also perform a likelihood fit to the measured and predicted top quark mass dependence of the inclusive cross section, which yields a measurement of the pole mass of the top quark. The extracted value is mt=172.8±1.1(theo)-3.1+3.3(exp) GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Local Recurrence in Women With Stage I Breast Cancer: Declining Rates Over Time in a Large, Population-Based Cohort

Purpose: To evaluate whether local recurrence (LR) risk has changed over time among women with stage I breast cancer treated with breast-conserving therapy. Methods and Materials: Subjects were 5974 women aged ≥50 years diagnosis with pT1N0 breast cancer from 1989 to 2006, treated with breast-conserving surgery and radiation therapy. Clinicopathologic characteristics, treatment, and LR outcomes were compared among 4 cohorts stratified by year of diagnosis: 1989 to 1993 (n=1077), 1994 to 1998 (n=1633), 1999 to 2002 (n=1622), and 2003 to 2006 (n=1642). Multivariable analysis was performed, with year of diagnosis as a continuous variable. Results: Median follow-up time was 8.6 years. Among patients diagnosed in 1989 to 1993, 1994 to 1998, 1999 to 2002, and 2003 to 2006, the proportions of grade 1 tumors increased (16% vs 29% vs 40% vs 39%, respectively, P<.001). Surgical margin clearance rates increased from 82% to 93% to 95% and 88%, respectively (P<.001). Over time, the proportions of unknown estrogen receptor (ER) status decreased (29% vs 10% vs 1.2% vs 0.5%, respectively, P<.001), whereas ER-positive tumors increased (56% vs 77% vs 86% vs 86%, respectively, P<.001). Hormone therapy use increased (23% vs 23% vs 62% vs 73%, respectively, P<.001), and chemotherapy use increased (2% vs 5% vs 10% vs 13%, respectively, P<.001). The 5-year cumulative incidence rates of LR over the 4 time periods were 2.8% vs 1.7% vs 0.9% vs 0.8%, respectively (Gray's test, P<.001). On competing risk multivariable analysis, year of diagnosis was significantly associated with decreased LR (hazard ratio, 0.92 per year, P=.0003). Relative to grade 1 histology, grades 2, 3, and unknown were associated with increased LR. Hormone therapy use was associated with reduced LR. Conclusion: Significant changes in the multimodality management of stage I breast cancer have occurred over the past 2 decades. More favorable-risk tumors were diagnosed, and margin clearance and systemic therapy use increased. These changes contributed to the observed declining LR rates among patients treated with breast-conserving therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Classification System for Identifying Women at Risk for Altered Partial Breast Irradiation Recommendations After Breast Magnetic Resonance Imaging

Purpose: To study the utility of preoperative breast MRI for partial breast irradiation (PBI) patient selection, using multivariable analysis of significant risk factors to create a classification rule. Methods and Materials: Between 2002 and 2009, 712 women with newly diagnosed breast cancer underwent preoperative bilateral breast MRI at Mayo Clinic Florida. Of this cohort, 566 were retrospectively deemed eligible for PBI according to the National Surgical Adjuvant Breast and Bowel Project Protocol B-39 inclusion criteria using physical examination, mammogram, and/or ultrasound. Magnetic resonance images were then reviewed to determine their impact on patient eligibility. The patient and tumor characteristics were evaluated to determine risk factors for altered PBI eligibility after MRI and to create a classification rule. Results: Of the 566 patients initially eligible for PBI, 141 (25%) were found ineligible because of pathologically proven MRI findings. Magnetic resonance imaging detected additional ipsilateral breast cancer in 118 (21%). Of these, 62 (11%) had more extensive disease than originally noted before MRI, and 64 (11%) had multicentric disease. Contralateral breast cancer was detected in 28 (5%). Four characteristics were found to be significantly associated with PBI ineligibility after MRI on multivariable analysis: premenopausal status (P=.021), detection by palpation (P<.001), first-degree relative with a history of breast cancer (P=.033), and lobular histology (P=.002). Risk factors were assigned a score of 0-2. The risk of altered PBI eligibility from MRI based on number of risk factors was 0:18%; 1:22%; 2:42%; 3:65%. Conclusions: Preoperative bilateral breast MRI altered the PBI recommendations for 25% of women. Women who may undergo PBI should be considered for breast MRI, especially those with lobular histology or with 2 or more of the following risk factors: premenopausal, detection by palpation, and first-degree relative with a history of breast cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Can Locoregional Treatment of the Primary Tumor Improve Outcomes for Women With Stage IV Breast Cancer at Diagnosis?

Purpose: To examine the effect of locoregional treatment (LRT) of the primary tumor on survival in patients with Stage IV breast cancer at diagnosis. Methods and Materials: The study cohort comprised 733 women referred to the British Columbia Cancer Agency between 1996 and 2005 with newly diagnosed clinical or pathologic M1 breast cancer. Tumor and treatment characteristics, overall survival (OS), and locoregional progression-free survival were compared between patients treated with (n = 378) and without (n = 355) LRT of the primary disease. Multivariable analysis was performed with Cox regression modeling. Results: The median follow-up time was 1.9 years. LRT consisted of surgery alone in 67% of patients, radiotherapy alone in 22%, and both in 11%. LRT was used more commonly in women with age <50 years, Eastern Cooperative Oncology Group (ECOG) performance status 0-1, Stage T1-2 tumors, N0-1 disease, limited M1 burden, and asymptomatic M1 disease (all p < 0.05). Systemic therapy was used in 92% of patients who underwent LRT and 85% of patients who did not. In patients treated with LRT compared with those without LRT, the 5-year OS rates were 21% vs. 14% (p < 0.001), and the rates of locoregional progression-free survival were 72% vs. 46% (p < 0.001). Among 378 patients treated with LRT, the rates of 5-year OS were higher in patients with age <50, ECOG performance status 0-1, estrogen receptor-positive disease, clear surgical margins, single subsite, bone-only metastasis, and one to four metastatic lesions (all p < 0.003). On multivariable analysis, LRT was associated with improved OS (hazard ratio, 0.78; 95% confidence interval, 0.64-0.94, p = 0.009). Conclusion: Locoregional treatment of the primary disease is associated with improved survival in some women with Stage IV breast cancer at diagnosis. Among those treated with LRT, the most favorable rates of survival were observed in subsets with young age, good performance status, estrogen receptor-positive disease, clear margins, and distant disease limited to one subsite, bone-only involvement, or fewer than five metastatic lesions.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Stage Presentation, Care Patterns, and Treatment Outcomes for Squamous Cell Carcinoma of the Penis

Purpose: Penile squamous cell carcinoma (SCC) is a rare entity, with few published series on outcomes. We evaluated the stage distributions and outcomes for surgery and radiation therapy in a U.S. population database. Methods and Materials: Subjects with SCC of the penis were identified using the National Cancer Institute Surveillance, Epidemiology and End Results (SEER) Program database between 1988 and 2006. Descriptive statistics were performed, and cause-specific survival (CSS) was estimated using Kaplan-Meier analysis. Comparisons of treatment modalities were analyzed using multivariate Cox regression. Subjects were staged using American Joint Committee on Cancer, sixth edition, criteria. Results: There were 2458 subjects identified. The median age was 66.8 years (range, 17-102 years). Grade 2 disease was present in 94.5% of cases. T1, T2, T3, T4, and Tx disease was present in 64.8%, 17.1%, 9.5%, 2.1%, and 6.5% of cases, respectively. N0, N1, N2, N3, and Nx disease was noted in 61.6%, 6.9%, 4.0%, 3.7%, and 23.8% of cases, respectively. M1 disease was noted in 2.5% of subjects. Individuals of white ethnicity accounted for 85.1% of cases. Lymphadenectomy was performed in 16.7% of cases. The CSS for all patients at 5 and 10 years was 80.8% and 78.6%. By multivariable analysis grades 2 and 3 disease, T3 stage, and positive lymph nodes were adverse prognostic factors for CSS. Conclusion: SCC of the penis often presents as early-stage T1, N0, M0, grade 1, or grade 2 disease. The majority of patients identified were treated with surgery, and only a small fraction of patients received radiation therapy alone or as adjuvant therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Comparing gas composition from fast pyrolysis of live foliage measured in bench-scale and fire-scale experiments

Background: Fire models have used pyrolysis data from oxidising and non-oxidising environments for flaming combustion. In wildland fires pyrolysis, flaming and smouldering combustion typically occur in an oxidising environment (the atmosphere). Aims: Using compositional data analysis methods, determine if the composition of pyrolysis gases measured in non-oxidising and ambient (oxidising) atmospheric conditions were similar. Methods: Permanent gases and tars were measured in a fuel-rich (non-oxidising) environment in a flat flame burner (FFB). Permanent and light hydrocarbon gases were measured for the same fuels heated by a fire flame in ambient atmospheric conditions (oxidising environment). Log-ratio balances of the measured gases common to both environments (CO, CO 2 , CH 4 , H 2 , C 6 H 6 O (phenol), and other gases) were examined by principal components analysis (PCA), canonical discriminant analysis (CDA) and permutational multivariate analysis of variance (PERMANOVA). Key results: Mean composition changed between the non-oxidising and ambient atmosphere samples. PCA showed that flat flame burner (FFB) samples were tightly clustered and distinct from the ambient atmosphere samples. CDA found that the difference between environments was defined by the CO-CO 2 log-ratio balance. PERMANOVA and pairwise comparisons found FFB samples differed from the ambient atmosphere samples which did not differ from each other. Conclusion: Relative composition of these pyrolysis gases differed between the oxidising and non-oxidising environments. This comparison was one of the first comparisons made between bench-scale and field scale pyrolysis measurements using compositional data analysis. Implications: These results indicate the need for more fundamental research on the early time-dependent pyrolysis of vegetation in the presence of oxygen.

54 ENVIRONMENTAL SCIENCES↗

Novel principal component analysis tool based on python for analysis of complex spectra of time-of-flight secondary ion mass spectrometry

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful surface analysis tool, which can simultaneously provide elemental, isotopic, and molecular information with part per million (ppm) sensitivity. However, each spectrum may be composed of hundreds of ion signals, which makes the spectra data complex. Principal component analysis (PCA) is a multivariate analysis technique that has been widely used to figure out the variances among samples in ToF-SIMS spectra data analysis and is showing great success in the explanation of complex ToF-SIMS spectra. So far, several software tools have been developed for PCA of ToF-SIMS spectra; however, none of them are freely available. Such a situation leads to some difficulties in extending applications of PCA to various research fields. More importantly, it has long been challenging for common researchers to understand PCA plots and extract chemical differences among samples. In this work, we developed a new and flexible software tool (named “advanced spectra pca toolbox”) based on python for PCA of complex ToF-SIMS spectra along with an easy-to-read manual. It can generate data analysis reports automatically to explain chemical differences among samples, allowing less experienced researchers to easily understand tricky PCA results. Moreover, it is expandable and compatible with artificial intelligence/machine learning functions. Pure goethite and different lignin adsorbed goethite samples were used as a model system to demonstrate our new software tool, proving that our software tool can be readily used in complex spectra data processing. Our new software tool is open-source, convenient, flexible, and expandable. We expect this open-source tool will benefit the ToF-SIMS community.

47 OTHER INSTRUMENTATION↗