Precision hot-melt freeform 3D printing for monolithic multilayer microfluidics

Miniaturization and integration of assays, chemical synthesis, and cell culture models onto microfluidic chips is an intensive area of research. Despite the diversity of these applications, the vast majority of microfluidic devices are fabricated from polydimethylsiloxane (PDMS) using the same lithography methods described in 1998. Limitations of the lithography/PDMS architecture include the requirement for rectangular channels of fixed height and the necessity of bonding multiple layers to make 3D constructs. The problem of fabricating networks of small tubes in diverse media is ubiquitous, yet there is still no “black box” that laboratories can buy to turn microfluidic designs into microfluidic chips. 3D printing predates soft lithography, yet only recently have 3D printing methods been applied to the fabrication of microfluidic devices. I will present a custom printer, which extrudes filaments of water-soluble, self-supporting material along 3D toolpaths. By printing the desired channel geometry, casting a curable material around it, then dissolving away the soluble printed material, it is possible to make complex, 3D networks of cylindrical channels. I develop design rules for constructing these sacrificial molds using a 3-axis stage, algorithms for processing designs into toolpaths, and a novel method for precision extrusion. To prove that channels can be fabricated with good fidelity, I produce a monolithic, multilayer microfluidic device that mixes two components in ratios ranging from 1:100 to 100:1. Due to its compatibility with a broad range of materials, freeform 3D printing may enable the construction of many different organ-on-chip models as well as micro-electromechanical systems, electrically small antennas, and polymer stents

The effect of endocrine responsiveness on high-risk breast cancer treated with dose-intensive chemotherapy: results of International Breast Cancer Study Group Trial 15-95 after prolonged follow-up

Background: The role of adjuvant dose-intensive chemotherapy and its efficacy according to baseline features has not yet been established. Patients and methods: Three hundred and forty-four patients were randomized to receive seven courses of standard-dose chemotherapy (SD-CT) or three cycles of dose-intensive epirubicin and cyclophosphamide (epirubicin 200 mg/m2 plus cyclophosphamide 4 mg/m2 with filgrastim and progenitor cell support). All patients were assigned tamoxifen at the completion of chemotherapy. The primary end point was disease-free survival (DFS). This paper updates the results and explores patterns of recurrence according to predicting baseline features. Results: At 8.3-years median follow-up, patients assigned DI-EC had a significantly better DFS compared with those assigned SD-CT [8-year DFS percent 47% and 37%, respectively, hazard ratio (HR) 0.76; 95% confidence interval 0.58-1.00; P = 0.05]. Only patients with estrogen receptor (ER)-positive disease benefited from the DI-EC (HR 0.61; 95% confidence interval 0.39, 0.95; P = 0.03). Conclusions: After prolonged follow-up, DI-EC significantly improved DFS, but the effect was observed only in patients with ER-positive disease, leading to the hypothesis that efficacy of DI-EC may relate to its endocrine effects. Further studies designed to confirm the importance of endocrine responsiveness in patients treated with dose-intensive chemotherapy are encourage

Long-term results of International Breast Cancer Study Group Trial VIII: adjuvant chemotherapy plus goserelin compared with either therapy alone for premenopausal patients with node-negative breast cancer

Background: The International Breast Cancer Study Group Trial VIII compared long-term efficacy of endocrine therapy (goserelin), chemotherapy [cyclophosphamide, methotrexate and fluorouracil (CMF)], and chemoendocrine therapy (CMF followed by goserelin) for pre/perimenopausal women with lymph-node-negative breast cancer. Patients and methods: From 1990 to 1999, 1063 patients were randomized to receive (i) goserelin for 24 months (n = 346), (ii) six courses of ‘classical' CMF (cyclophosphamide, methotrexate, 5-fluorouracil) chemotherapy (n = 360), or (iii) six courses of CMF plus 18 months goserelin (CMF→ goserelin; n = 357). Tumors were classified as estrogen receptor (ER) negative (19%), ER positive (80%), or ER unknown (1%); 19% of patients were younger than 40. Median follow-up was 12.1 years. Results: For the ER-positive cohort, sequential therapy provided a statistically significant benefit in disease-free survival (DFS) (12-year DFS = 77%) compared with CMF alone (69%) and goserelin alone (68%) (P = 0.04 for each comparison), due largely to the effect in younger patients. Patients with ER-negative tumors whose treatment included CMF had similar DFS (12-year DFS CMF = 67%; 12-year DFS CMF→ goserelin = 69%) compared with goserelin alone (12-year DFS = 61%, P= NS). Conclusions: For pre/perimenopausal women with lymph-node-negative ER-positive breast cancer, CMF followed by goserelin improved DFS in comparison with either modality alone. The improvement was the most pronounced in those aged below 40, suggesting an endocrine effect of prolonged CMF-induced amenorrhe

Patterns and risk factors for locoregional failures after mastectomy for breast cancer: an International Breast Cancer Study Group report

Background Rates and risk factors of local, axillary and supraclavicular recurrences can guide patient selection and target for postmastectomy radiotherapy (PMRT). Patients and methods Local, axillary and supraclavicular recurrences were evaluated in 8106 patients enrolled in 13 randomized trials. Patients received chemotherapy and/or endocrine therapy and mastectomy without radiotherapy. Median follow-up was 15.2 years. Results Ten-year cumulative incidence for chest wall recurrence of >15% was seen in patients aged 10%: ≥4 positive nodes (10.2%); for axillary failures of >5%: aged 15% were age <40, peritumoral vessel invasion or 0-7 uninvolved nodes. Age, number of positive nodes and number of uninvolved nodes were significant parameters for each locoregional relapse site. Conclusion PMRT to the chest wall and supraclavicular fossa is supported in patients with ≥4 positive nodes. With 1-3 positive nodes, chest wall PMRT may be considered in patients aged <40 years, with 0-7 uninvolved nodes or with vascular invasion. The findings do not support PMRT to the dissected axill

Premenopausal endocrine-responsive early breast cancer: who receives chemotherapy?

Background: The role of chemotherapy in addition to combined endocrine therapy for premenopausal women with endocrine-responsive early breast cancer remains an open question, yet trials designed to answer it have repeatedly failed to adequately accrue. The International Breast Cancer Study Group initiated two concurrent trials in this population: in Premenopausal Endocrine Responsive Chemotherapy (PERCHE), chemotherapy use is determined by randomization and in Tamoxifen and Exemestane Trial (TEXT) by physician choice. PERCHE closed with inadequate accrual; TEXT accrued rapidly. Methods: From 2003 to 2006, 1317 patients (890 with baseline data) were randomly assigned to receive ovarian function suppression (OFS) plus tamoxifen or OFS plus exemestane for 5 years in TEXT. We explore patient-related factors according to whether or not chemotherapy was given using descriptive statistics and classification and regression trees. Results: Adjuvant chemotherapy was chosen for 64% of patients. Lymph node status was the predominant determinant of chemotherapy use (88% of node positive treated versus 46% of node negative). Geography, patient age, tumor size and grade were also determinants, but degree of receptor positivity and human epidermal growth factor receptor 2 status were not. Conclusions: The perceived estimation of increased risk of relapse is the primary determinant for using chemotherapy despite uncertainties regarding the degree of benefit it offers when added to combined endocrine therapy in this populatio

Outcomes of special histotypes of breast cancer after adjuvant endocrine therapy with letrozole or tamoxifen in the monotherapy cohort of the BIG 1-98 trial

In the BIG 1-98 clinical trial of 4922 postmenopausal women treated with 5 years of letrozole or tamoxifen for endocrine-responsive breast cancer, 183 had the rare histotypes mucinous or tubular/cribriform. These women had better outcomes than those with other histotypes. The magnitude of the letrozole advantage compared with tamoxifen may not be as large in patients with these rare histotype

Identifying breast cancer patients at risk for Central Nervous System (CNS) metastases in trials of the International Breast Cancer Study Group (IBCSG)

Background: We sought to determine whether a high-risk group could be defined among patients with operable breast cancer in whom a search of occult central nervous system (CNS) metastases was justified. Patients and methods: We evaluated data from 9524 women with early breast cancer (42% node-negative) who were randomized in International Breast Cancer Study Group clinical trials between 1978 and 1999, and treated without anthracyclines, taxanes, or trastuzumab. We identified patients whose site of first event was CNS and those who had a CNS event at any time. Results: Median follow-up was 13 years. The 10-year incidence (10-yr) of CNS relapse was 5.2% (1.3% as first recurrence). Factors predictive of CNS as first recurrence included: node-positive disease (10-yr = 2.2% for > 3 N+), estrogen receptor-negative (2.3%), tumor size > 2 cm (1.7%), tumor grade 3 (2.0%), < 35 years old (2.2%), HER2-positive (2.7%), and estrogen receptor-negative and node-positive (2.6%). The risk of subsequent CNS recurrence was elevated in patients experiencing lung metastases (10-yr = 16.4%). Conclusion: Based on this large cohort we were able to define risk factors for CNS metastases, but could not define a group at sufficient risk to justify routine screening for occult CNS metastase