†Deceased (see In Memoriam at the end of this document) *Representative of the Pediatric and Congenital Electrophysiology Society (PACES) ‡Representative of the European Heart Rhythm Association (EHRA) xRepresentative of the Society of Thoracic Surgeons (STS) {Representative of the American College of Cardiology (ACC) #Representative of the Latin American Heart Rhythm Society (LAHRS) **Representative of the Infectious Diseases Society of America (IDSA) ‡ ‡Representative of the American Heart Association (AHA) xxRepresentative of the American Society of Anesthesiologists (ASA) {{Representative of the Asia Pacific Heart Rhythm Society (APHRS)
Background. The therapeutic resistance of pancreatic ductal adenocarcinoma (PDAC) is partly ascribed to ineffective delivery of chemotherapy to cancer cells. We hypothesized that physical properties at vascular, extracellular, and cellular scales influence delivery of and response to gemcitabine-based therapy.Methods. We developed a method to measure mass transport properties during routine contrast-enhanced CT scans of individual human PDAC tumors. Additionally, we evaluated gemcitabine infusion during PDAC resection in 12 patients, measuring gemcitabine incorporation into tumor DNA and correlating its uptake with human equilibrative nucleoside transporter (hENT1) levels, stromal reaction, and CT-derived mass transport properties. We also studied associations between CT-derived transport properties and clinical outcomes in patients who received preoperative gemcitabine-based chemoradiotherapy for resectable PDAC.Results. Transport modeling of 176 CT scans illustrated striking differences in transport properties between normal pancreas and tumor, with a wide array of enhancement profiles. Reflecting the interpatient differences in contrast enhancement, resected tumors exhibited dramatic differences in gemcitabine DNA incorporation, despite similar intravascular pharmacokinetics. Gemcitabine incorporation into tumor DNA was inversely related to CT-derived transport parameters and PDAC stromal score, after accounting for hENT1 levels. Moreover, stromal score directly correlated with CT-derived parameters. Among 110 patients who received preoperative gemcitabine-based chemoradiotherapy, CT-derived parameters correlated with pathological response and survival.Conclusion. Gemcitabine incorporation into tumor DNA is highly variable and correlates with multiscale transport properties that can be derived from routine CT scans. Furthermore, pretherapy CT-derived properties correlate with clinically relevant endpoints.Trial registration. Clinicaltrials.gov NCT01276613.
In a cohort of contemporary CIEDs, all cases of single-event upset malfunction occurred in the setting of notable neutron production, at a rate of 21% for neutron-producing RT and 0% for non-neutron-producing RT. Where clinically feasible, the use of non-neutron-producing RT is recommended. Given the lack of correlation between CIED malfunction and incident dose observed up to 5.4 Gy, invasive CIED relocation procedures in these settings can be minimized.
Purpose
Photon therapy has been reported to induce resets of implanted cardiac devices, but the clinical sequelae of treating patients with such devices with proton beam therapy (PBT) are not well known. We reviewed the incidence of device malfunctions among patients undergoing PBT.
Methods
From March 2009 through July 2012, 42 patients with implanted cardiac implantable electronic devices (CIEDs) (28 pacemakers and 14 cardioverter-defillibrators) underwent 42 courses of PBT for thoracic (23 [55%]), prostate (15 [36%]), liver (3[7%]), or base of skull (1 [2%]) tumors at a single institution. The median prescribed dose was 74 Gy(RBE) [range 46.8–87.5 Gy(RBE)], and the median distance from the treatment field to the CIED was 10 cm (range 0.8–40 cm). Maximum proton and neutron doses were estimated for each treatment course. All CIEDs were checked before radiation delivery and monitored throughout treatment.
Results
Median estimated peak proton and neutron doses to the CIED in all patients were 0.8 Gy (range 0.13–21 Gy) and 346 Sv (range 11–1100 mSv). Six CIED malfunctions occurred in five patients (2 pacemakers and 3 defibrillators). Five of these malfunctions were CIED resets, and one patient with a defibrillator (in a patient with a liver tumor) had an elective replacement indicator (ERI) after therapy that was not influenced by radiation. The mean distance from the proton beam to the CIED among devices that reset was 7.0 cm (range 0.9–8 cm), and the mean maximum neutron dose was 655 mSv (range 330–1100 mSv). All resets occurred in patients receiving thoracic PBT and were corrected without clinical incident. The generator for the defibrillator with the ERI message was replaced uneventfully after treatment.
Conclusions
The incidence of CIED resets was about 20% among patients receiving PBT to the thorax. We recommend that PBT be avoided in pacing-dependent patients and that patients with any type of CIED receiving thoracic PBT be followed closely.
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