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Pacemaker and radiotherapy in breast cancer: is targeted intraoperative radiotherapy the answer in this setting?

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We present the case of an 83 year old woman with a cardiac pacemaker located close in distance to a subsequently diagnosed invasive ductal carcinoma of the left breast. Short range intraoperative radiotherapy was given following wide local excision and sentinel node biopsy. The challenges of using ionising radiation with pacemakers is also discussed.
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C A S E R E P O R T Open Access
Pacemaker and radiotherapy in breast cancer: is
targeted intraoperative radiotherapy the answer
in this setting?
Mohammed RS Keshtgar
1*
, David J Eaton
2
, Claire Reynolds
2
, Katharine Pigott
2
, Tim Davidson
1
,
Benjamin Gauter-Fleckenstein
3
and Frederik Wenz
3
Abstract
We present the case of an 83 year old woman with a cardiac pacemaker located close in distance to a
subsequently diagnosed invasive ductal carcinoma of the left breast. Short range intraoperative radiotherapy was
given following wide local excision and sentinel node biopsy. The challenges of using ionising radiation with
pacemakers is also discussed.
Keywords: Pacemaker, Safety, Targeted intraoperative radiotherapy (TARGIT), INTRABEAM, Breast cancer
Background
Ionising radiation (IR) has been reported to interfere
with modern cardiac pacemakers (PM), which are
equipped with complementary metal oxide semicon-
ductor circuitry (CMOS) [1]. In 1994, the American As-
sociation of Physicists in Medicine (AAPM) stated that a
cardiac pacemaker can fail at radiotherapy doses as low
as 10 Gy, and even doses of 2 Gy could lead to signifi-
cant functional changes. This resulted in guidelines sug-
gesting that the dose to the PM should be limited to
2 Gy [2].
The cardiac conditions which lead to the implantation
of a PM are typically sick sinus syndrome, high grade
atrio-ventricular (AV) blockade IIb, type mobitz, or total
AV-blockade III. Patients suffering from high grade AV-
blockade depend highly on external functional cardiac
pacing since cardiac output is directly related to left ven-
tricular pump function and heart rate. Arrhythmia
results in inconstant and insufficient ventricular filling
and decreased ventricular ejection fraction. This, in
combination with a very low heart rate (3050 bpm),
gives rise to very low cerebral, coronary, intestinal, pul-
monary and renal perfusion pressure, leading to ische-
mia. The patients at highest risk from pacemaker
dysfunction are those who are absolutely dependent on
their PM, who are without a sufficient escape rhythm.
Cardiac pacemakers are programmed to sense brady-
cardia and to pace the heart through implanted metal
coil leads which are not sufficiently shielded against
radiation.
Modern PMs contain CMOS circuitry and random ac-
cess memory (RAM), in addition to the battery and leads
capable of sensing and pacing the heart. The CMOS is cap-
able of signal amplification and improves device reliability
and energy consumption. RAM is the programmable
part of the device, holding information about patient-
related anti-bradycardia pacing, detection settings and
frequency thresholds. It contains a small amount of en-
ergy which is highly volatile. Some cases have been
reported wherein no obvious damage to the device was
found following irradiation, but the RAM had been en-
tirely erased [3].
CMOS circuitry is built from metal-oxide-semiconductor
field effect transistors. The metal oxide used in the CMOS
is polycrystalline silicon (Si) and silicon dioxide (SiO
2
)is
used as insulation. Energy deposition during radiother-
apy using ionising radiation can result in excess elec-
tron holes in the electron valence band and electrons
can leave their valence band (tunnelling). This can result
in aberrant electrical pathways and reprogramming of the
devices. Possible effects on the PM include altered sensi-
tivity, amplitude changes, telemetry and programming
* Correspondence: m.keshtgar@ucl.ac.uk
1
The Breast Unit, Academic Department of Surgery, Royal Free and University
College Medical School, Pond Street, London NW3 2QG, UK
Full list of author information is available at the end of the article
© 2012 Keshtgar et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Keshtgar et al. Radiation Oncology 2012, 7:128
http://www.ro-journal.com/content/7/1/128
defects (even preventing reprogramming), adjustment
of function or loss of function for seconds, days or
permanently.
Several cases have been reported where the threshold
programming was deleted or the devices failed at low
doses [1]. Therefore, in cases where the PM is close to
the treatment fields for external beam radiotherapy
(EBRT), adjustments may be necessary. These include
modification of the field size and shape, moving the PM
surgically out of the field or even withholding radiother-
apy in some cases.
An alternative to EBRT for these patients might be
intraoperative radiotherapy (IORT). The TARGIT trial-
ists group has reported the result of a randomised con-
trolled trial with this technique, which has confirmed
the safety and efficacy [4].
Case presentation
An 83 year old female patient presented with a two week
history of a self detected lump in the upper outer quad-
rant of the left breast. Clinically there was a 15 mm sus-
picious lump in the left breast, mammography did not
reveal any abnormality (R1) and ultrasound scan find-
ings were consistent with the diagnosis of breast cancer
(U5). Clinical and ultrasound examination of the axilla
was unremarkable. Core biopsy of the lesion confirmed
the diagnosis of invasive ductal carcinoma.
During review of her past medical history, it was
noted that in 1996 she had a cardiac PM inserted for
persistent sinus bradycardia. In 2003 this was replaced
with a St. Jude Medical dual chamber PM (St. Jude
Medical Inc., St. Paul, MN, USA). The pacemaker was
programmed to VVIR 70 bpm, hysterises 60 bpm in sin-
gle chamber mode due to an atrial lead failure. The
dominant rhythm was atrial fibrillation with intermit-
tent ventricular pacing. The patients heart rate varied
between 60107 bpm. The patient had been self caring
and a recent transthoracic echocardiogram showed a
normal ejection fraction and left ventricular size. Ana-
tomically, the PM was located in a subcutaneous tissue
pocket in the upper pole of the left breast 9 cm away
from the primary tumour (Figure 1, Figure 2).
After discussion at the multidisciplinary meeting,
we recommended wide local excision and sentinel
node biopsy. In view of the size of the tumour and pres-
ence of the PM, it was also decided to offer the patient
intraoperative radiotherapy using the TARGIT technique.
Prior to surgery, the details of the PM were obtained
from the implanting hospital and the distance from the
tumour to the device was measured at an assessment
session. During surgery, after harvesting the sentinel
node and wide local excision, intraoperative radiotherapy
was performed using the Intrabeam
device (50 kV, Carl
Zeiss Surgical, Oberkochen, Germany). A 3 cm diameter
applicator was used, delivering approximately 20 Gy at
the surface of the breast tissue in direct contact with the
applicator, and 6 Gy at 1 cm from the surface, over a
time of 26 minutes. During the surgery, the radiation
Figure 1 Chest x-ray of the patient showing the pacemaker in
situ and the approximate position of the breast cancer.
Figure 2 Mammogram (mediolateral view) showing the
pacemaker. The breast cancer was mammographically occult.
Keshtgar et al. Radiation Oncology 2012, 7:128 Page 2 of 4
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dose to the PM was measured using thermoluminescent
dosimeters (TLD), which were placed on the edge of the
device closest to the x-ray source, and the distance be-
tween the applicator shaft of the Intrabeam and the PM
was recorded. The measured reading was converted to
dose using a batch calibration value corrected for supra-
linearity of dose response. The average reading of the
TLD packet was 0.08 Gy.
The patient tolerated the procedure very well and
there was no malfunction of the PM device during the
surgery or IORT. The patient made an uneventful recovery
and was discharged home the following day. The pace-
maker function was tested by the cardiology team before
and after treatment.
Histology confirmed the identification of a 14 mm
grade 2 invasive ductal carcinoma which was completely
excised. There was no lymphovascular invasion and the
sentinel node was free of tumour. The cancer was ER/PR
positive (quick score 8/8) and Her-2 negative. The pa-
tient was commenced on an Aromatase Inhibitor as an
adjuvant treatment.
Discussion
Although some centres treat patients in this age group
with surgery and adjuvant endocrine therapy alone,
within the TARGIT randomized trial there is no upper
age limit for the delivery of radiotherapy. This patient
would have been eligible to enter the trial were it not for
the contraindication to EBRT of a pacemaker so close in
distance to the tumour site. Moreover, this case is pre-
sented to highlight the issues concerning pacemakers
and radiotherapy and possible approaches to overcome
these problems.
As described in this case, the use of a short range kilo-
voltage energy x-ray source reduces the dose to normal
tissues and artificial devices which are sensitive to radi-
ation. By performing in vivo dosimetry using TLDs, we
confirmed a low radiation dose to the PM. Compared to
EBRT, during the IORT procedure the patient is closely
monitored by an anaesthetist. Furthermore, standard
monitoring such as ECG, pulse oximetry and blood pres-
sure monitoring would help to identify any arrhythmia
during the procedure. In some countries within Europe,
there is a requirement for the presence of a cardiologist
or a member of the cardiology team during or after IR
to ensure the correct functioning of a PM. This would
be reduced to a single visit for IORT in comparison to
daily visits for each fraction of EBRT.
At present, little is known about the effects of direct
and scattered radiation on PMs, especially the newer
PMs equipped with modern CMOS circuitry. However,
some manufacturers do provide estimates of the radi-
ation doses to which their PM models can be safely irra-
diated (e.g. St. Jude 2030 Gy [5], Medtronic 5 Gy [6],
Guidant n.n. [7]). The wide range of these stated doses
and recent in-vitro data showing that a PM can fail at
any dose [8] pose significant challenges to radiation
oncologists treating patients with a PM. Therefore, tech-
niques like IORT using the Intrabeam device are an at-
tractive alternative to existing approaches. In addition,
the Intrabeam device does not produce electromagnetic
interference which is a concern with linear accelerators
and implantable cardioverter defibrillators [9]. Further
research into the safe tolerance doses for modern PM
devices will hopefully be translated into safer designs for
the future. In the meantime, however, we believe that
intraoperative radiotherapy using Intrabeam is a very
good option for selected patients with a pacemaker.
Conclusions
Intraoperative radiotherapy using the Intrabeam device
was successfully used to treat an invasive ductal carcin-
oma of the left breast with a cardiac pacemaker located
close in distance to the treatment area. This approach
may form a viable alternative to conventional radiotherapy
which has been shown to adversely effect such devices.
Consent
Written informed consent was obtained from the patient
for publication of this case report and any accompanying
images. A copy of the written consent is available for re-
view by the Editor-in-Chief of this journal.
Abbreviations
TARGIT: Targeted intraoperative radiotherapy; IR: Ionising irradiation, CMOS,
Complementary metal oxide semiconductor; PM: Pacemaker;
AAPM: American Association of Physicists in Medicine; AV: Atrio-ventricular;
RAM: Random access memory; EBRT: External beam radiotherapy;
IORT: Intraoperative radiotherapy; TLD: Thermoluminescent dosimeter;
ECG: Electrocardiogram.
Competing interests
The authors declared that they have no competing interest.
Authorscontributions
MK: conception and design; MK, DE, CR, KP: patient treatment; Consultation
on background and discussion of interpretation MK, TD: surgical; KP, BG-F,
FW: radiation oncology, DE: physics; MK, BG-F: drafting manuscript; DE, CR,
KP, TD, FW: revising manuscript. All authors have read and approved the final
manuscript.
Author details
1
The Breast Unit, Academic Department of Surgery, Royal Free and University
College Medical School, Pond Street, London NW3 2QG, UK.
2
Department of
Radiotherapy, Royal Free Hospital, London, UK.
3
Department of Radiation
Oncology, University Medical Center Mannheim, University of Heidelberg,
Mannheim, Germany.
Received: 22 May 2012 Accepted: 19 July 2012
Published: 1 August 2012
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doi:10.1186/1748-717X-7-128
Cite this article as: Keshtgar et al.:Pacemaker and radiotherapy in breast
cancer: is targeted intraoperative radiotherapy the answer in this
setting?. Radiation Oncology 2012 7:128.
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... Contrastingly, there is no current consensus on the use of IORT in patients with breast cancer and concomitant pacemaker, and surgeons remain cautious because pacemaker failures due to radiation can theoretically occur at any dose (32). As a result, many of them opt to use surgery and adjuvant therapy to treat these patients (33). Furthermore, elderly patients, such as patient 1, who was 82 years old, could benefit from surgery and endocrine therapy while avoiding radiotherapy (34). ...
... The authors reported that the rate of local recurrence after 10 years was significantly higher in patients who did not receive radiation therapy compared to patients who did (9.8% vs. 0.9%), supporting our decision to treat this patient with radiotherapy. Although previous studies have evaluated the utility of IORT in patients with breast cancer, fewer have elucidated its use when associated with a presence of ipsilateral pacemaker (7,14,33). Chen et al. (29) assessed the dose for a patient with a pacemaker being treated in the left breast with IORT in phantom cases. They found that as the radial distance between the applicator and the pacemaker increases, the radiation exposure to the pacemaker decreases. ...
... In their study, despite the radiation dose being increased to 10-20 Gy, no pacemaker device malfunctions, or failures were observed. Additionally, Keshtgar et al. (33) reported a case of left-sided invasive ductal carcinoma of the breast with a pacemaker in an elderly woman. They reported a tumor-topacemaker distance of 9 cm that was successfully treated with IORT. ...
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Background Partial breast irradiation with Intra-operative radiotherapy (IORT) has become a popular management option as opposed to whole breast radiation using external beam radiotherapy for breast cancer patients. While previous studies have highlighted the use of IORT in breast cancer patients, there is a scarcity of literature on the use of IORT in those who also have ipsilateral pacemakers. Thus, the aim of our case report is to highlight the applicability of IORT in breast cancer patients who also have a pacemaker.Case ReportsTwo female patients with an implanted dual-chamber pacemaker presented with a diagnosis of left-sided invasive ductal carcinoma on mammogram. Mammography of the left breast revealed a 10 mm and 7 mm spiculated mass, respectively, further confirmed with an ultrasound-guided core biopsy that was conclusive of clinical Stage I T1 N0 grade 2, ER +, PR + Her2 – invasive ductal carcinoma. They met our eligibility criteria for IORT, which is being performed as a registry trial. These patients underwent a wide excision lumpectomy along with IORT.Conclusion Our findings underscore the successful use of targeted IORT for breast-conserving surgery in a patient with invasive ductal carcinoma and pacemaker, hence eliminating the necessity for relocating pacemaker surgeries in these patients. Furthermore, no device failure or malfunction for the pacemaker was recorded before, during, or after the surgery, demonstrating the safety of using IORT in patients with preinstalled pacemaker despite a lack of evidence on safe radiation dosage or manufacturer guidelines. Nonetheless, the effects of IORT on pacemaker < 10 cm were not studied in our patients and further clinical studies are recommended to reinforce the applicability and safe distance of IORT in breast cancer patients with pacemaker.
... The first documented case involved an 83-year-old woman diagnosed with invasive ductal carcinoma in the left breast, who also had a St. Jude Medical (St. Jude Medical Inc., St. Paul, MN, USA) dual chamber PM programmed to VVIR 70 bpm and hysteresis 60 bpm in single chamber mode [18]. The PM was located 90 mm from the tumor mass in the upper pole of the left breast and successfully received TARGIT using an applicator of 30 mm diameter, which delivered radiation doses of 20 Gy to the surgical margin and 6 Gy to an area 10 mm from the surgical margin, over a period of 26 min. ...
... Compared to the traditional EBRT, beam scattering is lower in IORT due to direct/close contact with the tumor bed. The generation of an electromagnetic field is also more limited in IORT compared to traditional linear accelerators [6,18]. The adverse impact of these factors on modern CMOS circuitry has been documented [5,19]. ...
... The adverse impact of these factors on modern CMOS circuitry has been documented [5,19]. Despite this theoretical advantage, the effects of traditional EBRT on cardiac PMs have been widely discussed [10,14,15,18], while the effects of IORT on patients with PMs are not well understood [13]. ...
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Case reports detailing the effects of targeted intraoperative radiation therapy (IORT) on patients with cardiac pacemakers (PMs) are rare. This growing population sub-group requiring IORT and lack of standardized guidelines necessitate more practical published research. An 81-year-old patient with clinical stage II, T1 N0 grade III, triple-negative invasive ductal carcinoma and an implanted single-lead chamber PM (VVIR mode, model: Biotronik, type Effecta SR) received targeted intraoperative radiotherapy at the time of wide local excision and sentinel lymph node biopsy. It presents the shortest distance between the outer diameter of the PM and IORT applicator in literature. Target IORT was performed utilizing an Intrabeam device (50 kV, Carl Zeiss Surgical, Oberkochen, Germany). This case elucidates the successful use of targeted IORT for breast-conserving surgery in a patient with a single ipsilateral chamber VVIR mode PM. No device failure or malfunction was reported for the PM before, during, or after the procedure. These findings support the use of targeted IORT for patients diagnosed with early-stage breast carcinomas who have a PM implanted. However, further research is needed to understand the safety of other methods and devices for IORT patients with cardiac implantable electronic devices.
... TARGIT-IORT enables some patients to have breast conservation when they would otherwise reluctantly choose mastectomy 53 or simply do not want to have conventional radiotherapy 24 because of their personal circumstances. Use of TARGIT-IORT in certain specific situations has also been described, e.g., in conjunction with oncoplastic surgery 54 , for DCIS 55 56 , or when external beam radiotherapy cannot be used or preferably avoided (such as in the presence of a pacemaker 57 , previous radiotherapy to the breast 58-61 , or breast implants 62 ). ...
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... Concerning brachytherapy, no in vitro studies are available so far and only a few case studies report on that topic. Intraoperative brachytherapy might be a promising option for patients with breast cancer, who wish for a breast-preserving therapy if the dose reaching the CIED can be kept very low [28,29]. A weakness of our set-up is for sure, that dose-distribution might be inconsistent in the devices, although we tried to reduce this effect by changing the positions of the devices throughout the experimental set-up. ...
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... Similarly, intraoperative RT is another modality available that has been reviewed in a case report where a low cumulative dose did not induce any effects. 100 ...
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Managing radiotherapy patients with implanted cardiac devices (Implantable Cardiac Pacemakers and Implantable Cardioverter‐defibrillators) has been a great practical and procedural challenge in radiation oncology practice. Since the publication of the AAPM TG‐34 in 1994, large bodies of literature and case reports have been published about different kinds of radiation effects on modern technology implantable cardiac devices and patient management before, during and after radiotherapy. This task group report provides the framework that analyzes the potential failure modes of these devices and lays out the methodology for patient management in a comprehensive and concise way, in every step of the entire radiotherapy process.
... Due to the small target volume implementation of APBI represents an alternative for limiting the radiation dose to critical structures [24] and may avoid the direct inclusion of CIEDs in the radiation fields which is uniformly recommended by guidelines and CIEDs manufacturers [9,11,15,16,25]. In fact, several reports described the feasibility of delivering APBI in presence of CIEDs [26][27][28]. Correspondingly, use of TLDs for in-vivo dosimetry had been reported 1 3 by many authors as an effective means of dose verification in RT [29,30]. The difficulty to obtain reliable dose measurements in the deep tissues has been already addressed. ...
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Purpose The management of patients with CIED receiving radiotherapy (RT) is challenging and requires a structured multidisciplinary approach. In order to stratify the risk of patients and approaching RT sessions appropriately, a consensus document from Associazione Italiana Aritmologia e Cardiostimolazione (AIAC), Associazione Italiana Radioterapia Oncologica (AIRO), Associazione Italiana Fisica Medica (AIFM) has been published on the International Journal of Cardiology in 2018. Along this line, the AIFM working group is promoting specific measurements to better investigate the role of RT on CIED. Methods In Consensus document potential radiation interactions on CIED such as recommendations for the estimation of the dose to the device are described and a multidisciplinary review of in vivo and in vitro data is presented. Further, a multi-center study to evaluate IGRT dose, neutron contamination assessment, and photon out-of-field dose are still being performed. To measure out-of-field dose to CIEDs two phantoms were created and sent to centers working with different treatment planning systems (TPS). Results Preliminary results show that the use of daily CBCT can add a considerable contribution to CIED dose up to 50 cGy like lung 4D protocol. Neutron contamination of photon and electron beams of energies ranging from 6 to 18 MV measured with REM counters show that neutron production for 10 MV photon beam is not negligible. It confirms that neutron produced by electron beam has to be taken into account for beam energy higher than 15 MeV. Comparisons between calculated and measured out-of-filed dose along with examining the behavior of different dosimeters are being studied. Working group is performing measurement to confirm that, in absence of out-of-field TPS commissioning, in vivo dosimetry is still recommended in the case of short distance CIED-field edge or dose close to 2 Gy. Conclusions A detailed approach for safe management of RT patients with CIEDs is now available with important implications for clinical practice. Only a multidisciplinary approach between medical physicists, radiation oncologists and electrophysiologists can really reduce the risk of malfunctions in patient with CIED undergoing RT. Results of the AIFM working group try to provide valuable support and further indications in this regard.
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Contemporary cardiac pacemakers can fail from radiation damage at doses as low as 10 gray and can exhibit functional changes at doses as low as 2 gray. A review and discussion of this potential problem is presented and a protocol is offered that suggests that radiation therapy patients with implanted pacemakers be planned so as to limit accumulated dose to the pacemaker to 2 gray. Although certain levels and types of electromagnetic interference can cause pacemaker malfunction, there is evidence that this is not a serious problem around most contemporary radiation therapy equipment.
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After breast-conserving surgery, 90% of local recurrences occur within the index quadrant despite the presence of multicentric cancers elsewhere in the breast. Thus, restriction of radiation therapy to the tumour bed during surgery might be adequate for selected patients. We compared targeted intraoperative radiotherapy with the conventional policy of whole breast external beam radiotherapy. Having safely piloted the new technique of single-dose targeted intraoperative radiotherapy with Intrabeam, we launched the TARGIT-A trial on March 24, 2000. In this prospective, randomised, non-inferiority trial, women aged 45 years or older with invasive ductal breast carcinoma undergoing breast-conserving surgery were enrolled from 28 centres in nine countries. Patients were randomly assigned in a 1:1 ratio to receive targeted intraoperative radiotherapy or whole breast external beam radiotherapy, with blocks stratified by centre and by timing of delivery of targeted intraoperative radiotherapy. Neither patients nor investigators or their teams were masked to treatment assignment. Postoperative discovery of predefined factors (eg, lobular carcinoma) could trigger addition of external beam radiotherapy to targeted intraoperative radiotherapy (in an expected 15% of patients). The primary outcome was local recurrence in the conserved breast. The predefined non-inferiority margin was an absolute difference of 2.5% in the primary endpoint. All randomised patients were included in the intention-to-treat analysis. This trial is registered with ClinicalTrials.gov, number NCT00983684. 1113 patients were randomly allocated to targeted intraoperative radiotherapy and 1119 were allocated to external beam radiotherapy. Of 996 patients who received the allocated treatment in the targeted intraoperative radiotherapy group, 854 (86%) received targeted intraoperative radiotherapy only and 142 (14%) received targeted intraoperative radiotherapy plus external beam radiotherapy. 1025 (92%) patients in the external beam radiotherapy group received the allocated treatment. At 4 years, there were six local recurrences in the intraoperative radiotherapy group and five in the external beam radiotherapy group. The Kaplan-Meier estimate of local recurrence in the conserved breast at 4 years was 1.20% (95% CI 0.53-2.71) in the targeted intraoperative radiotherapy and 0.95% (0.39-2.31) in the external beam radiotherapy group (difference between groups 0.25%, -1.04 to 1.54; p=0.41). The frequency of any complications and major toxicity was similar in the two groups (for major toxicity, targeted intraoperative radiotherapy, 37 [3.3%] of 1113 vs external beam radiotherapy, 44 [3.9%] of 1119; p=0.44). Radiotherapy toxicity (Radiation Therapy Oncology Group grade 3) was lower in the targeted intraoperative radiotherapy group (six patients [0.5%]) than in the external beam radiotherapy group (23 patients [2.1%]; p=0.002). For selected patients with early breast cancer, a single dose of radiotherapy delivered at the time of surgery by use of targeted intraoperative radiotherapy should be considered as an alternative to external beam radiotherapy delivered over several weeks. University College London Hospitals (UCLH)/UCL Comprehensive Biomedical Research Centre, UCLH Charities, National Institute for Health Research Health Technology Assessment programme, Ninewells Cancer Campaign, National Health and Medical Research Council, and German Federal Ministry of Education and Research (BMBF).
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The increasing human lifespan and development of technology over the last number of decades has seen an increase in the number of pacemaker and implantable cardioverter defibrillator (ICD) implantations worldwide. Given the number of risk factors common to both heart disease and cancer, it is not uncommon for several of these patients to present for radiation therapy treatment each year. A systematic review was conducted using online databases Medline and Scopus. Results were grouped into in vitro and in vivo studies. In 1994, the American Association of Physicists in Medicine (AAPM) defined guidelines for the management of these patients, which have since been adopted by many radiation oncology departments internationally. More recently, a number of studies have reported an increase in radiation sensitivity of these devices (encompassing the coiled metal leads and generator unit) due to the incorporation of complementary metal oxide semiconductor circuitry. Further avenues of device failure, such as the effect of dose rate and scatter radiation, have only more recently been investigated. There are also the unexplored avenues of electromagnetic interference on devices when incorporating newer treatment technologies such as respiratory gating and intensity modulated radiation therapy. It is suggested that each radiation oncology department employ a policy for the management of patients with ICDs and pacemakers, potentially based upon an updated national or international standard similar to that released by the AAPM in 1994.
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It is well documented that radiation therapy can have significant transitory and permanent effects on the function of cardiac pacemakers. In this study 18 multiprogrammable pacemakers were tested to establish any pattern by which these pacemakers are affected. The results confirm previous predictions on how pacemakers are damaged. The damage could be divided essentially into three types: (1) temporary change to interference or safety mode pacing lasting for the duration of the irradiation only; (2) change to interference mode pacing--from which recovery may occur after reprogramming the pacemaker; and (3) severe damage; in this case the pacemaker stops generating pulses. Recovery from this may occur a long time after the end of the treatment, but this recovery is mostly incomplete and the pacemaker cannot be used reliably thereafter. Therefore it is essential that patients with implanted pacemakers undergoing radiation therapy, should be monitored closely during the course of the treatment and for a few weeks thereafter.
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In this paper, we determine the influence of high-energy photon beam irradiation used for external radiotherapy on pacemakers, at different doses and dose rates. Ninety-six pacemakers of various origins and ages underwent in vitro high-energy photon irradiation under technical conditions close to external radiotherapy, using a linear accelerator delivering photons of high energy (18 MV). Various dose levels (up to 200 Gy for certain particularly resistant pacemakers) were delivered to pacemakers located in a water-equivalent phantom with several dose rates (from 0.05 to 8 Gy min??). Observed failures were sorted into eight classes of progressive harmfulness, some of them possibly lethal. One irradiated pacemaker exhibited an important defect at a dose rate of 0.2 Gy min??, for a cumulative dose of 0.15 Gy. Two pacemakers showed an important defect at a cumulative dose of 1 Gy, while nine pacemakers failed at a cumulative dose lower than or equal to 2 Gy and 13 failed at a cumulative dose lower than or equal to 5 Gy. The most important failure probability (70% of irradiated pacemakers) is observed for 8 Gy min??, whereas no pacemakers failed at a dose rate lower than or equal to 0.2 Gy min??. In conclusion, warnings given by manufacturers about the maximum tolerable cumulative radiation doses for safe operation of irradiated pacemakers (5 Gy), even reduced to 2 Gy, are not reliable. The spread of cumulative doses inducing failures is very large since our observations show an important failure at 0.15 Gy, while ten pacemakers withstood more than 140 Gy of cumulative dose. The safe operation of pacemakers under irradiation depends mainly on type and model. It depends also on dose rate. From our observations, for the safe operation of pacemakers, a recommendation of a maximum dose rate of 0.2 Gy min?? rejecting direct irradiation of the pacemaker at a standard dose rate for tumour treatment (2 Gy min??) is made.
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A case of a patient with runaway implantable cardioverter defibrillator (ICD) due to radiation therapy of a lung cancer is reported. This manifested as poorly tolerated wide complex tachycardia due to inappropriate rapid ventricular pacing, The event terminated with polymorphic VT, which inhibited pacing and ceased spontaneously before ICD discharge. The likely cause was corruption of device random access memory by ionizing radiation.
Rhythm Management Division: Radiation. Sylmar, USA: St
Rhythm Management Division: Radiation. Sylmar, USA: St. Jude Medical; 2005.
Impact of Therapeutic Radiation and Guidant ICD/CRT-p/Pacing Systems Review
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Vaidya JS, Joseph DJ, Tobias JS, Bulsara M, Wenz F, Saunders C, Alvarado M, Flyger HL, Massarut S, Eiermann W, Keshtgar M, Dewar J, Kraus-Tiefenbacher U, Sütterlin M, Esserman L, Holtveg HMR, Roncadin M, Pigorsch S, Metaxas M, Falzon M, Matthews A, Corica T, Williams NR, Baum M: Targeted intraoperative radiotherapy versus whole breast radiotherapy for breast cancer (TARGIT-A trial): an international, prospective, randomised, noninferiority phase 3 trial. Lancet 2010, 376:91-102.