Confronting Complexity: Stereotactic Body Radiation Therapy for Localized Lung Cancer with a Pacemaker

In the realm of cancer management, the coexistence of cardiac implantable electronic devices (CIEDs) with lung cancer introduces unique challenges in treatment planning, particularly when considering aggressive modalities such as stereotactic body radiation therapy (SBRT). Pacemakers, as sensitive electronic devices, are susceptible to external factors such as radiation [1]. SBRT precisely delivers high radiation doses to tumors while minimizing exposure to healthy tissues, but this precision also presents risks to nearby implanted devices. With the aging population and advancements in oncology and cardiology, the prevalence of individuals with both lung cancer and cardiovascular diseases is rising, leading to increased demand for radiotherapy in CIED patients [2, 3].

Surgery is the primary treatment for early-stage NSCLC in patients who are medically fit. For those who are medically inoperable due to significant comorbidities or who refuse surgery, SBRT, also known as stereotactic ablative radiotherapy (SABR), has emerged as the preferred alternative. However, the use of SBRT presents specific challenges for patients with pacemakers.

Ensuring safe SBRT delivery in pacemaker patients demands meticulous interdisciplinary coordination. Pretreatment cardiologist evaluation is crucial to assess device function and radiation risks. Continuous monitoring during treatment is vital to detect adverse pacemaker effects [4, 5]. Thus, providers must understand potential complications and adhere to guidelines for optimal management.

A 75-year-old patient, who smoked heavily for 2 decades at an average rate of 20 pack-years, managed to quit smoking 15 years ago. He also has a medical history marked by atrial fibrillation with bradycardia and underwent pacemaker placement in 2020 (Fig. 1). The patient does not have none history of chronic obstructive pulmonary disease.

The patient’s initial symptoms leading to consultation included hemoptysis, a dry cough, and an unexplained weight loss of 5 kg. Following an examination, a thoracic CT scan was performed, revealing a 4 cm lesion located in the right apical lung (Figs. 2, 3). Notably, there were no indications of parietal infiltration or mediastinal lymphadenopathy. Given the peripheral location of the tumor, bronchoscopy was performed and did not reveal any lesion. A percutaneous CT-guided biopsy led to a pathological diagnosis of lung adenocarcinoma, confirmed by immunohistochemistry (positive for CK7, negative for CK20, and positive for TTF1). Next-generation sequencing was not performed.

Further imaging, including an 18-FDG PET scan and a brain MRI, revealed a hypermetabolic mass measuring 4 cm in the right lung apex, with no evidence of lymphadenopathy or distant metastatic disease and no suspicious lesions in the brain. The patient exhibited a forced vital capacity of 3.2 L and forced expiratory volume in 1 s of 2.8 L, indicative of normal respiratory function. The cancer was staged as T2aN0M0, leading to a comprehensive discussion at the multidisciplinary tumor board.

Considering the patient’s comorbidities, particularly cardiac issues, surgical intervention was deemed unsuitable. SBRT was chosen (Fig. 4) with a dose of 48 Gy delivered in 4 fractions of 12 Gy, resulting in a biologically effective dose of 105.6 Gy.

The radiotherapy utilized a 6 MV flattening filter-free photon beam generated by the TrueBeam linear accelerator (Varian, CA) using volumetric modulated arc therapy technique (Fig. 5). A cone-beam computed tomography was performed before each arc. Treatment sessions were administered every other day. The gross tumor volume included the hypermetabolic tumor volume as determined from the 18-FDG PET scan. The planning target volume was delineated by adding a uniform 0.5 cm margin to the gross tumor volume.

The dose constraints for the organs at risk, including the lungs, chest wall, ribs, trachea, bronchi, spinal cord, brachial plexus, heart, as well as major blood vessels, were respected. However, it is crucial to note that the dose received by the pacemaker surpassed 10 Gy in EQD2, exceeding the tolerance dose to prevent malfunctioning. Therefore, the patient sought consultation with a rhythmologist to assess arrhythmia and the dependency on CIEDs prior to initiating treatment. The rhythmologist performed pretreatment assessments before each radiotherapy session, and continuous cardiac monitoring was diligently maintained throughout all treatment sessions.

An electrocardiogram before and after each treatment session was performed. The patient did not manifest any acute toxicity except for grade 1 fatigue, without any observed bradycardia.

In terms of adjuvant therapy, which involved radiotherapy without adjuvant chemotherapy, the patient’s progress was closely monitored. The decision to omit chemotherapy was influenced by several factors, including the patient’s overall health condition and the lack of randomized studies validating this indication.

During the follow-up period, the patient underwent routine clinical evaluations and radiological assessments, including 18-FDG PET scans (Fig. 6). At the 18-month follow-up, the results indicated a favorable outcome, with no radiological signs of local recurrence or metastasis. The patient also underwent further device interrogations at 1, 3, and 6 months after completing radiotherapy to monitor any potential malfunctions related to the irradiation.

Each lung cancer case is unique, necessitating a comprehensive understanding of therapeutic options and careful monitoring to adapt treatment over time. A multidisciplinary team, involving specialists from various medical disciplines, is crucial for achieving the best possible patient care [6]. This collaborative approach provides a holistic evaluation, integrating different treatment modalities such as surgery, chemotherapy, radiotherapy, and immunotherapy to complement each other effectively. Regular multidisciplinary team meetings enhance decision-making by pooling diverse expertise, ensuring more informed and balanced treatment plans.

While surgery stands as the cornerstone of lung cancer treatment, it is imperative to acknowledge the critical importance of patient-specific factors like chronic obstructive pulmonary disease status and the selection of the surgical approach. This recognition is paramount during the preoperative assessment and management of lung cancer patients [7]. By integrating these factors into care plans, healthcare providers can effectively reduce the likelihood of surgery-related complications, particularly respiratory failure, thereby enhancing patient safety and treatment outcomes.

SBRT has emerged as a promising treatment modality for patients with lung cancer, particularly those who are deemed ineligible for surgery or prefer noninvasive treatment options [8]. SBRT delivers highly precise, ablative doses of radiation to the tumor while minimizing exposure to surrounding healthy tissue. This approach typically involves fewer treatment sessions compared to conventional radiation therapy, often completed within one to five sessions. The effectiveness of SBRT in treating lung cancer has been well-documented, with numerous studies reporting high rates of local tumor control and favorable overall survival outcomes, especially in early-stage lung cancer patients [9, 10]. Additionally, SBRT offers the advantage of minimal invasiveness, reduced treatment duration, and the potential to preserve lung function compared to surgery [10].

However, despite its benefits, SBRT is not without risks. Potential side effects, such as radiation pneumonitis, chest wall toxicity, and esophagitis, may occur, although they are generally mild and manageable [11]. Patient selection, tumor size, location, and proximity to critical structures are crucial factors considered when determining eligibility for SBRT.

In our specific case, SBRT was deemed appropriate due to the patient’s cardiac issues, which rendered them unsuitable for surgery. This treatment strategy yielded excellent outcomes, particularly in terms of relapse-free survival.

The use of SBRT in patients with a pacemaker presents unique challenges due to the potential interaction between the radiation therapy and the implanted cardiac device [12, 13]. One primary concern is the risk of damage to the pacemaker or interference with its function caused by radiation exposure.

The latest recommendations from learned societies highlight crucial considerations in managing patients with pacemakers undergoing radiation therapy [14, 15]. During the initial consultation, the radiation oncologist meticulously assesses the pacemaker’s location relative to potential radiation fields. If the pacemaker is found to be within or in close proximity to these fields, the oncologist promptly involves the cardiologist to evaluate whether relocating or replacing the device is necessary to minimize radiation exposure risks [16]. Conversely, if the pacemaker is situated at a safe distance from the radiation fields, the oncologist collaborates with the cardiologist to verify the device’s proper functioning and assess the patient’s dependency on it. In the radiation planning phase, if there is a possibility of the pacemaker being positioned near a radiation beam, the oncologist ensures its precise delineation on the planning CT scan.

This step enables the medical team, including physicists, to accurately estimate the radiation dose received by the pacemaker. It’s crucial to ensure that the cumulative dose to the pacemaker does not surpass 5 Gy, as exceeding this threshold may prompt the cardiologist to consider relocating or replacing the device to prevent potential damage.

The safety of thoracic SABR treatment for patients with CIEDs hinges on adherence to specific guidelines. Recent guidelines recommend that the prescribed dose of SABR should not exceed 2 Gy to minimize the risk of adverse effects on CIEDs. Additionally, utilizing photon energy of 10 MV or lower during SABR treatment is advised to further mitigate potential impacts on CIEDs. Close monitoring of electrical parameters of CIEDs during and after SABR treatment is crucial to promptly detect any alterations. Moreover, implementing appropriate programming and management strategies for CIEDs is essential to maintain device functionality and prevent inappropriate interventions.

Throughout the radiation treatment sessions, the medical team closely monitors the pacemaker’s dose and the patient’s dependency on the device. Electrocardiograms are routinely performed to assess cardiac function and detect any abnormalities, particularly if the pacemaker’s dose is within the range of 2–5 Gy [17]. For patients with a lower pacemaker dose or non-dependency on the device, ECGs may be conducted before and after the initial session, mid-treatment, and at the treatment’s conclusion.

Following the completion of radiation therapy, vigilant monitoring continues as the cardiologist conducts regular follow-ups to detect any potential dysfunction or damage to the pacemaker caused by radiation exposure. Despite these challenges, SBRT remains a viable option for treating lung cancer in patients with pacemakers, especially when surgery is not feasible. Close collaboration between oncology and cardiology teams, along with careful monitoring, can help optimize treatment outcomes while minimizing risks to the patient’s cardiac device.

Several studies have compared limited resection versus SBRT for early-stage lung cancer. Wang et al. [18] demonstrate that SBRT is at least as effective as limited resection for localized lung cancer in terms of overall adverse event rates, with an odds ratio (OR) of 1.00 (95% confidence interval [CI]: 0.65–1.55 at 30 days) and OR: 1.27 (95% CI: 0.84–1.91 at 90 days). Importantly, SBRT is associated with significantly lower risks of infectious adverse events (OR: 0.05; 95% CI: 0.01–0.39 at 30 days and OR: 0.41; 95% CI: 0.17–0.98 at 90 days) and respiratory adverse events (OR: 0.36; 95% CI: 0.20–0.65 at 30 days and OR: 0.51; 95% CI: 0.31–0.86 at 90 days) [18].

In our case, we meticulously adhered to these recommendations, especially considering that the dose to the pacemaker exceeded 5 Gy. This precautionary measure was crucial in preventing any dysfunction of the device or the development of potentially severe cardiac toxicity. This case underscores the importance of interdisciplinary collaboration and careful monitoring to ensure optimal outcomes in such complex clinical scenarios.

Our case underscores the importance of careful consideration and adherence to guidelines when managing patients with pacemakers undergoing radiation therapy. Through interdisciplinary collaboration and meticulous monitoring, we successfully navigated the complexities of treating lung cancer with SBRT in a patient with cardiac comorbidities.

Our patient reported that he had tolerated the treatment well, particularly on the cardiac front, and that the received treatment was much easier than he had anticipated. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000540262).

Ethical approval was not required in accordance with the local guidelines for this retrospective, unplanned study. Written informed consent was obtained from the patient for treatment and for the publication of the case and images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

The authors have no conflicts of interest to declare.

The authors did not receive any funding.

Dr. Malak Chahid wrote the entire manuscript and conducted all the bibliographic research. Mrs. Hanae El Gouach, physicist, provided the figures on dosimetry. Dr. Reda Cherkaoui provided the radiology figures. Dr. Meriem Damou participated in the writing of the article and the bibliographical research concerning the case described. Dr. Mohammed Sqalli Houssaini participated in the writing of the article and the bibliographical research concerning the case described. Prof. Fadila Kouhen wrote the case report, participated in the writing of the article and the bibliographical research, and approved the final version of the manuscript. All the authors declare having read the final version of the manuscript.

Data supporting this manuscript are included within the article and supporting materials. Further inquiries can be directed to the corresponding author.