Ablative Approaches for Pulmonary Metastases

doi:10.1016/j.thorsurg.2015.09.004

Thoracic Surgery Clinics

Volume 26, Issue 1, February 2016, Pages 19-34

https://doi.org/10.1016/j.thorsurg.2015.09.004 Get rights and content

Section snippets

Key points

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Directed treatment of pulmonary metastases was traditionally limited to surgical resection in appropriately selected patients.
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More recently, for patients who are not surgical candidates, non-invasive approaches such as radiotherapy or radiofrequency or microwave ablation have been developed.
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These techniques can provide local control and survival benefit similar to that seen with surgery in well selected patients, such as those with oligometastatic disease.
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Further studies are needed to define

Background

Surgical resection of pulmonary metastases was described as early as the mid to late nineteenth century, likely because of advances in anesthesia and aseptic techniques.⁴ The use of other metastasis-directed therapies, such as radiotherapy and invasive ablative techniques, has been developed more recently.⁵ The use of metastasis-directed therapy techniques including surgery,⁶ radiotherapy,⁷ and invasive ablative strategies⁸ has been increasing, likely mirroring the increasing use and

Background

Traditionally, radiation therapy for lung metastases has been limited to palliation of symptoms, such as cough, hemoptysis, dyspnea, or pain. Many radiation dose-fractionation schedules are currently used for palliation of thoracic symptoms, including 50 Gy in 25 fractions, 30 Gy in 10 fractions, 20 Gy in five fractions, and 17 Gy in two fractions, all of which have demonstrated approximately equal palliation and disease control compared with 10 Gy in a single fraction.²² Although these

Technique

RFA uses an alternating electrical current of 400 to 500 kHz delivered to the target tissue via an interstitial probe. This current creates heat via oscillating ions, and when taken to temperatures greater than 60°C, coagulative necrosis results. Typical treatment duration is 12 to 15 minutes. Although more often used for ablation of hepatic tumors,⁶³ ablation of pulmonary tumors including metastases is increasingly performed. Regardless, the Food and Drug Administration recently issued a

Microwave ablation

Similar to RFA, MWA causes tumor destruction via hyperthermia. However, different from RFA, MWA uses higher frequencies of 915 MHz to 2.45 GHz. This induces rapid heating caused by forced rotation of polar molecules, mostly water, leading to higher temperatures compared with RFA. MWA can heat treated tumors in about 2 to 5 minutes, which is faster than the 12 to 15 minutes typical of RFA.⁷⁹ As a newer modality, the data reporting the outcomes of patients with MWA are less robust than that for

Summary

Pulmonary metastases are common in patients with metastatic cancer. Ablative therapy, via radiotherapy, RFA, or MWA, has the theoretic advantage over metastasectomy to be less invasive and more effective, because of lower morbidity rates, lower costs, and the potential for delivering ablative treatments on an outpatient basis. However, when treating patients with metastases, even if oligometastatic, selection criteria are a pivotal issue. In general, clinical indications are the same as those