Lung ablation may be readily performed by either microwave or cryoablation. Cryoablation may be favored near central structures, to better preserved collagen within or central bronchi/bronchioles. In addition, cryoablation may be more readily extended into the chest wall for locally invading tumors and involve less procedural pain. Cryoablation is quite flexible to “sculpt” large enough ice for coverage of all tumor margins. Similar to our large renal and hepatic cryoablation series, our upcoming thoracic cryoablation series is one of the largest and longest in the literature, again showing very low complication and recurrence rates, comparable to surgery.
These may be considered primary (e.g., non-small cell lung cancer = NSCLC) or metastatic tumors that have spread from other primary cancers (i.e., from cancers that arose in the colon, kidney, breast, etc.). The lower recurrence rates suggested for cryoablation over microwave may not be nearly as important as the additional risk of recurrence elsewhere in the lungs, brain, etc. due to the inherent disease risk for metastatic tumors, as well as NSCLC. Regardless of the ablation type, lung cancer screening benefits from having the option of lung ablation since it expands the criteria to patients who may not otherwise be surgical candidates, or refused to consider surgical options due to age or comorbidities.
Usually these are solitary tumors, but depending on the size, several tumors may be treated in the same or multiple sessions.
Approximately <5 cm (usually only for carcinoid or metastases) without evidence of extensive local spread, or likely metastases to adjacent nodes or elsewhere in the body. If the tumor is >1 cm, an additional PET/CT, chest/abdomen/pelvis CT or MRI may be necessary to better evaluate potential for other metastases.
Nearly any location within the lung for cryoablation, and anything >~1cm peripheral from major bronchi. Cryoablation may also have more flexibility for peripheral lung tumors extending into chest wall, as well as metastatic foci residing within the chest wall, yet abutting lung and thereby categorized within this “thoracic” category.
- An exception would be if the tumor has invaded pulmonary vasculature, more commonly going into the pulmonary vein for some metastases (e.g., alveolar soft part sarcoma).
- As above, tumors that have spread to the local lymph nodes or elsewhere in the body (i.e., liver, adrenal glands, pancreas, etc.) may require additional considerations of systemic therapy.
- Hydro(aero)-dissection: if the tumor is located near adjacent central airway (trachea), esophagus or chest wall, a small catheter (5F) may be placed between the tumor for infusing air or saline to protect that space, thereby preventing the ablation zone (ice or heat) from proceeding into the critical structure. Microwave ablation is frequently performed adjacent to the pleura using hydrodissection with lidocaine to also remove the potential associated greater pain/discomfort.
- Balloon interposition: rarely, when fluid is not sufficient to keep away adjacent bowel, a balloon may be placed via a different puncture site and placed through an introducing tube or sheath.
- Esophageal balloon protection: cryoablation is unique in allowing central or endoluminal protection of the esophagus by usually two side-by-side warming balloons, pumped with flowing warm water.