Recent prospective data regarding good survival outcome after radiofrequency ablation of lung metastases from colorectal cancer: the radiation oncologist point of view

摘要

About 20% of patients with colorectal cancer (CRC) present metastatic spread at diagnosis and another 20–30% of them will develop distant progression after curative resection of the primary tumor (1). In the last years, the available treatment for lung metastases has been progressively improved due to implementation of modern non-invasive or minimally invasive techniques. Their use could be able to improve survival in the oligometastatic state of selected categories of patient with slow growth tumor disease (2). Surgery is the most used treatment in the oligometastatic disease of patients with primary CRC, followed by stereotactic body radiotherapy (SBRT) called also stereotactic ablative radiotherapy (SABR). SABR is a non-invasive procedure that could be used in patients not suitable to surgery, due to comorbidities or advanced age, obtaining high rates of local control comparable to surgical series (3-5). A meta-analysis by Cao et al. (6) regarding SBRT of lung metastases analyzing 18 relevant studies in this field, reported 3-year local control (LC), overall survival (OS) and progression-free survival (PFS) of 60%, 52% and 13%, respectively. More recently, radiofrequency ablation (RFA) is acquiring an increased interest in the scientific community due to its effectiveness and safety. This kind of therapy is minimally invasive, could be performed with less costs in one treatment procedure and could be repeated in case of residual or recurrent local disease. However, evidence regarding RFA is still weak due to leak of large retrospective data and poor clinical use compared to surgery or SABR. Data analysis in a large series patients included in the CLOCC trial (7), reported 14,5% of local recurrence per patient an 6% per lesion after RFA of liver metastases from CRC. Moreover, for lesion <3 cm, tumor recurrence rates were demonstrated to be under 3%. RFA could also be repeated up to four times in the treatment of small lung metastases <2–3 cm (8).