Generally, Surgical resection is a more radical treatment approach than RFA. However, due to the limitations of the background of liver and the liver function situation, postoperative complications also need to be taken into account. RFA surgery is the relatively safe treatment approach, but the stability and thoroughness for RFA to treat liver cancer are difficult to determine[10, 11]. Although the evaluation of effectiveness between the two approaches is still in debate, in Western countries, especially in the United States, the treatment guidelines on liver cancer consistently require surgical resection for early liver cancer if the liver function allows and if there is no high vein pressure[12]. However, the guidelines also mention that due to the nearly 3% mortality rate after the liver resection surgery, other therapies to treat small liver cancer may be appropriate, of which ablation treatment is preferred. At present, the relevant mature ablation treatment is RFA treatment. There have been many studies on the effectiveness and reliability of the treatment of liver cancer using RFA and surgical resection. Although a unified opinion has not yet been reached, at present, we believe that the effect of RFA depends on the maximum diameter of the tumor. Current studies mostly define the gold standard of RFA to be smaller than 2.3-3cm. For a single tumor with diameter smaller than 3cm, RFA can achieve similar results to resection, and its safety can be ensured[13-15]. However, for a tumor with diameter in excess of 5cm, although some reports claim that three-dimensional RFA can achieve similar results to resection, at present most reports in the literature indicate the use of resection instead of RFA[4]. However, the focus of the current debate is on a single liver tumor of 3-5cm, and the treatment effectiveness of RFA and resection remains to be further investigated. Our study aims to promote an in-depth discussion of this subject.
Regarding tumor characteristics, there were more cases with the tumor located in the center of liver in the radiofrequency group than in the resection group, mainly due jointly to preoperative CT evaluation and intra-operative examination of tumor features and liver cirrhosis: when the tumor is located in the periphery of the liver, surgical resection is relatively easy, especially for a tumor of left lateral lobe; in contrast RFA ablation is prone to injure other surrounding tissues, such as the stomach or colon[6]. In addition, the implementation of RFA surgery on peripheral small liver cancer is more prone to cause tumor rupture and result in metastasis[4, 16]. When the tumor is located in the center of liver, however, especially at the junction of the donor on the segments V, VI, VII, and VIII of the right liver, liver resection will lose many normal liver tissues, leaving too small a volume of the residual liver[16]. Because most of the liver suffers from the cirrhosis background, the postoperative liver function cannot satisfy the organ metabolism, leading to liver function failure or even death. Moreover, when the tumor is close to large blood vessels, the result of using RFA is not good and often leaves behind part of the tumor tissue. Therefore, in the clinical application of RFA, we need to consider not only the diameter of the tumor but also its location, surrounding tissue and the background liver situation to achieve better results.
Although the small incision means that RFA surgery leads to significantly less blood loss, cases requiring blood transfusion are rare because the blood loss during resection surgery is also small in our hospital. Therefore, although the blood loss was different for the two groups, there was no significant difference in the rate of blood transfusion for two groups. Because the trauma of resection is relatively large, the surgery requires partial occlusion. The most commonly used method is semi-liver occlusion, which can prevent injury to the remaining liver due to continuous occlusion by the ischemia-reperfusion. However, in our analysis and comparison, although the intra-operative time is short, the blood loss during surgery is small, and the postoperative hospital stay is short, there is still a significant difference between the total treatment expense of the radiofrequency group and that of resection group, mainly because the domestic hospitals mostly use imported RFA needles. The RFA needle costs nearly 10,000 RMB Yuan, which accounts for most of the treatment cost of radiofrequency treatment, whereas the overall expense of surgical resection is low. Hence, there is no difference in the total treatment expense between resection group and radiofrequency group. Through the observation of postoperative complications, we found that although the occurrence rate of postoperative complications and the occurrence rate of serious complications for cases with resection surgery were both higher than in the RFA group, this difference was not statistically significant. One possible reason could be that our sample size is not large enough, and all our cases of RFA employed abdominal surgery. Therefore, in comparison with other statistical analyses, our data are more objective and accurate. However, this topic still needs a multi-center random comparison and study of a large sample to further explore the occurrence of postoperative complications for the two methods.
Our analysis indicates that the postoperative 1-, 3-, 5-year survival rates are similar for the RFA group and the resection group, which is similar to the results of the 18th national statistical analysis of Japan: they conducted a statistical analysis of over 10,000 cases of liver cancer with level A liver function. They found that RFA not only achieves the similar result to resection for the liver cancer smaller than 2cm but also that for liver cancer of 2-5cm, its effect is similar, and their observations have been as long as 10 years[17]. Meanwhile, our univariate and multivariate analyses contributing to overall survival or tumor-free survival rate indicated the resection or RFA did not contribute to overall survival or tumor-free survival. Our study again corroborates this point.
There are still some limitations on this study: although the sample size in this study is relatively large, all the cases are from a single center, and the study of cases from multiple centers is more persuasive; the essence of this study is a retrospective analysis. We retrospectively collected and compared the characteristics of two groups of cases. Because our selection of resection and RFA before and during the surgery is mainly determined according to the tumor position found by pre-operative CT and during the surgery, it cannot be assigned randomly. Therefore, a multi-center random comparative study with a large sample will be more persuasive, and this goal is also the direction of our future work.
Because there are fewer complications after RFA surgery, which has better intra-operative and post-operative data performance and a post-operative survival rate comparable to the resection surgery, abdominal RFA can be considered for wide application to single tumors with diameters of 3-5cm especially for central cases.