TACE is the treatment approach most commonly used for unresectable HCC. The effectiveness of TACE as an adjuvant therapy for HCC has been documented in clinical studies.[6] Downstaging therapy with TACE, as a selected local-regional strategy, reduces tumor burden and further make radical treatment acceptable, which improves survival rates in unresectable HCC patients. A retrospective study have shown that 1-year, 2-year and 3-year accumulating PFS were 68.8%, 40.6% and 31.3%, respectively after down-staging therapy by TACE ; 1-year, 2-year and 3-year accumulating OS were 84.4%, 71.9% and 53.1%, respectively after down-staging therapy by TACE. Kaplan-Meier curves showed that successful down-staging was correlated with longer PFS and OS.[17] In related studies, of the 179 patients after initial TACE, 44 (25%) achieved tumor of downstaging to within Milan criteria and showed significantly longer survival than non-downstaged ones (P = 0.02).[18] However, to our best knowledge, there is still no study about the factors affecting the efficacy of TACE on hepatocarcinoma downstaging.
It is still controversial as to which kind of patients can benefit from the TACE, related to the heterogeneity of the patients covered in the various studies and the diversity of the clinical elements influencing prognosis importance.[19] In our retrospective study, we have attempted to try to find the relevant factors affecting the efficacy of TACE on hepatocarcinoma downstaging.
In the study, AFP, PVTT, HBsAg, the number of tumor and tumor diameter were noted to be the independent predictors of successful downstaging through multivariate analysis. Recently, several studies showed that AFP can improve the predictive accuracy of post-LT survival in patients with HCC. Regarding downstaging of HCC in patients outside Milan, Yao at al showed that an AFP༞1000ng/ml was predictive factor of failed downstaging in a total of 122 HCC patients enrolled in the downstaging protocol treated by LRT. Only 1 of 8 patients with an AFP greater than 1000 ng/ml were successfully downstaged in their study.[20] Similarly, in our study only 5 of 44 patients with AFP level higher than 1000ng/ml were successfully downstagd. Whereas 21 out of 57 patients with the AFP level lower than 1000 ng/ml, were successfully downstaged. In a previous study showed that AFP can not only promote the proliferation of hepatocellular carcinoma cells and the formation of tumor blood vessels, but also enhance the antiapoptosis effect of cancer cells.[21] Thus, AFP plays an important role in the development and progression of HCC. It is could be an explanation of our finding in this study.
Meanwhile, we found that PVTT was also an important predictive factor to evaluate the efficacy of downstaging by TACE. Patients with PVTT usually have an aggressive disease course, decreased liver function reserve, limited treatment options, hinger recurrence rates after treatment, and, therefore, worse overall survival. Among untreated HCC patients with PVTT, the median overall survival has been reported as low as 2 to 4 months.[22, 23] Many aspects of PVTT have impacted the theoretical and practical safety and efficacy of treatment, for example, disordered blood flow and associated impairment of liver function, heat-sink effects of blood flow in the area of the PVTT, and tumor location in the blood vessel.[22] These data imply that PVTT may present adverse effect on the efficacy of downstaging.
In our study, HBsAg is a powerful predictive factor of efficacy of TACE. Long-term prognosis is unsatisfactory for patients with HBV-related disease because of frequent recurrence and poor residual hepatic function.[24] In the previous, Jing-Feng Liu at al showed the evidence that low pre- or post-operative levels of HBsAg may be associated with better long-term survival in patients with HBV-related HCC. Patients with low pre-operative serum levels of HBsAg showed significantly higher OS than those with high serum levels at 1 year (90.5% vs 85.3%), 3 years (78.0% vs 70.6%), and 5 years (69.4% vs 52.6%;P<0.01).[25] This poor prognosis is probably due in part to chronic HBV infection, which promotes not only carcinogenesis of recurrent HCC but also excessive inflammation and fibrosis in the liver, further reducing residual hepatic function.[25] Therefore, high HBsAg levels in serum may negatively affect the efficacy of downstaging.
In the previous study, Christian Toso at al showed that to establish a reliable selection policy by LRT, size/number or total tumor volume(TTV) of HCC have to be taken into account.[26] In related studies, combining a variety of LRT, TTV was noted to be an excellent independent predictor of successfully downstaging. Arvind R at al indicated that for every 1 cm3 increase in TTV, the odds of successful downstaging decreased by 2%. At a TTV cutoff of 200 cm3, 76% of patients below this threshold were successfully downstaged, whereas only 4.5% of patients outside this threshold were successfully downstaged.[6] Different studies showed larger tumors were assumed to have a higher incidence of satellite nodules and vascular invasion. So the consequent relation between larger TTV and the aggressive clinicopathological character of HCC led to the valuable studies of the prognostic value of TTV.[27] Therefore, we perform a multivariate regression analysis on the number of tumor and tumor diameter, which proved the number of tumor and tumor diameter can be used as the predictors of downstaging efficacy by TACE.
We have created statistically predictive model based on a predictive logistic regression model tailored to the individual patient and give accurate efficacy information of TACE in these patients. The model is simple and easy-to-use, intergrating 5 predictors that constitute the essentials of preoperative clinical evaluation. The predictive performance of the model was further certified by external validation set. The area under the ROC curve (AUROC) of the predictive equation was 0.90 (95% confidence interval, 0.83–0.95). The area under the ROC curve (AUROC) of the predictive equation by external validation set was 0.86 (95% confidence interval, 0.72–0.95).
Furthermore, The outcome of downstaging was not affected by age and gender in our study. The type of TACE did not influence the outcome of downstaging. Unexpectedly, molecular targeting drug did not influence the outcome of downstaging in our study. A randomized phase III study conducted in Japan evaluated the effectiveness of sorafenib therapy when initiated after TACE. Four hundred and fifty-eight patients were randomized to either sorafenib or placebo, with a median time to randomization of 9.3 weeks). The study failed to show that the addition of sorafenib after TACE prolonged PFS and OS.[28] A recent article suggested that the arterial blood supply of the tumor may be associated with the efficacy of sorafenib. HCC tumors with a good arterial blood supply benefited more than those with a poor arterial supply. [29] The results in our study may be related to this factor. In addition, this suggests that the optimal timing and efficacy of molecular targeting drug in relation to TACE has yet to be determined, which needs further studies.[30]
The present study had several limitations. The limitation of the present study are the small number of cases, the retrospective observational design of the study, and difficulty showing the small statistical significance. In this retrospective study, it is difficult to control confounding factors, leading to possible deviations in the result. Based on the promising results, assessment of a larger number of cases, well-designed randomized controlled trials, and comparison with other locoregional therapies are essential to further propose the importance of the TACE.