# Hepatic Reirradiation for Patients with Recurrent Hepatocellular Carcinoma
## 4 Discussion
Third, either CT scan or MRI only reveals anatomic abnormality; however, positron emission tomography (PET) scan reveals more metabolic information about cancer cells. [PERSON] et al. concluded that PET scans have high sensitivity up to 90-100% for detecting recurrent or metastatic hepatic tumors and good evaluation for therapeutic response. Besides, refined PET data may be helpful for avoiding false-positive results after local treatment [19]. Limited by reimbursement, we seldom used PET scans for pre- and posttreatment evaluation. Moreover, there might still be a difference between remarkable and slight PR; objective and effective criteria would be needed for more rigorous evaluation. All these limitations and the nature of the retrospective review deterred a rigorous assessment of treatment outcomes. Interestingly, the use of systemic therapy was found to have no association to OS; it even had no control benefit on OF and DM-PFS. Besides small study numbers and an even smaller proportion using systemic therapy restricted the analysis, diversity of systemic therapy is hard to correlate with outcome. Target therapies, such as sorafenib, lenvatinib and regrofenib, have recently established survival benefit for unresectable HCC even after local therapy [20; 21; 22]; however, the medication was not available for patients in the earlier period, and some patients experienced tumor recurrence after target therapy. Furthermore, some of systemic therapies were shown to have tumor control in phase 2 or smaller, nonrandomized phase 3 studies [23; 24]. Some patients would continue to receive these medications under salvage settings. This also complicated the analysis; therefore, we could only take whether patients were using systemic therapy or not as an analytic factor and adjust the effect by observing PFS of DM and OF. Consequently, there is a need to further clarify the effect of systemic therapy under a more exclusive recruitment in further research. This study was subject to inherent nature of a retrospective study design. Not only the small patient number in an over ten-year period but also the complexity of treatment course limited the analysis. Additionally, toxicity assessment was also expected to be more thorough under a prospective setting. Last, growing evidence has suggested survival benefits of a combination of RT and other local therapies, as well as target therapy [25; 26]. Although this study concluded that reirradiation for recurrent HCC may have better LC with survival benefit, well-designed prospective research is needed in future for further investigation on improving treatment strategies for unresectable HCC. The following are available online at [[https://www.mdpi.com/2076-341](https://www.mdpi.com/2076-341)]([https://www.mdpi.com/2076-341](https://www.mdpi.com/2076-341)) 7/11/4/1598/s1, Figure S1: Pattern of disease progression, Figure S2: Local control of all patients, Table S3: Correlation between risk factors and local control; Figure S4: (A). Overall survival for the patients with and without portal vein tumor thrombosis (B). In-field progression-free survival for the patients with and without portal vein tumor thrombosis; Table S5: Systemic therapy after re-irradiation; Table S6: Relationship between in-field progression-free survival and systemic therapy; Figure S7: Out-filed recurrence and/or distant metastasis free survival for subgroup with and without systemic therapy. [PERSON] coconeceived the study, participated in statistical analysis and drafted the manuscript. [PERSON] and [PERSON] contributed equally in retrieving clinical data and patients' info, performing statistical analysis and drafting the manuscript. [PERSON] conceived and coordinated the study. All authors have read and agreed to the published version of the manuscript. This research received no funding.