To the editor,

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related mortality worldwide [1]. Surgical resection represents a common approach to treat HCC and provides the possibility of cure [2]. Long-term prognosis after HCC resection is, however, still poor due to the high incidence of recurrence [3,4,5]. Transcatheter arterial chemoembolization (TACE) has been used in the postoperative setting as a means to decrease risk of recurrence and improve survival [6,7,8]. Whereas, in clinical practice, controversy persists relative to the role of adjuvant TACE for resected HCC [9,10,11]. The reasons for these disparate results are undoubtedly multifactorial, yet may relate to patient selection. Specifically, only certain high-risk patients with resected HCC may benefit from adjuvant TACE [12]. The objective of the current study was to construct a decision aid using a large multicenter database to predict which patient with resected HCC had a survival benefit from adjuvant TACE. In addition, we sought to estimate the magnitude of the survival benefit for given individual patients. A web-based decision tool was provided for clinicians and patients to aid in the decision-making process regarding adjuvant TACE after HCC resection. Patients and methods for this study are described in detail in Additional file 1.

Overall survival

All 2514 patients with HCC underwent curative liver resection were included (Additional file 2: Figure S1). Among them, 1755 and 759 patients were randomly segregated to the development and validation cohort, respectively (Table 1). Compared with patients who did not receive adjuvant TACE, patients who had adjuvant TACE had a longer survival in both the development and validation cohorts (all P < 0.001) (Additional file 3: Figure S2).

Table 1 Baseline characteristics of patients with and without adjuvant TACE in the developing and validation cohorts
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Independent predictors of survival

Univariable and multivariable Cox regression analyses of the development cohort demonstrated that independent predictors associated with overall survival after HCC resection among patients treated with and without adjuvant TACE included portal hypertension, Child–Pugh grade, preoperative AFP level, tumor size, tumor number, macrovascular invasion, microvascular invasion, and resection margin (all P < 0.05). (Additional file 4: Table S1 and Additional file 5: Table S2).

Development of the prediction models

Two different nomogram models that integrated independent factors associated with overall survival were constructed to predict outcomes among patients who did and did not receive adjuvant TACE (Fig. 1a, b). To estimate the net survival benefit from adjuvant TACE, these two nomograms were compared and the difference between the two estimates was the expected net survival benefit from the addition of adjuvant TACE.

Fig. 1
figure 1

Nomograms to calculate the expected survival time, and 3- and 5-year survival probabilities for a patients who attempt to undergo adjuvant TACE and b patients who attempt not to undergo adjuvant TACE. Thus, the difference of the expected values between the two estimates is the expected net survival benefit of adjuvant TACE. Calibration plots of the models for predicting 3-year and 5-year survival for patients with and without adjuvant TACE c in the developing cohort and d in the validation cohort, respectively. e Screenshots of the web-based calculator for individualized estimates of the expected net survival benefit of adjuvant TACE for patients with resected hepatocellular carcinoma. Website: http://www.asapcalculate.top/Cal5_en.html. For example, suppose there is a male patient without portal hypertension (Child–Pugh A) who have underwent curative resection for a single HCC tumor (tumor size: 8.0 cm, without macrovascular invasion but with microvascular invasion). His preoperative AFP level was 718 ug/L (≥ 400 ug/L), and the tumor resection margin was 0.8 cm (< 1 cm). After putting these data into these specific parameters, we can get the expected net survival time benefit of adjuvant TACE was 9.0 months, and the net survival benefits of 3-year and 5-year survival rates are 11.7% and 9.3%, respectively

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Validation of the prediction models

Bootstrapping with 400 resamples in the development cohort demonstrated good predictive performance, with the C-indexes of 0.791 (95% CI 0.742–0.840) and 0.810 (95% CI 0.779–0.841) for patients with and without adjuvant TACE, respectively. Accordingly, the C-indices were 0.756 (95% CI 0.678–0.834) and 0.765 (95% CI 0.720–0.810) in the validation cohort. There was also good calibration curve to predict 3- and 5-year survival probabilities among patients treated with and without adjuvant TACE, respectively (all P > 0.05) (Fig. 1c, d).

Construction of the online calculator

Based on the formula of the nomogram prediction models, an Internet browser-based software tool was constructed to predict the net survival benefit of adjuvant TACE for an individual patient, including the expected net survival time, and the increased 3- and 5-year survival probabilities (Fig. 1e). The corresponding score and the formula to calculate survival probability were provided (Additional file 6: Table S3). The online calculator is available for free use at: http://asapcalculate.top/Cal5_en.html. After the user inputs all the requested information relative to the prognostic factors, the predicted survival improvement associated with the addition of adjuvant TACE, including the expected survival time and the 3- and 5-year survival probabilities, is generated and displayed.

In summary, a survival prediction model that incorporated eight independent variables associated with survival was constructed to derive an individualized estimate of the net survival benefit of adding adjuvant TACE to a patient’s post-resection HCC treatment plan. The nomograms and online calculator had good predictive accuracy, and discrimination was validated. The calculator may help provide an estimate of the net survival benefit associated with adjuvant TACE for an individual patient following HCC resection. This tool may assist clinicians and patients in quantifying the benefit of adjuvant TACE after HCC resection and inform real-word discussions on this topic.