Propensity Score Matching Analysis of Changes in Alpha-Fetoprotein Levels after Combined Radiotherapy and Transarterial Chemoembolization for Hepatocellular Carcinoma with Portal Vein Tumor Thrombus

Abstract

Background and aim:
To investigate the value of changes in alpha-fetoprotein (AFP) levels for the prediction of radiologic response and survival outcomes in hepatocellular carcinoma (HCC) patients with portal vein tumor thrombus (PVTT) who received combined treatment of 3-dimensional conformal radiotherapy (3D-CRT) and transarterial chemoembolization (TACE).

Methods:
A database of 154 HCC patients with PVTT and elevated AFP levels (>20 ng/mL) treated with 3D-CRT and TACE as an initial treatment between August 2002 and August 2008 was retrospectively reviewed. AFP levels were determined 1 month after radiotherapy, and AFP response was defined as an AFP level reduction of >20% from the initial level. Radiologic response, overall survival (OS), and progression-free survival (PFS) rates were compared between AFP responders and non-responders. Propensity-score based matching analysis was performed to minimize the effect of potential confounding bias.

Results:
The median follow-up period was 11.1 months (range, 3.1-82.7 months). In the propensity-score matching cohort (92 pairs), a best radiologic response of CR or PR occurred in more AFP responders than AFP non-responders (41.3% vs. 10.9%, p < 0.001). OS and PFS were also longer in AFP responders than in non-responders (median OS 13.2 months vs. 5.6 months, p < 0.001; median PFS 8.7 months vs. 3.5 months, p < 0.001).

Conclusions:
AFP response is a significant predictive factor for radiologic response. Furthermore, AFP response is significant for OS and PFS outcomes. AFP evaluation after combined radiotherapy and TACE appears to be a useful predictor of clinical outcomes in HCC patients with PVTT.

Full text

RESEARCH ARTICLE
Propensity Score Matching Analysis of
Changes in Alpha-Fetoprotein Levels after
Combined Radiotherapy and Transarterial
Chemoembolization for Hepatocellular
Carcinoma with Portal Vein Tumor Thrombus
Yuri Jeong
1
, Sang Min Yoon
1,5
*, Seungbong Han
2
, Ju Hyun Shim
3,5
, Kang Mo Kim
3,5
,
Young-Suk Lim
3,5
, Han Chu Lee
3,5
, So Yeon Kim
4,5
, Jin-hong Park
1
, Sang-wook Lee
1
,
Seung Do Ahn
1
, Eun Kyung Choi
1
, Jong Hoon Kim
1,5
1Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul,
Korea, 2Department of Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Seoul,
Korea, 3Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine,
Seoul, Korea, 4Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine,
Seoul, Korea, 5Asan Liver Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul,
Korea
*drsmyoon@amc.seoul.kr
Abstract
Background and Aim
To investigate the value of changes in alpha-fetoprotein (AFP) levels for the prediction of
radiologic response and survival outcomes in hepatocellular carcinoma (HCC) patients with
portal vein tumor thrombus (PVTT) who received combined treatment of 3-dimensional con-
formal radiotherapy (3D-CRT) and transarterial chemoembolization (TACE).
Methods
A database of 154 HCC patients with PVTT and elevated AFP levels (>20 ng/mL) treated
with 3D-CRT and TACE as an initial treatment between August 2002 and August 2008 was
retrospectively reviewed. AFP levels were determined 1 month after radiotherapy, and AFP
response was defined as an AFP level reduction of >20% from the initial level. Radiologic
response, overall survival (OS), and progression-free survival (PFS) rates were compared
between AFP responders and non-responders. Propensity-score based matching analysis
was performed to minimize the effect of potential confounding bias.
Results
The median follow-up period was 11.1 months (range, 3.1–82.7 months). In the propensity-
score matching cohort (92 pairs), a best radiologic response of CR or PR occurred in more
AFP responders than AFP non-responders (41.3% vs. 10.9%, p <0.001). OS and PFS
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 1/10
OPEN ACCESS
Citation: Jeong Y, Yoon SM, Han S, Shim JH, Kim
KM, Lim Y-S, et al. (2015) Propensity Score Matching
Analysis of Changes in Alpha-Fetoprotein Levels
after Combined Radiotherapy and Transarterial
Chemoembolization for Hepatocellular Carcinoma
with Portal Vein Tumor Thrombus. PLoS ONE 10(8):
e0135298. doi:10.1371/journal.pone.0135298
Editor: Erica Villa, University of Modena & Reggio
Emilia, ITALY
Received: March 4, 2015
Accepted: July 20, 2015
Published: August 7, 2015
Copyright: © 2015 Jeong et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited.
Data Availability Statement: All relevant data are
within the paper and their Supporting Information
files.
Funding: These authors have no support or funding
to report.
Competing Interests: The authors have declared
that no competing interests exist.

were also longer in AFP responders than in non-responders (median OS 13.2 months vs.
5.6 months, p <0.001; median PFS 8.7 months vs. 3.5 months, p <0.001).
Conclusions
AFP response is a significant predictive factor for radiologic response. Furthermore, AFP
response is significant for OS and PFS outcomes. AFP evaluation after combined radiother-
apy and TACE appears to be a useful predictor of clinical outcomes in HCC patients with
PVTT.
Introduction
Despite surveillance programs for hepatocellular carcinoma (HCC) in high-risk populations,
most patients are diagnosed with advanced HCC with vascular invasions, and are therefore not
eligible for curative treatment. The prognosis of advanced HCC with portal vein tumor throm-
bus (PVTT) is extremely poor [1]. Because PVTT itself can cause intrahepatic dissemination or
extrahepatic metastasis and deteriorate liver function, it is a major obstacle to determining
effective treatment options. Although the Barcelona Clinic Liver Cancer (BCLC) staging and
treatment strategy indicates that sorafenib is the only recommended treatment for advanced
stage patients [2], the survival gain is modest and response rates are relatively low [3]. Partly
because of these somewhat disappointing results, other various modalities such as transarterial
chemoembolization (TACE), radioembolization, hepatic intra-arterial chemotherapy, external
beam radiotherapy, and surgical resection in selected cases have been attempted before and
after the use of sorafenib.
To reduce or stabilize PVTT and maintain portal blood flow, 3-dimensional conformal
radiotherapy (3D-CRT) with or without TACE has shown promising clinical outcomes and
safety in several studies [4–8]. Despite the effectiveness of this combined treatment, most
patients experience recurrences during the follow-up periods. Moreover, accurate radiologic
assessment of the treated HCC is difficult in cases of infiltrative primary tumors or in the pres-
ence of underlying liver cirrhosis. Therefore, additional tools to radiological evaluation are
needed to assess the prognosis of patients with advanced HCC.
The tumor marker alpha-fetoprotein (AFP) is secreted in 39–65% of HCC patients, and has
been used as a diagnostic tool [9,10]. Based on the hypothesis that AFP levels reflect the tumor
activity and burden, this marker has been frequently measured during the treatment. In several
studies, AFP response has been reported as a meaningful predictive factor for radiologic
response, recurrence, and survival in early and advanced HCC cases [11–16]. Although
3D-CRT with or without TACE has been used to treat advanced HCC patients with PVTT, the
predictive value of AFP levels after this combined treatment has not been assessed previously.
Therefore, we here investigated changes in AFP levels for the prediction of radiologic response
and survival outcomes in advanced HCC patients with PVTT who received combined treat-
ment of 3D-CRT and TACE.
Methods
Ethics statement
This study was approved by the Institutional Review Board of the Asan Medical Center, and
written informed consents were obtained from all patients.
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 2/10

Patients
Among the 412 HCC patients who were treated with TACE and 3D-CRT for PVTT between
August 2002 and August 2008 in our previous report [7], 229 patients underwent combined
3D-CRT and TACE as an initial treatment after diagnosis of advanced HCC. Of these, 30
patients with an AFP level of 20 ng/mL and 45 patients who had no AFP evaluation after
treatment were excluded from the present analysis. The remaining 154 patients were retrospec-
tively reviewed.
Treatment
The combination treatment procedure has been described in detail in our previous report [7].
For the TACE procedure, a mixture of 2–10 mL of iodized oil (Lipiodol; Laboratoire Andrè
Guerbet, Aulnay-sous-Bois, France) and 1 mg/kg cisplatin (Cisplatin; Dong-A Pharm. Co. Ltd,
Seoul, Korea) was infused with or without embolization using gelatin sponge cubes (Gelfoam;
Upjohn, Kalamazoo, MI). Radiotherapy was planned after the identification of PVTT at initial
presentation and was started 2–3 weeks after TACE. All patients underwent simulation with a
CT scanner (LightSpeed RT 16, GE Healthcare, Waukesha, WI). Radiotherapy was performed
with 6- or 15-MV X-rays from a linear accelerator (Varian, Palo Alto, CA). The fraction size
was 2 to 5 Gy, and the total dose was determined by the volume of normal liver, liver function,
and the maximum dose to the stomach or duodenum [7].
Evaluation
Serum AFP levels were measured by chemiluminescent microparticle immunoassay (ARCHI-
TECT i2000SR; Abbott, Chicago, IL). AFP response was defined as an AFP reduction of >20%
(compare to the initial level) at 1 month after completion of radiotherapy. Radiologic response
evaluation was performed by multiphase dynamic CT scans according to the modified
Response Evaluation Criteria in Solid Tumors (mRECIST) criteria [17].
Statistics
Patient characteristics were compared between AFP responders and AFP non-responders
using the student t, χ², and Fisher’s exact test. Overall survival (OS) and progression-free sur-
vival (PFS) rates were calculated from the date of start of treatment to the date of death or last
follow-up, and to the date of progression of HCC and/or PVTT, distant metastasis, death or
last follow-up, respectively, according to the Kaplan-Meier method and compared between the
two groups by the log-rank test. A Cox proportional hazards model was used to generate the
univariate and multivariate models describing the association of variables with OS and PFS.
Backward elimination Cox’s regression was used to select the principal risk factors in the multi-
variate model. Variables with p values 0.2 by univariate analysis were chosen for multivariate
analysis. To reduce potential confounding effects in this retrospective study, propensity-score
based matching analysis was performed, which included all possible variables. We performed
caliper matching on the PS (nearest available matching). Pairs (AFP responders and AFP non-
responders) on the PS logit were matched to within a range of 0.2 multiplied by the standard
deviations [18]. The balance of covariates was measured by their standardized differences. A
difference of >20% of the absolute value was considered significantly imbalanced. All statistical
tests were two-sided and performed at the 5% level of significance using SPSS version 18.0
(SPSS Inc., Chicago, IL) and R software version 2.13 (R Foundation for Statistical Computing,
Vienna, Austria; www.r-project.org).
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 3/10

Results
Patient characteristics are summarized in Table 1. The initial AFP level was 400 ng/mL in 52
(33.8%) patients. The median total radiation dose was 41.7 Gy (equivalent dose in 2 Gy frac-
tions (EQD2), α/β= 10) (range, 26–62.5 Gy). Of the 154 patients, 99 (64.3%) were AFP
responders and 55 (35.7%) were AFP non-responders. Liver function was significantly better
(Child-Pugh A 64.6% vs. 43.6%, p = 0.012) and tumor size was smaller (median 10.3 cm vs.
12.0 cm, p = 0.027) in AFP responders than in AFP non-responders. There were more patients
with hepatitis B virus (HBV) infection among AFP non-responders than among AFP respond-
ers. Otherwise, no other significant differences in patient characteristics were found between
the two groups. Propensity-score matching generated 92 matched pairs of AFP responders and
Table 1. Patient characteristics.
Entire patients Propensity score matched patients (92 pairs)
AFP
responder
AFP non-
responder
p-
value
a
AFP
responder
AFP non-
responder
p-
value
b
(n = 99) (n = 55) (n = 46) (n = 46)
Characteristics No. (%) No. (%) No. (%) No. (%)
Age (years) 0.074 0.570
Median (range) 53 (30–79) 48 (36–73) 52 (30–79) 51 (36–73)
Gender 0.583 0.758
Male/Female 86/13 46/9 41/5 39/7
Child-Pugh class 0.012 0.677
A 64 (64.6) 24 (43.6) 21 (45.7) 24 (52.2)
B 35 (35.4) 31 (56.4) 25 (54.3) 22 (47.8)
ECOG performance
status
0.763 0.814
0 18 (18.2) 11 (20.0) 7 (15.2) 10 (21.7)
1 70 (70.7) 36 (65.5) 32 (69.6) 30 (65.2)
2 11 (11.1) 8 (14.5) 7 (15.2) 6 (13.0)
Initial AFP (ng/mL) 0.879 1.000
400 33 (33.3) 19 (34.5) 13 (28.3) 14 (30.4)
>400 66 (66.7) 36 (65.5) 33 (71.7) 32 (69.6)
Viral etiology 0.041 1.000
HBsAg (+) 85 (85.9) 53 (96.4) 44 (95.7) 44 (95.7)
HBsAg (-) 14 (14.1) 2 (3.6) 2 (4.3) 2 (4.3)
Tumor size (cm) 0.027 0.993
Median (range) 10.3 (2.5–21.0) 12.0 (3.0–18.0) 11.1 (3.0–21.0) 11.1 (3.0–18.0)
Sites of PVTT 0.068 1.000
Main or
bilateral
46 (46.5) 34 (61.8) 25 (54.3) 26 (56.5)
Unilateral 53 (53.5) 21 (38.2) 21 (45.7) 20 (43.5)
Modified UICC stage 0.298 0.875
III 15 (15.2) 5 (9.1) 4 (8.7) 5 (10.9)
IVA 76 (76.8) 42 (76.4) 37 (80.4) 35 (76.1)
IVB 8 (8.1) 8 (14.5) 5 (10.9) 6 (13.0)
Abbreviations: AFP = Alpha-fetoprotein; ECOG = Eastern Cooperative Oncology Group; HBsAg = hepatitis B surface antigen; UICC = International Union
Against Cancer; PVTT = portal vein tumor thrombus. p-value
a
, student t, χ², and Fisher exact test; p-value
b
, weighted student t, χ², and Fisher exact test
using propensity score matching (92 matched pairs).
doi:10.1371/journal.pone.0135298.t001
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 4/10

AFP non-responders. In this matched cohort, there were no significant differences in baseline
characteristics between AFP responders and AFP non-responders (Table 1).
The best radiologic response was complete response (CR) or partial response (PR) in 56
(36.4%) patients and stable disease (SD) or progressive disease (PD) in 98 (63.6%) patients.
The median interval from the start of treatment to the best radiologic response was 2.8 months
(range, 1.4–8.8 months). The best radiologic response of CR or PR was higher in AFP respond-
ers than in AFP non-responders (50.5% vs. 10.9%, p <0.001). In the propensity-score match-
ing cohort, more patients had a best radiologic response of PR and SD among AFP
responders than among AFP non-responders (CR or PR, 41.3% vs. 10.9%; SD, 34.8% vs. 17.4%,
p<0.001). More patients with best radiologic response of PD existed in AFP non-responders
than in AFP responders (71.7% vs. 23.9%, p <0.001) (Table 2).
The median follow-up period was 11.1 months (range, 3.1–82.7 months). The median OS
was 11.0 months and 1- and 2-year OS was 44.8% and 21.4%, respectively (Fig 1). The median
OS was longer in AFP responders than in AFP non-responders (Fig 2A). PFS was also longer
in AFP responders than in AFP non-responders (Fig 3A). In the propensity-score matching
cohort (92 pairs), AFP responders still showed superior OS (AFP responders vs. AFP non-
responders, median 13.2 months vs. 5.6 months, p <0.001) and PFS (AFP responders vs. AFP
non-responders, median 8.7 months vs. 3.5 months, p <0.001) (Figs 2B and 3B).
On multivariate analysis, AFP response and best radiologic response were significant pre-
dictive factors for OS (AFP responder, HR = 0.312, p <0.001; best radiologic response of CR
Table 2. Best radiologic responses.
Entire patients (n = 154) Propensity score matched patients (92 pairs)
AFP responder AFP non-responder p-value AFP responder AFP non-responder p-value
Response No. (%) No. (%) No. (%) No. (%)
Complete response 8 (5.2) 8 (8.1) 0 (0) <0.001 1 (1.1) 1 (2.2) 0 (0) <0.001
Partial response 48 (31.2) 42 (42.4) 6 (10.9) 23 (25.0) 18 (39.1) 5 (10.9)
Stable disease 36 (23.4) 26 (26.3) 10 (18.2) 24 (26.1) 16 (34.8) 8 (17.4)
Progressive disease 62 (40.3) 23 (23.2) 39 (70.9) 44 (47.8) 11 (23.9) 33 (71.7)
doi:10.1371/journal.pone.0135298.t002
Fig 1. Survival outcomes. Overall survival rates (A) and progression-free survival rates (B) in all patients.
doi:10.1371/journal.pone.0135298.g001
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 5/10

or PR, HR = 0.213, p <0.001) and PFS (AFP responder, HR = 0.416, p = 0.001; best radiologic
response of CR or PR, HR = 0.231, p <0.001) (Table 3). In the propensity-score matching
analysis which included age, gender, Child-Pugh class, performance status, initial AFP level
(400 ng/mL vs. >400 ng/mL), viral etiology, tumor size, sites of PVTT, and stage, AFP
response remained a significant prognostic factor for OS (AFP responder, HR = 0.264,
p<0.001) and PFS (AFP responder, HR = 0.307, p <0.001) (Table 4).
Fig 2. Overall survival rates. Overall survival (OS) rates depending on the AFP response in all patients(A) and in the propensity score-matching cohort (B).
doi:10.1371/journal.pone.0135298.g002
Fig 3. Progression-free survival rates. Progression-free survival (PFS) rates depending on the AFP response in all patients (A) and in the propensity
score-matching cohort (B).
doi:10.1371/journal.pone.0135298.g003
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 6/10

Discussion
AFP response has not only been reported as a meaningful predictive factor for recurrence and
survival in early stage HCC patients who receive curative treatments [13,15,16] but also has
shown the prognostic value for radiologic response and survival rates in advanced HCC after
palliative treatments [11,12,14,19–21]. Regarding patients with PVTT, few studies to date have
analyzed the prognostic value of AFP response after treatment. In a study by Riaz et al., 55.8%
of patients showed an AFP response after TACE or radioembolization, and AFP responders
had higher radiologic response rates and significantly better survival rates than AFP non-
responders [14]. In two studies which analyzed prognostic value of AFP response after concur-
rent chemoradiotherapy, 68% to 78% of patients achieved an AFP response [12,19]. The
median survival duration in those studies were similar to that of our present study, with values
ranging from 13.3 to 17.6 months in AFP responders, which is significantly better than the val-
ues reported for AFP non-responders. Recently, 3D-CRT was used with or without TACE to
reduce PVTT and to maintain portal blood flow [4–6,8]. However, no studies have yet analyzed
the prognostic value of the AFP response after a combined 3D-CRT and TACE in patients
Table 3. Multivariate analysis for progression-free survival (PFS) and overall survival (OS) rates in the propensity score-matching cohort.
PFS OS
Variables HR (95% CI) P value HR (95% CI) P value
Gender (male) 1.985 (1.030–3.828) 0.041
Child-Pugh class (A) 1.367 (0.831–2.246) 0.218 1.597 (1.014–2.514) 0.043
ECOG performance status (0–1) 1.422 (0.769–2.629) 0.261
Initial AFP (400 ng/mL) 1.977 (1.143–3.420) 0.015 2.256 (1.320–3.856) 0.003
Tumor size (cm) 1.021 (0.955–1.091) 0.543 1.016 (0.951–1.085) 0.639
Modified UICC stage 0.014 0.173
IVA (III) 0.811 (0.344–1.912) 0.633 0.821 (0.353–1.910) 0.646
IVB (III) 2.283 (0.792–6.585) 0.127 1.560 (0.562–4.333) 0.393
AFP response (-) 0.416 (0.253–0.682) 0.001 0.312 (0.189–0.516) <0.001
Best radiologic response (-) 0.231 (0.115–0.466) <0.001 0.213 (0.114–0.400) <0.001
Abbreviations: PFS = progression-free survival; OS = overall survival; HR = hazard ratio; CI = confidence index; ECOG = Eastern Cooperative Oncology
Group; AFP = Alpha-fetoprotein; UICC = International Union Against Cancer; Variables with p values 0.2 by univariate analysis were chosen for
multivariate analysis.
doi:10.1371/journal.pone.0135298.t003
Table 4. Hazard ratio (HR) for clinical outcomes in the AFP responder group compared with the AFP non-responder group.
Unadjusted Multivariable adjusted
a
Adjusted by propensity matching
b
Outcomes HR (95% CI) pHR (95% CI) pHR (95% CI) p
OS 0.313 (0.219–0.447) <0.001 0.435 (0.291–0.650) <0.001 0.264 (0.175–0.400) <0.001
PFS 0.291 (0.200–0.423) <0.001 0.508 (0.341–0.757) 0.001 0.307 (0.206–0.457) <0.001
Reference = AFP non-responder group
Abbreviations: OS = overall survival; PFS = progression-free survival; HR = hazard ratio; CI = confidence index; AFP = Alpha-fetoprotein;
a
Adjusted age, gender, Child-Pugh class, performance status, Initial AFP (400 ng/mL vs. >), viral etiology, tumor size, sites of portal vein tumor
thrombus, stage, and best radiologic response;
b
all the possible variables (age, gender, Child-Pugh class, performance status, Initial AFP (400 ng/mL vs. >), viral etiology, tumor size, sites of portal
vein tumor thrombus, stage) were included for the propensity score matching.
doi:10.1371/journal.pone.0135298.t004
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 7/10

with PVTT. In our present analyses, AFP responders showed better survival and higher radio-
logic response rates than AFP non-responders in all patients. In addition, the AFP responders
showed a significantly better median survival of 13.2 months and higher radiologic response
rates than AFP non-responders in the propensity-score matching cohort after combined
3D-CRT and TACE.
Based on the criteria used in previous sorafenib studies, we defined an AFP response as a
reduction of >20% from the initial level. To improve the specificity and positive predictive
value, other studies have alternatively defined the AFP response as a reduction of >50% com-
pared to the initial level [14,15,20]. However, the proportion of AFP responders in those stud-
ies were similar to that of the present study, which may be due to similar evaluation times of
AFP response used among studies. In earlier studies that define AFP response as a >50%
reduction, the timing of the AFP responses were later than that in studies that define this
response as a 20% reduction [14,20]. In HCC patients with PVTT, most patients have a poor
prognosis and experience tumor progression during subsequent treatment. Hence, an early
AFP evaluation may be more useful to determine additional treatments if the ratio of respond-
ers to non-responders is similar.
The radiologic response rate in our current study subjects was 36.4% according to mRECIST
criteria. The radiologic response was found to be the strongest prognostic factor for OS and
PFS, and significantly more of our AFP responder subjects achieved a radiologic response of
CR or PR than the non-responders. The median time to best radiologic response from the start
of treatment was 2.8 months (range, 1.4–8.8 months). This range suggests varied and unpre-
dictable durations when compared to AFP responses that were usually evaluated at a constant
timing. Riaz et al. also reported the time to best radiologic response and AFP response [14].
According to the WHO criteria, these authors found that a radiologic response was achieved in
53% of AFP responders and in 24% of AFP non-responders. The median time to best radio-
logic response was 5.6 months (range, 3.9–8.5 months) and the median time to AFP response
was 3.3 months (range, 2.5–4.4 months). The authors suggested that an AFP response may be
able to predict treatment response before a radiologic response evaluation. Other studies have
evaluated radiologic response, and similar to our present study found higher radiologic
response rates among AFP responders [11,19]. As we noted above, the timing of radiologic
response varies between studies. Considering the prognostic value of the radiologic response
rate for survival outcomes, the evaluation of the AFP response may be a useful tool to predict
subsequent radiologic response in advanced HCC patients.
This study had several limitations of note. First, AFP elevation may be associated with
chronic liver diseases such as viral hepatitis and liver cirrhosis as well as HCC. In patients with
chronic liver disease, elevated AFP levels may reflect hepatic regeneration that occurs after
parenchymal damage [22]. In our present study, 89.6% of patients had HBV infection, but the
activity of hepatitis and use of antiviral agents were not considered in our analysis. Second, the
prognostic value of the AFP response is limited to patients with elevated AFP levels. In our
present study cohort, 30 patients were excluded from the analysis due to an initial AFP level of
20 ng/mL among 229 patients. Third, as mentioned above, most patients had HBV infection,
which is a higher rate than observed in western counties. Because the effect of viral etiology on
the prognostic value of AFP is uncertain, careful interpretation is needed. Lastly, because of the
retrospective nature of our present study, baseline characteristics were not evenly distributed
between the response groups at initial analysis. To address this problem, additional propensity-
score matching analysis was performed and the prognostic value of the AFP response was also
confirmed in this additional analysis.
Despite the abovementioned limitations, our present study is one of few investigations to
evaluate the prognostic value of the AFP response after combined 3D-CRT and TACE as an
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 8/10

initial treatment in HCC patients with PVTT. In advanced HCC patients with PVTT, the
assessment of radiologic response after treatment can be difficult due to diffusely infiltrative
tumors, underlying liver cirrhosis, or parenchymal changes after previous treatments. In addi-
tion, most patients with advanced HCC experience recurrences or progressions during the fol-
low-up periods, Hence, the AFP response may be a useful tool that may predict the radiologic
response and thus be used for the early prediction of clinical outcomes in HCC cases. This
would assist clinicians to determine the most appropriate additional treatments.
In summary, the AFP response is a significant predictive factor for the radiologic response.
Furthermore, the AFP response is statistically significantly associated with OS and PFS. AFP
evaluation after combined radiotherapy and TACE thus appears to be a useful tool to predict
clinical outcomes in HCC patients with PVTT.
Supporting Information
S1 Table. Raw data excel file for Tables 1and 2, Figs 1A, 1B,2A and 3A.This raw data excel
file shows patients characteristics (age, gender, Child-Pugh class, ECOG performance status,
initial AFP level, viral etiology, tumor size, site of PVTT, and modified UICC stage), treatment
outcomes (AFP response and best radiologic response), and oncologic outcomes (PFS and OS)
for entire patients (n = 154).
(XLS)
S2 Table. Raw data excel file for Tables 1,2,3and 4, Figs 2B and 3B.This raw data excel file
shows patients characteristics (age, gender, Child-Pugh class, ECOG performance status, initial
AFP level, viral etiology, tumor size, site of PVTT, and modified UICC stage), treatment out-
comes (AFP response and best radiologic response), and oncologic outcomes (PFS and OS) for
propensity score matched patients (92 pairs).
(XLS)
Author Contributions
Conceived and designed the experiments: YJ SMY YSL SYK JHK. Performed the experiments:
YJ SMY JHS KMK YSL HCL SYK JHP JHK. Analyzed the data: YJ SMY SH JHS KMK HCL
SYK JHP SWL. Contributed reagents/materials/analysis tools: SH SDA EKC. Wrote the paper:
YJ SMY SH YSL SYK JHK.
References
1. Yeung YP, Lo CM, Liu CL, Wong BC, Fan ST, Wong J. Natural history of untreated nonsurgical hepato-
cellular carcinoma. Am J Gastroenterol. 2005; 100: 1995–2004. PMID: 16128944
2. Llovet JM, Bru C, Bruix J. Prognosis of hepatocellular carcinoma: the BCLC staging classification.
Semin Liver Dis. 1999; 19: 329–338. PMID: 10518312
3. Llovet JM, Ricci S, Mazzaferro V, Hilgard P, Gane E, Blanc JF, et al. Sorafenib in advanced hepatocel-
lular carcinoma. N Engl J Med. 2008; 359: 378–390. doi: 10.1056/NEJMoa0708857 PMID: 18650514
4. Ishikura S, Ogino T, Furuse J, Satake M, Baba S, Kawashima M, et al. Radiotherapy after transcatheter
arterial chemoembolization for patients with hepatocellular carcinoma and portal vein tumor thrombus.
Am J Clin Oncol. 2002; 25: 189–193. PMID: 11943901
5. Kim DY, Park W, Lim DH, Lee JH, Yoo BC, Paik SW, et al. Three-dimensional conformal radiotherapy
for portal vein thrombosis of hepatocellular carcinoma. Cancer. 2005; 103: 2419–2426. PMID:
15822130
6. Yamada K, Izaki K, Sugimoto K, Mayahara H, Morita Y, Yoden E, et al. Prospective trial of combined
transcatheter arterial chemoembolization and three-dimensional conformal radiotherapy for portal vein
tumor thrombus in patients with unresectable hepatocellular carcinoma. Int J RadiatOncol Biol Phys.
2003; 57: 113–119. PMID: 12909223
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 9/10

7. Yoon SM, Lim YS, Won HJ, Kim JH, Kim KM, Lee HC, et al. Radiotherapy plus transarterial chemoem-
bolization for hepatocellular carcinoma invading the portal vein: long-term patient outcomes. Int J
Radiat Oncol Biol Phys. 2012; 82: 2004–2011. doi: 10.1016/j.ijrobp.2011.03.019 PMID: 21621346
8. Zeng ZC, Fan J, Tang ZY, Zhou J, Qin LX, Wang JH, et al. A comparison of treatment combinations
with and without radiotherapy for hepatocellular carcinoma with portal vein and/or inferior vena cava
tumor thrombus. Int J Radiat Oncol Biol Phys. 2005; 61: 432–443. PMID: 15667964
9. Chen CJ, Lu SN, You SL, Wu MH, Wang LY, Lee LT, et al. [Community-based hepatocellular carci-
noma screening in seven townships in Taiwan]. J Formos Med Assoc. 1995; 94 Suppl 2: S94–102.
PMID: 8672950
10. Daniele B, Bencivenga A, Megna AS, Tinessa V. Alpha-fetoprotein and ultrasonography screening for
hepatocellular carcinoma. Gastroenterology. 2004; 127: S108–112. PMID: 15508073
11. Chan SL, Mo FK, Johnson PJ, Hui EP, Ma BB, Ho WM, et al. New utility of an old marker: serial alpha-
fetoprotein measurement in predicting radiologic response and survival of patients with hepatocellular
carcinoma undergoing systemic chemotherapy. J Clin Oncol. 2009; 27: 446–452. doi: 10.1200/JCO.
2008.18.8151 PMID: 19064965
12. Lee MH, Kim SU, Kim do Y, Ahn SH, Choi EH, Lee KH, et al. Early on-treatment predictions of clinical
outcomes using alpha-fetoprotein and des-gamma-carboxy prothrombin responses in patients with
advanced hepatocellular carcinoma. J Gastroenterol Hepatol. 2012; 27: 313–322. doi: 10.1111/j.1440-
1746.2011.06867.x PMID: 21793906
13. Nobuoka D, Kato Y, Gotohda N, Takahashi S, Nakagohri T, Konishi M, et al. Postoperative serum
alpha-fetoprotein level is a useful predictor of recurrence after hepatectomy for hepatocellular carci-
noma. Oncol Rep. 2010; 24: 521–528. PMID: 20596642
14. Riaz A, Ryu RK, Kulik LM, Mulcahy MF, Lewandowski RJ, Minocha J, et al. Alpha-fetoprotein response
after locoregional therapy for hepatocellular carcinoma: oncologic marker of radiologic response, pro-
gression, and survival. J Clin Oncol. 2009; 27: 5734–5742. doi: 10.1200/JCO.2009.23.1282 PMID:
19805671
15. Shim JH, Han S, Lee YJ, Lee SG, Kim KM, Lim YS, et al. Half-life of serum alpha-fetoprotein: an early
prognostic index of recurrence and survival after hepatic resection for hepatocellular carcinoma. Ann
Surg. 2013; 257: 708–717. doi: 10.1097/SLA.0b013e318273be70 PMID: 23108121
16. Tsai MC, Wang JH, Hung CH, Kee KM, Yen YH, Lee CM, et al. Favorable alpha-fetoprotein decrease
as a prognostic surrogate in patients with hepatocellular carcinoma after radiofrequency ablation. J
Gastroenterol Hepatol. 2010; 25: 605–612. doi: 10.1111/j.1440-1746.2009.06115.x PMID: 20074164
17. Lencioni R, Llovet JM. Modified RECIST (mRECIST) assessment for hepatocellular carcinoma. Semin
Liver Dis. 2010; 30: 52–60. doi: 10.1055/s-0030-1247132 PMID: 20175033
18. Lim YS, Han S, Heo NY, Shim JH, Lee HC, Suh DJ. Mortality, liver transplantation, and hepatocellular
carcinoma among patients with chronic hepatitis B treated with entecavir vs lamivudine. Gastroenterol-
ogy. 2014; 147: 152–161. doi: 10.1053/j.gastro.2014.02.033 PMID: 24583062
19. Kim BK, Ahn SH, Seong JS, Park JY, Kim do Y, Kim JK, et al. Early alpha-fetoprotein response as a
predictor for clinical outcome after localized concurrent chemoradiotherapy for advanced hepatocellular
carcinoma. Liver Int. 2011; 31: 369–376. doi: 10.1111/j.1478-3231.2010.02368.x PMID: 21083802
20. Memon K, Kulik L, Lewandowski RJ, Wang E, Ryu RK, Riaz A, et al. Alpha-fetoprotein response corre-
lates with EASL response and survival in solitary hepatocellular carcinoma treated with transarterial
therapies: a subgroup analysis. J Hepatol. 2012; 56: 1112–1120. doi: 10.1016/j.jhep.2011.11.020
PMID: 22245905
21. Personeni N, Bozzarelli S, Pressiani T, Rimassa L, Tronconi MC, Sclafani F, et al. Usefulness of alpha-
fetoprotein response in patients treated with sorafenib for advancedhepatocellular carcinoma. J Hepa-
tol. 2012; 57: 101–107. doi: 10.1016/j.jhep.2012.02.016 PMID: 22414760
22. Bloomer JR, Waldmann TA, McIntire R, Klatskin G. Relationship of serum alpha-fetoprotein to the
severity and duration of illness in patients with viral hepatitis. Gastroenterology. 1975; 68: 342–350.
PMID: 163780
Alpha-Fetoprotein Response after Radiotherapy for HCC with PVTT
PLOS ONE | DOI:10.1371/journal.pone.0135298 August 7, 2015 10 / 10