DOI: https://doi.org/10.21203/rs.2.14548/v1
Hepatoblastoma is a rare type of primary malignant tumors of the liver that occurs in infants and children under 3 years, the pathological features consist of tissues resembling fetal liver cells, mature hepatocytes or biliary cells[1]. Further, the most common symptom is abdominal mass [2]. An important method of examination for hepatoblastoma is measuring the serum alpha-fetoprotein （AFP）value. The normal level for AFP in children is under 8ng/ml. The patient will be suspected of having hepatoblastoma if he or she has an AFP level higher than 500 (ng/ml). however, patient prognosis is still poor if AFP is not elevated at diagnosis. AFP is also used as a marker of successful treatment. If the tumor is completely removed ，the AFP value will drop to the normal level.
Currently, surgical tumor resection, chemotherapy and orthotopic liver transplantation have been used for the treatment of these tumors [3, 4]. However, the 5-year survival rate of patients with recurrence or refractory hepatoblastoma is still in a relatively low level, especially in patients with distant metastasis. [5]. Successful treatment of recurrent hepatoblastoma relies largely on surgical resection[6, 7]. When tumors are responsive, chemotherapy can be used to render patients resectability. Various chemotherapeutic regimens studied in small numbers of hepatoblastoma patients in phase I/II trials have shown limited responses[8–11]. The best available data indicate that doxorubicin (if not given during initial treatment) and irinotecan are the most active agents in recurrent hepatoblastoma. Stem cell transplantation and radiation therapy have been reported in several patients with unclear successes[12]. Advances in therapy for relapsed patients may require further research[13, 14]. Thus，it is significant to find the relevant factors for the recurrence of hepatoblastoma for further research.
A single-center retrospective analysis of 56 patients （28 of them were relapsed cases）with hepatoblastoma collected between June 2012 and September 2015 was performed to find out risk factors associated with the prognosis of this disease. These indicators can be used as important biomarkers for personalized treatment, assessment of treatment efficacy and prognostic indicators.
Study Subjects
Data from 28 patients (Male 18 cases and Female 10 cases) with relapsed hepatoblastoma were collected by Beijing Children’s Hospital from 2012 to 2015 as case group. The age ranged from 0.6 years to 12 years, with an average age of 3.9 years and the average time from postoperative to recurrence was 11.9 months. At the same time, data was collected from a corresponding 28 patients without recurrence (Postoperative follow-up time more than 3 years) in the same period, these were classified as the control group.
The current study was approved by the Committee on Human Study of the Beijing Children’s Hospital and the Ethics Review Committee of Beijing Children’s Hospital.
Diagnosis
These cases were diagnosed with hepatoblastoma according to pathological and clinical findings such as radiological examination and serum AFP level. They were categorized into four clinical stages on the basis of the pretreatment extension (PRETEXT) staging system [15] which adopted by the International Childhood Liver Tumors Strategy Group (SIOPEL).In addition, these cases were grouped based on pathology as fetal, embryonal, macro trabecular, small cell undifferentiated or embryonal-fetal mixed type [16][17]. The detailed categorization and clinical stages of the patients are listed in Table 1.
Treatment
Surgical operation was performed on patients in PRETEXT I patients of both groups following clinical diagnosis. After operation, patients underwent chemotherapy for 4–6 cycles. For PRETEXT II, III and IV cases ，Neoadjuvant chemotherapy was adopted after pathological examination by core needle biopsy for 2–4 cycles. Radiographic and serum AFP examinations were checked every 2 cycles. Then the patients underwent tumor resection. After surgery, patients need to undergo 6–9 cycles for chemotherapy. All patients had negative margins of pathological findings.Neoadjuvant chemotherapy consisted of 20 mg /m2 cisplatin on day 1–5, 300mg/m2 fluorouracil on day 1–2，vincristine for 1.5 mg/m2 on day 2 and. This was continued for 2–4 cycles. Adjuvant chemotherapy consisted of the AEP regimen (90 mg/m2 cisplatin on day 1, 25 mg/m2 pirarubicin on days 1–3 and 100 mg/m2 etoposide on days 1–4) and the ACP regimen (90 mg/m2 cisplatin on day 1, 25 mg/m2 pirarubicin on days 1–3 and 800–1,000 mg/m2 cyclophosphamide on day 1), alternately.
Followup
Follow-up was performed every three months until August 2018. Subjects were regarded as eliminated if they gave up treatment or were lost to follow-up. Patients with postoperative follow-up time of more than 3 years with no sign of recurrence were classified into the control group.
Clinical indicators
The clinical stage, pathological type, AFP level, tumor volume after preoperative chemotherapy, AFP level change trend and AFP level decline after surgical resection were recorded.
Statistical analysis
Data were expressed as the mean ± standard deviation. Data that distributed normally were compared by a standard t test. The χ2 test for comparing the number of patients. Comparison of data that did not distributed normally was made according to the Mantel-Cox log-rank test. SPSS software version 20.0was used for statistical analysis. P < 0.05 is considered to represent a significant difference in statistics.
The average age of patients in the relapse group was 3.9 years (ranging from 0.6 years to 12 years) and the average time from postoperation to recurrence was 11.9 months. Correspondingly, the non-relapsed hepatoblastoma patients were aged 2.6 years (ranging from 0.6 years to 4.4 years). Based on the results from pathological findings, patients were diagnosed as having fetal, embryonal, fetal-embryonal mixed, macro trabecular or small cell undifferentiated type hepatoblastoma, or, they were classified as ‘unable to determine pathology’ maybe due to the effects of chemotherapy. The number of patients in the relapsed group with embryonal, fetal, mixed-type, macro trabecular and small cell undifferentiated type were 5, 1, 16, 2, and 1, respectively. Meanwhile, the number of patients of each subtype in the non-recurring group were 4, 1, 19, 1, and 0, respectively. There were 3 cases for which we could not determine pathology after surgery. There was not any obvious difference in the numbers of patients with each of the pathology subtypes between the recurrence and non-recurrence groups (Figure 1).
In recurrent cases, the mean time from surgery to recurrence was 11.9 months. Recurrence of hepatoblastoma was detected in 3 stage I, 6 stage II, 18 stage III patients and 1 stage IV patients. Comparatively, the results from non-relapsed patients were as follows; 7 Stage I, 16 Stage II, 5 Stage III, and 0 Stage IV patients (Table 1). A comparison of the two groups shows that 19 patients with recurrent hepatoblastoma were stage III or IV, accounting for 68% of the recurrant cases, a proportion that is significantly higher than 18% patients being stage III or IV in the non-recurrent group.
The AFP levels are shown in Table 1. Serum AFP levels at onset ranged from 1,080,000 ng / ml to 1,778 ng / ml. After preoperative neoadjuvant chemotherapy, AFP levels fell to the normal range in 1 patient, whilst 1 patient’s AFP levels dropped normally within one month after surgery, and four fell normally within three months. AFP levels continued to beyond normal for the most patients after surgery. The AFP levels of non-recurrent cases in the same period was compared with the cases in the relapse group. Two data groups were compared using the chi-square test. There were no significant differences in onset AFP levels between the two groups (p>0.05). However, regarding the difference in the reduction trends in AFP level, there was a statistically significant difference after neoadjuvant chemotherapy between the relapsed group and the non-relapsed group (p<0.05). Similarly, the AFP level reduction rate after operation in the relapse group was lower than that in the non-relapse group. This is displayed by the fact that the proportion of patients in the relapsed group whose AFP level fell to the normal range was significantly lower than in the non-relapsed group (p<0.05).
According to the evaluation criteria of WHO solid tumor chemotherapy effect, they were divided into CR（tumor disappear），PR（50% decrease），SD（Neither PR nor PD ），PD（25% increase）[18]. In these two groups ，there were no CR cases in either of the two groups. The ratio of relapse vs non-relapse patients who had PR was 12(relapse):21(non-relapse), and for SD this ratio was 16:7. Finally, the rate of tumor volume reduction after preoperative chemotherapy in the relapse group was significantly lower than that in the non-recurrence group (p<0.05).
The main pathological hepatoblastoma types include fetal, embryonal, fetal- embryonal mixed, macro trabecular and small cell undifferentiated hepatoblastoma. People with familial Adenomatous polyposis (FAP), a syndrome of early-onset colonic polyps and adenocarcinoma, are prone to hepatoblastomas[19]. Further, Abnormal regulation of WNT B-catenin signaling pathway is common in patients with hepatoblastoma, occurring in as many as 67% of patients[ 20].
The study by SIOPEL suggested that, overall, hepatoblastoma patients have relatively good prognosis. Further, the prognosis of children with hepatoblastoma has been improved substantially over the past few years through the efforts of many cooperative study groups. However, there are still some recurrent cases[21][22].
The result of current study suggests that there is no significant difference between the two (relapse vs non-relapse) groups when comparing pathological types. Some experts have reported that pure fetal subtype had the best prognosis, while patients with the small cell undifferentiated form had the worst prognosis[23]. However, these are the least common forms of the disease amongst all groups. Thus, a comparative study is needed to further accumulate the number of cases. In our study, patients in stage II and above were given chemotherapy before surgery, and the in the mixed pathology group we included embryonal and fetal type hepatoblastoma, which accounted for the majority in both recurrence and non-recurrence groups. Furthermore, there were 3 patients for which we could not give a definite pathological classification. Further study is required to distinguish whether the results of our study are the effects of chemotherapy drugs on tumor cells or a change in the pathological type.
In the risk classification of the International Society of Pediatric Oncology (SIOP), patients with PRETEXT I, II and III were assigned to the standard risk group. While patients with stage IV were assigned to the high-risk group, suggesting the clinical prognosis is related to tumor stage. [24]. In our study, the number of patients in stage IV was low, and the proportion of stage III in the relapse group was obviously higher than that in the non-recurrent group. These results indicated that the recurrence of hepatoblastoma was associated with tumor stage, and the patients in the advanced stage were more likely to relapse due to more serious illness. Additionally, the invasion of liver was more extensive, and the surgical resection was more difficult, and subsequently, the relative recurrence probability was higher.
As an important serological tumor marker, AFP has clinical significance in the diagnosis and treatment of patients with hepatoblastoma [25]. It has been reported in the literature that AFP>1200000ng/ml is a high-risk factor in hepatoblastoma[26], but for the present study, there was no statistical difference in AFP level between the two groups at first onset. Furthermore, there was no significant association between tumor recurrence in patients and the absolute value of AFP at the time of first onset. However, by comparing the rate of AFP decline in preoperative chemotherapy between the two groups, a significant difference was observed. There is no significantly decrease in the relapse group, but comparatively, the AFP decrease was significantly more rapid in the non-recurrent group. In analyzing the reasons for this, we suppose that tumor cells in the non-recurrent group were more sensitive to chemotherapy, and that chemotherapy drugs have stronger inactivation effects on these patients. Further, since AFP is a glycoprotein secreted by hepatoblastoma cells, the tumor cell necrosis rate was faster after chemotherapy, which in turn led to a more significant decrease in AFP levels. The sensitivity of tumors to chemotherapy drugs aids postoperative chemotherapy, helping to achieve better results by inhibiting tumor cell proliferation[27–28].
Currently, hepatoblastoma is treated with chemotherapy, using cisplatin-based combination including cisplatin, fluorouracil, epirubicin, and vincristine[29–32]. The purpose of preoperative chemotherapy is to reduce the tumor volume, clear the tumor cells from the blood and remove micro-metastases in the body. This results in improving the success rate of surgical resection and reduces the chance of recurrence. The preoperative chemotherapy effect of patients in this study was evaluated according to the WHO standard. Subsequently, we found that the preoperative chemotherapy effect of the patients in the relapse group is not as good as that in the non-relapse group.
AFP studies in hepatoblastoma patients suggest that AFP should be significantly reduced after tumor resection[33, 34]. Additionally, most patients will fall to normal or near normal levels within one month after surgery[35]. However, only one of the relapsed patients in our study fell to the normal range within one month, and most of the cases did not fall to normal from postoperative to the time of tumor recurrence. When comparing the AFP level data from the patients with and without recurrence, it can be seen that there is a significant difference between the two groups. Our data indicated that the patients in the recurrent group are more likely to present with minor residual, and the tumor cells in the body are still continuing to secrete AFP, which may be causing the higher values that we identify. From these results, we can draw a conclusion that the monitoring of serum AFP levels in patients with hepatoblastoma can help clinicians to detect tumor recurrence in time and then take corresponding measures to deal with it.
In summary, the main factors involved in the recurrence of hepatoblastoma were preoperative staging, tumor volume reduction, and the rate of AFP level decrease to normal. These indicators can be used as an important biomarker for the personalized treatment, the evaluation of therapeutic effect and the predictive indicator of prognosis.
Compliance with Ethical Standards: All of the authors including Wei Yang，Yiwei Chen， Yijin Huang and Huanmin Wang declare that they had no conflict of interests.
Ethical approval: This article does not contain any studies with human participants performed by any of the authors.
Availability of data and materials: All data generated or analyzed during this study are included in this published article and its supplementary information files.
Acknowledgement: All authors revised the paper critically for important intellectual content and gave final approval of the version to be published.
[1]Bennett J, Kirby-Allen M, Ng V, Waye JS, Chung CT and Shaikh F. Hepatoblastoma in a Child With Early-onset Cirrhosis. J Pediatr Hematol Oncol 2019; 41: e30-e33.
[2]De Ioris M, Brugieres L, Zimmermann A, Keeling J, Brock P, Maibach R, Pritchard J, Shafford L, Zsiros J, Czaudzerna P and Perilongo G. Hepatoblastoma with a low serum alpha-fetoprotein level at diagnosis: the SIOPEL group experience. Eur J Cancer 2008; 44: 545–550.
[3]Ang JP, Heath JA, Donath S, Khurana S and Auldist A. Treatment outcomes for hepatoblastoma: an institution’s experience over two decades. Pediatr Surg Int 2007; 23: 103–109.
[4]Otte JB, Pritchard J, Aronson DC, Brown J, Czauderna P, Maibach R, Perilongo G, Shafford E, Plaschkes J and International Society of Pediatric O. Liver transplantation for hepatoblastoma: results from the International Society of Pediatric Oncology (SIOP) study SIOPEL–1 and review of the world experience. Pediatr Blood Cancer 2004; 42: 74–83.
[5]Otte JB, de Ville de Goyet J and Reding R. Liver transplantation for hepatoblastoma: indications and contraindications in the modern era. Pediatr Transplant 2005; 9: 557–565.
[6]Zhang B, He Q, Shi X, Wang X and Zhang X. Recurrent Scapular Metastasis From Hepatoblastoma Shown on FDG PET/CT and F-DOPA PET/CT. Clin Nucl Med 2017; 42: e449-e451.
[7]Liu B, Zhou L, Huang G, Zhong Z, Jiang C, Shan Q, Xu M, Kuang M and Xie X. Corrigendum: First Experience of Ultrasound-guided Percutaneous Ablation for Recurrent Hepatoblastoma after Liver Resection in Children. Sci Rep 2016; 6: 33424.
[8]Figarola MS, McQuiston SA, Wilson F and Powell R. Recurrent hepatoblastoma with localization by PET-CT. Pediatr Radiol 2005; 35: 1254–1258.
[9]Niwa A, Umeda K, Awaya T, Yui Y, Matsubara H, Hiramatsu H, Watanabe K, Adachi S, Itoh T, Uemoto S and Nakahata T. Successful autologous peripheral blood stem cell transplantation with a double-conditioning regimen for recurrent hepatoblastoma after liver transplantation. Pediatr Transplant 2009; 13: 259–262.
[10]Umeda K and Watanabe K. Autologous peripheral blood stem-cell transplantation with a double-conditioning regimen for recurrent hepatoblastoma after liver transplantation—a valid therapeutic option or just too much?—author reply. Pediatr Transplant 2009; 13: 794–795.
[11]Zsiros J, Brugieres L, Brock P, Roebuck D, Maibach R, Child M, Morland B, Casanova M, Pariente D, Paris C, de Camargo B, Ronghe M, Zimmermann A, Plaschkes J, Czauderna P and Perilongo G. Efficacy of irinotecan single drug treatment in children with refractory or recurrent hepatoblastoma—a phase II trial of the childhood liver tumour strategy group (SIOPEL). Eur J Cancer 2012; 48: 3456–3464.
[12]Matsunaga T, Sasaki F, Ohira M, Hashizume K, Hayashi A, Hayashi Y, Mugishima H, Ohnuma N and Japanese Study Group for Pediatric Liver T. Analysis of treatment outcome for children with recurrent or metastatic hepatoblastoma. Pediatr Surg Int 2003; 19: 142–146.
[13]Dunn CL, Lucas JT, Jr., Clark H and McLean TW. Successful Radiofrequency Ablation for Recurrent Pulmonary Hepatoblastoma. Pediatr Blood Cancer 2015; 62: 2242.
[14]Madabhavi I, Patel A, Choudhary M, Aagre S, Revannasiddaiah S, Modi G, Anand A, Panchal H, Parikh S and Raut S. Paraneoplastic recurrent hypoglycaemic seizures: an initial presentation of hepatoblastoma in an adolescent male-a rare entity. Case Rep Pediatr 2014; 2014: 104543.
[15]Czauderna P, Otte JB, Roebuck DJ, von Schweinitz D and Plaschkes J. Surgical treatment of hepatoblastoma in children. Pediatr Radiol 2006; 36: 187–191.
[16]Malogolowkin MH, Katzenstein HM, Meyers RL, Krailo MD, Rowland JM, Haas J and Finegold MJ. Complete surgical resection is curative for children with hepatoblastoma with pure fetal histology: a report from the Children’s Oncology Group. J Clin Oncol 2011; 29: 3301–3306.
[17]Schnater JM, Aronson DC, Plaschkes J, Perilongo G, Brown J, Otte JB, Brugieres L, Czauderna P, MacKinlay G and Vos A. Surgical view of the treatment of patients with hepatoblastoma: results from the first prospective trial of the International Society of Pediatric Oncology Liver Tumor Study Group. Cancer 2002; 94: 1111–1120.
[18]WHO，WHO Handbook for Reporting Results of Cancer Treatment. Geneva, Switzerland, World Health Orgnaization,1979,205–216.
[19]Hirschman BA, Pollock BH and Tomlinson GE. The spectrum of APC mutations in children with hepatoblastoma from familial adenomatous polyposis kindreds. J Pediatr 2005; 147: 263–266.
[20]Anna CH, Sills RC, Foley JF, Stockton PS, Ton TV and Devereux TR. Beta-catenin mutations and protein accumulation in all hepatoblastomas examined from B6C3F1 mice treated with anthraquinone or oxazepam. Cancer Res 2000; 60: 2864–2868.
[21]Semeraro M, Branchereau S, Maibach R et al, Relapses in hepatoblastoma patients：clinical characteristics and outcome-experience of the International Childhood Liver Tumors Strategy Group (SIOPEL).[J]. Eur J Cancer, 2013,49(4):915–922.
[22] Hishiki T, Matsunaga T, Sasaki F, et al. Outcome of hepatoblastomas treated using the Japanese Study Group for Pediatric Tumor (JPLT) protocol 2: Report from the JPLT. Pediatr Surg Int 2011;27:1–8.
[23]Meyers RL, Rowland JR, Krailo M, Chen Z, Katzenstein HM and Malogolowkin MH. Predictive power of pretreatment prognostic factors in children with hepatoblastoma: a report from the Children’s Oncology Group. Pediatr Blood Cancer 2009; 53: 1016–1022.
[24]Semeraro M, Branchereau S, Maibach R, Zsiros J, Casanova M, Brock P, Domerg C, Aronson DC, Zimmermann A, Laithier V, Childs M, Roebuck D, Perilongo G, Czauderna P and Brugieres L. Relapses in hepatoblastoma patients: clinical characteristics and outcome—experience of the International Childhood Liver Tumour Strategy Group (SIOPEL). Eur J Cancer 2013; 49: 915–922.
[25]Walhof CM, Van Sonderen L, Voute PA and Delemarre JF. Half-life of alpha-fetoprotein in patients with a teratoma, endodermal sinus tumor, or hepatoblastoma. Pediatr Hematol Oncol 1988; 5: 217–227.
[26] Rudolf Maibach, Derek Roebuck b, Laurence Brugieres, et al. Prognostic stratification for children with hepatoblastoma:The SIOPEL experience. European Journal of Cancer, 2012,48: 1543– 1549.
[27]Ortiz D, Harden A, Corrales-Medina FF, Saigal G, Tekin A and Garcia J. Pediatric patient with end-stage kidney disease secondary to Eagle-Barrett syndrome and metastatic unresectable hepatoblastoma treated successfully with chemotherapy and liver-kidney transplant. Pediatr Transplant 2018; 22:
[28]Papry A, Kamal M and Khalid MS. Hepatoblastoma in a child with dextrocardia and possible histopathological alteration reminiscent of hepatocellular carcinoma after neoadjuvant chemotherapy. Clin Case Rep 2018; 6: 1070–1073.
[29]Boucher AA, Mizuno T, Vinks AA, Goldstein SL, Tiao GM and Geller JI. Dose modifications and pharmacokinetics of adjuvant cisplatin monotherapy while on hemodialysis for patients with hepatoblastoma. Pediatr Blood Cancer 2019; 66: e27425.
[30]Yu Y, Zhao X, Zhang Y, Kang Y, Wang J and Liu Y. Antitumor activity of YM155, a selective survivin suppressant, in combination with cisplatin in hepatoblastoma. Oncol Rep 2015; 34: 407–414.
[31]Hiyama E, Ueda Y, Onitake Y, Kurihara S, Watanabe K, Hishiki T, Tajiri T, Ida K, Yano M, Kondo S, Oue T and Japanese Study Group for Pediatric Liver T. A cisplatin plus pirarubicin-based JPLT2 chemotherapy for hepatoblastoma: experience and future of the Japanese Study Group for Pediatric Liver Tumor (JPLT). Pediatr Surg Int 2013; 29: 1071–1075.
[32]Zsiros J, Brugieres L, Brock P, Roebuck D, Maibach R, Zimmermann A, Childs M, Pariente D, Laithier V, Otte JB, Branchereau S, Aronson D, Rangaswami A, Ronghe M, Casanova M, Sullivan M, Morland B, Czauderna P, Perilongo G and International Childhood Liver Tumours Strategy G. Dose-dense cisplatin-based chemotherapy and surgery for children with high-risk hepatoblastoma (SIOPEL–4): a prospective, single-arm, feasibility study. Lancet Oncol 2013; 14: 834–842.
[33]Kobrinsky NL, Sjolander DE, Goldenberg JA and Ortmeier TC. Successful treatment of doxorubicin and cisplatin resistant hepatoblastoma in a child with Beckwith-Wiedemann syndrome with high dose acetaminophen and N-acetylcysteine rescue. Pediatr Blood Cancer 2005; 45: 222–225.
[34]Neuwelt AJ, Wu YJ, Knap N, Losin M, Neuwelt EA, Pagel MA, Warmann S, Fuchs J, Czauderna P and Wozniak M. Using acetaminophen’s toxicity mechanism to enhance cisplatin efficacy in hepatocarcinoma and hepatoblastoma cell lines. Neoplasia 2009; 11: 1003–1011.
[35]Giorgio Perilongo, Rudolf Maibach, Elisabeth Shafford, et al. Cisplatin versus Cisplatin plus Doxorubicin for Standard-Risk Hepatoblastoma. New Englsnd Journal of Medicine, 2009,361:1662–70.
Table 1: Comparison of clinical features and AFP related conditons for the patients with hepatoblastoma between the two groups
|
Clincial feature |
|
|
|
|
||
|
Stage |
Relapsed hepatoblastoma (N=28) |
Non- relapsed hepatoblastoma (N=28) |
P-valve* |
|
||
|
|
|
|
|
|
||
|
Ⅰ |
3 |
7 |
0.21 |
|
||
|
Ⅱ |
6 |
16 |
0.06 |
|
||
|
Ⅲ |
18 |
5 |
0.055 |
|
||
|
Ⅳ |
1 |
0 |
/ |
|
||
|
AFP（ng/ml） |
|
|
|
|
||
|
Maximum |
1080000 |
1380000 |
0.32 |
|
||
|
Minimum value |
1778 |
1976 |
0.56 |
|
||
|
average value |
128205 |
120762 |
0.87 |
|
||
|
AFP changes |
|
|
|
|
||
|
Down to normal |
1 |
9 |
0.015 |
|
||
|
Decrease >50% |
11 |
13 |
|
|
||
|
Decrease <50% |
16 |
6 |
|
|
||
|
AFP falls to normal range time |
|
|
|
|
||
|
Within 30 days after surgery |
1 |
25 |
0.011 |
|
||
|
More than 30 days after surgery |
4 |
3 |
|
|
||
|
Not falling to normal |
23 |
0 |
|
|
||
|
Tumor volume change |
|
|
|
|
||
|
Decrease >50% |
12 |
21 |
0.002 |
|
||
|
Decrease <50% |
16 |
7 |
|
|
||
|
|
|
|
|
|||
P-valve* Normally distributed data were compared using the t test. The χ2 test was used to compare the number of patients. Comparison of data that did not follow a normal distribution was performed according to the Mantel-Cox log-rank test.