Abstract
Objectives
To evaluate the effect of pre- and postoperative C-reactive protein (CRP) levels on tumour recurrence following curative nephrectomy in patients with stage T1 clear cell renal cell carcinoma (CCRCC).
Methods
Patients with stage T1 CCRCC were recruited. CRP was quantified 3 days before and 4 weeks after surgery. Patients were followed-up for clinical outcome every 3 months. A subset of patients received lienal polypeptide as adjuvant treatment.
Results
Patients with elevated preoperative CRP levels (≥8.2 mg/l; n = 61) had higher grade tumours, were more likely to require radical nephrectomy and were more likely to experience recurrence than those with normal CRP levels. Non-normalization of elevated preoperative CRP was associated with tumour recurrence, but elevated CRP was not an independent risk factor of tumour recurrence.
Conclusion
Postoperative renormalization of elevated CRP is associated with decreased risk of recurrence in CCRCC.
Introduction
Kidney neoplasms represent around 3–5% of all cancers in developed countries, such as the USA. 1 Outcome varies according to tumour type, grade and stage, with recurrent and metastatic disease being predictive of poor survival.2–4 It is difficult to predict which early stage (T1) tumours will recur after curative nephrectomy, however.
Studies have investigated the relationship between systemic inflammatory biomarkers and clinical outcome in malignancies such as renal cell carcinoma (RCC). 5 The acute phase reactant, C-reactive protein (CRP), is predictive of poor prognosis in RCC: 6 elevated preoperative CRP is associated with higher tumour stage and grade, and is predictive of worse survival in clear cell RCC (CCRCC). 7 Although the prognostic value of the preoperative CRP level has been investigated, it is not known whether postoperative renormalization of CRP is related to clinical outcome of CCRCC.
The aim of the present prospective study was to investigate whether postoperative renormalization of CRP (compared with preoperative levels) was associated with tumour recurrence following curative nephrectomy in patients with stage T1 CCRCC.
Patients and methods
Study population
The study recruited patients undergoing curative nephrectomy for T1 CCRCC at Huashan Hospital of Fudan University, Shanghai, China, between January 2011 and June 2014. Tumour staging was determined by pathological examination and with reference to the 2010 tumour-node-metastasis classification. 8 Exclusion criteria were: (i) suspected lymph node or distant metastasis, according to preoperative computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET); (ii) acute or chronic inflammatory or autoimmune conditions; (iii) long term chronic disease, inducing organ dysfunction.
The study was approved by the internal review board of Huashan Hospital of Fudan University, and complied with the Declaration of Helsinki. All patients provided written informed consent prior to collection of blood samples.
Treatment
Venous blood was collected from each patient 3 days before surgery using standard methods; CRP was quantified via nephelometry using an Abbott AxSYM automated analyser (Abbott Laboratories, Lake Bluff, IL, USA). Postoperative CRP levels were quantified at 4 weeks after surgery. The CRP cut-off value was set as <8.2 mg/l.
A sex-, tumour stage-, tumour grade- and surgical technique-matched subset of patients with elevated preoperative CRP received adjuvant therapy with 10 ml/day lienal polypeptide injection (Jilin Fsens Pharmaceutical Co. Ltd., Jilin, China) for 3 days after surgery. This subset included all patients with elevated CRP levels who were treated between August 2013 and June 2014. These patients were compared with patients with elevated CRP levels who did not receive adjuvant therapy, who were treated between January 2011 and June 2013.
Patients underwent radical or partial curative nephrectomy (dependent on tumour size) by laparoscopy or open surgery. All surgeries used a retroperitoneal approach.
Follow-up
Patients were followed-up every 3 months until June 2015. Follow-up examinations included ultrasonography of the surgical area and chest X-radiography, with CT every 6 months. Patients with suspected recurrence underwent PET for additional diagnosis. Localized recurrence and distant metastasis were defined as postoperative recurrence and failure of surgical treatment.
Statistical analyses
Data were presented as mean ± SD, or n (%) of patients. Between-group differences were analysed using χ2-test, and Cox regression analysis was used to determine risk factors for recurrence. All tests were two-sided. Analyses were performed using using Stata® version 12.0 (StataCorp LP, College Station, TX, USA). P-values < 0.05 were considered statistically significant.
Results
Demographic and clinical characteristics of patients included in a study to investigate whether postoperative renormalization of C-reactive protein (CRP), compared with preoperative levels, is associated with tumour recurrence following curative nephrectomy for stage T1 clear cell renal cell carcinoma, stratified according to preoperative CRP level 8
Data presented as n (%) of patients.
NS, not statistically significant (P ≥ 0.05).
Elevated CRP ≥ 8.2 mg/l.
χ2-test.
Demographic and clinical characteristics of patients with stage T1 clear cell renal cell carcinoma, stratified according to tumour recurrence following curative nephrectomy 8
Data presented as n (%) of patients.
NS, not statistically significant (P ≥ 0.05); CRP, C-reactive protein.
χ2-test.
Multivariate Cox regression analysis of factors associated with tumour recurrence following curative nephrectomy, in patients with stage T1 clear cell renal cell carcinoma (n = 233) 8
CRP, C-reactive protein.
Demographic and clinical characteristics of patients with stage T1 clear cell renal cell carcinoma, stratified according to renormalization of C-reactive protein (CRP) following curative nephrectomy 8
Data presented as n (%) of patients.
NS, not statistically significant (P ≥ 0.05).
χ2-test
A subset of 40 patients with elevated preoperative CRP, treated between August 2013 and June 2014, received postoperative lienal polypeptide therapy; results were compared with those who did not receive treatment (treated between January 2011 and June 2013; n = 61). Significantly more patients who received lienal polypeptide had normalized postoperative CRP levels compared with those who did not (30 of 40 patients [75.0%] vs 33 of 61 patients [54.1%]; P = 0.034).
Discussion
Despite of timely and effective treatment of localized RCC, some patients with T1 tumours develop recurrent and metastatic disease, which substantially affects 5-year survival rates. 9 Inflammation is known to have a role in tumour development, 10 and the value of CRP as a prognostic biomarker in RCC has been established. 7
Preoperative elevated CRP levels were sometimes, but not always, normalized following curative nephrotomy in the present study. It is unclear what effect, if any, this modification in CRP has on clinical outcome of RCC. A study determined that elevated postoperative CRP was associated with metastasis and death after curative nephrectomy for CCRCC, but preoperative CRP levels were not evaluated. 11 A further study of 40 patients with metastatic RCC undergoing cytoreductive nephrectomy found that patients whose CRP levels did not normalize had worse prognosis than other patients, and that non-normalized CRP was an independent factor predicting poorer survival. 12 Patients with higher tumour grades (III/IV) were more likely to have elevated preoperative CRP in the present study, compared with those with tumour grades I/II. In addition, both elevated preoperative CRP and tumour grade were associated with tumour recurrence after curative surgery in the present study. In addition, in those patients with elevated preoperative CRP, non-normalized postoperative CRP was associated with tumour recurrence.
In general, patients with T1 RCC have an optimistic prognosis and require no adjuvant therapy. Treatment with the immunomodifier lienal polypeptide in the present study resulted in significantly more patients with normalization of CRP compared with those who did not receive adjuvant therapy. Detailed analysis of the mechanism of action and effect on prognosis of such treatment requires further study.
Our study has several limitations. CRP is an acute phase reactant and can be affected by many factors. CRP was only quantified once before and once after surgery, and these data may not fully reflect the clinical status of the patient. The inclusion of only patients with T1 CCRCC limits the generalizability of our findings. In addition, a longer duration of follow-up would be useful in determining the full impact of CRP normalization via adjuvant therapy. Further studies with larger patient cohorts and increased duration of follow-up are required to validate our findings.
In conclusion, postoperative renormalization of elevated CRP is associated with decreased risk of recurrence in CCRCC. It is unclear whether adjuvant therapy significantly improves postoperative outcome.
Footnotes
Declaration of conflicting interest
The authors declare that there are no conflicts of interest.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.