Abstract: Recently, many studies have shown that pretreatment serum albumin can be closely linked to the prognosis of cancer patients, including those with renal cell carcinoma (RCC). However, not all studies have reached the same conclusion. We therefore conducted a systematic review and meta-analysis to evaluate the prognostic value of pretreatment serum albumin in RCC patients. A total of 17 studies involving 6,447 patients were included in our meta-analysis. Our results indicated that a lower pretreatment serum albumin level yielded a worse overall survival (hazard ratio [HR]=2.46, 95% confidence interval [CI] 1.92–3.13), cancer-specific survival (HR=2.22, 95% CI 1.87–2.64), and relapse-free survival/progression-free survival (HR=1.75, 95% CI 1.28–2.38). Generally, these findings were particularly pronounced when stratified by tumor type, analysis type, cut-off value, and HR-obtaining method. In conclusion, a decreased pretreatment serum albumin level implies a poor prognosis for RCC patients, and can be monitored for risk stratification and individualized treatment in RCC patients.
Keywords: albumin, prognosis, renal cell carcinoma, meta-analysis
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INTRODUCTION
Renal cell carcinoma (RCC) is one of the most fatal types of urologic oncology and accounts for 2%–3% of adult malignancies. According to an American investigation, 58,000 patients are newly diagnosed with RCC, and nearly 13,000 patients die from this disease every year.1 Rapid progress has been made in treatment methods, but some RCC patients with local recurrence and distant metastasis do not survive for long.2 An effective prognostic model could be used to ascertain the malignant degree of the tumor, as well as to carry out risk stratification and allow individualized treatment for cancer patients. The postoperative tumor–node–metastasis (TNM) staging system is the conventional prognostic model used for RCC patients in clinical practice, but its precision may be unsatisfactory, with outcomes of patients at the same stage being significantly different. Moreover, the TNM staging system can only be evaluated in patients who undergo surgery. Therefore, a new laboratory index to complement the current risk stratification system of RCC patients is urgently required for clinical decision-making.
Serum albumin is synthesized by the liver and is the main serum protein.3 The concentration of normal serum albumin ranges from 3.5–5.0 g/dL for adults; when serum albumin is <3.5 g/dL, it is defined as hypoalbuminemia.4 Serum albumin is closely related to the degree of malnutrition, so it is often used for evaluating nutritional status.5,6 Furthermore, many studies have indicated that the inflammatory response also affects the concentration of serum albumin, which can therefore be used as a reliable indicator of inflammation.7,8 Cancer is often accompanied by malnutrition and chronic inflammation, which often develop into tumor cachexia and speed up the deterioration of cancer patients.9 In recent years, numerous studies have indicated that there is a close correlation between pretreatment serum albumin and tumor prognosis; specifically, the lower the concentration of pretreatment serum albumin, the worse the prognosis of cancer patients.10–13 Some of these studies have directly or indirectly elaborated the relationship between pretreatment serum albumin and the prognosis of RCC patients.14–28 However, owing to differences in research design, sampling protocols, and other factors, the prognostic value of pretreatment serum albumin in RCC patients is not consistent. Some investigations have shown that pretreatment serum albumin is related to the prognosis of RCC patients, but others have failed to draw similar conclusions. Therefore, a systematic review and meta-analysis are necessary to assess the prognostic value of pretreatment serum albumin in RCC patients.
