Biochemical parameters and nutritional status of surgical patients with gastrointestinal cancer: a literature review

This is an integrative literature review with the objective of identifying the relationship between biochemical parameters and the nutritional status of surgical patients with cancer of the gastrointestinal tract, developed in April 2019, encompassing the databases SCOPUS (Elsevier), PubMed Central® (PMC), and the Cochrane Virtual Health Library (BVS). We used the terms “Gastrointestinal Neoplasm” AND “Nutritional Status” AND “Blood Chemical Analysis” with the aid of the Academical software after the protocol validation. Out of 147 articles analyzed, seven were included in the review, as they met the inclusion criteria. There were relevant associations between biochemical parameters and nutritional status. Impaired nutritional status can negatively influence the postoperative outcome. The monitoring of interdisciplinary teams can assist in the recovery of these patients and prevent unfavorable outcomes.

Nutritional depletion is a problem commonly found in cancer patients and is associated with an unfavorable outcome. Patients with gastrointestinal tumors undergoing surgical procedures have a high prevalence of malnutrition due to reduced food intake and increased energy expenditure associated with surgical stress, resulting in the deterioration of nutritional status 6 .
In this sense, early detection of nutritional changes allows intervention at the right time, preventing the occurrence of morphological and functional alterations 5 .
In general, the nutritional assessment methods This study used the Content Analysis technique 12 to meet the proposed objective and followed three distinct phases, namely, 1) pre-analysis, material exploration and treatment of results, 2) inference, and 3) interpretation.
As this study did not involve human beings, it was not necessary to seek approval from the Ethics in Research Committee.

Bibliometric analysis
When analyzing the year of publication, we  were also significantly associated with nutritional status 22 .

Relationship between biochemical parameters and nutritional status
In this sense, researchers found a significant difference (p=0.010) in the levels of albumin between the three classification groups of the PG-SGA (A, B and C).
However, the same was not true for transferrin (p=0.416).
It is worth mentioning that these parameters were reduced in 97.9% of the followed patients 15 .
Another study showed statistically significant  Significant changes were also observed in the median body weight (p=<0.001), transferrin (p=0.032) and tricipital skin fold (p=0.05). However, the levels of albumin and total protein changed slightly, without statistical significance 19 .
Another analysis showed that the Body Mass Index (BMI), the percentage of muscular area of the arm and the percentage circumference of the calf were significantly lower in patients with sarcopenia. The Significant results were identified with regard to the Percentage Weight Loss (PWL), which is correlated with serum CRP levels (p=0.002), CRP/albumin ratio (p=0.002), PINI (p=0.002) and Glasgow score (p=0.000)17. Likewise, there were statistically significant associations between PWL and the inflammatory markers NLR, mPINI and NII 14 .
In disagreement with this finding, researchers observed the absence of inflammatory activity in the majority of the studied patients, with no significant correlation between serum albumin and CRP 25  Unintentional weight loss of more than 10% in the previous six months or more than 5% in the last month is the easiest nutritional status indicator to be

Postoperative death
Researchers have identified several parameters related to mortality. The inflammatory state evidenced by high levels of CRP and reduced levels of albumin were associated with an unfavorable clinical outcome and death.
The nutritional impairment observed by the PG-SGA also had a significant association with mortality. In addition, the Glasgow Prognosis score and the Inflammatory and Nutritional Prognosis Index were associated with the occurrence of complications and a higher incidence of death 17 .
Similarly, there was a statistically significant association between the three PG-SGA categories and the three categories of the GPS. Significant associations were also identified between the presence of complications and the PG-SGA and, as well as the GPS. However, in this study, only the GPS was a predictor of mortality 33 .
High levels of GPS, a prognostic score based on inflammation, are associated with higher short-term postoperative risks and lower long-term survival in patients with advanced stomach cancer. Notably, patients with GPS of two had a high hospital mortality rate (10%), while patients with GPS of zero and one displayed in-hospital mortality rates of 1.0% and 1.5%, respectively (p=0.006) 34 .
Likewise, in the assessment of independent factors associated with death, tumor staging (p=0.001) and albumin (p=0.004) were the only independent predictors of mortality 14 . Regarding NLR, this was the one that most correlated with death, as there were significantly higher NLR values in cases of death (p=0.033). However, after a multivariate analysis, this marker did not remain statistically significant as a predictor of mortality (p=0.139) 14 .
Another study observed data similar to these, finding that the higher the value of the total lymphocyte count (TLC), the smaller the number of days of hospitalization. The TLC of the elderly who died was lower than in the patients who were discharged, with a statistically significant result. According to the authors, immunological changes, such as reductions in TLC, increase the frequency and severity of infections and are the cause of mortality associated with malnutrition in surgical patients 35 .