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INTRODUCTION
The International Agency for Research on Cancer of the World Health Organization (WHO) estimates that the incidence and the worldwide mortality of cancer are increasing. About ten million new cases of cancer are reported annually 1. Seventy-eight percent of the cases of CC occur in developing countries in which the use of preservatives is infrequent and early diagnostic testing, in general, is not available for the population 2. In Mexico, CC is the second most common cause of malignant tumors in women ≥ 25 years old and the highest incidence rate is present in women older than 45 years, specifically in those between 60 and 64 years of age (incidence rate of 15.5), followed by those between 45 and 49 years of age (incidence rate of 12.6); in all cases, the rates are calculated for every 100,000 women more than ten years of age 3.
CC initiates as a cellular dysplasia of the cervix epithelium and has been found to be highly associated to the human papilloma virus (HPV), which is able to cause genetic transformation in the epithelial cells of the cervix, through the expression of proteins E6 and E7 which interact with p53 and RB proteins. Thus, affecting the cell cycle 4.
CC is classified histologically as: epidermoid carcinoma, adenocarcinoma, and adenosquamous carcinoma. There are several classifications of the clinical staging. The most commonly used is the classification established by the International Federation of Gynecology and Obstetrics (FIGO) 5. The treatment of CC depends on the stage of the disease and includes surgery, chemotherapy and radiation. However, chemotherapy and radiotherapy have serious side effects. For instance, 5-15% of patients treated with radiation will develop enteritis, which persists months or even years after therapy is completed 7.
About 5% of the total protein contents of leukocytes and 30-60% of their cytosolic protein is calprotectin (CP). In infectious and inflammatory processes, plasma CP levels increase 5 to 40 fold above normal values 6 7-8. The FCP is a marker strongly associated with colorectal inflammation; when fecal CP/plasma CP ratio is higher than 6, it has a 100% sensitivity and 94% specificity in the diagnosis of enteritis 6,7,8. For this reason, FCP level has been chosen in this study as a measurement of the enteric inflammatory status.
Symbiotics are products that contain both prebiotics and probiotics (Bacteroides, Eubacterium, Lactobacilli and Bifidobacteria), which are known to exert various health benefits, such as immunomodulation, reduction of glucose and cholesterol, inactivation of carcinogens, anti-inflammatory and maintenance of intestinal integrity 9,11. Prebiotics, such as inulin and oligofructose, are substances that stimulate the growth of non-pathogenic bacteria such as Lactobacilli and Bifidobacteria, which inhibit the growth of pathogenic bacteria, thus decreasing inflammation. Oral supplementation with symbiotics has been shown to reduce the inflammatory process in intestinal diseases such as interspecific chronic ulcerative colitis, Crohn's disease and radiation enteritis 12 13-14. In addition, prebiotics such as oligofructose-enriched inulin are associated with an early reduction in FCP 14,15. Therefore, the aim of this work is to assess the effect of dietary symbiotic supplementation on FCP, bacterial DNA levels, and gastrointestinal adverse effects in patients with CC who were treated with chemotherapy and radiotherapy at the Jalisco Institute of Cancerology (IJC).
MATERIAL AND METHODS
STUDY DESIGN
This study was a randomized, double-blind, controlled trial in patients with the diagnosis of CC, histologically classified as adenocarcinoma or epidermoid, in stage II and III of FIGO, who were currently in treatment with chemotherapy and radiotherapy at the Jalisco Institute of Cancerology. The size of the sample was obtained with the calculation of the formula when it is expected to find a difference in averages and the standard deviation is known, given a 95% reliability and a power of 80%, using as a variable the fecal calprotectin 16. All participants were fully informed of the study procedures and provided written informed consent. This study was performed according to the updated Declaration of Helsinki, the General Health Law on Research for Health and the Guidelines for Good Clinical Practices in Research for Health 2012. All procedures were approved by the Committee of Ethics, Teaching and Research of the Jalisco Institute of Cancerology (Registry number 008/2011). Identification numbers were assigned to assure patient confidentiality. Patients were randomly assigned in a 1:1 ratio to receive symbiotic treatment or placebo, with a computer-generated randomization sequence. To ensure masking between the symbiotic and placebo, gels were identical in appearance, packaging, and labeling. The symbiotic used contained: 1 x 107 colony-forming unit (CFU)/g biogel of Lactobacillus acidophilus NCFM, Bifidobacterium lactis Bi-07 1 x 106 CFU/g biogel, and blue agave inulin.
These patients were divided into two groups: 35 patients received the symbiotic supplement and 35 received placebo. Both groups received 20 g gels; patients had to ingest one gel 30 minutes before breakfast, one gel 30 minutes before lunch and one gel 30 minutes before dinner, for seven weeks. The diet of each patient was monitored every 15 days to ensure that no diet modifications were done throughout the intervention. This was supervised by the nutritionist's team at the IJC.
Patients were randomly assigned in a 1:1 ratio to receive oral symbiotics or placebo, with a computer-generated randomization sequence (blocks of 2-4). To ensure masking between the symbiotics and the placebo, gels were identical in appearance, packaging and labeling.
SAMPLE COLLECTION
Fecal samples (> 10 g) were collected from each participant in a sterile container at 0, 4 and 7 weeks. Fecal samples were immediately frozen at -70 °C until use.
DETERMINATION OF FECAL CALPROTECTIN
Fecal calprotectin was quantified using the enzyme-linked immunosorbent assay, with a highly specific monoclonal antibody for calprotectin, known as the rapid test of calprotectin Quantum Blue®. The assays were performed according to the manufacturer's instructions. The signal intensities of the samples were measured quantitatively by the Quantum Blue® reader from BÜHLMANN 9.
DNA EXTRACTION AND REAL-TIME PCR
The proportions of bacteria of interest in stool samples were determined using the ZR Fecal DNA MiniPrep(tm) kit (catalog no. D6010, Zymo research) according to the manufacturer's instructions. For the amplification of the specific genomes of the bacteria of interest, the oligonucleotides described elsewhere were used 17,18. The oligonucleotides were synthesized by the company Invitrogen and working solutions were prepared at 2.5 pmol/ml, as indicated previously 17,18.
DETERMINATION OF GASTROINTESTINAL SIDE EFFECTS
The instrument validated to measure the characteristics of diarrheal evacuations in patients was the Bristol stool form scale (BSFS) and nausea and vomiting was measured with the INC (scale of the National Institute of Cancerology of the United States). The BSFS is a diagnostic medical tool designed to classify the form of human feces ranging from the hardest (type 1) to the softest (type 7). Types 1 and 2 represent hard stools and a slow transit (constipation). Types 3, 4 and 5 are usually considered to be the most "normal" stool form. Types 6 and 7 are considered as abnormally loose/liquid stools (and in conjunction with other symptoms, indicative of diarrhea) 19.
ADHESION TO TREATMENT
Participants reported daily consumption of the supplement in a consumption posting sheet. The percentage adherence for each subject was determined by the following formula: (number of gels consumed) / (number of gels returned to the physician) × 100. We considered it as an optimal adherence if the percentage was higher than 80%.
STATISTICAL ANALYSIS
The statistical analysis was performed with the Microsoft Excel system (Windows 8), and with the Statistical Package for Social Sciences (SPSS) in its version 20.0. Results are presented in graphs and comparative tables for each of the variables using descriptive statistics, univariate and multivariate contrasts, parametric statistics (Student's t-test and ANOVA), non-parametric statistics (Friedman, Wilcoxon, Mann-Whitney and Kolmogorov-Smirnov tests). With regard to the sociodemographic characteristics of the patients, such as marital status, number of sexual partners, place of origin and occupation, they were also performed and analyzed with both programs (Excel and SPSS), making the descriptive statistics with their respective case numbers, as well as the total percentages for both groups with the respective p value.
RESULTS
SOCIODEMOGRAPHIC AND CLINICAL DATA
At the beginning of the study, a total of 165 medical records of patients with CC at the JIC were reviewed. Ninety-seven patients met the inclusion criteria for the study. Seventeen patients were excluded from the study: five patients were taking dietary supplements, five died, and seven refused to sign the informed consent, leaving a total of 80 patients. During the study, five patients in each group were removed from the protocol due to changes in treatment, poor adherence to the supplement consumption (< 80%) and presentation of side effects other than nausea and diarrhea.
Patients in both groups had similar sociodemographic (Table 1) and clinical (Table 2) characteristics at baseline. The mean age of both groups of treatment was similar (p = 0.441). No significant differences were found in the marital status (p = 0.586), occupation (p = 0.586), clinical staging (p = 0.502) and histological variant (p = 0.374) between both groups (Table 2).
Table I. Sociodemographic characteristics of patients with cervical cancer treated with placebo or symbiotics
OUTCOMES MEASUREMENTS
A significant increase in the level of FCP was observed at week 7 in the placebo group (p < 0.001) at the end of the intervention. In contrast, a significant decrease in the level of fecal CP was detected in the symbiotic group at week 7 (p < 0.001) (Fig. 1).
Stool consistency in the placebo and symbiotic groups was similar at baseline. A significant improvement in stool consistency was obtained in both groups at the end of the intervention (p < 0.001). However, there is no statistical significance between both groups after a seven-week treatment (Fig. 2).
Figure 2. Percentage of cases according to the categories of the Bristol stool form scale in patients with uterine cervical cancer treated with placebo or symbiotics.
The levels of nausea in patients with cervical cancer treated with placebo and symbiotics were compared before, during and after the intervention and they were statistically similar. The levels of nausea the patients presented during the intervention significantly diminished in both groups; a p < 0.001 was obtained using the Friedman and Wilcoxon tests (Fig. 3).
Figure 3. Percentage of cases according to the scale of nausea in patients with uterine cervical cancer treated with placebo or symbiotics.
We report the number and percentage of cases according to the degree of vomiting in patients with CC treated with placebo or symbiotics. In the control group, vomiting results for grade 2 in 75% of patients before treatment, and this effect was subsequently present in only 10% of the patients.
For grade 1, corresponding to the presence of a vomiting in 24 hours, there was an increase of 25% of the patients to 90%, which showed improvement in relation to this side effect. In the other group treated with symbiotics, for vomiting grade 2, 63.9% of the patients presented it before treatment, and after the intervention only in 5.6% of the patients, for grade 1 vomiting occurs in 36.1% of the patients before treatment, for 94% of the patients after the intervention. With the Chi-square test analysis, the comparison of the degree of vomiting between treatments at each of the evaluated moments was significant only during the treatments (p = 0.025); the Friedman test and the Wilcoxon test were significant for both treatments (p < 0.001) (Fig. 4).
Figure 4. Percentage of cases according to the scale of vomiting in patients with uterine cervical cancer treated with placebo or symbiotics.
The results of the qPCR in this study did not show significant changes in relation to the concentrations and total proportions of the probiotic bacteria: Acid lactic and Bifidobacteria versus the pathogenic bacteria, E. coli and Salmonella, both in the placebo group and the symbiotic group (Fig. 5).
DISCUSSION
The average age of the patients enrolled in this study was 49 years and was similar to the results published previously for Mexico 4 and the statistics published by the WHO, in which the highest prevalence was found between the ages of 35-50 (WHO 2016). Sociodemographic data showed that 71% of the patients enrolled in this study have a low educational level and 85% do not have a job. These data coincide with studies reporting that a low socioeconomic level is a risk factor for developing CC. Regarding the number of sexual partners of the patients, this study reports that two patients were nubile, 48.5% had one sexual partner, 40% had two to five sexual partners, and 8.5% had more than five sexual partners. These data are in consonance with those previously reported, suggesting that having multiple sexual partners is a risk factor for CC 4.
In this study, FCP levels at the end of the clinical assay were found to increase significantly in the placebo group. In contrast, a significant decrease of calprotectin levels was found in the symbiotics group (p < 0.001) (Fig. 3). Fecal calprotectin is a non-invasive marker for the evaluation of the excretion of macrophages in the intestinal lumen and is strongly associated with colorectal inflammation with 100% sensitivity and 94% specificity 22.
The FCP values were used to determine response to treatment and to evaluate asymptomatic patients, as well as to predict relapses of inflammatory bowel disease, taking into consideration that the reference values for healthy individuals are < 50 µg/kg of wet feces. Calprotectin levels ranging 100-500 µg/kg of wet feces are indicative of colorectal cancer, and 200-20,000 µg/kg of wet feces are characteristic of chronic inflammatory bowel disease 23.
The anti-inflammatory effect of the symbiotic treatment is demonstrated by the decrease in the concentration of FCP. In fact, it has been proposed that calprotectin level is the surrogate marker for treatment outcome in relapsing inflammatory bowel disease.
There is increased awareness of the role of the microbiota in maintaining health, since gut microbes are capable of producing a vast range of essential molecules for the human metabolism. For instance, many enzymes produced by microbes influence digestion and health. Therefore, it has been suggested the consumption of symbiotics, lactic ferments of probiotics associated with prebiotic substances such as vitamins and fructo-oligosaccharides, to strengthen the immune system 12,20,21. Probiotic bacteria are effective when they demonstrate: a) effective cell adhesion, which impedes the adhesion of pathogenic bacteria; b) resisting the medium and multiplying; c) being safe, non-invasive, and non-cancerous; and d) living together with the saprophyte microbiota 11,12,20.
The mechanisms of action of probiotics in the human organism is to competitively exclude the enteric pathogens, promote the synthesis of cytokines, adhere to the surface of intestinal cells, produce toxic metabolites such as hydrogen peroxide, neutralize dietary carcinogens, inhibit bacterial growth through the production of lactic acid and bacteriocins, reestablish the saprophytic bacterial microbiota after the antibiotic therapy, and stimulate trophic enterocyte 12,20. It is advisable to incorporate symbiotic foods into the diet in order to strengthen the immune system and inhibit the development of cancer. The symbiotics act as inhibitors of certain oncogenes, and as modulators of the immunological response to combat the infectious agents that have colonized the gastrointestinal tract 20. The groups of pathogenic bacteria with the greatest antagonism against probiotic bacteria are E. coli and Salmonella species, a situation that was considered in this study to determine and quantify the interaction of these bacterial groups against the probiotic bacteria such as Lactobacilli and Bifidobacteria 12,20.
In a previous study using an endotoxic shock model, it was found that symbiotic treatment has beneficial effects. For instance, symbiotic treatment improved the survival rate of lipopolysaccharide-treated rats, ameliorated the clinical symptomatology, reduced the production of serum proinflammatory cytokines (TNF-α, IL-6, IL-1), and preserved the mitochondrial membrane fluidity and ATPase activity 24. In a recent, randomized, double-blind, placebo-controlled clinical trial conducted in two public hospitals, it was found that the administration of a symbiotic gel is a safe and simple way to get a significant reduction in prevalence and monthly episodes of vomit, heartburn, and stomachache, as well as a significant decrease in gastrointestinal symptoms severity in hemodialysis patients 25. Furthermore, short-term symbiotic treatment in patients with end-stage renal disease can lead to the increase of Bifidobacterium counts, maintaining the intestinal microbial balance 26.
Our data support the potential prophylactic role of symbiotics for the treatment of some gastrointestinal side effects of radiotherapy and chemotherapy in patients with CC. However, it is necessary to do longer studies to investigate if the treatment with symbiotics improves the levels of probiotic bacteria in these patients.
There were some limitations in this study: one was the sample size to evaluate the microbiological outcomes and, regarding patient care, it lacks long term follow-up evaluations. It is important to mention that we are currently starting a new project with a microarray assay where we will directly analyze the microbiota before, during and after the treatment with these symbiotics.
