|Year : 2019 | Volume
| Issue : 4 | Page : 179-183
Association between serum folate level and invasive cervical cancer at a university teaching hospital in South-West Nigeria
Adebayo I Sekumade1, Kehinde S Okunade2, Gbenga Olorunfemi3, Ebunoluwa O Daramola1, Muisi A Adenekan1, Adeyemi A Okunowo2, Rose I Anorlu2
1 Department of Obstetrics and Gynaecology, Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria
2 Department of Obstetrics and Gynaecology, Lagos University Teaching Hospital, Idi-Araba; Department of Obstetrics and Gynaecology, College of Medicine, University of Lagos, Lagos, Nigeria
3 Division of Epidemiology and Biostatistics, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
|Date of Submission||23-Apr-2019|
|Date of Decision||20-Jun-2019|
|Date of Acceptance||27-Sep-2019|
|Date of Web Publication||22-Nov-2019|
Dr. Kehinde S Okunade
Department of Obstetrics and Gynaecology, College of Medicine, University of Lagos, PMB 12003, Idi-Araba, Lagos
Source of Support: None, Conflict of Interest: None
Background: Cervical cancer is a common cause of cancer-related morbidity and mortality in developing countries. Serum folate may modify cancer risk through its role in DNA synthesis and methylation. Objective: To determine the association between serum folate levels and the occurrence of cervical cancer among women seen at a university teaching hospital in South-West Nigeria. Patients and Methods: This was an analytical cross-sectional study involving two groups of participants including 50 cases with invasive cervical cancer (ICC) and 50 controls with a normal cervix. Data analysis was performed between discrete baseline characteristics of the cases and controls using the Pearson's Chi-square test, whereas the mean serum folate levels of the cases and controls were compared using the independent sample t-test. P<0.05 was considered statistically significant. Results: There was no significant positive association between low serum folate and the occurrence of ICC (adjusted odds ratio: 2.99; P = 0.088). Conclusions: The findings of this study showed that low serum folate was not independently associated with an increased risk of ICC. However, a robust multicenter long-term longitudinal study will provide further evidence on the role of serum folate in the occurrence of ICC.
Keywords: Cervical cancer, cervical intraepithelial neoplasia, folate, invasive cervical cancer, Nigeria
|How to cite this article:|
Sekumade AI, Okunade KS, Olorunfemi G, Daramola EO, Adenekan MA, Okunowo AA, Anorlu RI. Association between serum folate level and invasive cervical cancer at a university teaching hospital in South-West Nigeria. J Cancer Res Pract 2019;6:179-83
|How to cite this URL:|
Sekumade AI, Okunade KS, Olorunfemi G, Daramola EO, Adenekan MA, Okunowo AA, Anorlu RI. Association between serum folate level and invasive cervical cancer at a university teaching hospital in South-West Nigeria. J Cancer Res Pract [serial online] 2019 [cited 2020 Jan 28];6:179-83. Available from: http://www.ejcrp.org/text.asp?2019/6/4/179/271499
| Introduction|| |
Cervical cancer is the fourth most common cancer in women and the seventh overall worldwide. Moreover, cervical cancer reflects the health inequity between developed and developing countries. The highest incidence and mortality rates of cervical cancer are in Eastern, Western, and Southern Africa; South-Central Asia; and South America, whereas the lowest rates are found in Western Asia and Australia/New Zealand., The GLOBOCAN report estimated that there were 570,000 new cases of cervical cancer and 311,000 deaths related to cervical cancer in 2018, with 70% of those deaths occurring in developing countries. The annual number of cervical cancer cases in Nigeria is 14,089, and the annual number of deaths is 8240. The natural history of cervical cancer has been extensively studied in the past three decades, and persistent infection of the cervix with certain oncogenic human papillomavirus (HPV) infection has been well documented as a cause of cervical cancer. The early detection and treatment of precancerous and early invasive cervical cancer (ICC) can result in a reduction in cervical cancer incidence, as demonstrated in reports from most developed countries that have recorded reductions in cervical cancer of almost 80% with the use of high-quality cytology-based Papanicolaou testing. Folate is thought to modulate cancer risk through its role in DNA synthesis, and it is also involved in DNA methylation through one-carbon metabolism involving homocysteine and methionine. DNA methylation confers genetic stability and exerts an epigenetic influence on genetic expression. Low folate levels may lead to an impairment in these functions, thereby leading to carcinogenesis. It has been further hypothesized that incorporation of the HPV genome into the human genome, which is a critical step in cervical carcinogenesis, occurs at fragile or unstable sites. The instability of the genes in the human DNA may occur due to inadequate DNA precursors including folate. The diets in many developing countries are deficient in essential nutrients including folate and other vitamins,, which may provide the basis for routine folate supplementation to reduce the risk of the occurrence of cancerous precursor lesions and invasive disease. However, the findings of epidemiological studies on the association between folate status and the risk of cervical cancer have been inconsistent.,,, To the best of our knowledge, no published study has investigated the folate status of African women with ICC. Therefore, this study will add to the increasing body of knowledge in this regard and elucidate the possible role of this important micronutrient in the prevention and improvement of the prognosis of this deadly disease.
| Patients and Methods|| |
Study design and setting
This analytical cross-sectional study was carried out at a university teaching hospital in Southwest Nigeria. The hospital is one of the largest tertiary health institutions in Nigeria. It has an 800-bed capacity and it is a referral center for a wide range of specialist consultations, particularly for patients in the Southwest region but also in Nigeria in general. The hospital has a gynecological oncology unit in its department of obstetrics and gynecology. This unit provides specialized multidisciplinary oncology care with clinicians in the departments of radiotherapy, radiodiagnosis, anatomic molecular pathology, general surgery, and urology. The unit also oversees weekly outpatient and cytology clinics and a daily colposcopy clinic where patients with preinvasive and ICC are diagnosed, evaluated, and offered the appropriate treatment. This study was carried out after obtaining approval from the Lagos University Teaching Hospital's Health Research Ethics Committee (LUTHHREC NO: ADM/DCST/HREC/APP/1069 obtained on August 19, 2016), and ethical principles according to the Declaration of Helsinki were considered throughout the course of the study.
Participants were recruited from among women who sought care from the hospital's gynecology outpatient, cytology, and colposcopy clinics. The participants included women with newly diagnosed ICC who had undergone clinical staging (case group) and control women with no cytological or histological evidence of preinvasive or invasive cervical lesions (control group). Eligible women for the study were those who gave written informed consent and had the physical and mental capacity to provide reliable answers. Women with recent or ongoing pregnancy and those on routine folic acid and vitamin supplementations in the last 3 months before their enrollment were excluded.
Sample size determination
The sample size (N) for the study was determined using the formula for the comparison of two means:
Using data from a published study by Wang et al., the standard deviation (SD) was 1.42 ng/mL, the unit normal deviate corresponding to the desired Type I error rate of 5% at 95% confidence interval (CI) (u) was 1.96, the desired Type II error rate of 20% (v) was 0.84, and the between-group mean difference in serum homocysteine level (d) was 0.80 ng/mL. The minimum sample size required per group was 49. However, for ease of data collection, collation, and analysis, 100 women including 50 with ICC and 50 with a normal cervix as controls were enrolled at the point of entry for the study.
Participant recruitment and data collection
Consecutively consenting participants who had not received any form of treatment by way of conservative surgery/procedure, radical surgery, or radiotherapy were recruited for the study from the gynecology outpatient, cytology, and colposcopy clinics. A pretested questionnaire was used to interview the consenting participants to obtain information on their sociodemographic characteristics, including age, educational level, occupation, marital status, and the presence of risk factors for cervical cancer. The participants were subsequently requested to fast for about 6-8 h overnight before their next follow-up appointment. A fasting blood sample of about 5 mL was collected by venipuncture and carefully transferred into specimen bottles without anticoagulants and then sealed with a rubber cap. The specimens were transported to the central research laboratory of the hospital within 8 h of collection for centrifugation and serum separation. Serum was then stored frozen at −20°C until batch analysis for serum folate. The determination of serum folate was done using ACCUBIND ELISA microwell folate test system kits (Monobind Inc., Lake Forest, CA 92630, USA). A low folate concentration was defined as a concentration of <2 ng/mL (reference range, 2-20 ng/mL).
Data management and statistical analysis
The data were entered into a password-protected personal computer. Data analysis was done using Stata Version 13 Statistical package (StataCorp, College Station, TX 77845, USA). The sociodemographic and biological characteristics of the participants were presented as comparative frequency tables. The mean and SD for normally distributed data as well as median and interquartile range for skewed data were included in the frequency tables. Comparisons between the categorical baseline characteristics of the two groups were done using the Pearson's Chi-square test. Fisher's exact test was also used where appropriate. The means of age and serum folate level and other normally distributed continuous variables of the two groups were compared using the independent sample t-test where appropriate, whereas the Mann-Whitney U-test was used for comparisons of skewed data. P < 0.05 was considered statistically significant. The effects of serum folate level on the occurrence of ICC were examined using binary logistic regression analysis where the control participants were used as the base outcome. Univariate analysis was conducted between the independent variables and the serum folate categories of the case and control groups. Variables with P < 0.2 were used in a backward stepwise regression model to build the final multivariate model that corrected for confounding variables. In the multivariate analysis, odds ratios (ORs) were adjusted for age, parity, coitarche, and social class.
| Results|| |
The overall mean age of the participants was 48.96 ± 7.03 years. There were statistically significant differences in the mean age (P = 0.033), coitarche age (P = 0.022), and parity (P = 0.007) between the two groups of participants. There were no differences in educational status (P = 0.162), social class (P = 0.111), marital status (P = 0.098), age at menarche (P = 0.360), alcohol consumption (P = 0.945), and previous use of hormonal contraception (P = 0.079) between the two groups of participants [Table 1].
|Table 1: Sociodemographic and biological characteristics of the study participants|
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The mean serum folate levels in the ICC and control groups were statistically similar (7.45 ± 3.89 ng/mL vs. 8.76 ± 3.86 ng/mL; P = 0.076) [Figure 1]. As shown in [Table 2], up to two-fifths (40.0%) of the ICC group had a low serum folate level compared to only about a fourth (24.0%) of the control group (P = 0.034). However, subgroup analysis of the participants in the ICC group did not reveal a statistically significant relationship between serum folate level and the stage of cervical cancer (P = 0.880) [Table 3].
|Figure 1: Serum folate levels among the study participants. The mean serum folate levels in the participants with invasive cervical cancer and the control group with a normal healthy cervix were 7.45 ± 3.89 ng/mL and 8.76 ± 3.86 ng/mL, respectively (P = 0.076)|
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|Table 2: The relationship between serum folate categories and the two groups of participants|
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|Table 3: Comparison of mean serum folate levels in different stages of invasive cervical cancer|
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After adjusting for age, parity, and prior use of hormonal contraceptives, there was no independent relationship between serum folate level and the occurrence of cervical cancer (adjusted OR = 2.99, 95% CI: 0.81-10.96, P = 0.088) [Table 4]. However, the previous use of hormonal contraceptives was independently associated with the occurrence of ICC (adjusted OR = 5.51, 95% CI: 2.85-8.31, P = 0.002).
|Table 4: The multivariable analyses of the relationship between serum folic acid levels and invasive cervical cancer (ICC)|
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| Discussion|| |
The study was carried out to investigate a possible association between serum folate levels and cervical cancer among women at a university teaching hospital in Southwest Nigeria. Previous studies have suggested the possible role of blood folate in colorectal cancer and cervical cancer.,, The key finding in the current study was a positive but statistically insignificant association between low serum folate level and cervical cancer. Similar findings of a nonsignificant positive association have been reported by investigators in India and the USA. In the study carried out in the USA, Weinstein et al. found that participants with low serum folate had a slightly increased risk of developing ICC with an OR of 1.30, whereas Ragasudha et al. in India found that the association between low serum folate and ICC only became statistically insignificant after adjusting for confounding variables such as age and HPV status, with ORs of 2.66 and 2.25, respectively. In a multicountry case-control study conducted in four Latin American countries in 1991, Potischman et al. also reported no association between serum folate and the risk of cervical cancer; however, Flatley et al. reported statistically significant associations between red cell folate and the risk of HPV infection, cervical intraepithelial neoplasia, and ICC. The findings of Flatley et al. may be attributed to the measurement of red cell folate instead of serum folate, which has a much wider analytical variability.
As similar to the work of Potischman et al., our study revealed no statistical relationship between serum folate level and the stage of cervical cancer. This may be because the hypothesized protective effect of folate may have been lost after the occurrence of cervical cancer. A previous study suggested that the long-term use of oral contraceptive agents was a cofactor in cervical cancer occurrence, and the previous use of hormonal contraceptives was the only independent risk factor for ICC in our study. Oral contraceptives are thought to cause cervical epithelial alterations that increase the HPV infection rate and persistence. On the other hand, the use of oral contraceptives may also alter the pattern of menstrual flow and thus lead to the ingestion of multivitamin supplements to curb anemia in these with probable resultant alterations in serum folate levels. The cross-sectional design of this study made it difficult to ascribe any causality in the association between serum folate and cervical cancer. It is also possible that some of the participants were unknowingly taking multivitamin supplements that may have affected their serum folate levels.
| Conclusions|| |
The findings of this study showed that low serum folate was not independently associated with an increased risk of ICC. However, a robust multicenter long-term longitudinal study will provide further evidence on the role of serum folate in the occurrence of ICC.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]