Oxidative Balance Scores in Cancer Survivors: A Nationwide Cross-Sectional Study

By Jae Hyuck Lee¹, In Cheol Hwang¹, Hong Yup Ahn²

Affiliations

1. Department of Family Medicine, Gil Medical Centre, Gachon University College of Medicine, Incheon, South Korea
2. Department of Statistics, Dongguk University, Seoul, South Korea

doi: 10.29271/jcpsp.2025.08.1068

ABSTRACT
Although some studies have investigated the relationship between oxidative imbalance and adverse outcomes, there is a lack of data on oxidative balance in cancer survivors. Using data of the 2013-2020 Korean nationwide surveys, this study examined the oxidative balance score (OBS) of non-survivors, short-term survivors (<5 years), and long-term survivors. Approximately 4.6% of the study subjects were cancer survivors, and of these, three-fifths were long-term survivors. Male and female short-term survivors had higher OBS than non-survivors, but the mean OBS of female long-term survivors was reversed. Physicians should periodically remind cancer survivors, particularly women, of the risks associated with unhealthy lifestyles.

Key Words: Cancer survivors, Oxidative stress, Population surveillance.

Oxidative stress refers to an imbalance of pro-oxidants and antioxidants. Under normal conditions, humans keep a balance between pro-oxidants and the antioxidant system. However, if the reactive oxygen species production by pro-oxidants out-weighs the scavenging capacity of the antioxidant system, it triggers oxidative damage, leading to cellular degeneration and impaired physiological function. Various dietary components and health-related behaviours affect the level of oxidative stress in the body. Given the complex interactions between pro- oxidants and antioxidants, there is no single oxidative stress- related factor for the assessment of overall oxidative homeostasis. To solve this problem, researchers developed the OBS, which calculates an individual’s exposure to pro-oxidants and antioxidants to assess overall oxidative balance status, reflecting the impact of diet and lifestyle on the oxidative/antioxidant system.¹ OBS has been widely used in epidemiological studies, and it has been shown to be negatively associated with a variety of diseases including cancer.¹

Cancer survivorship has become a major main medical and social issue due to the rapidly increasing number of survivors. Given the higher incidences of various conditions (e.g., cancer recurrence, second primary cancer, and chronic illnesses), cancer survivors need comprehensive healthcare and should permanently adopt healthy behaviours.²

Some studies have investigated the relationship between OBS and cancer risk/mortality; however, little is known about the relationship between OBS and cancer survivorship based on the duration after cancer diagnosis. This study compared OBS levels between cancer survivors and non-survivors, and further examined OBS among cancer survivors based on time elapsed since cancer diagnosis.

Data from the Korean National Health and Nutrition Examination Surveys (KNHANES; from 2013 to 2020) were used. From 62,687 subjects, 47,841 aged 19 to 79 years were included. After excluding the subjects who had not any OBS information, data of 33,898 subjects were finally analysed. Detailed information on KNHANES has been described in Kweon et al.’s study.³ Time since cancer diagnosis was evaluated by subtracting age at diagnosis from the age at the time of survey. Cancer survivors were dichotomised for the analysis into short-term and long-term cancer survivors, about five years after diagnosis.

OBS is calculated using scores allocated to ten factors related to oxidative stress: Five pro-oxidants (polyunsaturated fatty acid, n-6 fatty acid, smoking, alcohol, and body mass index), and five antioxidants (carotene, retinol, vitamin C, n-3 fatty acid, and physical activity). Detailed OBS scoring has been described in a previous study.⁴ Briefly, the OBS components were divided into quartiles, with quartile 1 being the lowest quartile (predominance of pro-oxidants) and reference. For dietary antioxidants, the first to fourth quartiles were assigned 0-3 points, whereas the pro-oxidants were assigned 0 points for the highest quartile and 3 points for the lowest quartile. Overall scores are extracted by summing factor scores, with higher scores indicating antioxidant predominance. Dietary variables and physical activities were classified based on distributions in the study cohort.

Table I: Subject characteristics by cancer history and duration.

Cancer diagnosis
Parameters	Non-survivors	Within 5 years	Over 5 years	p-values
No. of subjects	32,340	589	969	-
Age (years)	48.6 ± 15.8	57.8 ± 12.6	61.2 ± 11.5	<0.001
Women	17,683 (54.7)	337 (57.2)	588 (60.7)	0.001
Low incomea	12,909 (40.0)	280 (47.7)	521 (53.8)	<0.001
Hypertension	6,588 (20.4)	191 (32.4)	312 (32.2)	<0.001
Type II diabetes	2,608 (8.1)	80 (13.6)	157 (16.2)	<0.001
CVDb	891 (2.8)	16 (2.7)	46 (4.8)	0.001
OBS	17.1 ± 3.3	18.3 ± 3.1	18.0 ± 3.3	<0.001
CVD: Cardiovascular disease, OBS: Oxidative balance score. Data are shown as means ± standard deviations or numbers (percentages). The p-values were extracted from one-way ANOVA or the Chi-square test, as appropriate.aLess than median household income.bIncludes myocardial infarction and stroke.

Figure 1: Oxidative balance score by time after cancer diagnosis.

From the KNHANES database, the following information was also collected as covariates: Demographics (age, gender, and economic status) and comorbid conditions (physician-diagnosed hypertension, Type II diabetes, and cardiovascular diseases, such as stroke and myocardial infarction). Mean monthly income per family size was used as an indicator of economic status.

Characteristics are compared using number (%) or mean ± standard deviation. The intergroup differences were assessed by one-way ANOVA or the χ² test, as appropriate. Multivariate regression models were used to estimate OBS in each group. The STATA MP version 17.0 (Stata Corp., College Station, TX, USA) was used for all analyses, and a p-value of <0.05 was considered statistically significant.

Approximately 4.6% of the study subjects were cancer survivors, and of these, three-fifths were long-term survivors. Individuals with a cancer history were more likely to be older, female, had a poorer economic status, and had comorbid conditions, which tended to be greater for long-term survivors. An inverse U-shaped pattern was observed for OBS (Table I).

Figure 1 depicts OBS patterns since the cancer diagnosis. Short-term survivors had a higher mean OBS than the non-survivors in both genders (both p <0.001), but the mean OBS of long-term female survivors was significantly lower (p = 0.017).

A p-value was obtained by a multivariate regression model, adjusting for age, economic status, and cardiovascular disease.

This nationally representative data indicate that increased oxidative balance after cancer diagnosis diminishes with time, especially among women. This finding is consistent with the results of a recent meta-analysis, in which, pooled analysis of cancer survivor adherence to at least two lifestyle behaviours revealed that short-term survivors exhibited better adherence than long-term survivors (31% vs. 25%).⁵ Cancer diagnosis per se probably motivates the individuals to make behavioural changes in acute treatment phase,⁶ however, these changes might not be long-lasting. Physicians should periodically remind patients of the risks associated with unhealthy lifestyles.

This study has several limitations. First, this study has a cross-sectional nature, which precludes inferences regarding causal and temporal relationships. Longitudinal studies are required to confirm or refute the findings. Second, assessing dietary factors is vulnerable to recall bias. Third, the popula- tion was limited to the Korean adults. Nevertheless, this is the first study to examine oxidative stress status among the Korean cancer survivors and shows that a favourable oxidative balance regresses over time among women. Sustained efforts are required to support health-related behavioural changes among women across the cancer continuum.

FUNDING:
This work was supported by the Gachon University Gil Medical Centre (Grant No: FRD2021-14).

ETHICAL  APPROVAL:
The researchers followed the guidelines set forth in the Declaration of Helsinki. The Institutional Review Board of Gachon University Gil Medical Centre (IRB No: GCIRB 2022-099) approved the study protocol.

COMPETING  INTEREST:
The authors declared no conflict of interest.

AUTHORS’  CONTRIBUTION:
JHL: Contribution to writing of the manuscript.
ICH: Design of the work, interpretation of the data, and revision of the manuscript.
HYA: Analysis and interpretation of the data.
All authors approved the final version of the manuscript to be published.

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