Background
Colorectal cancer (CRC) is the second most common cancer and cause of cancer death in Europe [
1], and the number of CRC survivors is increasing [
2]. Alcohol consumption is a major risk factor for CRC. The authoritative report of the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) on lifestyle and cancer prevention states that all alcohol is disadvantageous and there is no difference in cancer risk between beer, wine, and liquor [
3]. Moreover, the WRCF/AICR report recommends limiting alcohol consumption after a cancer diagnosis because of adverse effects on cancer prognosis and risk of other diseases (e.g., cardiovascular disease) [
3]. However, findings on how alcohol consumption, including specific alcoholic beverage types, is related to psychosocial outcomes after a cancer diagnosis are inconsistent at present.
In cancer survivors, psychosocial problems are prevalent in roughly one third of the population, and these complaints often persist years after treatment [
4]. Psychosocial problems are not only associated with various late effects of cancer, but they have also been shown to have a negative impact on morbidity and mortality [
5] and might be a barrier for behavioral changes [
6]. Alcohol consumption is also suggested to play a role in reduced psychosocial wellbeing, such as lower health-related quality of life (HRQoL) in head and neck squamous cell carcinoma patients [
7]. Cross-sectional studies have observed associations between hazardous alcohol use and major depressive episodes in head and neck cancer patients [
8] and between alcohol problems and clinical anxiety in testicular cancer patients [
9]. Additionally, in 155 CRC survivors 2–10 years post-diagnosis, a less healthy lifestyle (i.e., high alcohol use, low physical activity level, unhealthy dietary habits, high BMI, and current smoking) was cross-sectionally associated with worse physical functioning and more fatigue, but not with depression or anxiety, and there were no separate analyses of alcohol consumption [
10]. Another study, which was longitudinal, investigated female CRC survivors up to 20 years post-diagnosis and found that anxiety, more than depression, was related to a less healthy lifestyle (including alcohol) during their follow-up [
11]. However, in these female survivors, lower alcohol consumption was reported among women with more anxiety or depression in the first 8 years post-diagnosis [
11]. Generally, alcohol is believed to reduce negative and enhance positive emotions, to emphasize feelings of relaxation, and to increase social bonding [
12].
Nevertheless, not all studies have found an association between alcohol and psychosocial outcomes. One study found that depression in advanced gastrointestinal cancers was mainly related to tobacco use instead of alcohol consumption and that tobacco smokers were more emotionally affected by their disease [
13]. Furthermore, in a randomized psychosocial counseling intervention study among 204 cervical cancer patients, no associations were observed between baseline (9–30 months post-diagnosis) alcohol consumption and quality of life, depression, anxiety, or distress, only an association between patients’ general lifestyle (including physical activity, smoking, and alcohol consumption) and these psychosocial outcomes [
14].
Overall, most of the previous research was cross-sectional, performed in survivors with other cancer types than CRC or long after diagnosis. No longitudinal studies have been performed on the relationship over time between alcohol use and psychosocial outcomes immediately after CRC diagnosis and treatment. Moreover, none of the previous studies has shed light on the role of different alcoholic beverage types. Therefore, we aimed to assess longitudinal associations of alcohol consumption (both total alcohol and beer, wine, and liquor) with anxiety, depression, and HRQoL as psychosocial outcomes in CRC survivors prospectively followed up from diagnosis until ~ 2 years post-diagnosis, using pooled data from the Dutch EnCoRe and PROCORE cohorts.
Discussion
We examined longitudinal associations of alcohol consumption with anxiety, depression, and HRQoL in colorectal cancer survivors from diagnosis up to 2 years post-diagnosis. Overall, we observed that consuming more alcoholic drinks was related to lower anxiety and depression and to better HRQoL over time, after correction for cohort, months since diagnosis, and sociodemographic, lifestyle, and clinical factors. The associations between alcohol and psychosocial outcomes were only significant for beer and wine consumption, not for liquor consumption. In stratified analyses, significant associations were mostly observed in male and in younger (≤ 67 years) CRC survivors.
Our findings were somewhat unexpected, as various other studies have found the opposite: in patients with various types of cancer, alcohol consumption was shown to be related to more anxiety and depression and lower HRQoL [
7‐
9]. These studies mostly focused on alcohol problems, as defined by high scores on the Alcohol Use Disorders Identification Test and not by the amount of alcoholic drinks calculated per person, which were associated with clinical anxiety and depression [
9] or more co-morbidity with depression [
8]. One study looked at drinking as a way of coping and found this to be related to lower quality of life [
7]. They also measured alcohol consumption and observed relations with lower HRQoL, although their analyses were only corrected for age, sex, neuroticism, and smoking and not for relevant other lifestyle or clinical factors [
7].
In addition, some studies have looked at total lifestyle (including alcohol) and not at the separate associations of alcohol with psychosocial outcomes [
10,
14]. A study among cervical cancer patients reported that after cancer treatment patients adhering to lifestyle guidelines (i.e., less alcohol, no smoking, more exercise) reported less depression, anxiety, and distress [
14]. In their intervention study, patients improved their lifestyle (less alcohol and smoking and more physical activity), although only benefits for quality of life were observed and not for depression, anxiety, or distress [
14]. Another study reported that there was no clear association between alcohol and psychosocial outcomes in testicular cancer survivors and found that mostly smoking was related to depressive symptoms [
27]. However, this study was between 2 and 10 years post-diagnosis [
27], whereas we focused on the first 2 years post-diagnosis. A study among head and neck cancer patients reported that there was a large overlap in depression, alcohol consumption, and smoking [
8]. Unfortunately, they did not analyze exact associations between drinking rate and depression scores [
8].
Despite the above contradictory results, findings from other research [
11,
28,
29] are in line with our findings. In a longitudinal study among female CRC survivors, lower alcohol consumption in women was associated with more anxiety or depression in the first 8 years post-diagnosis [
11]. Additionally, among individuals aged 55 to 80 years with type 2 diabetes mellitus, moderate alcohol intake (specifically wine) was significantly associated with lower risk of depression relative to alcohol abstainers [
28]. A recent systematic review also reported that lower alcohol intake was related to chemotherapy-related nausea and vomiting in several cancer types (including CRC) [
29].
Clinical implications
Potentially, consumption of alcohol can reduce tension, offering a way of coping with life’s demands and increasing social bonding [
12]. In some individuals, alcohol use may elicit either positive emotional reactions (e.g., social bonding) or negative reactions (e.g., social anxiety) [
12]. Overall, our findings could be a reflection of survivors slowly regaining their habitual lifestyle habits when things get back to normal after the cancer, including increased participation in social life that may be accompanied by more casual alcohol use (social drinking) and a general sense of feeling better. Moreover, survivors of cancer may express higher gratitude and appreciation for life, and they perhaps view some positive aspects of their cancer diagnosis [
30]. Anxiety, depression, and HRQoL are multifactorial constructs, and our findings suggest that alcohol consumption could be one of the factors contributing to these psychosocial outcomes. Future research is needed to gain more knowledge about the specific reasons for consuming alcohol, e.g., whether survivors drink as a coping mechanism or as a social activity. Since we saw more associations between consumption of beer or wine and better psychosocial outcomes, we hypothesize that these beverages are perhaps consumed more often as social activities, while liquor might be consumed more often as a coping mechanism.
Study limitations
Potential limitations of this study are that we did not measure anxiety, depression, and HRQoL pre-diagnosis. Moreover, we cannot differentiate between former drinkers that may have more depressive symptoms than lifetime abstainers [
31]. Even though our study was longitudinal, we cannot conclude anything about causality due to its observational character. Additionally, we pooled and harmonized two studies that had slightly different time points at follow-up after diagnosis. Therefore, we corrected all analyses for months since diagnosis and cohort. Another limitation was that all lifestyle factors were self-reported, and we cannot exclude the possibility that participants answered questions in a socially desirable manner. Graham et al. have also reported that there was a difference in the interpretations of findings on the relationship between alcohol and depression, based on the measurement of alcohol or psychosocial factors and sex [
31]. They state that the relationship is often stronger for women vs. men, when depression is measured as a clinical diagnosis instead of depressive symptoms, or when alcohol use is measured as the quantity that persons drink per occasion vs. the frequency of drinking, the total volume and quantity, or the number of heavy drinkers [
31]. The strengths of this study were its size with two pooled longitudinal studies that measured CRC survivors repeatedly from diagnosis until 2 years post-diagnosis. We also have data on beverage type consumption at each time point.
Acknowledgements
We thank all patients and their physicians for their participation in the study. In addition, we would like to thank the EnCoRe and PROCORE study participants and research team and the registration teams and scientific staff of the Comprehensive Cancer Centre Netherlands.
The current study was supported by ERAB: The European Foundation for Alcohol Research (number EA 18 20). The EnCoRe study was supported by grants from the Stichting Alpe d’HuZes within the research program “Leven met kanker” of the Dutch Cancer Society (Grant No. UM-2010-4867 and UM-2012-5653), grants from Kankeronderzoekfonds Limburg as part of Health Foundation Limburg (Grant No. 00005739), Wereld Kanker Onderzoek Fonds (WKOF), as part of the World Cancer Research Fund International grant program (grant number 2016/1620), and ERA-NET on Translational Cancer Research (TRANSCAN/Dutch Cancer Society, the Netherlands, project no. UM 2014-6877).
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