Journal of the New Zealand Medical Association, 08-June-2012, Vol 125 No 1356
Dietary patterns and information needs of colorectal cancer patients post-surgery in Auckland
Ryan Cha, Melissa J Murray, John Thompson, Clare R Wall, Andrew Hill, Mike Hulme-Moir, Arend Merrie, Michael P N Findlay
Colorectal cancer (CRC) is the third most common cancer worldwide.1 The incidence varies greatly from one country to another with the highest rates present in North America, Australia, New Zealand, Western Europe and Japan.2
In New Zealand, it is the second most common cancer in non-Maori and the fourth most common cancer in Maori people.3 Despite the fact that CRC incidence and mortality within the New Zealand population is generally decreasing, the disease is still highly prevalent and a cause of substantial morbidity to many New Zealanders.3
There are many studies that have explored the relationship between diet and the development of CRC.4 Studies have suggested that a “Western diet,” characterised by high meat, fat and refined grains intake, is associated with a significantly increased risk of colon cancer, while a “prudent diet,” characterised by high fruit, vegetable and fish intake is non-significantly associated with a reduced risk of developing colon cancer.5,6
Patients diagnosed with cancer are often eager to find out about their diet, dietary supplement use and nutritional complementary therapies, and they are motivated to adjust their dietary patterns accordingly.1,7
The relationship between dietary factors and development of colon cancer is strong worldwide, particularly relating to meat consumption.8 Whereas the global average consumption of meat and poultry contribute 9% to the total energy of diet, in New Zealand meat and poultry provide around 20% of the total energy,9 indicating that NZ diet favours meat. This could in part account for the on-going high incidence of colon cancer in New Zealand.9
It has recently been suggested that diet not only influences CRC incidence, but also re-occurrence rates and survival post treatment.10 A prospective study of 1009 patients with stage III CRC treated with surgery and adjuvant chemotherapy demonstrated that people with a high intake of a Western-type diet had worse disease-free survival at 5 years.10
Diet can affect gut mucosa either directly from the luminal side or indirectly through whole-body metabolism,11 and food-derived compounds can shift the cellular balance towards harmful outcomes via genetic and/or epigenetic changes.11 Thus diet may not only affect the development of CRC but also patient outcomes post diagnosis. It is therefore very important that appropriate, accurate and easy to access dietary information is available for CRC patients.
Along with these potential effects on patient outcomes, accurate and accessible dietary information is inherently important to this patient group due to the symptoms of the disease and the side-effects of treatment, and the impacts of these on quality of life. A previous survey investigating overall patient satisfaction in CRC patients from the Auckland region suggested that this patient group felt that they had unmet information needs regarding dietary advice (M Murray, personal communication).
Another study in the CRC patient population of Southern DHB (SDHB) also found that information needs were not being met, leading to the development of a dietary guide for optimising health after treatment for colorectal cancer called, “Healthy Eating after Colorectal Cancer” (Pullar, Chisholm and Jackson, University of Otago, see article in the same issue of the NZMJ).
The aim of this study was to pilot collection of data to describe the dietary intakes and dietary patterns of CRC patients in the Auckland region, and to investigate what the current information resources are for CRC patients in the Auckland region, and patient satisfaction with these resources.
Participants were recruited from the three district health boards in Auckland regions: Waitemata District Health Board (WDHB), Auckland District Health Board (ADHB) and Counties Manukau District Health Board (CMDHB). Eligible criteria included any patient with a diagnosis of CRC who had received surgical resection (with curative intent) of their tumour in the last 1-4 months.
Patients with stage I tumours removed by polypectomy or who had received palliative treatment (including palliative surgery such as ileostomy formation) were excluded. Eligible participants were identified and approached by local clinicians, registrars, clinical nurse specialists and patient navigators within the surgical and medical oncology departments of the Co-Investigators at each DHB. Participants either provided written or verbal consent form to allow their name and address details to be given to the researchers.
A study information sheet, consent form, decline participation form, questionnaire and a reply-paid envelope were posted to each of the patients whose details have been provided to the researchers. The questionnaire was a modified version of the qualitative food frequency questionnaire (FFQ) used by the New Zealand Ministry of Health in the National Nutritional Survey 1997. 12 Demographics such as gender, age and ethnicity were collected. The FFQ consisted of questions on both dietary habits and food frequency consumption.
The dietary habits questions were based on the frequency of consumption of the MoH core food groups (fruit and vegetables, dairy products, breads and cereals and meat). The remainder of the questionnaire included 168 food items and inquired about average frequency of consumption of these foods.
Participants were asked to complete these questions based on their normal food intake prior to surgery. There were up to 9 possible responses, which ranged from never to 6 or more times per day. Data on age, weight and height was collected in bands, as per previous questionnaires. Three additional questions regarding vitamin and supplement use and nutritional information needs were added to the questionnaire.
Participants were given 3 weeks to complete the questionnaire. A reminder letter along with another copy of the questionnaire and reply-paid envelope were sent to all participants who had not responded one week prior to the end of the study period. Additional clinical data on participant co-morbidities, the extent of disease (disease stage) and treatment received were obtained from the participants’ medical records if specific consent was given. Data from the questionnaires and medical records were anonymised and entered into an Access database.
Demographic and dietary data were interpreted by simple statistics. Dietary patterns were analysed by factor analysis (principal component) of the food frequency questions using the FACTOR PROCEDURE in SAS with a Varimax rotation factor. Ethics approval for this research project was obtained from New Zealand Upper South A Regional Ethics Committee (URA/11/EXP/023).
Forty patients signed the release of information form and were sent the survey. Of these, 6 declined participation and 29 returned signed consent forms with completed surveys. The overall response rate was 35/40 (88%), with 29 people taking part in the study by completing the surveys (73%).
Demographics—Table 1 shows the attributes of the 29 participants. Most of the participants were New Zealand/European (69%). The next most prevalent ethnic group was Maori (10%). The majority of participants were males (69%). The most commonly selected age band selected by participants was 70+. Forty-one percent of participants were ex-smokers and 2 participants (7%) were current smokers. Four participants (14%) did not specify their smoking status. Thirty-one and 48% of participants respectively reported taking either none or less than 5 standard alcoholic drinks per week.
Vitamin and supplement use—Participants were asked if they took any dietary supplements, vitamins, minerals and/or herbal supplements. 11 participants (37%) reported vitamin or supplement use, with the majority reporting daily dosing. The most common supplements were multivitamins or minerals and fish oil (both n=4, 36%).
Information needs—Participants were asked if they had received any information on diet post operatively. Less than half of the participants reported that they had received dietary information after surgery (n=13, 43%). Participants were then asked if they felt that no information, less information, the same amount of information or more information should be available post bowel surgery. Nearly half of the participants (n=14, 47%) suggested that they would like to have had more information provided to them.
A third of participants were satisfied with the amount of information provided to them (n=10, 33%). The remainder felt that less information that what was provided to them was required (n=6, 20%)
Table 1. Summary of characteristics of the study participants
Dietary characteristics—Participants were asked about their consumption of a variety of foods and drinks, including their self-reported eating pattern pre-operation. Participants were asked whether they included animal products in their diet. Only 1 participant (3%) reported avoiding meats other than fish and chicken.
Specific questions were asked regarding daily fruit, vegetable and bread servings. Sixty-seven percent of participants reported consumption of 2 or more servings of fruit per day (n=20). Fifty percent reported daily vegetable servings of 3 or more per day (n=15, 50%). The most common type of bread each was wholemeal or wholegrain bread, followed by white bread. Nearly half of participants reported consumption of 1-2 slices of bread per day (n=14; 47%).
Dietary patterns—Participant responses to the food frequency questions were analysed by principal component factor analysis to investigate if any dietary patterns could be described for this patient group. Data was missing for a minimum of one variable of the frequency analysis in 27 of 30 completed surveys (90%).
Participants who had greater than 50% of the data missing for these questions were excluded from the analysis (n=2, 7%). For the remaining participants, missing data was assumed to ‘never’ for the purposes of analysis. Four dietary patterns were suggested by the principal component factor analysis (Table 2.)
Table 2.The four dietary patterns of patients with CRC in Auckland
This was a pilot study to investigate the feasibility of collecting data on the diet and information needs of patients with CRC in Auckland. The food frequency questionnaire, from the National Nutritional Survey of New Zealand in 1997, was used to investigate dietary patterns and dietary intake of these patients. The survey was completed by 75% of patients approached to participate in the study, suggesting that the topic is relevant and of importance to this patient group.
It is notable that only half of the study population met the daily vegetable requirements and two-thirds the daily fruit requirements as in the New Zealand Food and Nutrition Guidelines (FNG –MoH). 13 The fact that a significant proportion of the study population are not meeting these requirements suggests that awareness of the benefits of these food types needs to be improved in this patient group.
In contrast, wholemeal/wholegrain bread was the most popular choice for our participants. This may reflect public awareness of the suggested benefits of wholemeal breads. It has been found that high consumption of whole grain foods, especially hard whole grain rye bread, may reduce the risk of colon cancer. 14 It has also been shown to reduce the risk of other chronic diseases including coronary heart disease, and diabetes. 15
In this study, 36% of participants reported use of one or more vitamin or dietary supplements. This is the first time vitamin or supplement use has been reported for this patient group in New Zealand. By comparison in America, routine use of vitamin, mineral and other non-vitamin-non-mineral dietary supplements is common among older persons, with an estimated 50% of persons aged 57-85 years old reported as taking a dietary supplement regularly (at least once per week). 16
This shows that in comparison to the general population of the United States, New Zealand colorectal patients seem to take less vitamins and/or dietary supplements. The association between vitamins and dietary supplements and all-cause mortality (and thus mortality in CRC patients) is not currently known. 17
The information collected was able to be used to suggest four different dietary patterns present in this patient cohort as per principal component factor analysis. The diets identified are distinct from those identified in an American study on colorectal cancer and diet by Meyerhardt, 10 which is likely to reflect the distinct population of Auckland, being a particularly multicultural city.
As this was a pilot study, the sample size is too small to investigate association between the dietary patterns and specific ethnic groups. These results confirm that this type of dietary assessment is useful and appropriate in this patient population, and that future studies can use this analysis to determine dietary types and their associations with outcomes.
A limitation of this study was the proportion of completed surveys that contained missing data (n = 27, 90%). The survey was 12 pages long and comprised of 23 dietary-related questions that varied in format between single answer, multiple selections, and food frequency counts. Missing data in multiple answer questions tended to be related to the question design which included a yes/no selection relating to consumption of a particular food type, followed by multiple selections of the food frequency consumption examples of the food type if yes was selected.
Several participants did not select yes or no but then selected examples of the food type, and thus were considered to eat the food type. However the most common questions to contain missing data were the food frequency questions.
Despite having the option of selecting “never” many food types were left with no selection. This may have been because the participant might not have known what some of the listed foods were, or found the concept of allocating a frequency of consumption difficult. In other cases, two ticks had been entered into the same row followed by a blank row, suggesting that the participant had not moved on to the next row down.
There are several suggestions that could improve these issues. Other studies using FFQs have included pictures of the food types to improve understanding. The method most likely to substantially reduce missing data is through interview collection of the survey data. The primary difficulty with conducting surveys via interview is the time required, which was not feasible in this pilot study.
Other limitations of this study include recall bias regarding both recollection of dietary intake prior to surgery, and of information given. Also, the tool used was a qualitative questionnaire that does not collect information on portion size and caloric intake.
Of interest, 5 participants completed all of the demographics questions on the first page of the survey except for their smoking status, which was left blank. This may be due to tobacco “denormalisation” within our society, which influenced social norms, related to tobacco use, targeting tobacco products the tobacco industry and smoking itself.18
With increased stigmatization and less acceptance towards smoking, some participants may have been found it uncomfortable to state their smoking status. People might also have found it personal issue, which might have led them to decide that they have the right not to indicate it on the survey.
On the other hand, every participant has specified his or her alcohol consumption. This shows that people may be more willing to openly talk about alcohol than tobacco use.
More than half of the participants in this study reported that they had not received any nutritional information post their surgery. Almost half expressed that they felt more information should be provided. This shows a significant unmet information need in this patient group. The authors would like to suggest the implementation of a nationally standardized nutritional information booklet for CRC patients, such as that developed by Pullar et al. The effect of such an implementation could be quantified in a randomised interventional study assessing both quality of life and survival outcomes in New Zealand CRC patients.
This study has demonstrated that the assessment of dietary intake and patterns using an FFQ in this patient group is possible. Improvements on the current FFQ for future diet-related studies would include more user-friendly surveys and interview administration of surveys.
Currently, not all of the Auckland CRC patient population are meeting the daily recommended servings of fruit and vegetables, which is suggestive of a lack of nutritional knowledge. This is further strengthened by our findings that the information needs with respect to nutritional advice post surgery are not being met for this patient group.
Competing interests: None declared.
Author information: Ryan Cha, Medical Student, School of Medicine, The University of Auckland; Melissa J Murray, Project Manager and Clinical Research Officer, Cancer Trials New Zealand, Faculty of Medical and Health Sciences, The University of Auckland; John Thompson, Senior Research Fellow, Paediatrics Department, Faculty of Medical and Health Sciences, The University of Auckland; Clare Wall, Senior Lecturer, Nutrition Department, Faculty of Medical and Health Sciences, The University of Auckland; Andrew Hill, Professor of Surgery, Department of Surgery, Faculty of Medical and Health Sciences, The University of Auckland; Mike Hulme-Moir, General Surgeon, Waitemata District Health Board, Auckland; Arend Merrie, Head Colorectal Surgical Unit, Auckland District Health Board, Auckland; Michael P N Findlay, Professor of Oncology, Discipline of Oncology, Faculty of Medical and Health Sciences, The University of Auckland
Acknowledgements: We thank all the participants of our survey as well as the staff at the hospitals that aided recruitment to the study.
Correspondence: Melissa Murray, Cancer Trials New Zealand, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand. Fax: +64 (0)9 3737927; email: firstname.lastname@example.org
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