COLON-study
Colorectal cancer: Longitudinal, Observational study on Nutritional and lifestyle factors that influence colorectal tumour recurrence, survival and quality of life

Colorectal cancer is the third most common type of cancer worldwide. It
accounted for about 1 million new cancer diagnoses and about 529000 deaths in
2002. Lifestyle and nutritional factors influence colorectal cancer risk. The
evidence that consumption of a Western type of diet, -i.e. high consumption of
red and processed meat and alcohol - increases the risk of colorectal cancer is
convincing. In addition, body fatness and abdominal fatness increases the risk
of colorectal cancer, while physical activity protects against colorectal
cancer.

In contrast to the extensive knowledge about the role of nutrition and
lifestyle in the prevention of cancer, not much is known about the role of diet
and lifestyle during and after treatment of colorectal cancer. Only few, mainly
non-European prospective studies reported on factors that influence colorectal
cancer survival and recurrence.

There is some evidence that if colorectal cancer patients increase their level
of physical exercise, this may reduce recurrence and mortality. Moreover, a
higher BMI and higher waist circumference of cancer patients could possible
increase colorectal cancer recurrence and mortality.

It is unclear how dietary supplements affect colorectal cancer recurrence and
survival, but effects are not necessarily beneficial. Some vitamins, eg folic
acid, may be involved in progression of established neoplasms; ingestion of
folic acid and other B-vitamins may therefore not be harmless for colorectal
cancer patients.

Most studies that assessed the intake of dietary supplements in colorectal
cancer patients were performed in the US. Patients tended to increase their
intake of supplements after the diagnosis. More than 40% of American colorectal
cancer patients take vitamin and/or mineral supplements. Physicians are not
always aware of their patients supplement intake; a US-study among elderly
cancer patients showed that only 28% of patients taking dietary supplements had
this supplementation documented in their medical record. No data are available
on supplement use among European colorectal cancer patients.

We will start a Dutch prospective cohort study of colorectal cancer patients.
In this cohort we will assess the intake of dietary supplements, dietary intake
and life style factors of colorectal cancer patients. We will study if and how
those factors are associated with colorectal cancer recurrence and survival and
with quality of life.
The main objectives of this study are:
- to evaluate dietary supplement use among colorectal cancer patients in the
Netherlands,
- to study the association of dietary supplement intake with colorectal cancer
recurrence and survival

This study is a prospective cohort study. We aim to include a total of 1,000
colorectal cancer patients from regional and academic hospitals in the
Netherlands. The total recruitment procedure will take 2-3 years, with a 5 year
follow-up period.

We will recruit patients shortly after they have been diagnosed with colorectal
cancer, but before surgery. Patients who want to participate have to give their
informed consent. Patients are asked to fill out several questionnaire: a food
frequency questionnaire, a dietary supplement questionnaire, a quality of life
questionnaire and a questionnaire about lifestyle factors. Patients are asked
to donate a blood sample, in addition we will collected a tissue sample from
the tumor. And we will collect a stool sample during surgery.
Patients are contacted again after 6 months, 2 years and 5 years and are asked
to fill out the questionnaires again and to donate blood samples and stool
samples.

Colorectal cancer recurrence will be assessed from hospital registries and the
Dutch cancer registries. Recovery from surgery will be assessed from hospital
reports. Tumor characteristics will be assessed from pathology reports and
PALGA-registry. Mortality/survival will be assessed from the databases from the
GBA (Gemeentelijke Basis Administratie) and CBS (Centraal Bureau Statistiek).

This cohort study does not involve any intervention. Participants of this
cohort will contribute to the evidence base about lifestyle and cancer
recurrence; this will help future colorectal cancer survivors to modify their
risk of colorectal cancer recurrence.

Risks associated with participation in this cohort are confined to the normal
risks of taking blood samples (risk of fainting and of bruising). Since the
drawing of blood will be done by professionals, risks are low. The only burden
for participants is, that participants are regularly asked to fill out
questionnaires about nutritional and lifestyle factors and they are asked to
donate blood and stool samples.