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Does chemotherapy affect the vitamin C status of cancer patients?

A 2019/2020 Summer Studentship research project

Vitamin C plays a fundamental role in many biochemical functions in all cells of the body. Preliminary data has suggested that some cancer patients undergoing chemo- or immunotherapy may have suboptimal plasma levels, but we don’t know how repeated treatment affects vitamin C status. We hypothesize that patients with cancer which is metastatic or affecting the digestive tract may have lower vitamin C levels than those not receiving adjuvant therapy, and that vitamin C levels may reduce further during repeated cycles of chemotherapy. It has been established that plasma levels above 50 µM are adequate and below are inadequate. This study will determine the prevalence of inadequate plasma vitamin C levels in patients during chemotherapy for cancer. The results may lead to clinical recommendations specifically for this group of people.

Student: Rebecca van Berkel and Maria Nonis
Supervisors: Associate Professor Gabi Dachs, Professor Bridget Robinson, CDHB; Professor Margreet Vissers, UOC
Sponsor: Cancer Society of New Zealand, Canterbury-West Coast Division and Cancer Society Rangiora and Hokitika Groups

Introduction

Data on vitamin C status of cancer patients and those undergoing therapy is sparse. During last year’s summer studentships, two groups of patients were investigated; those prior to surgery to remove their cancer and those undergoing chemo- or immunotherapy. Our data demonstrated that a significant proportion of patients with cancer in Canterbury have suboptimal levels of circulating vitamin C. In addition, those undergoing therapy appeared to have slightly lower vitamin C levels compared to the pre-surgery patients. Of interest was also that those patients who reportedly did more exercise during treatment had higher levels of measured vitamin C. We currently do not know a) how repeated cycles of chemotherapy affect the vitamin C status of cancer patients, and b) how exercise and vitamin C status are related.

We hypothesize that cancer patients undergoing chemotherapy may be at particular risk of vitamin C depletion, and that repeated cycles of therapy may negatively impact on their vitamin C status and their ability to exercise.

Aim

The aim of this study is to measure plasma levels of vitamin C, repeatedly, in patients during their course of chemotherapy for cancer, and to relate these measurements to their treatment cycle, and to their exercise levels.

Method

Patients starting (or are within their first 2 cycles of) their chemotherapy at the Oncology Services, Christchurch Hospital, will be approached by the student and invited to take part in the study. Patients are asked to consent to providing a small blood sample (5ml) during at least two clinical visits; this will enable intra-patient monitoring of vitamin C status through several rounds of therapy. Consented patients will answer a simple health questionnaire (diet, BMI, exercise), have weight, height, cancer diagnosis and stage, and chemotherapy regimen recorded from their medical records. Each patient will also be given a Fitbit for monitoring step counts as a measure of exercise. The blood sample will be rapidly processed for batched vitamin C analysis, which is measured using HPLC-EC (high performance liquid chromatography with electrochemical detection). The HPLC method of ascorbate measurement is well established in our group, is highly accurate and represents the international gold standard. We aim to recruit 100 patients to this study, which is feasible from our previous summer studentship data. Prevalence of inadequate vitamin C in this patient cohort will be determined and analyzed with respect to patient demographics, clinicopathological and treatment information. Exercise will be estimated from the questionnaire data and their Fitbit step-counts, and categorized into low, medium and high.

Student researcher’s component of the study

The student will explain the study to potential participants, consent the patients, administer a simple questionnaire, rapidly transfer the blood tubes to the laboratory and process the plasma for analysis. The student will, with laboratory support, analyze the plasma samples for vitamin C content using HPLC-EC. The student will then assist with analysis and potential drafting of a manuscript.

Student Prerequisites

Medical student

How to apply

Email gabi.dachs@otago.ac.nz