Adherence and patients' experiences with the use of capecitabine in cancer treatment: The exploration of factors affecting the use in daily practice

Adherence to treatment is a complex and multifaceted issue that can
substantially alter the outcomes of therapy. Variation in plasma concentration
may be due to variability in pharmacokinetics. Even in a clinical trial setting
there is a considerable variability in efficacy and side effects of
capecitabine. In a less controlled environment, like the use of capecitabine in
daily practice, adherence may also play a significant role. Only few studies
have focused on the use of oral anticancer drugs in daily practice and the
influence of adherence to its effectiveness. Information about the reasons for
non-adherence among cancer patients taking the oral anticancer drug
capecitabine is essential for the development of interventions that may
increase adherence.

Primary objective: Adherence in patients starting the use of capecitabine and
the influence of patients attitudes and side effects on adherence.
Secondary objective: The second part of this study contains 1) a validation
study of the adherence measurements and 2) an explorative study. The
relationships between the following parameters will be explored: patient
characteristics, disease characteristics, side effects, quality of life,
patients beliefs and attitude towards disease and medicines, satisfaction with
information, adherence, dose adjustments and plasma concentration of 5*-DFUR,
5-FU and FBAL in patients with cancer will be studied.

Prospective observational cohort study in which 90 patients starting with
treatment with capecitabine will be followed up until five cycles of three
weeks.

Before the start of therapy with capecitabine and during the second week of
cycle 1, 3 and 5 patients will be asked to fill in a questionnaire. Before the
start of therapy with capecitabine baseline blood samples are collected.
Furthermore in the second week of cycle 1, 3 and 5 blood samples are collected,
which will be analysed for plasma concentration of 5*-DFUR, 5-FU and FBAL.