Inclusion criteria:  In order to be eligible to participate in this study, a subject must meet all of the following criteria:  Patients with metastatic cancer (≥18 years); Starting with slow release or transdermal opioids for pain; Able to complete a Dutch questionnaire. Previous treatment with opioids is allowed, if discontinued more than 4 weeks ago.  Exclusion Criteria:  A potential subject who meets any of the following criteria will be excluded from participation in this study:  Patients with contra-indications for laxatives Use of laxatives during the last four weeks Severely impaired renal function (serum creatinine >180 umol/l) Estimated life expectancy <3 months