Evaluating the necessity of paracetamol in cancer pain management

PARASTOP - Paracetamol With Strong Opioids. A Randomized, Double-blind, Parallel-group Non-inferiority Phase III Withdrawal Trial of Paracetamol Versus Placebo in Conjunction With Opioids for Moderate to Severe Cancer-related Pain

Phase 3 Interventional Oslo University Hospital · NCT05051735

This study is testing if people with cancer pain can manage their pain just as well without taking paracetamol while they are already on strong opioid medications.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment204 (estimated)
Ages18 Years and up
SexAll
SponsorOslo University Hospital Academic / other
Locations15 sites (Milano and 14 other locations)
Trial IDNCT05051735 on ClinicalTrials.gov

What this trial studies

This study investigates whether stopping paracetamol affects pain control in patients with cancer-related pain who are already taking strong opioids. Participants will be randomly assigned to either continue taking paracetamol or switch to a placebo, allowing researchers to assess the non-inferiority of pain management without paracetamol. The goal is to determine if the inconvenience of taking additional tablets is justified in this patient population. The study aims to provide clarity on the role of paracetamol in conjunction with opioids for cancer pain relief.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older with metastatic cancer who are currently receiving strong opioids and paracetamol for pain management.

Not a fit: Patients who are not on strong opioids or those with a life expectancy of less than two months may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could simplify pain management for cancer patients by potentially eliminating unnecessary medication.

How similar studies have performed: Previous studies have shown benefits of paracetamol in other pain management contexts, but this specific approach in cancer pain is novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Participants must be ≥ 18 years of age inclusive, at the time of signing the informed consent.
* ≥50 kg (due to paracetamol dosage)
* Participants who are under palliative care or oncology service review
* Diagnosis of metastatic cancer
* Clinician-predicted life expectancy \>2 months
* Receiving daily regular strong opioids for cancer pain
* Receiving stable scheduled opioid dose last 48 hours\*
* Receiving paracetamol 1 gram x three or four times a day for at least five days
* Average pain intensity past 24 hours ≥ 2 and ≤ 7 (NRS 0-10)\*
* Able to take study drug/placebo as tablets
* Able to comply with all study procedures
* Capable of giving signed informed consent as described in Appendix 1 which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.

  * It is allowed to repeat procedure within the screening period without considering the participant being a rescreen

Exclusion Criteria:

* History of allergy or hypersensitivity to any of the active substances or excipients in the study drug
* Known severe liver or renal failure equivalent with CTCAE Grade 3 or 4\* precluding continuation of paracetamol. (\*Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0)
* Participants receiving subcutaneous, intravenous, intrathecal, or epidural opioid therapy
* Participants receiving systemic anticancer treatment during the intervention period if they are anticipated to have increasing pain or other symptoms related to the treatment
* Co-enrolment in other drug trials. Participants will not be enrolled in any other on-going interventional clinical trial. Study participants may be enrolled in non-interventional research (e.g. questionnaire, tissue collection studies)
* Previously enrolled in this study
* Pregnant or lactating women

Where this trial is running

Milano and 14 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Cancer PainCancerPainAnalgesicsSensory System AgentsPhysiological Effects of Drugs
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.