Cancer PainPhase 3PARASTOPNCT05051735
PARASTOP - Paracetamol With Strong Opioids
A Phase 3 study testing Paracetamol in people with Cancer Pain and Cancer, run by Oslo University Hospital at 15 sites in 4 countries.
Trial summary
Current guidelines recommend all people with cancer-related pain should be prescribed paracetamol, even those receiving high doses of strong pain killers (opioids) such as morphine. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Cancer Pain, Cancer
- What is being tested?
- Paracetamol
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 204 participants
- Where
- 15 sitesin 4 countries
- Study dates
- 20 Oct 2021to 18 Feb 2026
- Phase
- Phase 3
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Show all 13Show fewer
- 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
Who cannot join
- 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
Trial locations and contacts
15 sites in 4 countries.
15 sites in 4 countries
Norway12 sites
Helse Møre og Romsdal
Ålesund, 6026
Vestre Viken Hospital Trust
Drammen, Drammen, 3004
Førde Hospital Trust
Førde, Førde, 6812
Sørlandet Hospital Trust
Kristiansand, Kristiansand, 4604
Akershus University Hospital
Lørenskog, 1478
OsloUH
Oslo, 0424
Østfold Hospital Trust
Sarpsborg, Grålum, 1714
Telemark Hospital Trust
Skien
Stavanger University Hospital
Stavanger, Stavanger, 4011
Vestfold Hospital trust
Tønsberg, 3103
Universitetssykehuset Nord-Norge
Tromsø, 9019
St. Olavs Hospital
Trondheim, 7030
About this study
Official title: 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
Current guidelines recommend all people with cancer-related pain should be prescribed paracetamol, even those receiving high doses of strong pain killers (opioids) such as morphine. Although this has been shown in studies to be beneficial in other conditions, for instance dental work and after surgery, it has not been shown to further improve pain in people with cancer-related pain. Taking tablets is burdensome to patients and the study aims to determine whether the inconvenience of taking eight extra paracetamol tablets per day can be justified.
The study plans to show whether or not pain control is changed (non-inferior) when stopping paracetamol compared to continued use of paracetamol in people already taking strong pain killers for cancer-related pain. Voluntary participants who are taking a combination of paracetamol and a strong opioid are recruited to the study.
- Conditions
- Cancer Pain, Cancer
- Being tested
- Paracetamol, Placebo
- Keywords
- Cancer Pain, Pain, Analgesics, Sensory System Agents, Physiological Effects of Drugs
- Medical subject headings
- Cancer Pain, Neoplasms, Pain
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ParacetamolDrug
Also called Acetaminophen
Paracetamol 500 mg
PlaceboDrug
Placebo
| Study group | Role | What they receive |
|---|---|---|
| Paracetamol | Experimental | Paracetamol P.O. 500 mg 2 tablets four times a day for 7 days Receives: Drug: Paracetamol |
| Placebo | Placebo comparator | Placebo P.O. 2 tablets four times a day for 7 days Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
To establish whether placebo with strong opioids compared to paracetamol together with strong opioids provides non-inferior analgesia for cancer-related pain.
Numeric Rating Scale 0-10: Average pain intensity past 24 hours
Measured: 7 days
Secondary outcomes (3)
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes opioid related side effects.
Opioid Side Effects Questionnaire
Measured: 7 days
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes global rating of improvement.
Patient Global Impression of Change
Measured: 7 days
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes opioid requirements.
Opioid consumption
Measured: 7 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Sep 2021
- Study start20 Oct 2021
- Primary completion11 Feb 2026
- Study completion18 Feb 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cancer PainStudies of the same condition, open and under way.
- More trials run by Oslo University HospitalThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 204 participants (actual)
Sponsor and investigators
- Lead sponsor
- Oslo University Hospital
- Sponsor type
- University, hospital or other
- Collaborators
- Sykehuset Telemark
- Responsible party
- Principal investigator, Ørnulf Paulsen, Oslo University Hospital
- Investigators
- Ørnulf Paulsen, Principal investigator, Telemark Hospital Trust
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05051735
- Sponsor's protocol ID
- 180946
- Acronym
- PARASTOP
- Status last verified
- Feb 2026
- First submitted
- 11 Sep 2021
- Last updated
- 25 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 25 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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
- ClinicalTrials.gov ID
- NCT05051735
- Acronym / sponsor ID
- PARASTOP / 180946
- Conditions
- Cancer Pain, Cancer
- Keywords
- Cancer Pain, Pain, Analgesics, Sensory System Agents, Physiological Effects of Drugs
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 204 participants (actual)
- Lead sponsor
- Oslo University HospitalUniversity, hospital or other
- Collaborators
- Sykehuset Telemark
- Study start
- 20 Oct 2021 (actual)
- Primary completion
- 11 Feb 2026 (actual)
- Study completion
- 18 Feb 2026 (actual)
- First posted
- 21 Sep 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Current guidelines recommend all people with cancer-related pain should be prescribed paracetamol, even those receiving high doses of strong pain killers (opioids) such as morphine. Although this has been shown in studies to be beneficial in other conditions, for instance dental work and after surgery, it has not been shown to further improve pain in people with cancer-related pain. Taking tablets is burdensome to patients and the study aims to determine whether the inconvenience of taking eight extra paracetamol tablets per day can be justified.
The study plans to show whether or not pain control is changed (non-inferior) when stopping paracetamol compared to continued use of paracetamol in people already taking strong pain killers for cancer-related pain. Voluntary participants who are taking a combination of paracetamol and a strong opioid are recruited to the study.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Paracetamol | Experimental | Drug: ParacetamolParacetamol P.O. 500 mg 2 tablets four times a day for 7 days |
| Placebo | Placebo comparator | Drug: PlaceboPlacebo P.O. 2 tablets four times a day for 7 days |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (13 listed)
- 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
Key exclusion criteria (7 listed)
- 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)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ParacetamolAlso: AcetaminophenParacetamol 500 mg | Drug | Paracetamol |
| PlaceboPlacebo | Drug | Placebo |
Primary outcome
To establish whether placebo with strong opioids compared to paracetamol together with strong opioids provides non-inferior analgesia for cancer-related pain.
Time frame: 7 days
Numeric Rating Scale 0-10: Average pain intensity past 24 hours
3 secondary outcomes
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes opioid related side effects.
Time frame: 7 days
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes global rating of improvement.
Time frame: 7 days
To establish whether placebo with strong opioids compared to paracetamol with strong opioids changes opioid requirements.
Time frame: 7 days
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Feb 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Ørnulf Paulsen principal investigator
Telemark Hospital Trust
15 sites in 4 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Paracetamol in people with Cancer Pain and Cancer, run by Oslo University Hospital at 15 sites in 4 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 13 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 25 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 15 sites in Norway, Italy, Uganda, United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
To establish whether placebo with strong opioids compared to paracetamol together with strong opioids provides non-inferior analgesia for cancer-related pain. (time frame: 7 days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 Feb 2026.