Here are summaries of each study:

1. Portenoy et al. (2012) — Nabiximols Graded-Dose Trial 

[1]

Randomized, double-blind, placebo-controlled, graded-dose study of 360 patients with advanced cancer and opioid-refractory pain. Patients received placebo or nabiximols at low (1–4 sprays/day), medium (6–10), or high (11–16) doses over 5 weeks. The primary endpoint (≥30% responder rate) was not significant (P = .59). However, secondary continuous responder analyses favored nabiximols overall (P = .035), specifically at the low-dose (P = .008) and medium-dose (P = .039) levels. The high-dose group had more adverse events without additional benefit. The study suggested efficacy and safety at lower doses and informed dose selection for future trials.

2. Johnson et al. (2010) — THC:CBD vs. THC vs. Placebo 

[2]

Multicenter, double-blind, placebo-controlled trial of 177 patients with advanced cancer and intractable pain despite chronic opioids, randomized to THC:CBD extract (n=60), THC extract (n=58), or placebo (n=59) for 2 weeks. The primary endpoint of change in mean pain NRS was statistically significant for THC:CBD vs. placebo (−1.37 vs. −0.69), but not for THC alone (−1.01 vs. −0.69). Twice as many patients in the THC:CBD group achieved ≥30% pain reduction compared with placebo (43% vs. 21%; significant OR). No change in opioid use was observed across groups. Nausea/vomiting worsened with THC:CBD. This was the first RCT to demonstrate superiority of a combined THC:CBD extract over THC alone and placebo for cancer pain.

3. Lichtman et al. (2018) — Phase 3 Nabiximols Trial 

[3]

Phase 3, double-blind, placebo-controlled trial of 397 advanced cancer patients with pain NRS 4–8 despite optimized opioids, randomized to nabiximols (n=199) or placebo (n=198). After a 2-week titration and 3-week treatment period, the primary ITT endpoint was not met (median pain improvement 10.7% vs. 4.5%, P = 0.085). However, the per-protocol analysis was significant (15.5% vs. 6.3%, P = 0.038), and nabiximols was superior on quality-of-life measures. Post hoc analyses showed greater benefit in U.S. patients, potentially related to lower baseline opioid doses and different pain type distributions. Safety was consistent with prior studies.

4. Hardy et al. (2025) — Medicinal Cannabis for Symptom Control 

[4]

Double-blind, placebo-controlled RCT of 144 patients with advanced cancer randomized to 1:1 THC:CBD oil or placebo, dose-escalated over 14 days and continued to day 28. The primary endpoint — change in total symptom distress score (TSDS) on the ESAS — showed no difference between arms (P = 0.76). A statistically significant improvement in ESAS pain scores favored medicinal cannabis (−1.42 vs. −0.46, P = 0.04), but this came at the expense of greater psychomimetic toxicity. General well-being improved more with placebo. The conclusion was that 1:1 THC:CBD oil was no better than palliative care alone for overall symptom burden.

5. Zylla et al. (2021) — Feasibility of Medical Cannabis in Stage IV Cancer 

[5]

Pilot RCT of 30 patients with stage IV cancer requiring opioids, randomized 1:1 to early cannabis (EC, immediate access through a state program) vs. delayed-start cannabis (DC, standard care for 3 months). This was primarily a feasibility study. Interest was high (36% enrollment of eligible patients). Mean daily THC and CBD at 3 months were 34 mg and 17 mg, respectively. A higher proportion of EC patients achieved reduced opioid use and improved pain control, though the study was not powered for efficacy. No serious safety issues arose. The study demonstrated that conducting RCTs through state cannabis programs is feasible.

6. Segar et al. (2026) — Dronabinol for Cancer-Induced Bone Pain 

[6]

Single-arm pilot study of 14 evaluable breast cancer patients with bone metastases on opioid therapy, treated with dronabinol 10 mg BID for 8 weeks. The primary endpoint — proportion achieving ≥20% opioid reduction — was met by 4 of 14 patients (29%). Patients reported significant improvements in pain severity, interference scores, quality of life, and insomnia. One grade 3 adverse event (dizziness) occurred. Notably, a significant decrease in serum C-terminal telopeptide (a bone resorption marker) was observed, suggesting a potential effect on bone remodeling. Results were deemed promising but require validation in larger controlled studies.

7. Clarke et al. (2022) — THC/CBD Nanoparticle Spray Pilot 

[7]

Non-blinded, single-arm, two-stage pilot study of a novel water-soluble nanoparticle oro-buccal spray (MDCNS-01) containing THC/CBD in patients with advanced cancer and uncontrolled pain. Stage I (n=5) assessed single escalating doses and pharmacokinetics; Stage II (n=25) assessed up-titrated dosing. The nanoparticle formulation demonstrated dose-dependent plasma concentrations and higher systemic exposure of THC vs. CBD. A subgroup with breast and prostate cancer bone metastases showed the greatest pain improvement (~40% from baseline). Common adverse events included drowsiness (44%) and nausea/vomiting (72%). The study provided preliminary evidence of acceptable bioavailability, safety, and analgesic potential for this novel formulation.

8. Braun et al. (2024) — ASCO Guideline on Cannabis and Cannabinoids 

[8-9]

The first ASCO guideline on cannabis/cannabinoids in adults with cancer, based on 13 systematic reviews and 5 additional primary studies. Key recommendations:

• Clinicians should routinely and nonjudgmentally inquire about cannabis use

• Recommend against cannabis as cancer-directed treatment outside clinical trials

• For refractory CINV despite guideline-concordant antiemetics, dronabinol, nabilone, or a quality-controlled 1:1 THC:CBD extract may be considered (weak recommendation; moderate evidence for dronabinol/nabilone, low for THC:CBD)

• Insufficient evidence to recommend for or against cannabis for cancer pain or other symptoms

• Recommend against high-dose CBD (≥300 mg/day) for symptom management due to lack of efficacy and hepatotoxicity risk

• The guideline highlights the critical need for more research and notes that cannabis use among cancer patients has outpaced the supporting evidence

Here is a concise evidence focused summary of the eight studies you listed. An important theme across them is that cannabinoids sometimes improve cancer pain, but the results are inconsistent, and convincing evidence that they substantially reduce opioid requirements is still limited. The newer studies largely reinforce that conclusion.

1. Portenoy et al., 2012

Nabiximols for Opioid Treated Cancer Patients With Poorly Controlled Chronic Pain

This was a relatively large randomized, double blind, placebo controlled dose finding trial involving 360 patients with advanced cancer whose pain remained inadequately controlled despite opioids. Nabiximols, an oromucosal THC plus CBD preparation, was tested at low, medium, and high spray doses over five weeks.

The prespecified primary outcome, the proportion achieving at least a 30% improvement in pain, did not significantly differ between nabiximols and placebo overall. However, a secondary continuous responder analysis favored nabiximols, particularly at the low and medium doses. Low dose treatment also produced statistically significant improvements in average pain, worst pain, and sleep disruption.

Adverse effects increased with dose. The low and medium doses were reasonably tolerated, while the high dose performed less favorably than placebo from a tolerability standpoint.

Takeaway: This trial provided an early signal that low to moderate doses of THC:CBD might provide adjunctive analgesia in opioid refractory cancer pain, but the primary endpoint was negative. The dose response was also unusual because higher dosing did not produce greater benefit.

2. Johnson et al., 2010

THC:CBD Extract and THC Extract in Intractable Cancer Related Pain

This randomized, double blind study included 177 patients with advanced cancer pain despite ongoing opioid therapy. Participants received THC:CBD extract, THC alone, or placebo for two weeks.

Pain scores improved by approximately 1.37 points with THC:CBD versus 0.69 points with placebo, a statistically significant difference. THC alone produced an approximately 1.01 point improvement and was not significantly superior to placebo.

A particularly notable finding was the responder analysis. About 43% of THC:CBD patients achieved greater than 30% pain reduction versus 21% with placebo. THC alone had a responder rate of approximately 23%, essentially similar to placebo.

However, opioid consumption did not decrease, and THC:CBD was associated with worsening nausea and vomiting on one quality of life measure. Most treatment related adverse effects were mild or moderate.

Takeaway: One of the stronger positive trials. It suggests the combination of THC and CBD may be more effective than THC alone for opioid refractory cancer pain. Importantly, improved pain did not translate into measurable opioid sparing.

3. Lichtman et al., 2018

Nabiximols as Adjunctive Therapy in Advanced Cancer With Uncontrolled Pain

This phase III randomized, double blind trial included 397 patients with advanced cancer and persistent moderate to severe pain despite optimized opioid therapy, with 199 receiving nabiximols and 198 placebo. Patients first titrated the spray for two weeks and then continued their selected dose for three weeks.

The primary endpoint was negative. Median improvement in average pain was approximately 10.7% with nabiximols versus 4.5% with placebo, with P = 0.0854, meaning the difference did not reach conventional statistical significance.

Some secondary and subgroup analyses suggested possible benefit, particularly among certain younger patients, but those findings were insufficient to establish overall efficacy.

Takeaway: This larger phase III trial weakened the case created by the earlier positive studies. Nabiximols did not demonstrate a statistically significant overall analgesic benefit when added to optimized opioid therapy.

That discrepancy between studies 1 and 2 and this larger study is an important reason guidelines remain cautious.

4. Hardy et al., 2025

1:1 THC:CBD for Symptom Control in Advanced Cancer

This newer double blind randomized trial studied a 1:1 THC:CBD oil containing 10 mg/mL of each cannabinoid in patients receiving palliative care for advanced cancer. A total of 144 patients were randomized, allowing 120 patients to be evaluated at the primary 14 day endpoint.

The primary endpoint was not pain alone but overall symptom burden, measured using the Edmonton Symptom Assessment Scale.

Total symptom distress improved by:

THC:CBD: about 6.30 points
Placebo: about 6.98 points

There was essentially no difference between treatments, P = 0.76.

Pain specifically did show a modest advantage:

THC:CBD: 1.42 point improvement
Placebo: 0.46 point improvement
P = 0.04.

However, this benefit came with greater psychomimetic toxicity, meaning effects such as altered perception, cognition, or feeling intoxicated. General wellbeing actually favored placebo.

Takeaway: THC:CBD did not improve overall cancer symptom burden, although it produced a small statistically significant improvement in pain. The magnitude of benefit was modest and accompanied by additional toxicity.

This is especially important because it is substantially newer than the nabiximols trials.

5. Zylla et al., 2021

Medical Cannabis in Patients With Stage IV Cancer

This was a small pilot randomized trial of only 30 patients with stage IV cancer who required opioids. Fifteen patients received immediate access to medical cannabis through Minnesota's state program, while 15 continued standard care for three months before receiving cannabis later.

Unlike the nabiximols trials, the cannabis product and administration were individualized by pharmacists rather than being one standardized THC:CBD medication.

At three months, estimated average daily exposure was approximately:

THC: 34 mg/day
CBD: 17 mg/day.

A greater proportion of the early cannabis group experienced improved pain and reduced opioid consumption. No major safety problems were identified, and patient satisfaction was high.

Takeaway: Encouraging, particularly regarding possible opioid reduction, but this should be considered hypothesis generating rather than definitive evidence. With only 30 patients and flexible cannabis formulations, the trial cannot reliably establish how large the effect is or which cannabis formulation produced it.

6. Segar et al., 2026

Dronabinol to Decrease Opioid Use for Cancer Induced Bone Pain

This is the newest study on your list, published July 16, 2026. One correction is important: this was not a randomized controlled trial. It was a small, single arm pilot study.

It studied patients with metastatic breast cancer and painful bone metastases who were already receiving opioids. Dronabinol was gradually increased to 10 mg orally twice daily and continued for eight weeks.

Fourteen patients were evaluable. The primary endpoint was the proportion reducing opioid consumption by at least 20%.

4 of 14 patients achieved at least a 20% opioid reduction.

Patients also reported statistically significant improvements in:

pain severity,
pain interference,
quality of life,
and insomnia.

There was one grade 3 treatment related adverse event, dizziness. Three participants discontinued treatment because of adverse events.

Interestingly, serum C terminal telopeptide, a marker of bone resorption, also declined, although this exploratory biological finding requires confirmation.

Takeaway: This is potentially interesting evidence for dronabinol as an opioid sparing adjunct specifically for metastatic breast cancer bone pain, but 14 evaluable participants and the absence of a placebo group mean the results should be considered preliminary.

7. Clarke et al., 2022

THC/CBD Nanoparticle Oro Buccal Spray

This was not a blinded RCT. It was a small, open label, single arm pilot study evaluating a novel water soluble nanoparticle formulation containing approximately equal amounts of THC and CBD.

The study had two stages. Five patients participated in the pharmacokinetic stage, followed by 25 advanced cancer patients with opioid refractory pain in the dose titration stage. Twenty two completed all stages.

One particularly interesting subgroup consisted of patients with breast or prostate cancer and bone metastases. Their mean pain reduction was approximately:

40% without adjustment,
33% after adjustment for rescue analgesic use.

However, because there was no placebo group, that improvement cannot confidently be attributed to the cannabinoid treatment.

Side effects were common. Drowsiness occurred frequently, and nausea or vomiting occurred in a substantial proportion of participants.

Takeaway: The formulation appears pharmacologically active and produced a potentially substantial pain signal, especially in bone metastasis patients, but the study is far too small and uncontrolled to prove analgesic efficacy.

Interestingly, this study and the 2026 dronabinol study both raise the possibility that cannabinoids might be particularly worth studying in cancer induced bone pain.

8. Braun et al., 2024

ASCO Guideline on Cannabis and Cannabinoids in Adults With Cancer

This is not a clinical trial but a systematic evidence based guideline from the American Society of Clinical Oncology. The panel examined 13 systematic reviews plus five additional primary studies, including four randomized trials. For most cancer related outcomes, the certainty of evidence was considered low or very low.

ASCO makes several important distinctions.

Cannabis or cannabinoids should not be used instead of established anticancer treatment, and clinicians should recommend against using them to augment cancer directed treatment outside a clinical trial.

There is meaningful evidence that cannabinoids may help refractory chemotherapy induced nausea and vomiting when added to otherwise guideline appropriate antiemetic therapy.

For other supportive care indications, including cancer pain, appetite, sleep, anxiety, and general quality of life, ASCO concluded that the evidence remained uncertain.

Takeaway: ASCO does not currently endorse cannabis or cannabinoids as a routine treatment for cancer pain or as an established opioid sparing therapy. Their clearest evidence supported role is refractory chemotherapy induced nausea and vomiting.

What these eight papers collectively show

The studies form a fairly coherent picture despite apparently conflicting results.

Cancer pain: There is a genuine analgesic signal. Johnson 2010 was positive, Portenoy 2012 had positive secondary outcomes, Hardy 2025 found a small pain benefit, while the large Lichtman 2018 phase III trial failed its primary endpoint.

Opioid reduction: Evidence is considerably weaker. The Johnson trial found no reduction in opioid use, while the small Zylla and Segar studies suggest that opioid sparing may occur in some patients. Those latter studies are much too small to establish this conclusively.

THC plus CBD versus THC alone: Johnson's study is particularly interesting because THC:CBD improved pain whereas THC alone did not significantly outperform placebo, suggesting the combination may have advantages in some settings.

Dose matters: More THC is not necessarily better. Portenoy found the strongest results at lower and intermediate nabiximols doses, while adverse effects increased at higher doses.

Bone metastasis pain may be a particularly interesting target: Both the Clarke 2022 nanoparticle study and the Segar 2026 dronabinol study produced encouraging signals in patients with bone metastases. That is interesting biologically and clinically, but it still needs a properly powered placebo controlled RCT.

Overall conclusion: The evidence supports saying that THC containing cannabinoid therapies may provide modest additional analgesia for some patients with difficult cancer pain, but they have not yet been shown consistently to provide large pain reductions or reliably replace opioids. Psychoactive effects, dizziness, sedation, nausea, and other dose related toxicity limit treatment for some patients. This is consistent with ASCO's cautious 2024 position.

If you are using these papers for a literature review, manuscript, presentation, or evidence table, I can next put all eight into a single comparison table with sample size, cancer type, cannabinoid/dose, comparator, pain outcome, opioid outcome, adverse events, statistical significance, and level of evidence.

Here are summaries of the requested clinical trials and guidelines evaluating cannabis and cannabinoids in oncology:

1. Nabiximols for Opioid-Treated Cancer Patients With Poorly-Controlled Chronic Pain (Portenoy et al., 2012)

• Design: A randomized, placebo-controlled, graded-dose trial of 360 patients with advanced cancer whose pain responded poorly to traditional opioid analgesics.

• Findings: Patients received placebo or nabiximols (an oromucosal THC/CBD spray) at low (1-4 sprays/day), medium (6-10 sprays/day), or high (11-16 sprays/day) doses. The study demonstrated that low and medium doses of nabiximols provided significantly better analgesia than the placebo. The low-dose group also experienced significantly reduced sleep disruption. However, the high-dose group compared unfavorably with the placebo due to a higher rate of dose-related adverse events without improved pain relief.

2. THC:CBD Extract and THC Extract in Patients With Intractable Cancer-Related Pain (Johnson et al., 2010)

• Design: A multicenter, double-blind, randomized, placebo-controlled trial involving 177 advanced cancer patients with pain unsuccessfully managed by opioids.

• Findings: The study compared a THC:CBD extract (nabiximols), a THC-only extract, and a placebo. Patients treated with the THC:CBD extract experienced a statistically significant reduction in pain scores and required significantly fewer doses of breakthrough pain medications compared to placebo. The THC-only extract did not show a statistically significant improvement in pain scores compared to the placebo.

3. Study of Nabiximols Oromucosal Spray as an Adjunctive Therapy (Lichtman et al., 2018)

• Design: A Phase III, double-blind, randomized, placebo-controlled study investigating nabiximols as an add-on therapy for advanced cancer patients with chronic, uncontrolled pain.

• Findings: The trial did not meet its primary endpoint, as the improvement in daily pain scores for patients receiving nabiximols was nonsignificant compared to the placebo group. Despite this, the nabiximols group did show improvements in several secondary endpoints, including reduced sleep disruption and better quality-of-life scores.

4. Medicinal Cannabis for Symptom Control in Advanced Cancer (Hardy et al., 2025)

• Design: A multicenter, double-blind, randomized, placebo-controlled trial assessing a 1:1 THC:CBD combination oral oil versus placebo in 144 patients with advanced cancer to measure its impact on total symptom burden.

• Findings: Both the cannabis and placebo arms showed improvements in the total symptom distress score over time, but there was no significant difference between the two groups. While the medicinal cannabis arm showed a small but statistically significant improvement in specific pain scores, this came at the expense of higher psychomimetic toxicity (side effects). Interestingly, improvements in general well-being were greater in the placebo group.

5. A Randomized Trial of Medical Cannabis in Patients With Stage IV Cancers (Zylla et al., 2021)

• Design: A pilot randomized controlled trial of 30 stage IV cancer patients on opioids to assess the feasibility of using state-program medical cannabis. Patients were randomized to receive early cannabis (immediate access) or delayed cannabis (standard care for 3 months first).

• Findings: The study proved that conducting clinical trials using state medical cannabis programs is feasible. A higher proportion of patients in the early cannabis group achieved better pain control and a reduction in their opioid use. No serious safety issues were reported, and patients expressed high overall satisfaction with the addition of medical cannabis to their standard oncology care.

6. Evaluation of Dronabinol to Decrease Opioid Use for Cancer-Induced Bone Pain (Segar et al., 2026)

• Design: A single-arm clinical pilot study enrolling 14 breast cancer patients with bone metastases to determine if 10 mg of twice-daily dronabinol (a synthetic THC agonist) could decrease their opioid reliance for cancer-induced bone pain (CIBP).

• Findings: The study met its primary endpoint, with 4 of the 14 evaluable patients successfully decreasing their opioid use by 20% or more. Patients reported significant improvements in pain severity, pain interference, insomnia, and quality of life. Additionally, biomarker analysis showed a significant decrease in serum C-terminal telopeptide (a marker of bone degradation).

7. Pilot Clinical and Pharmacokinetic Study of THC/CBD Nanoparticle Oro-Buccal Spray (Clarke et al., 2022)

• Design: A non-blinded, single-arm, two-stage pilot study evaluating a novel water-soluble nanoparticle THC/CBD oro-buccal spray in patients with advanced incurable cancer and intractable pain.

• Findings: The nanoparticle spray provided acceptable bioavailability (with higher systemic exposure for THC than CBD) and was generally safe and tolerable, with mild-to-moderate drowsiness and nausea being the most common adverse events. It provided preliminary evidence of analgesic efficacy—particularly in a subgroup of patients with breast and prostate cancer bone metastases, who experienced up to a 40% improvement in pain scores from baseline.

8. Cannabis and Cannabinoids in Adults With Cancer: ASCO Guideline (Braun et al., 2024)

• Design: Clinical practice guidelines issued by the American Society of Clinical Oncology (ASCO) after a rigorous review of 366 publications (including clinical trials and systematic reviews) to guide oncology clinicians and patients.

• Findings: ASCO explicitly recommends against using cannabis or cannabinoids as a direct cancer treatment outside the context of a clinical trial. For supportive care, the strongest evidence supports using cannabinoids to manage refractory, chemotherapy-induced nausea and vomiting when standard-of-care antiemetics fail. The guidelines note there is currently insufficient data to confirm safety and efficacy for other areas of supportive care (like pain and anxiety) and call for more high-quality research, while urging clinicians to maintain open, nonjudgmental conversations with their patients about cannabis use.