Cannabis formulations reduced tamoxifen effectiveness against breast cancer cells in lab
In breast cancer cell lines, combining cannabinoids with tamoxifen diminished the drug's anti-proliferative activity, especially with recreational-type cannabis ratios.
Quick Facts
What This Study Found
Simultaneous treatment of MCF-7 breast cancer cells with various cannabinoid formulations and tamoxifen resulted in diminished anti-proliferative activity of tamoxifen, with the effect more pronounced with recreational cannabis formulations (higher THC).
Key Numbers
An intra-entourage effect was found in MCF-7 cells with recreational but not medicinal cannabis formulations. No inter-entourage effects in either cell line. Tamoxifen's anti-proliferative activity was diminished when combined with cannabinoids, especially recreational formulations.
How They Did This
In vitro study using two breast cancer cell lines (MCF-7 and MDA-MB-231). Tested purified phytocannabinoid combinations mimicking medicinal and recreational cannabis strains, a Cannabis sativa extract, and combinations with tamoxifen.
Why This Research Matters
Many cancer patients use cannabis for symptom management during treatment. If cannabinoids interfere with tamoxifen effectiveness, this could have real clinical consequences for breast cancer outcomes.
The Bigger Picture
This is one of the first studies to directly test whether cannabis formulations interfere with a commonly prescribed breast cancer drug. The results raise a cautionary flag for the growing number of cancer patients using cannabis alongside conventional treatment.
What This Study Doesn't Tell Us
This is a cell-line study, and in vitro results may not reflect what happens in the human body. Only two cell lines were tested. The cannabinoid concentrations used may not match those achieved in human tissue.
Questions This Raises
- ?Does this tamoxifen interference occur at cannabinoid concentrations achievable in human breast tissue?
- ?Would the same interference apply to other hormonal breast cancer treatments?
- ?Should cancer patients be advised about timing of cannabis use relative to tamoxifen doses?
Trust & Context
- Key Stat:
- Recreational cannabis formulations most reduced tamoxifen effectiveness
- Evidence Grade:
- Preliminary: in vitro cell-line study only, no human or animal data.
- Study Age:
- Published in 2022.
- Original Title:
- Cannabis with breast cancer treatment: propitious or pernicious?
- Published In:
- 3 Biotech, 12(2), 54 (2022)
- Database ID:
- RTHC-04202
Evidence Hierarchy
Watches what happens naturally without intervening.
What do these levels mean? →Frequently Asked Questions
How did cannabis affect tamoxifen?
When cannabinoid formulations were applied simultaneously with tamoxifen to breast cancer cells, tamoxifen was less effective at stopping cancer cell growth. The interference was greater with high-THC recreational formulations.
Why might THC interfere with tamoxifen specifically?
The researchers found THC may partially exert its effects through the estrogen receptor, which is the same receptor tamoxifen targets in ER-positive breast cancer cells (MCF-7).
Should breast cancer patients stop using cannabis?
This study alone cannot answer that question. It provides a laboratory signal that warrants further investigation, but human studies are needed to determine whether this interaction occurs in actual patients.
Read More on RethinkTHC
- CBD-oil-quality-guide
- anxiety-medication-after-quitting-weed
- cannabis-chemotherapy-nausea
- cannabis-chronic-pain-research
- cannabis-epilepsy-CBD-Epidiolex
- cbd-anxiety-research-evidence
- cbd-for-weed-withdrawal
- cbd-vs-thc-difference
- medical-benefits-of-cannabis
- quitting-weed-before-surgery
- quitting-weed-medication-interactions
- quitting-weed-pregnancy
- quitting-weed-pregnant
- seniors-older-adults-cannabis-risks-medications
- weed-breastfeeding-THC-breast-milk
Cite This Study
https://rethinkthc.com/research/RTHC-04202APA
Schoeman, Recardia; de la Harpe, Amy; Beukes, Natasha; Frost, Carminita L. (2022). Cannabis with breast cancer treatment: propitious or pernicious?. 3 Biotech, 12(2), 54. https://doi.org/10.1007/s13205-021-03102-1
MLA
Schoeman, Recardia, et al. "Cannabis with breast cancer treatment: propitious or pernicious?." 3 Biotech, 2022. https://doi.org/10.1007/s13205-021-03102-1
RethinkTHC
RethinkTHC Research Database. "Cannabis with breast cancer treatment: propitious or pernici..." RTHC-04202. Retrieved from https://rethinkthc.com/research/schoeman-2022-cannabis-with-breast-cancer
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.