Peptides and Cancer: What Memorial Sloan Kettering Says
Memorial Sloan Kettering published a patient-facing article on 3 September 2026 about what is known and unknown regarding peptides. It quotes Larry Norton, a breast medical oncologist who is Senior Vice President in the Office of the President at MSK and Medical Director of the Evelyn H. Lauder Breast Center.
His opening position is blunt. The article quotes him saying that we do not know what these products actually do in the body, because there have not been appropriate scientific experiments.
We supply peptides to laboratories, so it would be easy to skip this. It is more useful to report what a major cancer centre actually said, including the parts that apply to how any peptide reaches anyone.
A framing note. Peptra Labs supplies characterised reference material to laboratories on a research use only basis. Nothing below is guidance about human use, and the article we are reporting is addressed to patients rather than to researchers.
The distinction MSK draws between peptides
The piece separates two categories that get discussed as though they were one.
On one side are approved peptide medicines, and the article lists them: insulin, growth hormones, GLP-1 agonists, and hormone-blocking medications used in prostate and breast cancer. Norton is quoted saying these are prescribed by doctors and have passed scrutiny proving they are safe and effective for people with certain medical conditions.
On the other side are what the article calls wellness peptides, promoted by health and fitness influencers, widely available online, and marketed for benefits from boosting immunity to speeding muscle recovery. Norton says this is not the same situation, and that the newer products are being promoted without rigorous evidence.
The article also does something small and useful: it defines the terms. Peptides are short chains, generally up to 50 amino acids. Proteins are much longer, typically several hundred. Both act as chemical signals that help regulate cell function.
What the article says peptides would need
Norton sets out the standard he is applying, which is worth quoting because it is the same standard we apply when we write about a compound.
He says a peptide would need rigorous laboratory testing, then controlled clinical trials with adequate follow-up time to look for longer-term side effects, and that this foundational research is limited for many of the products currently marketed.
He adds that trials are a well-developed process for determining the safety and efficacy of chemicals put into the body, and that until these peptides are evaluated that way there are too many questions about both possible benefits and dangers.
That is not an argument that these molecules do nothing. It is an argument that nobody has done the work to find out.
The part about how peptides are handled, not what they do
The section on harm is the one that lands closest to a supplier, and we are not going to paraphrase around it.
The article reports concerns about the quality and safety of these products, and specifically that there is a lot that is not known about how these compounds are manufactured, stored and shipped. Depending on how they are transported, the article says, they could lose their effectiveness in transit, and they could contain harmful impurities.
Every one of those is a real, measurable property of a physical product rather than a claim about biology.
We covered a study of how quickly peptides aggregate under stress earlier this month, from a group at Merck, which found that ordinary agitation degraded a peptide and that a common stabilising additive made it worse. That is the mechanism behind the transit concern, measured.
The distinction that matters here is documentation. A characterised batch with a certificate of analysis, identity confirmation and traceable handling either exists for a given vial or it does not. Our own writing on the risk profile of research peptides and on where the research use boundary sits covers what that paperwork is for.
Why cancer patients are singled out
Asked whether there are special considerations for people with cancer, Norton is quoted saying that we do not really know, because what many of these compounds do in the body and how they affect cells remains an open question.
The specific worry he raises is worth understanding. Some peptides are marketed for reducing inflammation and promoting wound healing, and the article notes that could possibly affect the growth of cancer cells.
That is a hypothesis rather than a finding, and the article presents it as one. The logic is straightforward: a compound promoted for stimulating tissue repair is, by description, a compound that acts on cell proliferation, and proliferation is what oncology spends its time trying to restrain.
Norton also raises a non-biological harm: someone may take a peptide to relieve symptoms of what turns out to be a serious condition, delaying the diagnosis.
What the article says about the compounding vote
The piece covers the FDA advisory committee that recommended adding several of these peptides to the list of substances compounding pharmacies may use.
It presents both sides. Those in favour argued compounding would be a safer route than ordering from unregulated internet sources. Opponents argued that permitting it would give these products the appearance of legitimacy.
The article notes the FDA has not issued a final ruling, and Norton adds the distinction that matters most: allowing compounding is not the same thing as an approval based on rigorous clinical trials.
We covered the 503A bulks list vote when the committee met, and made the same point about advisory votes not being approvals.
The bottom line the article reaches on peptides
Norton’s closing argument is a pharmacological one rather than a regulatory one.
He is quoted saying these are potentially potent substances with possible short-term and long-term harms, and that any peptide with a positive effect can also have a negative effect. The example he gives is insulin: correct in the right person at the right amount, dangerous in the wrong one.
That is the most defensible sentence in the article, and it applies as much to compounds we supply as to anything sold as wellness. A molecule potent enough to be worth studying is potent enough to do harm, which is the whole reason the research and the documentation exist.
What it means for the catalogue
Our position is narrower than the one the article criticises, and the distinction only holds if we keep saying what it is.
BPC-157 and MOTS-c are in the group of compounds MSK is describing when it talks about products promoted for healing and recovery. The published evidence for both is preclinical, we have said so in every article we have written about them, and neither has the trial record Norton is asking for.
What we can offer is the other half of his complaint: material that is characterised, documented and supplied for laboratory work, where manufacture, storage and shipping are recorded rather than unknown.
That answers the quality question. It does not answer the evidence question, and pretending otherwise would be exactly the behaviour the article is objecting to.
We covered a case report of a product bought online last week that illustrates what happens when both halves are missing at once.
References
- Grisham J. Reality Check: What You Should Know About Peptides and Cancer. Memorial Sloan Kettering Cancer Center, 3 September 2026
- Hamada N, Wuelfing WP, Su Y, Ling J. Impact of surfactants on the stability of therapeutic peptides under interfacial stress. Journal of Pharmaceutical Sciences, 2 September 2026, 104493
- Branine N. Online-Sourced Retatrutide Complicating Impending Diabetic Ketoacidosis in a Patient With Type 1 Diabetes and Concurrent Shigella Gastroenteritis. Cureus, 26 August 2026, 18(8):e115260
The products referenced on this site are supplied for laboratory research use only. They are not medicines and are not intended for human or veterinary use. This article summarises published research for informational purposes and is not medical advice. Statements about third-party studies belong to their authors.
