In brief
- A study of 176,149 cancer surgery patients found that perioperative ketamine does not reduce mortality at 3 or 5 years.
- The hypothesis was based on laboratory studies suggesting a potential antitumor effect of the substance.
- A minor exploratory signal appeared: slightly fewer indications of cancer progression after 6 months in those who received ketamine.
Researchers in Israel have published the largest study to date on whether administering ketamine during cancer surgery changes long-term prognosis. The answer, based on data from tens of thousands of patients, is no: those who received ketamine on the day of their operation did not live longer than those who did not.
Where the hope came from
Ketamine has been used for decades as an anesthetic and as an analgesic adjunct in the operating room, long before anyone considered it an antidepressant. In recent years, several laboratory studies had suggested that, in addition to its known effects, it might interfere with tumor cell growth or modulate the immune response in a way that hinders cancer spread after surgery. This hypothesis fueled the idea that a drug already inexpensive and available in any hospital could, incidentally, improve cancer survival.
What the data shows
The team, led by Tomer Talmy and published in the British Journal of Anaesthesia, reviewed records from the TriNetX network in the United States: adults who underwent major solid tumor surgery between 2014 and 2023. After matching for age, comorbidities, tumor type, and surgical procedure, 29,547 pairs of patients remained, half having received ketamine on the day of the operation and half having not. Mortality at 3 years was 16.7% in the ketamine group versus 16.0% in the non-ketamine group—a difference that does not reach statistical significance once corrected for multiple comparisons. At 5 years, there was also no difference. The result held when the analysis was repeated by cancer type and by different combinations of drugs used in anesthesia.
A minor, exploratory finding did appear: among those who received ketamine, there were slightly fewer indirect indications of disease progression—such as the initiation of chemotherapy, radiotherapy, or palliative care—after the first six months. The authors themselves describe this as a weak signal, not as proof that ketamine stops cancer.
What it implies
This is an observational study, not a randomized trial: although matching for characteristics reduces bias, it does not eliminate it entirely, and we do not know why some patients were given ketamine and others were not. Even so, with this sample size, the message is clear and honest: there is no reason to think that adding ketamine in the operating room prolongs life after cancer surgery, no matter how much the laboratory research promised. The authors themselves frame it alongside other large recent studies that have also failed to find that the choice of anesthetic changes cancer survival. Ketamine remains useful for what we already knew it did—analgesia, opioid reduction, and in other contexts, rapid relief of depressive symptoms, with the nuances we have already seen regarding how long that effect lasts—without the need to attribute extra properties to it that the data, for the moment, does not support.
Source
- Talmy T, et al. Ketamine administration and postoperative mortality after major cancer surgery: a propensity-matched population-based study. British Journal of Anaesthesia, August 2026.
Educational content written from a harm reduction perspective and with respect for individual freedom. It is not a substitute for advice from a healthcare professional and is not intended to encourage or condemn any drug use.
