Painkiller Morphine May Worsen the Spread of Cancer

Evidence from human and animal studies has been accumulating for several years to suggest that the painkiller morphine, ubiquitous in the treatment of pain related to cancer surgery and also to end-stage cancer, may actually worsen the spread of cancer itself. 

Some early evidence that this may be the case came out of a study in Ireland where researchers examined the records of women who had a mastectomy for breast cancer using one of two anesthetic techniques.  One group was given regional paravertebral anesthesia along with general anesthesia, while the other was given morphine along with general anesthesia.  Regional paravertebral anesthesia involves using a needle with a numbing medication similar to novocaine to numb up the nerves that supply feeling to the breast and chest. 

Although the study was retrospective, observational, and not a randomized controlled trial (which would have allocated patients into one of two treatment arms randomly, thereby reducing the chance that there would be a difference between the groups at the start of the trial, known or unknown), the authors reported that they found no pre-surgical difference between the groups, including no difference in tumor presentation. 

Ninety-four percent of patients treated with regional anesthesia during surgery survived to 36 months, whereas only 77% of patients treated with morphine analagesia during surgery survived to 36 months.  That's a risk difference of 17%.  Although it is a stretch to make this conclusion since the trial was not a prospective randomized controlled trial, the results nonetheless suggest that for every 6 people treated with regional analgesia during mastectomy surgery rather than morphine, one additional patient would survive to 36 months (number needed to treat). 

This finding was in contrast to that of a study by Page et al done more than a decade earlier that suggested that morphine prevented the spread of cancer in rats.  This was interpreted to mean that pain itself promoted the spread of cancer.

Now researchers from Chicago claim to have discovered both the cause of morphine-induced tumor spread and also a treatment for it: morphine appears to increase the formation of blood vessels and affects the permeability of those blood vessels near tumor cells, while an opiate blocker called methylnaltrexone appears to prevent those effects.  These findings were reported at the American Association for Cancer Research in Boston this fall. 

While less studied, morphine-related opiates such as fentanyl and sufentanyl also appear to suppress the activity of the immune system, possibly predisposing to metastasis of cancer, according to Beilin et al.

Researchers out of the Cleveland Clinic are spearheading a randomized multicenter trial to test the theory that regional anesthesia improves outcomes of breast cancer patients requiring surgery compared to volatile anesthesia with post-operative opioid pain control. 

For patients due to undergo surgery for cancer, it is probably worthwhile for them to have a frank discussion with their surgeon and anesthesiologist about whether regional anesthesia is feasable and safe in their case, and whether opiate analgesia can be minimized. 

Please read our legal disclaimer.

Write a comment

Name:
Email:*
Subject:
Comment:*

I would like to receive news and updates from MedPie.com Yes No

Help prevent spam - enter security code above:
 

GeriPal
Posts: 1

Changing Practice over a Single Study???
Reply #1 on : Thu December 31, 2009, 22:19:48

---

What are we supposed to have a frank discussion about - that a small retrospective review from a single institution shows benefit of regional anesthesia over general anesthesia? Do we let a retrospective review of a single institutions data influence our medical decisions? Should we do this for every small retrospective review?

You also make a baseless claim that morphine is the culprit in for the harms seen in this retrospective review ("6 people treated with regional analgesia during mastectomy surgery rather than morphine"). Morphine, nor any other opioid, was <a href="http://www.geripal.org/2009/11/does-morphine-stimulate-cancer-growth.html">evaluated during this study</a>. Rather these studies out of Ireland were comparisons between anesthetic techniques. The study’s own authors acknowledge that “<a href="http://www.geripal.org/2009/11/does-morphine-stimulate-cancer-growth.html">relevant information such as the amount of morphine given</a>” was not available in the records.

If you happen to believe a single center experience (which I suggest you don't), then opioids should not be singled out as the causative agent of the apparent benefit of regional anesthesia. Benefit of regional anesthesia may be due to a myriad of other effects of regional anesthesia including the lack of volatile anesthetic agents or an improved stress response.

Sponsored Links