Tuesday, November 24, 2009

Debunked: Morphine Causes Cancer.

Thanks to the exceptional folks at GeriPal for debunking the latest meme that morphine stimulates cancer growth:

Over the last week Reuters, ABC news, MSNBC, BBC News, and more than 75 other outlets reported on how two "two new studies add to growing evidence that morphine and other opiate-based painkillers may promote the growth and spread of cancer cells." What was most shocking were the headlines used to promote the stories:
All these articles (most stemming from an initial Reuters report) discussed the recent presentation by a group from the University of Chicago on the mu-opioid antagonist methylnaltrexone (otherwise known as Relistor or “that new opioid induced constipation medication”). This work, as presented at a meeting in Boston, revealed that use methylnaltrexone prevented tumor-cell proliferation and migration in cultured lung cancer cells. The group also presented work revealing that genetically altered rodents lacking the mu-opiate receptor failed to develop tumors after being injected with Lewis lung carcinoma cells, something that did occur in normal mice. This is an interesting line of research and one that gave the makers of Relistor a shot in the arm (as one website put it – “a possible new indication for Progenix's Relistor could revive its fortunes”.) I find the pathophysiology behind this incredibly interesting from an academic standpoint, however it is neither something that would warrant such dramatic headlines nor spur thoughts that it is anything but research in its infancy.

What about the claim that there is “mounting clinical evidence” that morphine may accelerate cancer growth? The only real clinical studies in this regard come from a single institution in Ireland and are basically a couple retrospective cohort studies comparing regional versus
general anesthesia. The first one of these articles (Anesthesiology. 2006; 105(4):660-4) showed a beneficial relation between paravertebral block and cancer recurrence in women undergoing breast cancer surgery. The study’s authors acknowledge that “selection bias and the effects of unmeasuredconfounding variables” could not be excluded, as well as the fact that “relevant information such as the amount of morphine given” was not available in the records. The second study was nearly identical except it was in patients undergoing radical prostate surgery (Anesthesiology. 2008;109(2):180-7)

The most important take home point is that none of these studies actually looked at opioid use (although many of the news articles vaguely cite these studies as evidence for morphine’s deleterious effects on cancer). Even if you want to argue that these were high quality studies and there is a clear benefit of regional anesthesia, opioids should not be singled out as the cause. 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. These studies are noteworthy, but I agree with the authors of these articles that they should “be viewed as generating a hypothesis and an estimated
effect size for future large randomized controlled trials”.

So if you have a patient on morphine asking you whether “morphine will make my cancer worse”, the answer is no. There is no clinical evidence that morphine, or any other opioids, cause real harm through stimulating cancer growth. There is though significant high quality evidence for their benefit in relieving
pain and suffering.

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Blogger Robert said...

Hi, I have incurable prostate cancer in the last stages. I have been recently started on carboplatin chemotherapy and was researching the drug when I came upon articles telling that morphine actually caused tumors to grow. I am on very high doses of morphine to control the massive pain I would have in several joints without it. I have tumors in my spine, left leg, both arms and in the side of my skull. My last PSA was 950...guess it won't be long now. But as you can figure I was very depressed when I found the artices I mentioned. So I looked farther and found this site. As you can well figure I was very happy to find this very knowledgeable counterpoint to the cancer growth theory. Thank you for being here for me and probably so many others who may not take the time to write. I also would like help in finding God if that is possible. I know that may sound funny reading it here but for years, and after being raised in the Baptist religion and with a very strong working knowledge of the Bible and being saved at the age of 16, I have lost any belief in the Almighty, God, Jesus, Heaven and the whole 9 yards. And I admit this with guilt feelings but I don't know why. Now in my condition I really want to believe in my Baptist faith and align myself with God and Heaven. So how do I get it back? I've prayed very much but with a feeling that I'm pouring water into a rusty bucket with no bottom. Is God real? I've asked for him to give me a sign which I know is selfish and against the teachings. Or do I have nothing to worry about...going to Hell and all that because it doesn't really exist? Even with this death sentence on me I would be a happy man to be resolved in this matter. Can anyone help? btw I am 56 years old, a bit too young for this mess. Thanks.

September 18, 2010 at 10:50 AM  
Blogger Ann Neumann said...


I'm sorry to hear about the state of your prostate cancer. I hope that you and your doctors are able to find a pain management system that works and will optimize the quality of your days.

On "finding God," I'm afraid that we either believe or we don't. According to my personal belief, there's no shame in doubting, in abiding by a faith, or in just saying we don't know. Sometimes strength of faith is a comfort to those facing terminal illnesses yet my hospice experience shows me that most of those who seek peace with God in the face of an untimely illness have grave doubts.

It seems that your job right now is to let go of those guilts and pressures associated with both faith and illness. Live. Love. Enjoy your days. What we don't know and can't control is beyond all of us. Be good to yourself. I expect that that's what any God would demand of you.

September 20, 2010 at 9:07 AM  
Blogger Weldon Williford said...

I see nothing but your OPINION in this article to refute actual STUDIES on the subject. Give me some facts and I'll listen, otherwise I agree morphine causes inflammation. Unless you have your head in the sand and don't believe inflammation causes cancer then you have to correlate the two.

April 23, 2011 at 1:29 PM  

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