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Will Odors Help Us Find Cancer Early?

by Dr. Len January 29, 2010

Bow-wow or squeak-squeak?


When it comes to “sniffing” out cancer, it looks like you may have a choice.


New medical research suggests that dogs and mice may just give us the clue to finding cancer early.


An article in the current issue of the online medical journal PLoS One describes the research of a group of scientists in Philadelphia that trained mice to smell the urine of other mice to determine which mice had lung cancer.


And the experiment was a success: the “smeller” mice were able to tell which of the other mice had lung cancer with a fairly high degree of success.  Unfortunately, their success was limited to later stage cancers and the very early stage lung cancers were missed.


In the next step of the experiment, the researchers did laboratory studies to look at what are called “volatile compounds” in the urine by analyzing the urine samples on a specialized machine that can identify small quantities of chemicals.


(Volatile compounds are substances that can exist in a liquid and gas phase.  So, while they may be contained in urine, once passed out of the body they move into a “gaseous” phase which accounts for their smell.  Humans can smell these compounds if the concentration is sufficiently high.  However, the amount of these compounds in the body in humans or mice with cancer is probably microscopic, and therefore you need a more sensitive sniffer—like a trained dog or mouse, whose sense of smell is much more delicate than a human’s—to pick up the characteristic odors that may be associated with a cancer.)


The investigators then looked at the results of their chemical analysis, and identified a number of compounds that could have explained the results of the mouse experiment.  To their surprise, many of these compounds were found in lower quantities in the urine of mice with lung cancer compared to the mice without lung cancer.


They go on to point out that smell is based on a combination of a number of different compounds, and that lower amounts of a compound may change the smell of the urine just the same as a larger amount of a compound.


Further analysis showed that the researchers could actually plot the differences in the chemical structures of the urine from the mice with and without lung cancer, once again with a reasonably high degree of accuracy.


Their conclusion?


“The data in this paper are consistent with the hypothesis that diagnostically useful volatile compounds are produced in patients with lung cancer and secreted into the urine, thus providing support for this diagnostic approach in the context of lung cancer.”


They also noted that using urine samples for this process is probably a better bet than using breath samples, which has been the approach utilized by some other investigators.  And they are moving forward with studies in human patients to determine if these interesting results are in fact applicable in the real world and will help us detect cancer at an earlier stage than currently possible.


This isn’t the first time I have written or commented on this type of research.


I can recall a paper that appeared a number of years ago in a British medical journal that reported—as best I recall—using dogs to sniff urine samples of cancer patients to detect bladder cancer.  That experiment was a modest success, and it did get a lot of media attention.


More recently, in another such report dog trainers were able to get neighborhood dogs to sniff breath samples from cancer patients and identify them accurately when compared to breath samples from people without cancer.


When I heard about article #1, I laughed and went on with other business.  When I heard about article #2, I actually thought maybe this thing was real after all.


At the time, my comments were generally along the lines of the currently reported research.  Namely, is it so far out to believe that a cancer could produce a compound in such small amounts that we humans can’t smell it or identify it, but dogs—with their great sense of smell--may in fact be able to discriminate the minute quantities of volatile compounds present in urine, breath, or other bodily fluids of cancer patients? (If you don’t think dogs have a great sense of smell, you ought to see my “untrained” golden retriever find his tennis ball on a two acre piece of land late at night.)


When I wrote my blog on the topic, I thought I was done with the subject only to have it become one of the most enduring posts on this site.  After four years, people are still posting comments on that blog.  Obviously, there is a lot of interest in this subject.


So before you start laughing about mice smelling urine samples or dogs smelling breath samples to detect cancer, I would suggest you take a step back and give the idea some serious thought and consideration.


I learned a long time ago never to say never.  And when it comes to detecting cancer early by a smell test, well….stranger things have happened.


Gotta go, now.  Kobi (my dog) wants me to throw his tennis ball…


2/1/2010 6:44:25 PM #

Sheila Engh

My husband has prostate cancer and it is now in his bones.  About 3 months ago I began to notice a peculiar and not every pleasant smell emanating from him, especially at night.

My brother died of pancreatic cancer last spring and I remember when visiting him in the weeks before he died that there was a particular, distinctive scent in his room.  My sister-in-law is a nurse and she said this is very common in cancer patients.

I remember reading years ago that doctors were once discouraged from smoking in the past because it affected their sense of smell - and that many diseases have distinctive smells.

Of course, I have also been hearing about dogs detecting breast cancer in their owners.

Fascinating subject.

Sheila Engh

2/2/2010 9:07:57 AM #

Faye Lane

I remember "smelling" cancer when I first began my LPN nursing course.  This was a patient that was suffering with advanced cancer and I smelled her before I entered her room. This was in 1975 and I still remember it to this day.

I once read that dogs could sniff out skin cancer. I always tease with my family that when I come home I get a "schnauzer scan" if anyone hugged me or if I cheated on my dogs by playing with other dogs.

Faye Lane

2/2/2010 5:53:48 PM #


This is a very helpful article, but wish there could be a better description of the ACTUAL SMELL, to help us know if what we may be smelling on people (or even ourselves) IS "the cancer smell" or other physiological odors. For example, a "ketogenic diet" can produce a body odor, but it is not clear if the "cancer odor" is related or similar to that "Ketone smell." Some medical conditions can produce a strong salty, fatty perspiration odor that resembles rancid chicken soup! Have smelled this on a woman at church and on a woman selling flowers at a street vendor site. Please describe more details about the "smell of cancer." Please post additional info if and when available. MANY thanks.  PS On a related thread on this site, at least one other person cited a "chicken soup" smell, but the times I've smelled that smell, the person did not have (any known) cancer. One of them had polycystic kidney disease. Thanks again.


2/8/2010 11:35:57 PM #


This article is extremely helpful, and the subject is simply fascinating. I've heard from cancer survivors before that there is a distinctive smell that is usually associated with the cancer. Typically though, they've only been able to pick up on it in advanced stages. It also says that humans don't have smell heightened enough to detect it themselves. I hope this will develop sometime soon through science and technology. As you say, never say never.


2/13/2010 8:31:54 PM #

Nancy Mahon

On January 25 my sister passed away due to lung cancer. In 1991 my father died from prostate cancer and in 1995 my mother died from colon cancer. In 1997 my brother died from lung cancer and in 2007, my niece died from colon cancer. I hear many people say they can smell people in their families when they have cancer, however, I never remember any of my family members having an odor. I do believe dogs are able to be trained to identify people with cancer because they are trained to identify many other odors. Hopefully identification by odor would be a way of saving lives sooner or give people more time.

Nancy Mahon

2/15/2010 12:55:26 PM #

Janet Fritz

Very interesting.  I just finished my 6th and last cycle  of chemo for TNBC.  About 4 to 7 days after receiving treatment, my husband smells a metalic smell, but both of my grown sons smell a very offense rotten smell...My oncologist says she has not heard of this before.

Janet Fritz

9/10/2011 5:08:31 PM #

Eleonor Summers

It was after seeing a report about the ability of dogs to spot cancer by its odour that I remembered the distinct chemical odour I had notice in my urine when I had a lung cancer. It was intense enough to be noticed. After the lung was removed the odour disappeared. After hearing about the research I was really interested to share my experience but could not find out what entity was studying the subject. Now it seems that I have found out.

Eleonor Summers

10/1/2011 9:50:35 PM #

gwin jackson

can cancer smell like onions after a shower  

gwin jackson

11/4/2011 11:38:46 PM #


Each time I arrive home my dog wants to smell my breath. He doesn't seem to want to smell anyone else's breath, but he is obsessed with getting right in my face. If I blow in his face he will sniff, then leave me alone. My neighbor's dog wants to smell my face as well. Same scenario. Didn't think much about it until now.  Does this mean I should have some type of testing done? If so, then what?


2/11/2012 8:46:37 PM #


My experience is so exactly the same as Ms Eleonor Summers one that the only thing I can add is that the odour is definitely chemical. I also had the lung removed and am a survivor after 5 years of the operation, I refused having chemotherapy after the operation because making some researches listening to specialist nurses I heard that some people who had the treatment survived, some who abondoned the treatment survived, some who took it died, some who did not take like me survived so I came to the conclusion that chemotherapy does not make any difference to the survival and just causes more suffering. Recently the Time magazine published an article by a doctor discussing exactly this point.
Now something that can really make a difference to the matter is the factor that can cause cancer. Everybody knows that radiation can cause cancer we learned that from Japan after the atomic bomb, from Chernobyl after the explosion of the nuclear plant, from Iraq after the bombardment with uranium in 2001. Now why people in other parts of the globe far from any source of radiarion get cancer, specialy lung cancer ?  It called my attention a piece of news soon after I had the problem telling that there had happened an epidemic of lung cancer in the States and the unusual fact was that some 1300 women that had never smoked, like me were affected. In my case it was even more unusual because there has never been a cancer in my family, in my ancestor's line.
More recently a documentary on TV about DUST showed that dust can travel around the world carrying even  bacterias let alone radiation. Now let's think about the tempests of sand in Iraq and what they could have spread around the world. Carcasses of polar bears in the Artic showed signs of the normal polution in great cities. In Wales there are still  pastures that cannot be used because contaminated with radiation from Chernobyl.
Has anybody heard that those institutions that make researches to find drugs capable of killing cancer have ever measured the level of radiation in people with cancer ?


About Dr. Len

Dr. Len

J. Leonard Lichtenfeld, MD, MACP - Dr. Lichtenfeld is Deputy Chief Medical Officer for the national office of the American Cancer Society.