This article is from WeChat public account: Pineapple factor (ID: checkpoint_1) , author: pineapple, Photo by Overture Creations on Unsplash
One
Cancer should be detected early, treated early, and cured early. The survival rate of early tumors is usually above 90%, but if it is advanced, the effect is much worse.
However, early detection of cancer is not easy, as most cancers have no symptoms at an early stage. Pancreatic cancer, bile duct cancer and other overall mortality rates are high, the main reason is the lack of good screening methods, found that basically is advanced, lost the opportunity for radical surgery.
Other tumors, such as lung cancer, bowel cancer, and cervical cancer, can be screened, but the technology is not perfect. For example, for lung cancer, although there are screening methods such as low-dose spiral CT, the accuracy needs to be improved and there are false positives. Second, there is some radiation itself, and ordinary people cannot use it frequently. Third, there are equipment and charges. It is difficult to popularize backward areas.
Therefore, finding non-invasive, safe, and convenient new screening methods has always been the direction of scientists.
Some people follow the rules and try to optimize image detection, genetic testing and other methods, but others also go away, open their brains, and yell, “Let the dog come!”
They believe that dogs can smell a special smell from cancer patients.
This is not science fiction. In fact, decades ago, it has been suggested that tumor cells can release unique chemical molecules due to their different growth status from normal cells . There may be “cancer smell” in the patient’s blood, urine, or even breath, which can be captured by animals with a keen sense of smell.
Speaking of animals with a sharp sense of smell, we are most familiar with them, of course, dogs.
The smell of dogs is N million times that of humans, and they can sense many chemical signals that human noses can’t capture at all. Dogs are not the same as dogs. Some breeds belong to dog fighters, and they are particularly good at smelling things, including beagles and German shepherds. They are called olfactory hounds.
These dogs have a sharp sense of smell because there are many olfactory receptors in their nasal cavity . Beagles have about 230 million olfactory receptors. In comparison, humans have an average of 5 million olfactory receptors, which is weak.
Second
Opened decades agoThere have been reports that some people’s pet dogs can smell cancer.
It started with superficial skin cancer.
In 1989, exactly 30 years ago, the famous “The Lancet” magazine reported a magical case: a woman in the United States had a mole on her body without any symptoms, but her dog (belongs to the olfactory hound) I especially like to smell her mole, and I even want to bite it off many times. Feeling weird, she ran to the hospital to take a sample and was taken aback by surprise. The mole was actually a malignant melanoma, a type of skin cancer!
Coincidentally, after two years, The Lancet published a case again. A 66-year-old man had a rash on the inner side of his left leg. For 18 years, the area grew slowly. But apart from the occasional itching, I didn’t feel special. Later, he kept a Labrador (also belongs to the scent dog) , he loved to run to him, desperately arched his legs to smell this Where there is a rash. The old man ran to the hospital for examination and was finally diagnosed with basal cell carcinoma and another skin cancer!
These stories show that some dogs with a strong sense of smell are indeed likely to find a unique smell from certain tumor cells. As of this writing, I have considered whether to keep a hunting dog at home as a cancer screening tool.
If the dog in your family suddenly starts to show unusual interest in some part of your body, maybe you should go to the hospital to see it.
Encouraged by these cases, over the past 30 years, many scientists have begun to do various studies to test the dog’s ability to detect cancer. There are many topics worth studying, including:
What cancers can be smelled?
From which samples can dogs smell cancer?
Can early cancer be smelled?
Can dogs who smell lung cancer smell breast cancer?
To the endSmell what chemical molecules the tumor emits?
…
Hundreds of papers have been published so far.
Many types of cancer have been reported to be smelled by dogs, including lung cancer, colorectal cancer, cervical cancer, prostate cancer, bladder cancer, etc.
The samples that dogs can detect are also various, including blood, urine, saliva, etc. Some studies even say that dogs can judge whether a person has lung cancer from the breath they breathe.
There are also reports that dogs trained to recognize lung cancer can smell breast cancer by the way. This shows that the odors that cancer cells in different parts may release are similar.
The dog really looks like a screening expert.
Three
In recent years, scientists have become increasingly enthusiastic about using dogs for screening, and even double-blind trials have begun.
For example, in a paper published in June this year, three Beagle dogs were trained to identify patients with non-small cell lung cancer. In subsequent tests, 50 blood samples (10 lung cancer patients and 40 healthy people) were randomly given to dogs to see if they could be identified. This is a double-blind test, so even the trainer doesn’t know what each sample is.
Results All three dogs performed very well, with a sensitivity of 96.7% and a specificity of 97.5%. Dog No. 2 is the fighter inside, all 50 samples are correct!
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This data far exceeds any current screening methods.
Four
People will definitely ask, if it’s really so powerful, why haven’t we seen the “Dog Cancer Early Screening Center” on the street?
Because there are still many unresolved issues.
The biggest problem: Because it depends on the individual dog, the test results are very unstable.
The results are very different for different dogs. Some dog breeds are accurate, and some dog breeds are not. Even with the same breed, some dogs can, and some can’t. This is probably the same as human beings. It is also a species. Some are the strongest brains that can carry maps.
The influence of the dog’s own status is also great.
The same dog eats and drinks today with 100% accuracy, but if he does n’t sleep well and feels bad, he may not be allowed. In the above study, in addition to the three dogs that were reported to be successful, there was actually one dog, but shortly after the trial began, he suddenly refused to cooperate, and was kicked out during the trial.
The machine can be repaired if it is broken. There is really no way for the dog to strike.
To resolve this, I’m afraid we can only rely on continuous screening and training. Find the most reliable dog and breed more of the same type.
Scientists are already doing this. The No. 1 dog, which can smell lung cancer, has successfully mated with another dog that can only smell breast cancer, and gave birth to 6 puppies. It is reported that all of these puppies will enter special tumor olfactory reconnaissance camps and undergo devil training at an early age.
Long Shenglong, Feng Shengfeng, the offspring of cancer detection dogs may be more useful!
Five
The bigger scientific problem is that we still don’t know what the dog nose smells! ?
This severely prevents scientists from further research on “cancer smell.”
If there is a “cancer smell”, is it a chemical molecule or a combination of multiple molecules?
If there is a “cancer smell”, are different cancers similar in taste, or are they completely different? How many different dogs do you need to screen for cancer?
If such a molecule can be identified, is it possible to develop an “electronic nose” to identify it so that