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“Is this cancer?”
I got a text from my daughter.
It looked like a photo I found online of cutaneous hemangiosarcoma 😱
Online photo of cutaneous hemangiosarcoma
“You should have it looked at,” I answered back.
Leo, our daughter’s six-year-old golden retriever, was examined at the local clinic in San Francisco, and the small mass was removed.
We waited nervously for the biopsy results and were relieved when the result returned negative.
If there is a lump or a bump, a clinician can do a fine-needle aspirate or biopsy to find out if the mass is malignant or benign. But too often, there are no external signs, and cancer is found at an advanced stage.
Early cancer detection saves lives
When cancer is found early, especially before it has had a chance to spread, there are more treatment options, and a dog has a chance at a cure.
The incidence rate of cancer increases with age, and some groups are recommending cancer screening start around 6 -7 years and, for some large breed dogs, early as four years based on a large study that analyzed the age at which dogs were diagnosed with cancer.
Source: PetDX
Different cancer screening tests are now available
Here are some examples that analyze blood/urine/saliva samples:
How accurate are they?
What are their false negative and false positive rates? In other words, could they miss the presence of cancer or trigger false alarms?
It’s important to know that these tests can tell that the probability is high that your dog has some kind of cancer but can't tell the actual type of cancer a dog has. They measure general cancer signals using different technologies.
Another important thing to know is that the sensitivity to different cancer types varies greatly. Depending on the test, it might be much better at detecting the presence of hemangiosarcoma than mast cell tumors.
For example, OncoK9 (PetDX) test measures cell-free DNA in the blood.
They reported an 85.4% detection rate averaged across the three most aggressive cancers: lymphoma, hemangiosarcoma, and osteosarcoma (n=137). A lower average detection rate (61.9%) was measured for eight most common cancers: lymphoma, hemangiosarcoma, osteosarcoma, soft tissue sarcoma, mast cell tumor, mammary gland carcinoma, anal sac adenocarcinoma, and melanoma.
The table below shows the measured detection rate (or sensitivity) for each type of cancer as well as the number of canine patients involved. The detection sensitivity is under 50% for many cancer types, including indolent lymphoma, liver, melanoma, thyroid, nasal cavity, soft tissue sarcoma, mast cell tumors, anal sac adenocarcinoma, and urothelial carcinoma. For bladder cancer (urothelial carcinoma), the sensitivity is less than 10%.
Oncok9 was available until early 2024 and was considered one of the more reliable tests, with data published in multiple peer-reviewed journal articles. It was also one of the more expensive tests, priced at around $1000.
Let's now talk about three tests that are currently available.
Nu-Q Test
Nu-Q Test is a blood test that measures nucleosomes, bead-like structures made of DNA coiled around the histone protein core. When a patient (human or canine) has cancer, nucleosomes from those cancer cells are released into the blood, and they can be measured using antibodies that are specific to nucleosomes.
It’s a test that can be ordered by a veterinarian and involves a blood sample drawn at the clinic.
Based on a published study including over 500 dogs, the test had the highest sensitivity for hemangiosarcoma (81.8%) and lymphoma (76.9%). However, the sensitivity for localized solid tumors such as mast cell tumors and osteosarcoma was much lower.
For example, sensitivity was 50% or less for melanoma, osteosarcoma, soft tissue sarcoma, and mast cell tumors at 97% specificity.
Nu-Q test is much better at detecting systemic cancer types like hemangiosarcoma and lymphoma compared to solid tumors that are local.
By the way, some researchers are studying how Nu-Q test might be used to monitor hemangiosarcoma progression. The nucleosome concentration may drop, for example, after surgery, and remain low while the patient is in remission. But the blood test may reveal the return of cancer showing increasing nucleosome concentration even before clinical signs appear.
ScoutMD
ScoutMD is a relatively new test that relies on trained scent-detection dogs to detect volatile organic compounds in the saliva sample.
The test is inexpensive and convenient; the saliva sample can be collected at home and sent in.
Research has shown that dogs can be trained to detect many illnesses, including COVID-19, Parkinson’s disease, and cancer. How well can dogs be trained to discriminate between the odors of saliva samples from dogs developing cancer and healthy dogs?
This study, published by a team from the University of Alabama at Birmingham and the University of Wisconsin-Madison (collaborating with ScoutMD company), described the training and evaluation procedures. Samples from 139 dogs with cancer were used to train dogs and evaluate test accuracy. The cancer types included lymphoma, mast cell tumor, osteosarcoma, melanoma, soft tissue sarcoma, squamous cell carcinoma, and urothelial cell carcinoma.
In their evaluation, they used ten samples from dogs with cancer and 22 healthy canine samples. Six trained dogs could accurately distinguish between the two groups of samples with a mean sensitivity of 90% and a mean specificity of 98%.
It’s important to point out that this ‘sensitivity’ measure is different from the cancer detection rate measured by the PetDx and NuQ tests. In the PetDx and Nu-Q tests, hundreds of cancer samples were used in the evaluation, compared to only 10 samples used to evaluate canine scent detection success rate per dog.
Between February and March 2024, Canine Cancer Alliance volunteers worked with ScoutMD, and samples were sent in from healthy dogs and dogs diagnosed with different types of cancer.
We were pleasantly surprised when 4 out of 4 osteosarcoma samples were correctly positively identified. However, samples from 2 dogs with hemangiosarcoma came back negative.
Past research studies have shown the ability of dogs to detect cancers such as lung, breast, ovarian, and prostate cancer with varying degrees of sensitivity rates ranging from 70% to over 90% and specificity rates that can also be quite high.
There is currently a lack of sufficient data for multi-cancer scent-based detection, and we are looking forward to the ScoutMD team publishing detection sensitivity across different cancer types with larger sample sizes in the future.
Oncotect
Oncotect is a urine-based test that uses C. elegans or nematodes. Nematodes have a highly sensitive olfactory system and are naturally attracted to specific VOCs emitted by cancer cells.
Some past studies have measured nematodes' ability to distinguish between urine samples from healthy dogs and dogs with cancer with high accuracy. For example, some studies have shown sensitivity and specificity rates above 90%.
A recently published study sponsored by the company behind Oncotect measured the sensitivity to different types of canine cancer. The specificity was 95%.
While these sensitivity numbers look promising, averaging 85% (and they advertise that their test has ~90% accuracy), their evaluation was based on a relatively small number of samples: 48 cancer and 30 healthy samples. Samples from only five cancer types were included.
To fully understand this test's reliability, more data involving more canine patients and different types of cancer are needed.
Cancer screening tests for people
In Japan, a nematode-based test is already available for early detection of human cancers and is becoming popular.
Called the N-Nose test, it can be ordered for about $100 ( 15800 yen ) and is claimed to be sensitive to a wide range of cancers, including stomach, colorectal, lung, pancreatic, breast, prostate, bladder, liver, ovarian, and esophageal cancers.
However, the test has been quite controversial due to the high false incidence rates reported by some hospitals in Japan. It may be burdensome for hospitals to test many patients who turned out to have received false positive test results. But for the patients who received true positive early screening results, the test is a lifesaver.
In the US, Grail’s Galleri blood test is now commercially available. The test measures DNA fragments circulating in the blood and analyzes methylation patterns. It is still undergoing an FDA approval process and is not covered by insurance. However, the test can be ordered for about $1000 and is advertised to be able to screen for over 50 different cancer types.
Momo’s test results
Recently, I tried the ScoutMD test, sending in a urine sample from Momo, our 8-year-old Golden Retriever. I was expecting a healthy result, but the test unexpectedly came back positive. All five scent detection dogs indicated that there was something suspicious.
I took Momo to see a veterinarian and asked for Nu-Q testing. I also ordered the Oncotect urine test. These two tests came back negative.
I became confused and anxious about what to do next. Our local vet did not have much experience with these screening tests and couldn’t provide any suggestions other than taking her to a specialist for an ultrasound scan.
Remembering that 12 months earlier, Momo had been diagnosed with and treated for Epulis (also known as acanthomatous ameloblastoma), I made a re-check appointment with her oncologist. After a thorough exam that included ultrasound and X-ray imaging, the conclusion was that they could not find anything suspicious.
I am still not convinced that Scout MD scent detection dogs were wrong. But for now, I am relieved and monitoring her carefully.
HT Vista
One last test I want to mention is a hand-held scanner that can determine if a cutaneous or subcutaneous mass is more likely to be benign or malignant. It relies on heat diffusion imaging technology.
This test was invented in Israel and is slowly being introduced in the USA, so it is not yet widely available. For example, only two clinics are now using the scanner in Washington state.
Some of the advantages of this test include the fact that it’s completely noninvasive and reports are generated in real-time at the clinic. There is no need to leave our pet for a stressful biopsy, and the low cost is another advantage.
But like all the other tests, there will be false negative and false positive results.
According to their study, they examined over 500 malignant and benign masses. HT Vista correctly classified 45 out of 53 malignant masses and 253 out of 378 benign masses, so the sensitivity was 85%, and specificity was 67%.
If Leo's mass was scanned and came back "most likely benign", could we have avoided the anxious wait and stressful biopsy exam?
Summary
New multi-cancer cancer screening tests are rapidly becoming available. And they may offer a convenient way to find out if your dog might have cancer. However, it’s important to remember that:
These tests detect general cancer signals and cannot determine the location or type of cancer your dog might have.
It’s important to understand the limitations of these tests. There is a finite chance that cancer will be missed. There is also a finite chance that you will be told that the cancer risk is high but discover that your dog is healthy after further testing.
Even though some ads may boast high accuracy, the evaluation may have been based on small sample size and in a controlled (not real world) setting
These new tests will not replace thorough tests and exams at veterinary clinics but may offer a convenient way to perform more frequent, regular screening between visits, especially as pets get older.
If you have tried one of these tests, please let us know your experience by emailing info@ccralliance.org
Here is a table that provides a quick summary of these tests.
The information on the Canine Cancer Alliance website is for informational purposes only and is not intended to substitute for professional veterinary advice.
Always seek guidance from your veterinarian with any questions regarding your pet’s health and medical condition.
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Questions? Email us at info@ccralliance, and we'll get back to you as soon as we can!
Canine Cancer Alliance is a non-profit organization supporting research for canine cancer cures.