OncoK9® Test Limitations and Risks | PetDx®
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OncoK9® Test Limitations and Risks

The purpose of the OncoK9 test is to improve your veterinarian’s ability to detect cancer in your dog. As with any laboratory test, there are important considerations to keep in mind when using this test:   

  • The risk of cancer in dogs increases with age and is also increased in certain breeds.1,2 OncoK9 is recommended as an annual screening test for all dogs starting at 7 years of age and starting at younger ages for dogs belonging to breeds in which cancer tends to develop earlier in life.3  
  • OncoK9 is also recommended as an aid-in-diagnosis for dogs in which cancer is suspected based on clinical signs or other clinical findings.   
  • Not all cancer types, sizes, or stages are detectable with this test. Results of this test should be interpreted by a veterinarian in the context of your dog’s medical history and clinical signs.   
  • The OncoK9 test will typically return a Cancer Signal Detected (positive) or a Cancer Signal Not Detected (negative) result. Rarely, the OncoK9 test may return an Indeterminate result; this can happen when genomic alterations are detected in DNA from the patient’s blood sample, but the significance of these findings is uncertain (the test is not clearly positive and not clearly negative). Rarely, the OncoK9 test may return a Sample Failed result; this can happen as a result of sample-related issues, such as underfilled tubes, inadequate plasma volume, tube failures, or testing failures. In the case of an Indeterminate or Sample Failed result, a new blood sample will be requested, and PetDx will test the new sample at no additional cost. Your veterinary clinic may apply additional fees for the appointment, supplies, and/or staff time required to collect the new blood sample. The OncoK9 Test Interpretation Guide provides further details about the significance of each result type.  
  • The OncoK9 test does not provide a definitive diagnosis of cancer. If your dog receives a Cancer Signal Detected result, more testing will likely be recommended to look for the source of the cancer signal and to establish a diagnosis; this may include additional physical exams, blood or urine tests, imaging tests like x-rays and/or ultrasound, and analysis of tissue samples from areas found to be abnormal, such as lumps, masses, or enlarged lymph nodes. 
  • The OncoK9 test looks for cancer in your dog’s body at the time of the blood draw. It does not determine the future risk of developing cancer. For dogs at higher risk of cancer (such as dogs over the age of 7 or dogs belonging to breeds known to be at higher risk of cancer), regularly scheduled (e.g., annual) cancer screening that includes the OncoK9 test is recommended to increase the chances for early cancer detection throughout their lifetime.    
  • In rare cases, the OncoK9 test may detect a cancer signal but a confirmatory cancer evaluation may not find current evidence of cancer. If this happens, your veterinarian may recommend additional testing and/or very close monitoring over time to look for early signs of cancer in your dog.   
  • As with any laboratory test, false positive results may occur with the OncoK9 test, suggesting the presence of cancer in a patient that is actually cancer-free. In a large validation study,4 the OncoK9 test has shown a very low false positive rate of 1.5%. In other words, only about 3 in every 200 cancer-free dogs would be expected to incorrectly receive a positive test result.   
  • As with any laboratory test, false negative results may occur with the OncoK9 test, suggesting the absence of cancer in a patient that actually has cancer. In a study evaluating dogs with a wide variety of cancer types, the OncoK9 test had an overall cancer detection rate of 55%.4 This means that about 45% of cancer cases may go undetected (false negative results) after one use of the test. For this reason, a negative OncoK9 test result cannot rule out the possibility of cancer, and your veterinarian may recommend further testing if there is still a high suspicion of cancer after a negative OncoK9 result. Screening at regular intervals (e.g., annually) will likely increase the cumulative detection rate of the test across a dog’s lifetime.   
  • When a Cancer Signal Detected (positive) result is issued, the estimated positive predictive value (PPV) of the test – the chance that a patient who receives a positive result actually has cancer – is expected to range from 76% (when the test was used as a screening test in a dog not suspected to have cancer prior to testing) to 97% (when the test was used as an aid in diagnosis in a dog in which cancer was suspected prior to testing).4 For further information on how PPV is determined and how test results can be interpreted, please see the OncoK9 Test Interpretation Guide.  
  • When a Cancer Signal Not Detected (negative) result is issued, the estimated negative predictive value (NPV) of the test – the chance that a patient who receives a negative result actually does not have cancer – is expected to range from 68% (when the test was used as an aid in diagnosis in a dog in which cancer was suspected prior to testing) to 96% (when the test was used as a screening test in a dog not suspected to have cancer prior to testing).4  For further information on how NPV is determined and how test results can be interpreted, please see the OncoK9 Test Interpretation Guide.  
  • The OncoK9 test has been shown to detect 30 different cancer types. The detection rate varies among cancer types. Furthermore, the ability of the OncoK9 test to detect cancer may vary based on the size, stage, and location of the cancer in the body.4   
  • Because the OncoK9 test does not provide a definitive diagnosis of cancer, it should never be used as the sole basis for making important decisions such as treatment or euthanasia. Please discuss the results, and the most appropriate next steps, with your veterinarian.   
  • Rx Only. This test can only be performed by or on the order of a veterinarian. 
  • OncoK9 requires a blood collection performed under the care of a licensed veterinarian, and test results are returned to the veterinarian for communication to the pet owner. As with any laboratory test, OncoK9 results should be interpreted by a veterinarian in the context of each patient’s medical history and clinical presentation.  

References

  1. Dobson JM. Breed-predispositions to cancer in pedigree dogs. Isrn Vet Sci. (2013) 2013:1–23. doi: https://doi.org/10.1155/2013/941275 
  2. Fleming JM, Creevy KE, Promislow DEL. Mortality in North American dogs from 1984 to 2004: an investigation into age-, size-, and breed-related causes of death. J Vet Intern Med. (2011) 25:187–98. doi: https://doi.org/10.1111/j.1939-1676.2011.0695.x 
  3. Rafalko JM, Kruglyak KM, McCleary-Wheeler AM, et al. Age at cancer diagnosis by breed, weight, sex, and cancer type in a cohort of over 3,000 dogs: determining the optimal age to initiate cancer screening in canine patients. bioRxiv 2022.03.30.486448; doi: https://doi.org/10.1101/2022.03.30.486448 
  4. Flory A, Kruglyak KM, Tynan JA, et al. (2022) Clinical validation of a next-generation sequencing based multi-cancer early detection “liquid biopsy” blood test in over 1,000 dogs using an independent testing set: The CANcer Detection in Dogs (CANDiD) study. PLoS ONE 17(4): e0266623. https://petdx.science/candid-study/web

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