AP reported on canine cancer-detection research in 2019. A published study by Heather Junqueira and colleagues tested trained beagles on blood-serum samples from people with non-small-cell lung cancer and healthy controls.
That controlled research does not establish the accuracy of a home screening kit, breath testing, all cancer types or ordinary daily-life alerts. The old article mixed different sample types and promoted commercial tests using a broad “95% accurate” claim; those claims and prices have been removed.
Discuss symptoms and appropriate screening with a qualified clinician. Do not delay assessment or recommended tests because of a dog’s response or lack of response. Further research and validation are different from a clinically established diagnostic service.