Scientists from various countries have confirmed that dogs can accurately detect can.cer in human samples by using their highly developed sense of smell. Their ability lies in identifying volatile organic compounds (VOCs) — substances released by the body when can.cerous cells are present.
These VOCs can be found in breath, urine, and even tumor tissue, and they begin to appear in the body’s fluids even during the earliest stages of can.cer.
In recent years, three notable studies have explored how trained dogs can detect these compounds, each using different methods and targeting different types of can.cer.
The results from these investigations have been encouraging and suggest that dogs could play a vital role in developing noninvasive, quick, and affordable diagnostic tools for can.cer detection.
What Studies Have Shown So Far
The researchers analyzed various experiments where dogs were trained to detect can.cer — particularly lung can.cer — through patients’ breath samples. They also included findings from their own lab to evaluate the consistency of results across different studies.
Among the most important takeaways was the observation that dogs were highly responsive to certain VOCs like 2-pentanone and ethyl acetate.
However, the review also pointed out that many studies lack consistency in methods, sample preparation, and dog training, which hinders comparability. The researchers emphasized the need for standardized double-blind trials and outlined a few major conclusions:
- Dogs can reliably distinguish between healthy and can.cerous breath samples.
- Accuracy varies depending on the can.cer type and study setup.
- The exact VOCs triggering the dogs’ response are still unidentified.
- Clear guidelines for training and testing are essential for future progress.
Can Dogs Detect Multiple Can.cers with One Training?
Researchers in South Korea investigated whether dogs trained to detect one kind of can.cer could recognize another type without additional training.
Their findings, published in PLOS ONE, focused on dogs trained to detect breast can.cer. When presented with colorectal can.cer samples, the same dogs were also able to correctly identify them.
This implies that certain metabolic byproducts of can.cer might share a common scent profile, regardless of can.cer type. The study used laboratory-grown cell lines — 4T1 for breast can.cer and CT26 for colorectal can.cer — and found that:
- Both dogs achieved over 90% accuracy in identifying can.cer samples.
- Researchers used double-blind tests and cross-validation to avoid biased results.
- Plans are underway to test this in real human samples, outside of lab conditions.
One Dog, One Sample, Remarkable Accuracy
In Japan, a team from Nippon Medical School, led by Shoko Kure, conducted a study with a single Labrador retriever trained to detect breast can.cer through urine samples. The study involved 40 confirmed breast can.cer patients, 142 patients with other can.cers, and 18 healthy individuals.
Remarkably, the dog correctly identified all breast can.cer samples in 40 double-blind tests, achieving 100% sensitivity and specificity. This highlights the enormous potential of using dogs in non-invasive, low-cost screening, particularly in early detection.
The team sees this as the first step toward building an artificial detection device, or “electronic nose,” that mimics the dog’s scent detection ability.
Benefits and Challenges
The use of trained dogs offers multiple benefits:
- No need for invasive procedures like biopsies or scans.
- Sample collection is simple and painless.
- It’s affordable and can be implemented in settings without advanced medical technology.
- Results are nearly immediate.
Yet, researchers also acknowledge ongoing challenges. Differences in how dogs are trained, the sample types used, and study conditions make it hard to replicate or compare results.
Identifying the specific VOCs that trigger dogs’ responses is also crucial — not only to improve training but also to develop electronic alternatives in the future.
Final Thoughts: A Nose That Could Save Lives
Dogs may become unexpected heroes in the realm of early can.cer detection. Their ability to pick up on chemical changes in the body offers a promising alternative to conventional screening tools.
Though more research is needed to validate these methods for clinical use, recent studies suggest that a dog’s nose, with proper training, could become a life-saving diagnostic aid in the near future.
