Most of the time, doctors can determine where a cancer began. Sometimes, however, its origin remains unknown. Most broad profiling tests now use AI to predict a tumor's likely origin when pathology alone cannot provide a clear answer. Small panels do not read enough of the tumor to do this. These tools can also flag cases where the tumor's profile does not match the original diagnosis. Because treatment options depend on the type of cancer, clarifying its origin can change which therapies a patient may qualify for.
In published research, Caris' GPSai returned a likely tissue of origin for the large majority of the cancers of unknown primary it was run on. Across all tumors profiled, not only those of unknown origin, it also prompted a change to the original diagnosis in a small share of cases, and in most of those the change affected which targeted treatments the patient qualified for.
For Example
A patient's cancer is found in the liver, but scans and pathology cannot determine where it started. A tissue-of-origin prediction points to the bile ducts instead, guiding the care team toward treatments and clinical trials built for that specific cancer type rather than a generic approach.
A patient is originally diagnosed with breast cancer based on where the tumor was found. Broader genomic profiling, using a tool like GPSai, instead points to lung as the tumor's true origin. Because breast and lung cancers respond to very different treatments, that change can significantly shift which therapies are likely to help.
Questions To Ask Your Oncologist
- Is the origin of my cancer fully certain, or is there some doubt?
- Does the profiling test you're ordering include a tissue-of-origin prediction?