We have known for well over a century that exposure to certain environmental agents can result in DNA mutations that ultimately cause cancer. However, it has been tricky to explicitly link specific tumors to individual culprits, such as UV light or tobacco smoke. Now a team of UK scientists has for the first time developed a way to identify specific mutational signatures in tumors that can be linked to certain carcinogens.

"Mutational signatures are the fingerprints that carcinogens leave behind on our DNA, and just like fingerprints, each one is unique," says Serena Nik-Zainal, a researcher from the University of Cambridge working on the project. "They allow us to treat tumors as a crime scene and, like forensic scientists, allow us to identify the culprit – and their accomplices – responsible for the tumor."

To create this catalog of mutational signatures, the researchers began by exposing induced pluripotent stem cells to a variety of environmental carcinogens. Using whole genome sequencing the researchers were able to identify specific mutational fingerprints from 41 carcinogenic agents, such as chemicals found in tobacco smoke, diesel fumes or certain foods.

The study was also able to measure how damaging each specific carcinogen could actually be, unsurprisingly confirming some well-known explicit cancerous connections, including UV with melanoma and smoking with lung cancer. Other carcinogenic agents analyzed presented smaller effect sizes, and the researchers urge caution in using this study to affirm conclusive relationships between some cancers and specific environmental exposures.

Of course, the research isn't geared at finding a single conclusive cause for all individual cancers. Many of the carcinogenic agents examined presented such weak mutagenic signatures that it is suggested it would be difficult to conclusively claim the agent as the sole cause of a given tumor. Further work is inevitably needed to better catalog these mutagenic signatures found in tumors, as the legal implications of this research could be incredibly significant for those working in industries where exposure to certain carcinogenic agents is common.

The work is undeniably an impressive breakthrough in helping scientists more clearly understand the specific origins of individual cancers. Homing in on exactly what has contributed to the generation of a given tumor will help health care providers offer better advice for avoiding exposure to those carcinogenic agents in the future.

"Our reference library will allow doctors in future to identify those culprits responsible for causing cancer," says Nik-Zainal. "Such information could be invaluable in helping inform measures to reduce people's exposure to potentially dangerous carcinogens."

The study was published in the journal Cell.