Still, he noted "thoughts about their role being diminished in the future is speculative." Esener, who uses gene sequencing machines from Illumina and Pacific Biosciences of California (PacBio) for research looking to detect liver cancer in its earliest stages, noted the field of early cancer detection is diverse, with about 30 companies working on five different methods of testing for signs of very early cancer – including the types Grail and its rivals are focused on. If proven to work, early cancer detection tests could help doctors identify cancer risk in patients long before symptoms or other indicators develop.