Ashworth was a key member of the team that discovered the BRCA2 gene, which is linked to an increased risk of breast, ovarian and other cancers.

He has also been a pioneer in the use of the genetic principle of synthetic lethality in cancer therapy in particular for the use of the drugs PARP inhibitors for the treatment of BRCA1 and BRCA2-related cancers.

His work exemplifies the translation of deep biological understanding into clinical benefit. This has led to dozens of clinical trials, FDA approvals and standard of care use for the treatment of ovarian and breast cancers.