After joining the Parliament, Trillet-Lenoir was a member of the Committee on the Environment, Public Health and Food Safety.

During that time, she took part in the development of predictive tests to ascertain the sensitivity of cancers to chemotherapy.

[4] Starting in 2013, Trillet-Lenoir served as president of the board of directors of the Cancéropôle Lyon Auvergne-Rhône-Alpes (CLARA), a research cluster dedicated to cancer.

She visited the university from 2011, having contributed to the establishment of the first master's degree programme in oncology.

[10][11] She was also her parliamentary group's rapporteur on measures against cancer[12] and on the Health Emergency Preparedness and Response Authority (HERA).