Gemma Peters is Chief Executive Officer of Macmillan Cancer Support, appointed in January 2023, leading one of the UK’s largest and most influential cancer charities. Since joining, she has overseen the development of a new strategic direction focused on expanding reach, strengthening cancer support services, and addressing persistent inequalities in cancer care and outcomes across the UK. Under her leadership, Macmillan continues to support millions of people affected by cancer each year, with an emphasis on patient-centred care, financial and practical support, and ensuring lived experience informs decision-making.
Prior to Macmillan, Peters served as Chief Executive of Blood Cancer UK, where she led the organisation through the COVID-19 pandemic, advocated nationally for immunocompromised patients during vaccine rollout, and implemented a transformation programme that expanded reach and embedded people with lived experience into governance. Earlier, she spent twelve years at King’s College London and King’s Health Partners as Executive Director of Fundraising & Supporter Development, leading the award-winning World Questions | King’s Answers campaign, which raised more than £610 million. Her leadership combines large-scale fundraising, health system partnership, and patient-centred advocacy, shaping Macmillan’s role in cancer support, policy influence, and community engagement.
The 100 CEOs featured here reflect the diversity and complexity of modern oncology leadership. In 2025, some lead the world’s largest cancer institutions; others guide specialized societies or emerging innovators. What unites them is responsibility: for millions of patients, for the integrity of science, and for the future direction of cancer care globally.
This list is not a celebration of power, but a recognition of stewardship, accountability, and impact – and of the leaders whose choices continue to shape the fight against cancer. For the many deserving individuals not mentioned in this list, we will continue to acknowledge, honor and elevate your voices in our daily publications from across the world.
See the full list of The 100 Influential CEOs in Oncology in 2025 and stay tuned for other special category nominations.
