Marjolein de Jong is a leading medical professional and healthcare innovator in the Netherlands, known for her transformative work in breast cancer care. As co-founder of the Breast Care Netherlands (and Europe) and President of the Board of the Alexander Monro Breast Cancer Hospital, she has been instrumental in shaping a new model of specialized, patient-centered care with international relevance.

She holds degrees in both Medicine and Clinical Psychology from Vrije Universiteit Amsterdam. During her studies, she gained clinical experience at the Bijlmer Penitentiary, where she worked as an interim clinical psychologist. Following her medical education, she specialized in oncologic surgery and practiced for several years in various hospitals across the Netherlands.

Driven by the ambition to improve the fragmented landscape of breast cancer care, she co-founded Breast Care Netherlands and the Breast Care Foundation—initiatives that laid the groundwork for the Alexander Monro Breast Cancer Hospital, which opened in 2012 as the country's first and only hospital fully dedicated to breast cancer and benign breast conditions.

Under her leadership, the hospital has achieved exceptional outcomes: higher-than-average survival rates, significantly lower complication rates, and outstanding patient satisfaction scores (9.5/10 on average). Marjolein advocates strongly for the concentration of expertise, combined with a warm, personal environment and a commitment to patient autonomy and shared decision-making. These principles form the backbone of the care model she champions.

A leading voice in personalized healthcare, she emphasizes the importance of second opinions—at the Alexander Monro Hospital, more than 25% of second-opinion consultations result in a relevant different diagnosis or treatment plan. Her approach ensures that every patient is empowered to make informed decisions in close collaboration with a multidisciplinary medical team.

Marjolein is also the founder of "KNOW YOUR BREASTS", a nationwide awareness campaign aimed at educating women about the 12 early signs of breast cancer—most of which are unknown to the general public, beyond the commonly recognized lump. The campaign introduces accessible tools like the Breast Cancer Alphabet and highlights Dense Breast Tissue (Dense D) as a major, underrecognized diagnostic challenge. Women with dense breasts often require additional imaging (MRI) to ensure early and accurate detection—a cause Marjolein actively advocates for in both public education and clinical practice.