“The MARI procedure has been developed entirely within our organization, which is wonderful,” says jury member Jacqueline Stouthard, member of the Executive Board with a focus on Care and Care development. “They deserve this award because of the tremendous impact on the quality of life of a large group of patients in the Netherlands as well as internationally.”
2500 colleagues in the Netherlands are diagnosed with breast cancer with metastases in the lymph nodes every year. Most of these patients used to be treated with chemotherapy followed by surgical removal of the axillary lymph nodes. This surgery is not easy: many women experience unpleasant side effects like limitations in movement, fluid retention in the arms, and nerve pain.
There must be another way, breast cancer surgeon Marie-Jeanne Vrancken Peeters believed. The only issue was that there wasn’t a good indication of whether chemotherapy was effectively treating the cancer cells in the axillary lymph nodes: there was no way to see whether they were ‘clean’, and safe to keep.
Marie-Jeanne developed the MARI procedure together with other specialists at the Netherlands Cancer Institute. Thanks to this smart method, 4 out of 5 patients at the Netherlands Cancer Institute can now keep their axillary lymph nodes after chemotherapy. Research from earlier this year confirmed that the women who underwent the MARI procedure procedure have the same five-year survival rates as the women whose lymph nodes were surgically removed.
At the heart of this success story is a radioactive iodine seed, about the size of a grain of sugar. If a radiologist places this seed in a lymph node that contains tumor cells: the MARI node. MARI stands for Marking Axillary lymph node with a Radioactive Iodine seed. After chemotherapy, the surgeon can selectively remove this “MARI node.” If it doesn’t contain tumor cells, we can safely assume that the other axillary lymph nodes are also clean, and a full lymph node dissection is no longer necessary.
“Many women worldwide still undergo unnecessary axillary lymph node surgery,” Marie-Jeanne says. This is a major concern for her breast cancer team, which conducts extensive research into overtreatment and how to prevent it. “Our MARI procedure can help change that.”
“At the Netherlands Cancer Institute, we have been using this method since 2014, and it has been included in the national guidelines since 2022. Other hospitals in the country are now also adopting he procedure. 100 patients a year at our institute alone can be spared the burden of lymph node removal. That number could climb upwards to 2,000 in the Netherlands as a whole, and many, many more worldwide.
This innovation was financially made possible in part by the AVL Foundation. Incidentally, the name MARI is not only derived from the technical description, Marking Axillary lymph node with a Radioactive Iodine seed, but also references the women who helped pioneer the procedure: Marieke Straver and Marie-Jeanne Vrancken Peeters.
The Patient Impact Award is the Netherlands Cancer Institute’s annual award for clinical innovations that are expected to lead to – or have already led to – the improvement of diagnostics, survivorship, and/or treatment of patients with cancer.
Research at the Netherlands Cancer Institute is financially supported by the AVL Foundation and KWF Dutch Cancer Society.
The results of the MARI procedure in JAMA Oncology and The Breast in 2025
More about the Patient Impact Award and previous winners.