Breast cancer surgery – Jana de Boniface's research group

We conduct both register-based and prospective clinical research aiming to individualise and de-escalate breast cancer surgery to minimize its potentially negative impact on patients' quality of life without compromising survival outcomes.

Sketch of the Wargentin building, KI Campus Solna

Our Breast cancer surgery research group includes a core of PhD students and postdocs cooperating with affiliated multidisciplinary researchers from the fields of epidemiology, biostatistics, oncology, nursing, exercise oncology, imaging and pathology/translational research. We have a strong focus on patient-centered clinical research with extensive national and international collaboration. Below follow some examples of ongoing research projects:


This international randomized non-inferiority trial included patients with clinically node-negative breast cancer and 1-2 sentinel lymph node macrometastases in five European countries between January 2015 and December 2021. The aim was to show the non-inferiority of the omission of completion axillary dissection regarding the primary endpoint overall survival. The study population consists of 2766 randomized patients. The secondary endpoint recurrence-free survival has been published in the New England Journal of Medicine in April 2024 and shows no benefit of completion axillary dissection after a median follow-up of four years. Instead, we could show that patients avoiding completion axillary dissection report significantly less arm problems after surgery. The trial is supported by funding from Vetenskapsrådet, Cancerfonden, Bröstcancerförbundet, and the Nordic Cancer Union.

The Neo-ACT Trial

This international randomized trial test the hypothesis that a remote physical exercise intervention via a mobile application improves pathological complete response rates in patients with breast cancer receiving preoperative systemic treatment. Apart from this primary endpoint, the trial explores patient-reported quality of life, toxicity, treatment completion rates, imaging-based tumor response and residual cancer burden, in addition to a number of translational hypotheses using blood, tissue, and faeces samples. The trial has opened at the end of 2022 and has so far recruited over 150 of 790 planned patients. The trial is supported by funding from Vetenskapsrådet, Bröstcancerförbundet, Cancerfonden and Radiumhemmets forskningsfonder.

Stockholm Breast Reconstruction Database

This population-based database includes all women who have received immediate implant-based breast reconstruction in Stockholm in the years 2005-2015. It encompasses a wide range of clinical variables and follow-up and has enabled us to investigate patient-reported outcomes, consequences of postoperative radiotherapy, age inequality and oncological safety of diverse surgical concepts. 

The Stockholm DCIS project

This project aims to investigate surgical and oncological outcomes after oncoplastic breast-conserving surgery for ductal carcinoma in situ. Several clinical collaborators are collecting clinical data from medical charts to complete data received from the National Quality Register for Breast Cancer. Secondary aims are to investigate the role of preoperative MRI in these patients, surgical margins and reoperation rates.

The AXSANA Study

This is a enormous international effort initiated by the EUBREAST group, prospectively including patients with clinically node-positive breast cancer who receive preoperative systemic treatment and thereby convert to clinical node negativity. The main aim is to study different surgical approaches in different countries and evaluate their impact on survival, diagnostic accuracy and patient-reported arm function and quality of life. Our group is responsible for the collection and reporting of patient-reported data.


This is an international randomised trial evaluating physical well-being as reported by patients after either submuscular placement of the implant in immediate breast reconstruction, or implant placement on top of the pectoral muscle. Our group leader is the national coordinator for Sweden and responsible for reporting early complications. 

Staff and contact

All members of the group

Other people connected to the group

  • Liu, Yihang
  • Obondo, Christine

Visiting address

Karolinska Institutet, Department of Medical Epidemiology and Biostatistics, Nobels väg 12A, Stockholm, 17177, Sverige

Postal address

Karolinska Institutet, Department of Medical Epidemiology and Biostatistics, PO Box 281, Stockholm, 17177, Sverige

The Neo-ACT trial