Neoadjuvant systemic treatment in breast cancer (MANS study)

MANS study

Neoadjuvant systemic treatment in breast cancer

– The eight Dutch Snapshot study –

Participating centers

5th of January 2022


The use of neoadjuvant systemic therapy (NST) in patients with breast cancer has increased over the years and the results are promising. Downstaging of the tumor by applying NST has resulted in growing numbers of breast conserving surgery (BCS) 1,2, Compared to mastectomy, BCS results in less morbidity, improved cosmetic outcomes and better quality of life3,4. Another benefit of NST includes the opportunity of axillary down staging (ADS) with less extensive axillary surgery and the related postoperative complications. At this moment, indications for NST varies greatly between hospitals in the Netherlands because current criteria for NST are not well defined.5This is likely to result in different treatment outcomes such as surgical treatment of the breast or axilla and differences in the amount of radiotherapy, cosmetic outcomes and quality of life.

Study population

All newly diagnosed patients with primary breast cancer receiving NST followed by a surgical procedure as breast conserving surgery or a mastectomy, can be included in this snapshot study. Patients under the age of 18, not receiving surgery, receiving palliative treatment, with a history of breast cancer, benign breast tumors, metastatic disease or pregnancy are not eligible for participation.


The objective of this study is to investigate the next three questions considering NST in primary breast cancer patients:
1. What are the different reasons for applying NST in primary breast cancer patients in the Netherlands?
2 a. How often does NST result in conversion to BCT from a mastectomy in different tumor types?
2 b. What are the surgical outcomes (volumes, margins, re-excisions)?
3. How often does NST result in axillary down staging by which an ALND is omitted in the different tumor types?

Main outcomes

The primary outcome is to create an overview of the different reasons to apply NST in breast cancer patients in the Netherlands and whether the upfront set goal has been reached. Furthermore, insight is given in how often NST, in different tumor types, results in conversion from mastectomy to BCT as well as how often NST results in axillary down staging by which ALND is omitted. Secondary, more knowledge about the surgical and, indirectly, cosmetic outcomes after NST will be obtained.

Study design

All hospitals providing breast cancer care in The Netherlands will be contacted for participation in this study. When the hospital accepts to participate, prospective data considering the indication of NST as well as demographic factors together with preoperative, perioperative and postoperative information will be registered. This generates a population-based overview, which rapidly provides insight in current clinical practice on a national scale.

Other projects

Eleven other projects are performed by the Dutch Snapshot Research Group.

Read more
MANS website

Read more about the MANS study on

Read more