br The NBCA br The NABON Breast Cancer

The NBCA
The NABON Breast Cancer Audit (NBCA) is a multidisciplinary nationwide registry of all diagnostic and treatment modalities of patients who are surgically treated for newly diagnosed breast cancer in the Netherlands. All 89 hospitals in the Netherlands participating in breast cancer care participate in this nationwide registry. Data completeness of the NBCA is estimated to be at least 95%. Available data from the NBCA dataset include demographic variables (year of incidence, age), tumour variables (histologic sub-type, clinical tumour stage, clinical nodal stage and hormone re-ceptor status) and treatment variables (use of systemic therapy, radiotherapy and type of surgery). Furthermore, the volume and type of hospital is being registered. Hospital volume was based on the surgical volume, which was defined as the mean annual number of breast cancer surgeries during the Chlorpromazine 2012e2016. The cut-off points of <150 and 300<, were based on those reported in a publi-cation of the European Society of Breast Cancer Specialist (EUSOMA) [16]. Hospital type was described as academic, teaching and general. Academic hospitals are part of a university, and both academic and teaching hospitals provide medical training to surgical residents.
Data selection
Data records of patients aged 18e98 years diagnosed with cT1-4N0-3M0 invasive breast cancer between July 2011 and June 2016 were abstracted from the NBCA. We excluded patients with a prior cancer diagnosis or unknown timing of chemotherapy. Neoadjuvant chemotherapy (NAC) was defined as chemotherapy given within four weeks prior to surgery. In accordance with international guidelines, the Dutch national breast cancer guidelines indicate NAC for patients with locally advanced disease (stage III) and recommended it in patients with stage II disease with an indication for systemic treat-ment [17,18]. Trends in the use of NAC and the surgical performance after NAC during the years were analysed.
Surgical performance
Type of surgery (BCS or mastectomy) and the pathology report of the surgical specimen was derived from the NBCA database. Resection margins of the surgical specimen were defined according to the Dutch guidelines and in accordance with the definition of the quality indicator defined by the NBCA audit [19]. In the Dutch guidelines, the definition for focally involved margins for invasive breast cancer is described as residual tumour in the resection sur-face over a maximum length of 4 mm. More than focally involved margins is defined as residual tumour in the resection surface over more than 4 mm. According to the Dutch guidelines, focally involved margins do not mandate re-excision. In case of more than focally involved (positive) margins, a re-excision is indicated unless the positive margin is the dorsal margin and the fascia has been resected. In addition to radiation after BCS, a radiation therapy boost may be applied when one or more of the following in-dications is present: age <50 years, an estimated local recurrences risk 1% per year, grade 3, positive tumour margins and lymph  vascular space invasion [20,21].
Statistical analysis
Statistical analysis was performed in PASW Statistics version 20 (SPSS inc Chicago, IL, USA). Descriptive analyses were used to report on the trends in the use of NAC and in the surgical outcomes after NAC. Bivariate comparisons of surgical outcomes of BCS with and without NAC were performed with chi-square tests. Secondly, a multivariable logistic regression model was used to determine which factors were independent associated for tumour involved margins in BCS with and without NAC. Statistical tests were 2-sided and statistical significance was defined as a p value < 0.05.
Results
Trends in the surgical performance after NAC
Table 1
Clinical-pathological and hospital characteristics of patients with invasive cT1-4M0 breast cancer (N ¼ 8195) who have received NAC followed by surgery (2012e2016).
Year of incidence
Age
Histologic subtype
DCIS component
Clinical tumour stage
Clinical nodal stage
Hormone receptor status
Type of hospital
Hospital surgical volume
Surgical outcomes of BCS after NAC
Table 3 shows the surgical outcomes of ‘BCS after NAC’ in terms of focally or more than focally involved invasive margins and re-excision rates. Of all patients treated with BCS after NAC between 2011 and 2016 (N ¼ 4170), 8,5% (n ¼ 355) had focally involved
Table 2
Patients with invasive cT1-4M0 breast cancer who have received NAC followed by surgery, per tumour stage; 2012 compared to 2016.
Total NAC % Followed by surgery No NAC %
Primary surgery
BCS Mastectomy
BCS Mastectomy
Fig. 1. aTrends in NAC followed by BCS per tumour stage in patients with cN0 disease; 2012e2016. *N ¼ patients treated with NAC. b. Trends in NAC followed by BCS per tumour stage in patients with nodal involvement; 2012e2016. *N ¼ patients treated with NAC.