Long-term trends in incidence, characteristics and prognosis of screen-detected and interval cancers in women participating in the Dutch breast cancer screening programme

BACKGROUND

No studies are available in which changes over time in characteristics and prognosis of patients with interval breast cancers (ICs) and screen-detected breast cancers (SDCs) have been compared. The aim was to study these trends between 1995 and 2018.

METHODS

All women with invasive SDCs (N = 4290) and ICs (N = 1352), diagnosed in a southern mammography screening region in the Netherlands, were included and followed until date of death or 31 December 2022.

RESULTS

The 5-year overall survival rate of women with SDCs increased from 91.4% for those diagnosed in 1995-1999 to 95.0% for those diagnosed in 2013-2018 (P < 0.001), and from 74.8 to 91.6% (P < 0.001) in the same periods for those with ICs. A similar trend was observed for the 10-year survival rates. After adjustment for changes in tumour characteristics, the hazard ratio (HR) for overall survival was 0.47 (95% confidence interval (CI): 0.38-0.59) for women with SDCs diagnosed in the period 2013-2018, compared to the women diagnosed in the period 1995-1999. For the women with ICs this HR was 0.27 (95% CI: 0.19-0.40).

CONCLUSION

The prognosis of women with ICs has improved rapidly since 1995 and is now almost similar to that of women with SDCs.

De-escalation of axillary treatment in the event of a positive sentinel lymph node biopsy in cT1-2 N0 breast cancer treated with mastectomy: nationwide registry study (BOOG 2013-07)

BACKGROUND

Trials have demonstrated the safety of omitting completion axillary lymph node dissection in patients with cT1-2 N0 breast cancer operated with breast-conserving surgery who have limited metastatic burden in the sentinel lymph node. The aim of this registry study was to provide insight into the oncological safety of omitting completion axillary treatment in patients operated with mastectomy who have limited-volume sentinel lymph node metastasis.

METHODS

Women diagnosed in 2013-2014 with unilateral cT1-2 N0 breast cancer treated with mastectomy, with one to three sentinel lymph node metastases (pN1mi-pN1a), were identified from the Netherlands Cancer Registry, and classified by axillary treatment: no completion axillary treatment, completion axillary lymph node dissection, regional radiotherapy, or completion axillary lymph node dissection followed by regional radiotherapy. The primary endpoint was 5-year regional recurrence rate. Secondary endpoints included recurrence-free interval and overall survival, among others.

RESULTS

In total, 1090 patients were included (no completion axillary treatment, 219 (20.1%); completion axillary lymph node dissection, 437 (40.1%); regional radiotherapy, 327 (30.0%); completion axillary lymph node dissection and regional radiotherapy, 107 (9.8%)). Patients in the group without completion axillary treatment had more favourable tumour characteristics and were older. The overall 5-year regional recurrence rate was 1.3%, and did not differ significantly between the groups. The recurrence-free interval was also comparable among groups. The group of patients who did not undergo completion axillary treatment had statistically significantly worse 5-year overall survival, owing to a higher percentage of non-cancer deaths.

CONCLUSION

In this registry study of patients with cT1-2 N0 breast cancer treated with mastectomy, with low-volume sentinel lymph node metastasis, the 5-year regional recurrence rate was low and comparable between patients with and without completion axillary treatment.

Predictors of re-attendance at biennial screening mammography following a false positive referral: A study among women in the south of the Netherlands

AIM

A false positive (FP) referral after screening mammography may influence a woman's likelihood to re-attend the screening program. The impact of having a FP result in the first or subsequent screening round on re-attendance after a FP result was investigated. In addition, we aimed to study differences in re-attendance rates between women who underwent non-invasive and invasive additional examinations as part of the diagnostic work-up following a FP referral.

METHODS

A consecutive series of 13,597 women with a FP referral following biennial screening mammography in the south of the Netherlands between 2009 and 2019 was included.

RESULTS

The screening re-attendance rate was 81.2% after a FP referral, and 91.3% when also including women who had clinical mammographic follow-up. Women who received a FP referral in the first screening round were less likely to re-attend the screening programme in the following three years, compared to those with a FP test in any subsequent round (odds ratio (OR): 0.59, 95%-confidence interval (CI): 0.51-0.69). Women with a FP referral who underwent invasive examinations after referral were less likely to re-attend the screening programme than those who only received additional imaging (OR, 0.48; 95% CI 0.36-0.64).

CONCLUSION

Women with a FP referral are less likely to re-attend the screening programme if this referral occurs at their first screening round or when they undergo invasive diagnostic workup. Hospitals and screening organizations should prioritize informing women about the importance of re-attending the programme following a FP referral.

Evaluation of the Implementation of the Dutch Breast Cancer Surveillance Decision Aid including Personalized Risk Estimates in the SHOUT-BC Study: A Mixed Methods Approach

BACKGROUND

To improve Shared decision-making (SDM) regarding personalized post-treatment surveillance, the Breast Cancer Surveillance Decision Aid (BCS-PtDA), integrating personalized risk information, was developed and implemented in eight hospitals. The aim of this mixed-methods study was to (1) assess the implementation and participation rates, (2) identify facilitators and barriers for use by health care professionals (HCPs), (3) quantify the observed level of SDM, and (4) evaluate risk communication and SDM application in consultations.

METHODS

Implementation and participation rates and patients' BCS-PtDA use were calculated using hospital registry data and BCS-PtDA log data. HCPs' perspective on facilitators and barriers were collected using the MIDI framework. Observed SDM levels in consultation transcripts were quantified using the OPTION-5 scale. Thematic analysis was performed to assess consultation content.

RESULTS

The average PtDA implementation and participation rates were, respectively, 26% and 61%. HCPs reported that the PtDA supported choice awareness. Reported barriers for implementation were mainly increased workload and a lack of perceived benefits. The consultation analysis (n = 64) showed patients were offered a choice, but deliberation was lacking. Risk communication was generally adequate.

DISCUSSION

When the BCS-PtDA was used, patients were clearly given a choice regarding their post-treatment surveillance, but information provision and SDM application can be improved.

Quality assurance of radiation therapy after breast-conserving surgery among patients in the BOOG 2013-08 trial

BACKGROUND AND PURPOSE

In the BOOG 2013-08 trial (NCT02271828), cT1-2N0 breast cancer patients were randomized between breast conserving surgery with or without sentinel lymph node biopsy (SLNB) followed by whole breast radiotherapy (WBRT). While awaiting primary endpoint results (axillary recurrence rate), this study aims to perform a quality assurance analysis on protocol adherence and (incidental) axillary radiation therapy (RT) dose.

MATERIALS AND METHODS

Patients were enrolled between 2015 and 2022. Data on prescribed RT and (in 25% of included patients) planning target volumes (PTV) parameters were recorded for axillary levels I-IV and compared between treatment arms. Multivariable linear regression analysis was performed to determine prognostic variables for incidental axillary RT dose.

RESULTS

1,439/1,461 included patients (98.5%) were treated according to protocol and 87 patients (5.9%) received regional RT (SLNB 10.9%, no-SLNB 1.5 %). In 326 patients included in the subgroup analysis, the mean incidental PTV dose at axilla level I was 59.5% of the prescribed breast RT dose. In 5 patients (1.5%) the mean PTV dose at level I was ≥95% of the prescribed breast dose. No statistically or clinically significant differences regarding incidental axillary RT dose were found between treatment arms. Tumour bed boost (yes/no) was associated with a higher incidental mean dose in level I (R2 = 0.035, F(6, 263) = 1.532, p 0.168).

CONCLUSION

The results indicate that RT-protocol adherence was high, and that incidental axillary RT dose was low in the BOOG 2013-08 trial. Potential differences between treatmentarms regarding the primary endpoint can thus not be attributed to different axillary radiation doses.

Gene expression profiles in clinically T1-2N0 ER+HER2- breast cancer patients treated with breast-conserving therapy: their added value in case sentinel lymph node biopsy is not performed

PURPOSE

Omitting sentinel lymph node biopsy (SLNB) in breast cancer treatment results in patients with unknown positive nodal status and potential risk for systemic undertreatment. This study aimed to investigate whether gene expression profiles (GEPs) can lower this risk in cT1-2N0 ER+ HER2- breast cancer patients treated with BCT.

METHODS

Patients were included if diagnosed between 2011 and 2017 with cT1-2N0 ER+ HER2- breast cancer, treated with BCT and SLNB, and in whom GEP was applied. Adjuvant chemotherapy recommendations based on clinical risk status (Dutch breast cancer guideline of 2020 versus PREDICT v2.1) with and without knowledge on SLNB outcome were compared to GEP outcome. We examined missing adjuvant chemotherapy indications, and the number of GEPs needed to identify one patient at risk for systemic undertreatment.

RESULTS

Of 3585 patients, 2863 (79.9%) had pN0 and 722 (20.1%) pN + disease. Chemotherapy was recommended in 1354 (37.8% guideline-2020) and 1888 patients (52.7% PREDICT). Eliminating SLNB outcome (n = 722) resulted in omission of chemotherapy recommendation in 475 (35.1% guideline-2020) and 412 patients (21.8% PREDICT). GEP revealed genomic high risk in 126 (26.5% guideline-2020) and 82 patients (19.9% PREDICT) in case of omitted chemotherapy recommendation in the absence of SLNB. Extrapolated to the whole group, this concerns 3.5% and 2.3%, respectively, resulting in the need for 28-44 GEPs to identify one patient at risk for systemic undertreatment.

CONCLUSION

If no SLNB is performed, clinical risk status according to the guideline of 2020 and PREDICT predicts a very low risk for systemic undertreatment. The number of GEPs needed to identify one patient at risk for undertreatment does not justify its standard use.

Trends in the pre-operative diagnosis and surgical management of axillary lymph node metastases in women with screen-detected breast cancer

AIM

The aim of the current study was to investigate time-trends in pre-operative diagnosis and surgical treatment of axillary lymph node metastases in breast cancers detected at screening mammography.

METHODS

We included all women who underwent screening mammography in the South of the Netherlands between 2005 and 2020. During a follow-up period of at least two years, data on clinical radiological examinations, biopsy procedures and surgical interventions were obtained. The 15 years of inclusion were divided into five cohorts of three years each.

RESULTS

Of the 4049 women with invasive breast cancer, 22.1 % (896/4049) had axillary lymph node metastasis at pathology (ALN+). Percutaneous axillary biopsy was performed in 39.6 % (355/896) of these women, with the proportions of fine needle aspiration biopsy (FNAB) decreasing from 97.6 % (40/41) in 2005-2007 to 41.6 % (37/89) in 2017-2019 and core needle biopsy (CNB) rising from 2.4 % (1/41) in 2005-2007 to 58.4 % (52/89) in 2017-2019 (P < 0.001). Sensitivity of FNAB and CNB was comparable (77.4 % (188/243, 95%CI = 71%-82 %) versus 82.4 % (103/125), 95%CI = 74%-88 %) (P = 0.26). Pre-operative confirmation of ALN + by percutaneous biopsy ranged from 27.3 % (56/205) in 2011-2013 to 39.0 % (80/205) in 2017-2019, with no significant trend changes over time (P = 0.103). The proportion of ALN + women who underwent axillary lymph node dissection (ALND) decreased from 96.0 % (97/101) in 2005-2007 to 16.6 % (34/205) in 2017-2019 (P < 0.001).

CONCLUSION

Pre-operative confirmation of axillary lymph node metastasis by ultrasound-guided biopsy did not rise despite the increased use of CNB at the expense of less invasive FNAB. A significant reduction in ALND was observed through the years.

Impact of the COVID-19 pandemic on breast cancer incidence and tumor stage in the Netherlands and Norway: A population-based study

BACKGROUND

Comparing the impact of the COVID-19 pandemic on the incidence of newly diagnosed breast tumors and their tumor stage between the Netherlands and Norway will help us understand the effect of differences in governmental and social reactions towards the pandemic.

METHODS

Women newly diagnosed with breast cancer in 2017-2021 were selected from the Netherlands Cancer Registry and the Cancer Registry of Norway. The crude breast cancer incidence rate (tumors per 100,000 women) during the first (March-September 2020), second (October 2020-April 2021), and Delta COVID-19 wave (May-December 2021) was compared with the incidence rate in the corresponding periods in 2017, 2018, and 2019. Incidence rates were stratified by age group, method of detection, and clinical tumor stage.

RESULTS

During the first wave breast cancer incidence declined to a larger extent in the Netherlands than in Norway (27.7% vs. 17.2% decrease, respectively). In both countries, incidence decreased in women eligible for screening. In the Netherlands, incidence also decreased in women not eligible for screening. During the second wave an increase in the incidence of stage IV tumors in women aged 50-69 years was seen in the Netherlands. During the Delta wave an increase in overall incidence and incidence of stage I tumors was seen in Norway.

CONCLUSION

Alterations in breast cancer incidence and tumor stage seem related to a combined effect of the suspension of the screening program, health care avoidance due to the severity of the pandemic, and other unknown factors.

Needs and preferences of breast cancer survivors regarding outcome-based shared decision-making about personalised post-treatment surveillance

PURPOSE

In this study, we explored how patients experience current information provision and decision-making about post-treatment surveillance after breast cancer. Furthermore, we assessed patients' perspectives regarding less intensive surveillance in case of a low risk of recurrence.

METHODS

We conducted semi-structured interviews with 22 women in the post-treatment surveillance trajectory in seven Dutch teaching hospitals.

RESULTS

Although the majority of participants indicated a desire for shared decision-making (SDM) about post-treatment surveillance, participants experienced no SDM. Information provision was often suboptimal and unstructured. Participants were open for using risk information in decision-making, but hesitant towards less intensive surveillance. Perceived advantages of less intensive surveillance were: less distressing moments, leaving the patient role behind, and lower burden. Disadvantages were: fewer moments for reassurance, fear of missing recurrences, and a higher threshold for aftercare for side effects.

CONCLUSIONS

SDM about post-treatment surveillance is desirable. Although women are hesitant about less intensive surveillance, they are open to the use of personalised risk assessment for recurrences in decision-making about surveillance.

IMPLICATIONS FOR CANCER SURVIVORS

To facilitate SDM about post-treatment surveillance, the timing and content of information provision should be improved. Risk information should be provided in an accessible and understandable way. Moreover, fear of cancer recurrence and other personal considerations should be addressed in the process of SDM.

The QUILT study: quilting sutures in patients undergoing breast cancer surgery: a stepped wedge cluster randomized trial study

BACKGROUND

Seroma is the most common complication following breast cancer surgery, with reported incidence up to 90%. Seroma causes patient discomfort, is associated with surgical site infections (SSI), often requires treatment and increases healthcare consumption. The quilting suture technique, in which the skin flaps are sutured to the pectoralis muscle, leads to a significant reduction of seroma with a decrease in the number of aspirations and surgical site infections. However, implementation is lagging due to unknown side effects, increase in operation time and cost effectiveness. Main objective of this study is to assess the impact of large scale implementation of the quilting suture technique in patients undergoing mastectomy and/or axillary lymph node dissection (ALND).

METHODS

The QUILT study is a stepped wedge design study performed among nine teaching hospitals in the Netherlands. The study consists of nine steps, with each step one hospital will implement the quilting suture technique. Allocation of the order of implementation will be randomization-based. Primary outcome is 'textbook outcome', i.e.no wound complications, no re-admission, re-operation or unscheduled visit to the outpatient clinic and no increased use of postoperative analgesics. A total of 113 patients is required based on a sample size calculation. Secondary outcomes are shoulder function, cosmetic outcome, satisfaction with thoracic wall and health care consumption. Follow-up lasts for 6 months.

DISCUSSION

This will be one of the first multicentre prospective studies in which quilting without postoperative wound drain is compared with conventional wound closure. We hypothesize that quilting is a simple technique to increase textbook outcome, enhance patient comfort and reduce health care consumption.

Effect of different quilting techniques on seroma formation after breast surgery: retrospective study

BACKGROUND

Quilting, a technique in which skin flaps are sutured to the underlying muscle, reduces seroma after mastectomy and/or axillary lymph node dissection. The aim of this study was to assess the effect of different quilting techniques on the formation of clinically significant seroma.

METHODS

This was a retrospective study including patients undergoing mastectomy and/or axillary lymph node dissection. Four breast surgeons applied the quilting technique based on their own discretion. Technique 1 was performed using Stratafix in 5-7 rows placed at 2-3 cm distance. Technique 2 was performed using Vicryl 2-0 in 4-8 rows placed at 1.5-2 cm distance. Technique 3 was performed using Vicryl 0/1 in 3 rows placed at 3-4 cm distance. Technique 4 was performed using Vicryl 0 in 4-5 rows placed at 1.5 cm distance. The primary outcome was clinically significant seroma.

RESULTS

A total of 445 patients were included. Clinically significant seroma incidence was 4.1 per cent (six of 147) for technique 1, which was significantly lower than that for the other techniques (25.0 per cent (29 of 116), 29.4 per cent (32 of 109), and 33 per cent (24 of 73) for techniques 2, 3, and 4 (P < 0.001) respectively). The duration of surgery was not significantly longer for technique 1 compared with the other three techniques. The length of hospital stay, number of additional visits to the outpatient clinic, and reoperations did not differ significantly between the four techniques.

CONCLUSION

Quilting using Stratafix and placing 5-7 rows with 2-3 cm distance between the stitches associates with low clinically significant seroma incidence without adverse effects.

Failure of stereotactic core needle biopsy in women recalled for suspicious calcifications at screening mammography: frequency, causes, and final outcome in a multi-institutional, observational follow-up study

OBJECTIVES

We determined the failure rate of stereotactic core needle biopsy (SCNB) and its causes and final outcome in women recalled for calcifications at screening mammography.

METHODS

We included a consecutive series of 624,039 screens obtained in a Dutch screening region between January 2009 and July 2019. Radiology reports and pathology results were obtained of all recalled women during 2-year follow-up.

RESULTS

A total of 3495 women (19.6% of 17,809 recalls) were recalled for suspicious calcifications. SCNB was indicated in 2818 women, of whom 12 had incomplete follow-up and another 12 women refused biopsy. DCIS or invasive cancer was diagnosed in 880 of the remaining 2794 women (31.5%). SCNB failed in 62 women (2.2%, 36/2794). These failures were mainly due to a too posterior (n = 30) or too superficial location (n = 17) of the calcifications or calcifications too faint for biopsy (n = 13). Of these 62 women, 10 underwent surgical biopsy, yielding one DCIS (intermediate grade) and two invasive cancers (one intermediate grade and one high grade) and another two women were diagnosed with DCIS (both high grade) at follow-up. Thus, the malignancy rate after SCNB failure was 8.1% (5/62). Calcifications were depicted neither at SCNB specimen radiography nor at pathology in 16 women after (repeated) SCNB (0.6%, 31/2732). None of them proved to have breast cancer at 2-year follow-up.

CONCLUSIONS

The failure rate of SCNB for suspicious calcifications is low but close surveillance is warranted, as breast cancer may be present in up to 8% of these women.

KEY POINTS

• The failure rate of stereotactic core needle biopsy (SCNB) for calcifications recalled at screening mammography was 2.2%. • Failures were mainly due to calcifications that could not be reached by SCNB or calcifications too faint for biopsy. • The management after failed SCNB was various. At least, close surveillance with a low threshold for surgical biopsy is recommended as breast cancer may be present in up to 8% of women with SCNB failure.

De-escalation of radiotherapy after primary chemotherapy in cT1-2N1 breast cancer (RAPCHEM; BOOG 2010-03): 5-year follow-up results of a Dutch, prospective, registry study

BACKGROUND

Primary chemotherapy in breast cancer poses a dilemma with regard to adjuvant locoregional radiotherapy, as guidelines for locoregional radiotherapy were originally based on pathology results of primary surgery. We aimed to evaluate the oncological safety of de-escalated locoregional radiotherapy in patients with cT1-2N1 breast cancer treated with primary chemotherapy, according to a predefined, consensus-based study guideline.

METHODS

In this prospective registry study (RAPCHEM, BOOG 2010-03), patients referred to one of 17 participating radiation oncology centres in the Netherlands between Jan 1, 2011, and Jan 1, 2015, with cT1-2N1 breast cancer (one to three suspicious nodes on imaging before primary chemotherapy, of which at least one had been pathologically confirmed), and who were treated with primary chemotherapy and surgery of the breast and axilla were included in the study. The study guideline comprised three risk groups for locoregional recurrence, with corresponding locoregional radiotherapy recommendations: no chest wall radiotherapy and no regional radiotherapy in the low-risk group, only local radiotherapy in the intermediate-risk group, and locoregional radiotherapy in the high-risk group. Radiotherapy consisted of a biologically equivalent dose of 25 fractions of 2 Gy, with or without a boost. During the study period, the generally applied radiotherapy technique in the Netherlands was forward-planned or inverse-planned intensity modulated radiotherapy. 5-year follow-up was assessed, taking into account adherence to the study guideline, with locoregional recurrence rate as primary endpoint. We hypothesised that 5-year locoregional recurrence rate would be less than 4% (upper-limit 95% CI 7·8%). This study was registered at ClinicalTrials.gov, NCT01279304, and is completed.

FINDINGS

838 patients were eligible for 5-year follow-up analyses: 291 in the low-risk group, 370 in the intermediate-risk group, and 177 in the high-risk group. The 5-year locoregional recurrence rate in all patients was 2·2% (95% CI 1·4-3·4). The 5-year locoregional recurrence rate was 2·1% (0·9-4·3) in the low-risk group, 2·2% (1·0-4·1) in the intermediate-risk group, and 2·3% (0·8-5·5) in the high-risk group. If the study guideline was followed, the locoregional recurrence rate was 2·3% (0·8-5·3) for the low-risk group, 1·0% (0·2-3·4) for the intermediate-risk group, and 1·4% (0·3-4·5) for the high-risk group.

INTERPRETATION

In this study, the 5-year locoregional recurrence rate was less than 4%, which supports our hypothesis that it is oncologically safe to de-escalate locoregional radiotherapy based on locoregional recurrence risk, in selected patients with cT1-2N1 breast cancer treated with primary chemotherapy, according to this predefined, consensus-based study guideline.

FUNDING

Dutch Cancer Society.

TRANSLATION

For the Dutch translation of the abstract see Supplementary Materials section.

Relations between recurrence risk perceptions and fear of cancer recurrence in breast cancer survivors

PURPOSE

This study aimed to: (1) determine the accuracy of Dutch breast cancer survivors' estimations of the locoregional recurrence risk (LRR); (2) examine which variables influence (the accuracy of) risk estimations, and risk appraisals; and (3) investigate the influence of the objective LRR risk (estimated using the INFLUENCE-nomogram), risk estimations and risk appraisals on fear of cancer recurrence (FCR). Findings of this study will inform clinicians on risk communication and can improve communication about FCR.

METHODS

In a cross-sectional survey among 258 breast cancer survivors, women's recurrence risk estimations (in odds) and risk appraisals (in high/low), FCR, demographics and illness perceptions, about one year after surgery were measured and compared to the objective risk for LRRs estimated using the INFLUENCE-nomogram.

RESULTS

Half of the women (54%) accurately estimated their LRR risk, 34% underestimated and 13% overestimated their risk. Risk estimations and risk appraisals were only moderately positively correlated (r = 0.58). Higher risk appraisals were associated with radiotherapy (r = 0.18) and having weaker cure beliefs (r = - 0.19). Younger age was associated with overestimation of risk (r = - 0.23). Recurrence risk estimations and risk appraisals were associated with more FCR (r = 0.29, r = 0.39). In regression, only risk appraisal contributed significantly to FCR.

CONCLUSION

Although women were fairly accurate in recurrence risk estimations, it remains difficult to predict over- or underestimation. Recurrence risk estimations and risk appraisal are two different concepts which are both associated with FCR and should therefore be addressed in patient-provider communication.

Effectiveness and implementation of SHared decision-making supported by OUTcome information among patients with breast cancer, stroke and advanced kidney disease: SHOUT study protocol of multiple interrupted time series

INTRODUCTION

Within the value-based healthcare framework, outcome data can be used to inform patients about (treatment) options, and empower them to make shared decisions with their health care professional. To facilitate shared decision-making (SDM) supported by outcome data, a multicomponent intervention has been designed, including patient decision aids on the organisation of post-treatment surveillance (breast cancer); discharge location (stroke) and treatment modality (advanced kidney disease), and training on SDM for health care professionals. The SHared decision-making supported by OUTcome information (SHOUT) study will examine the effectiveness of the intervention and its implementation in clinical practice.

METHODS AND ANALYSIS

Multiple interrupted time series will be used to stepwise implement the intervention. Patients diagnosed with either breast cancer (N=630), stroke (N=630) or advanced kidney disease (N=473) will be included. Measurements will be performed at baseline, three (stroke), six and twelve (breast cancer and advanced kidney disease) months. Trends on outcomes will be measured over a period of 20 months. The primary outcome will be patients' perceived level of involvement in decision-making. Secondary outcomes regarding effectiveness will include patient-reported SDM, decisional conflict, role in decision-making, knowledge, quality of life, preferred and chosen care, satisfaction with the intervention, healthcare utilisation and health outcomes. Outcomes regarding implementation will include the implementation rate and a questionnaire on the health care professionals' perspective on the implementation process.

ETHICS AND DISSEMINATION

The Medical research Ethics Committees United in Nieuwegein, the Netherlands, has confirmed that the Medical Research Involving Human Subjects Act does not apply to this study. Bureau Onderzoek & Innovatie of Santeon, the Netherlands, approved this study. The results will contribute to insight in and knowledge on the use of outcome data for SDM, and can stimulate sustainable implementation of SDM.

TRIAL REGISTRATION NUMBER

NL8374, NL8375 and NL8376.

Health care professionals' perspectives on shared decision making supported by personalised‐risk‐for‐recurrences‐calculations regarding surveillance after breast cancer

Objective

Breast cancer patients for whom less intensive surveillance is sufficient can be identified based on the risk for locoregional recurrences (LRRs). This study explores health care professionals' (HCPs) perspectives on less intensive surveillance, preferences for shared decision‐making (SDM) about surveillance and perspectives on the use of patients' estimated personal risk for LRRs in decision‐making about surveillance.

Methods

We conducted semi‐structured interviews with 21 HCPs providing follow‐up care for breast cancer patients in seven Dutch teaching hospitals (Santeon hospitals).

Results

HCPs were predominantly positive about less intensive surveillance for women with a low risk for recurrences. They mentioned important prerequisites such as clearly defined surveillance schedules based on risk categories, information provision and communication support for patients and HCPs. Most HCPs supported SDM about surveillance and were positive about using patients' estimated personal risk for LRRs. HCPs specified prerequisites such as clear visualisation and explanation of risk information, attention for fear of cancer recurrence (FCR) and defined surveillance schedules for specific risk groups.

Conclusion

Mentioned prerequisites for less intensive surveillance need to be accounted for. Information needs and existing misconceptions need to be addressed. Outcome information regarding risks for LRRs and FCR can enrich the SDM process about surveillance.

Using Guideline-Based Clinical Decision Support in Oncological Multidisciplinary Team Meetings: A Prospective, Multicenter Concordance Study

Background

Multidisciplinary team meetings formulate guideline-based individual treatment plans based on patient and disease characteristics and motivate reasons for deviation. Clinical decision trees could support multidisciplinary teams to adhere more accurately to guidelines. Every clinical decision tree is tailored to a specific decision moment in a care pathway and is composed of patient and disease characteristics leading to a guideline recommendation.

Objective

This study investigated (1) the concordance between multidisciplinary team and clinical decision tree recommendations and (2) the completeness of patient and disease characteristics available during multidisciplinary team meetings to apply clinical decision trees such that it results in a guideline recommendation.

Methods

This prospective, multicenter, observational concordance study evaluated 17 selected clinical decision trees, based on the prevailing Dutch guidelines for breast, colorectal and prostate cancers. In cases with sufficient data, concordance between multidisciplinary team and clinical decision tree recommendations was classified as concordant, conditional concordant (multidisciplinary team specified a prerequisite for the recommendation) and non-concordant.

Results

Fifty-nine multidisciplinary team meetings were attended in 8 different hospitals, and 355 cases were included. For 296 cases (83.4%), all patient data were available for providing an unconditional clinical decision tree recommendation. In 59 cases (16.6%), insufficient data were available resulting in provisional clinical decision tree recommendations. From the 296 successfully generated clinical decision tree recommendations, the multidisciplinary team recommendations were concordant in 249 (84.1%) cases, conditional concordant in 24 (8.1%) cases and non-concordant in 23 (7.8%) cases of which in 7 (2.4%) cases the reason for deviation from the clinical decision tree generated guideline recommendation was not motivated.

Conclusion

The observed concordance of recommendations between multidisciplinary teams and clinical decision trees and data completeness during multidisciplinary team meetings in this study indicate a potential role for implementation of clinical decision trees to support multidisciplinary team decision-making.

Quilting following mastectomy reduces seroma, associated complications and health care consumption without impairing patient comfort

Background

An important complication following mastectomy is seroma formation. Quilting, in which skin flaps are sutured to the underlying muscle, is reported to reduce seroma incidence, but might induce pain and impair shoulder function. Main objective is to compare quilting with conventional wound closure, regarding seroma incidence, health care consumption, and patient discomfort.

Methods

In a combined prospective and retrospective study, 254 patients undergoing mastectomy and/or axillary lymph node dissection (ALND) were included. Patients received quilting sutures or conventional closure. Primary outcome was clinical significant seroma (CSS). In prospectively included patients shoulder function and analgesic use was observed.

Results

CSS incidence was 12.9% in the quilted versus 62.3% in the nonquilted cohort (p < 0.001). Surgical site infections were reported significantly less in the quilted cohort. Duration of hospital stay was shorter and outpatient clinic visits were less in the quilted cohort. Surgical procedure required 10 additional minutes for quilting. No significant differences were observed in postoperative shoulder function and analgesic use.

Conclusion

Quilting following mastectomy reduces CSS incidence. Quilting requires 10 additional minutes during surgery. It facilitates day treatment and results in less additional outpatient clinic visits culminating in reduced health care consumption. Shoulder function and pain are not affected by quilting.

Follow-up after breast cancer: Variations, best practices, and opportunities for improvement according to health care professionals

Objective

Follow‐up after breast cancer can be divided into surveillance and aftercare. It remains unclear how follow‐up can ideally be organised from the perspective of health care professionals (HCPs). The aim of this study was to gain insight in the organisation of follow‐up in seven Dutch teaching hospitals and to identify best practices and opportunities for improvement of breast cancer (all stages) follow‐up as proposed by HCPs.

Methods

Semi‐structured in‐depth group interviews were performed, one in each of the participating hospitals, with in total 16 HCPs and 2 patient advocates. To describe the organisation of follow‐up, transcripts were analysed using a deductive approach. Best practices and opportunities were derived using an inductive approach.

Results

Variation was found in the organisation of aftercare, especially in timing, frequency, and disciplines of involved HCPs. Less variation was observed for surveillance, which was guided by the national guideline. Best practices focused on case management and adequate collaboration between HCPs of different disciplines. Mentioned opportunities were improving the structured monitoring of patients' needs and a comprehensive guideline for organisation and content of aftercare.

Conclusions

Variation in follow‐up existed between hospitals. Shared decision‐making (SDM) about surveillance is desirable to ensure that surveillance matches the patient needs, preferences, and personal risk for recurrences.

Impact of the COVID-19 pandemic on diagnosis, stage, and initial treatment of breast cancer in the Netherlands: a population-based study

BACKGROUND

The onset of the COVID-19 pandemic forced the Dutch national screening program to a halt and increased the burden on health care services, necessitating the introduction of specific breast cancer treatment recommendations from week 12 of 2020. We aimed to investigate the impact of COVID-19 on the diagnosis, stage and initial treatment of breast cancer.

METHODS

Women included in the Netherlands Cancer Registry and diagnosed during four periods in weeks 2-17 of 2020 were compared with reference data from 2018/2019 (averaged). Weekly incidence was calculated by age group and tumor stage. The number of women receiving initial treatment within 3 months of diagnosis was calculated by period, initial treatment, age, and stage. Initial treatment, stratified by tumor behavior (ductal carcinoma in situ [DCIS] or invasive), was analyzed by logistic regression and adjusted for age, socioeconomic status, stage, subtype, and region. Factors influencing time to treatment were analyzed by Cox regression.

RESULTS

Incidence declined across all age groups and tumor stages (except stage IV) from 2018/2019 to 2020, particularly for DCIS and stage I disease (p < 0.05). DCIS was less likely to be treated within 3 months (odds ratio [OR]wks2-8: 2.04, ORwks9-11: 2.18). Invasive tumors were less likely to be treated initially by mastectomy with immediate reconstruction (ORwks12-13: 0.52) or by breast conserving surgery (ORwks14-17: 0.75). Chemotherapy was less likely for tumors diagnosed in the beginning of the study period (ORwks9-11: 0.59, ORwks12-13: 0.66), but more likely for those diagnosed at the end (ORwks14-17: 1.31). Primary hormonal treatment was more common (ORwks2-8: 1.23, ORwks9-11: 1.92, ORwks12-13: 3.01). Only women diagnosed in weeks 2-8 of 2020 experienced treatment delays.

CONCLUSION

The incidence of breast cancer fell in early 2020, and treatment approaches adapted rapidly. Clarification is needed on how this has affected stage migration and outcomes.

The Impact of Preoperative Breast MRI on Surgical Margin Status in Breast Cancer Patients Recalled at Biennial Screening Mammography: An Observational Cohort Study

Background

This study aimed to examine the association between preoperative magnetic resonance imaging (MRI) and surgical margin involvement, as well as to determine the factors associated with positive resection margins in screen-detected breast cancer patients undergoing breast-conserving surgery (BCS).

Methods

Breast cancer patients eligible for BCS and diagnosed after biennial screening mammography in the south of The Netherlands (2008–2017) were retrospectively included. Missing values were imputed and multivariable regression analyses were performed to analyze whether preoperative MRI was related to margin involvement after BCS, as well as to examine what factors were associated with positive resection margins, defined as more than focally (>4 mm) involved.

Results

Overall, 2483 patients with invasive breast cancer were enrolled, of whom 123 (5.0%) had more than focally involved resection margins. In multivariable regression analyses, preoperative MRI was associated with a reduced risk of positive resection margins after BCS (adjusted odds ratio [OR] 0.56, 95% confidence interval [CI] 0.33–0.96). Lobular histology (adjusted OR 2.86, 95% CI 1.68–4.87), large tumor size (per millimeter increase, adjusted OR 1.05, 95% CI 1.03–1.07), high (>75%) mammographic density (adjusted OR 3.61, 95% CI 1.07–12.12), and the presence of microcalcifications (adjusted OR 4.45, 95% CI 2.69–7.37) and architectural distortions (adjusted OR 1.85, 95% CI 1.01–3.40) were independently associated with positive resection margins after BCS.

Conclusions

Preoperative MRI was associated with lower risk of positive resection margins in patients with invasive breast cancer eligible for BCS using multivariable analysis. Furthermore, specific mammographic characteristics and tumor characteristics were independently associated with positive resection margins after BCS.

Conditional local recurrence risk: the effect of event-free years in different subtypes of breast cancer

Background

After breast cancer treatment, follow-up consists of physical examination and mammography for at least 5 years, to detect local and regional recurrence. The risk of recurrence may decrease after event-free time. This study aims to determine the risk of local recurrence (LR) as a first event until 5 years after diagnosis, conditional on being event-free for 1, 2, 3 and 4 years.

Methods

From the Netherlands Cancer Registry, all M0 breast cancers diagnosed between 2005 and 2008 were included. LR risk was calculated with Kaplan–Meier analysis, overall and for different subtypes. Conditional LR (assuming x event-free years) was determined by selecting event-free patients at x years, and calculating their LR risk within 5 years after diagnosis.

Results

Five-year follow-up was available for 34,453 patients. Overall, five-year LR as a first event occurred in 3.0%. This risk varied for different subtypes and was highest for triple negative (6.8%) and lowest for ER+PR+Her2− (2.2%) tumors. After 1, 2, 3 and 4 event-free years, the average risk of LR before 5 years after diagnosis decreased from 3.0 to 2.4, 1.6, 1.0, and 0.6%. The risk decreased in all subtypes, the effect was most pronounced in subtypes with the highest baseline risk (ER−Her2+ and triple negative breast cancer). After three event-free years, LR risk in the next 2 years was 1% or less in all subtypes except triple negative (1.6%).

Conclusion

The risk of 5-year LR as a first event was low and decreased with the number of event-free years. After three event-free years, the overall risk was 1%. This is reassuring to patients and also suggests that follow-up beyond 3 years may produce low yield of LR, both for individual patients and studies using LR as primary outcome. This can be used as a starting point to tailor follow-up to individual needs.

Improved risk estimation of locoregional recurrence, secondary contralateral tumors and distant metastases in early breast cancer: the INFLUENCE 2.0 model

PURPOSE

To extend the functionality of the existing INFLUENCE nomogram for locoregional recurrence (LRR) of breast cancer toward the prediction of secondary primary tumors (SP) and distant metastases (DM) using updated follow-up data and the best suitable statistical approaches.

METHODS

Data on women diagnosed with non-metastatic invasive breast cancer were derived from the Netherlands Cancer Registry (n = 13,494). To provide flexible time-dependent individual risk predictions for LRR, SP, and DM, three statistical approaches were assessed; a Cox proportional hazard approach (COX), a parametric spline approach (PAR), and a random survival forest (RSF). These approaches were evaluated on their discrimination using the Area Under the Curve (AUC) statistic and on calibration using the Integrated Calibration Index (ICI). To correct for optimism, the performance measures were assessed by drawing 200 bootstrap samples.

RESULTS

Age, tumor grade, pT, pN, multifocality, type of surgery, hormonal receptor status, HER2-status, and adjuvant therapy were included as predictors. While all three approaches showed adequate calibration, the RSF approach offers the best optimism-corrected 5-year AUC for LRR (0.75, 95%CI: 0.74-0.76) and SP (0.67, 95%CI: 0.65-0.68). For the prediction of DM, all three approaches showed equivalent discrimination (5-year AUC: 0.77-0.78), while COX seems to have an advantage concerning calibration (ICI < 0.01). Finally, an online calculator of INFLUENCE 2.0 was created.

CONCLUSIONS

INFLUENCE 2.0 is a flexible model to predict time-dependent individual risks of LRR, SP and DM at a 5-year scale; it can support clinical decision-making regarding personalized follow-up strategies for curatively treated non-metastatic breast cancer patients.

Comprehensive trends in incidence, treatment, survival and mortality of first primary invasive breast cancer stratified by age, stage and receptor subtype in the Netherlands between 1989 and 2017

Our study aimed to provide a comprehensive overview of trends in incidence, survival, mortality and treatment of first primary invasive breast cancer (BC), according to age, stage and receptor subtype in the Netherlands between 1989 and 2017. Data from all women diagnosed with first primary stage I to IV BC (N = 320 249) were obtained from the Netherlands Cancer Registry. BC mortality and general population data were retrieved from Statistics Netherlands. Age-standardised incidence and mortality rates were calculated with annual percentage change (APC) and average annual percentage change (AAPC) statistics. The relative survival (RS) was used as estimator for disease-specific survival. The BC incidence for all BC patients combined significantly increased until 2013 from 126 to 158 per 100 000 person-years, after which a declining trend was observed. Surgery became less extensive, but (neo-)adjuvant systemic treatments and their combinations were given more frequently. The RS improved for all age groups and for most stages and receptor subtypes, but remained stable for all subtypes since 2012 to 2013 and since 2000 to 2009 for Stage IV BC at 15 years of follow-up. Overall, the 5- and 10-year RS increased from 76.8% (95% confidence interval [CI]: 76.1, 77.4) and 55.9% (95% CI: 54.7, 57.1) in 1989 to 1999 to 91.0% (95% CI: 90.5, 91.5) and 82.9% (95% CI: 82.2, 83.5), respectively, in 2010 to 2016. BC mortality improved regardless of age and overall decreased from 57 to 35 per 100 000 person-years between 1989 and 2017. In conclusion, the BC incidence in the Netherlands has steadily increased since 1989, but the latest trends show promising declines. Survival improved markedly for most patients and the mortality decreased regardless of age.

Minimally invasive breast cancer excision using the breast lesion excision system under ultrasound guidance

Purpose

To assess the feasibility of completely excising small breast cancers using the automated, image-guided, single-pass radiofrequency-based breast lesion excision system (BLES) under ultrasound (US) guidance.

Methods

From February 2018 to July 2019, 22 patients diagnosed with invasive carcinomas ≤ 15 mm at US and mammography were enrolled in this prospective, multi-center, ethics board-approved study. Patients underwent breast MRI to verify lesion size. BLES-based excision and surgery were performed during the same procedure. Histopathology findings from the BLES procedure and surgery were compared, and total excision findings were assessed.

Results

Of the 22 patients, ten were excluded due to the lesion being > 15 mm and/or being multifocal at MRI, and one due to scheduling issues. The remaining 11 patients underwent BLES excision. Mean diameter of excised lesions at MRI was 11.8 mm (range 8.0–13.9 mm). BLES revealed ten (90.9%) invasive carcinomas of no special type, and one (9.1%) invasive lobular carcinoma. Histopathological results were identical for the needle biopsy, BLES, and surgical specimens for all lesions. None of the BLES excisions were adequate. Margins were usually compromised on both sides of the specimen, indicating that the excised volume was too small. Margin assessment was good for all BLES specimens. One technical complication occurred (retrieval of an empty BLES basket, specimen retrieved during subsequent surgery).

Conclusions

BLES allows accurate diagnosis of small invasive breast carcinomas. However, BLES cannot be considered as a therapeutic device for small invasive breast carcinomas due to not achieving adequate excision.

Transformation of the National Breast Cancer Guideline Into Data-Driven Clinical Decision Trees

PURPOSE

The essence of guideline recommendations often is intertwined in large texts. This impedes clinical implementation and evaluation and delays timely modular revisions needed to deal with an ever-growing amount of knowledge and application of personalized medicine. The aim of this project was to model guideline recommendations as data-driven clinical decision trees (CDTs) that are clinically interpretable and suitable for implementation in decision support systems.

METHODS

All recommendations of the Dutch national breast cancer guideline for nonmetastatic breast cancer were translated into CDTs. CDTs were constructed by nodes, branches, and leaves that represent data items (patient and tumor characteristics [eg, T stage]), data item values (eg, T2 or less), and recommendations (eg, chemotherapy), respectively. For all data items, source of origin was identified (eg, pathology), and where applicable, data item values were defined on the basis of existing classification and coding systems (eg, TNM, Breast Imaging Reporting and Data System, Systematized Nomenclature of Medicine). All unique routes through all CDTs were counted to measure the degree of data-based personalization of recommendations.

RESULTS

In total, 60 CDTs were necessary to cover the whole guideline and were driven by 114 data items. Data items originated from pathology (49%), radiology (27%), clinical (12%), and multidisciplinary team (12%) reports. Of all data items, 101 (89%) could be classified by existing classification and coding systems. All 60 CDTs could be integrated in an interactive decision support app that contained 376 unique patient subpopulations.

CONCLUSION

By defining data items unambiguously and unequivocally and coding them to an international coding system, it was possible to present a complex guideline as systematically constructed modular data-driven CDTs that are clinically interpretable and accessible in a decision support app.

Reliability of MRI tumor size measurements for minimal invasive treatment selection in small breast cancers

INTRODUCTION

Due to the shift towards minimal invasive treatment, accurate tumor size estimation is essential for small breast cancers. The purpose of this study was to determine the reliability of MRI-based tumor size measurements with respect to clinical, histological and radiomics characteristics in small invasive or in situ carcinomas of the breast to select patients for minimal invasive therapy.

MATERIALS AND METHODS

All consecutive cases of cT1 invasive breast carcinomas that underwent pre-operative MRI, treated in two hospitals between 2005 and 2016, were identified retrospectively from the Dutch cancer registry and cross-correlated with local databases. Concordance between MRI-based measurements and final pathological size was analyzed. The influence of clinical, histological and radiomics characteristics on the accuracy of MRI size measurements were analyzed.

RESULTS

Analysis included 343 cT1 breast carcinomas in 336 patients (mean age, 55 years; range, 25-81 years). Overall correlation of MRI measurements with pathology was moderately strong (ρ = 0.530, P < 0.001), in 42 cases (12.2%) MRI underestimated the size with more than 5 mm. Underestimation occurs more often in grade 2 and grade 3 disease than in low grade invasive cancers. In DCIS the frequency of underestimation is higher than in invasive breast cancer. Unfortunately, none of the patient, imaging or biopsy characteristics appeared predictive for underestimation.

CONCLUSION

Size measurements of small breast cancers on breast MRI are within 5 mm of pathological size in 88% of patients. Nevertheless, underestimation cannot be adequately predicted, particularly for grade 2 and grade 3 tumors, which may hinder patient selection for minimal invasive therapy.

Better survival after surgery of the primary tumor in stage IV inflammatory breast cancer

INTRODUCTION

Information regarding the effects of resection of the primary tumor in stage IV inflammatory breast cancer (IBC) is scarce. We analyzed the impact of resection of the primary tumor on overall survival (OS) in a large stage IV IBC population.

MATERIALS AND METHODS

Patients diagnosed with stage IV IBC between 2005 and 2016 were selected from the Netherlands Cancer Registry, excluding patients without any treatment. To correct for immortal time bias, we performed a landmark analysis including patients alive at least six months after diagnosis. With propensity score matching, patients undergoing surgery of the primary tumor were matched to patients not receiving surgery. Multivariable Cox proportional hazard analyses were performed to determine the association between treatment strategy and OS in the non-matched and matched cohort.

RESULTS

Of the 580 included patients after landmark analysis, 441 patients (76%) received only non-surgical treatments and 139 (24%) underwent surgery (96% mastectomy). Median follow-up was 28.8 and 20.0 months in the surgery and no surgery group, respectively. Surgery in the non-matched cohort was independently associated with better survival (HR0.56[95%CI:0.42-0.75]). In the matched cohort (n = 202), surgically treated patients had improved survival over nonsurgically treated patients (p < 0.005). Multivariable analysis of the matched cohort revealed that surgery was still associated with better survival (HR0.62[95%CI:0.44-0.87]).

CONCLUSION

Although residual confounding and confounding by severity cannot be ruled out, this study suggests that surgery of the primary tumor is associated with improved OS and should be considered as part of the treatment strategy in stage IV IBC.

Accelerated Tissue Processing With Minimal Formalin Fixation Time for 9-Gauge Vacuum-Assisted Breast Biopsy Specimens

Objectives

Vacuum-assisted biopsy (VAB) of the breast seems unsuitable for rapid processing due to large size. We tested microwave-based acceleration.

Methods

As a proof-of-principle study, 9-gauge VAB specimens were taken from eight mastectomy specimens. Forty-two biopsy specimens were processed. Quality of H&E was evaluated in 84 slides, and estrogen receptor (ER), progesterone receptor (PR), E-cadherin, and human epidermal growth factor receptor 2 (HER2) stains were evaluated in six slides. Preoperative biopsy specimens were used as a control.

Results

Diagnostic quality of H&E slides was good in 87%, reasonable in 12%, and low in 1%. Quality of E-cadherin was good in 75% and reasonable in 25%. Quality of ER was good in 83% and reasonable in 17%. PR and both HER2 immunohistochemistry and fluorescence in situ hybridization were good in all slides. Quality of experimental slides was similar to control slides.

Conclusions

Nine-gauge VAB specimens can be processed within 4 hours. Slides are suitable for all routine pathologic stains. This enables a same-day diagnosis.

Metastatic behavior and overall survival according to breast cancer subtypes in stage IV inflammatory breast cancer

BACKGROUND

Distant metastatic disease is frequently observed in inflammatory breast cancer (IBC), with a poor prognosis as a consequence. The aim of this study was to analyze the association of hormone receptor (HR) and human epidermal growth factor receptor-2 (HER2) based breast cancer subtypes in stage IV inflammatory breast cancer (IBC) with preferential site of distant metastases and overall survival (OS).

METHODS

For patients with stage IV IBC, diagnosed in the Netherlands between 2005 and 2016, tumors were classified into four breast cancer subtypes: HR+/HER2-, HR+/HER2+, HR-/HER2+, and HR-/HER2-. Patient, tumor, and treatment characteristics and sites of metastases were compared. OS of the subtypes was compared using Kaplan-Meier curves and the log-rank test. Association between subtype and OS was assessed in multivariable models using logistic regression.

RESULTS

In total, 744 eligible patients were included: 340 (45.7%) tumors were HR+/HER2-, 148 (19.9%) HR-/HER2+, 131 (17.6%) HR+/HER2+, and 125 (16.8%) HR-/HER2-. Bone was the most common metastatic site in all subtypes. A significant predominance of bone metastases was found in HR+/HER2- IBC (71.5%), and liver and lung metastases in the HR-/HER2+ (41.2%) and HR-/HER2- (40.8%) subtypes, respectively. In multivariable analysis, the HR-/HER2- subtype was associated with significantly worse OS as compared to the other subtypes.

CONCLUSION

Breast cancer subtypes in stage IV IBC are associated with distinct patterns of metastatic spread and display notable differences in OS. The use of breast cancer subtypes can guide a more patient-tailored staging directed to metastatic site and extend of disease.

Validation of the online prediction model CancerMath in the Dutch breast cancer population

PURPOSE

CancerMath predicts the expected benefit of adjuvant systemic therapy on overall (OS) and breast cancer-specific survival (BCSS). Here, CancerMath was validated in Dutch breast cancer patients.

METHODS

All operated women diagnosed with stage I-III primary invasive breast cancer in 2005 were identified from the Netherlands Cancer Registry. Calibration was assessed by comparing 5- and 10-year predicted and observed OS/BCSS using χ² tests. A difference > 3% was considered as clinically relevant. Discrimination was assessed by area under the receiver operating characteristic (AUC) curves.

RESULTS

Altogether, 8032 women were included. CancerMath underestimated 5- and 10-year OS by 2.2% and 1.9%, respectively. AUCs of 5- and 10-year OS were both 0.77. Divergence between predicted and observed OS was most pronounced in grade II, patients without positive nodes, tumours 1.01-2.00 cm, hormonal receptor positive disease and patients 60-69 years. CancerMath underestimated 5- and 10-year BCSS by 0.5% and 0.6%, respectively. AUCs were 0.78 and 0.73, respectively. No significant difference was found in any subgroup.

CONCLUSION

CancerMath predicts OS accurately for most patients with early breast cancer although outcomes should be interpreted with care in some subgroups. BCSS is predicted accurately in all subgroups. Therefore, CancerMath can reliably be used in (Dutch) clinical practice.

A systematic review on the use of the breast lesion excision system in breast disease

Purpose

To outline the current status of and provide insight into possible future research on the breast lesion excision system (BLES) as a diagnostic and therapeutic device.

Methods

A systematic search of the literature was performed using PubMed, Embase, and the Cochrane databases to identify relevant studies published between January 2002 and April 2018. Studies were considered eligible for inclusion if they evaluated the diagnostic or therapeutic accuracy or safety of BLES.

Results

Ultimately, 17 articles were included. The reported underestimation rates of atypical ductal hyperplasia and ductal carcinoma in situ (DCIS) ranged from 0 to 14.3% and from 0 to 22.2%, respectively. Complete excision rates for invasive ductal carcinoma and DCIS ranged from 5.3 to 76.3%. Bleeding was the most frequently reported complication (0–11.8%). Device-related complications may arise, with an empty basket being the most common (0.6–3.6%). Thermal damage of the specimen, caused by the use of a radiofrequency cutting wire, was reported in eight of the included studies. Most thermal artifacts were reported as superficial and small (0.1–1.9 mm).

Conclusions

The BLES, an automated, image-guided, single-pass biopsy system for breast lesions using radiofrequency is designed to excise and retrieve an intact tissue specimen. It is an efficient and safe breast biopsy method with acceptable complication rates, which may be used as an alternative to vacuum-assisted biopsies. The variable rate of complete excision raises questions about the possibility to use BLES as a therapeutic device for the excision of small lesions. Further research should focus on this aspect of BLES.

Different statistical techniques dealing with confounding in observational research: measuring the effect of breast-conserving therapy and mastectomy on survival

PURPOSE

Propensity trimming, hierarchical modelling and instrumental variable (IV) analysis are statistical techniques dealing with confounding, cluster-related variation or confounding by severity. This study aimed to explain (dis)advantages of these techniques in estimating the effect of breast-conserving therapy (BCT) and mastectomy on 10-year distant metastasis-free survival (DMFS).

METHODS

All women diagnosed in 2005 with primary T1-2N0-1 breast cancer treated with BCT or mastectomy were selected from the Netherlands Cancer Registry. We used multivariable Cox regression to correct for confounding. Propensity trimming was used to create a more homogeneous population for which the treatment choice was not self-evident. Hospital of surgery was used as hierarchical level to handle hospital-related variation, and as IV to deal with unmeasured confounding.

RESULTS

Multivariable Cox regression showed higher 10-year DMFS for BCT than mastectomy [HR 0.70 (95% CI 0.60-82)]. Propensity trimming on the 10-90th and the 20-80th percentile of the propensity score distribution and hierarchical modelling showed similar HRs. IV analysis showed no significant difference between BCT and mastectomy.

CONCLUSION

Unmeasured confounding is very difficult to eliminate in observational research. We cannot conclude that BCT or mastectomy has a causal relationship with 10-year DMFS. It is crucial to critically evaluate all model's assumptions, and to be careful in drawing firm conclusions.

Ten-year conditional recurrence risks and overall and relative survival for breast cancer patients in the Netherlands: Taking account of event-free years

BACKGROUND

Survival estimates from diagnosis are of limited importance for (ex-)breast cancer patients who survived several years, as it includes information on already deceased patients. This study analysed the 10-year conditional risk of recurrent breast cancer in specific prognostic subgroups. Second, we investigated 10-year conditional overall survival (OS) and relative survival (RS), adjusted for confounding.

PATIENTS AND METHODS

All women diagnosed in 2005 with operated T1-2N0-1 breast cancer were selected from the Netherlands Cancer Registry. Patients were classified into T1N0, T1N1, T2N0 and T2N1 stage. Ten-year conditional recurrence rates were calculated from diagnosis, and for patients without an event (local [LR], regional recurrence [RR], distant metastasis [DM] or death) every year following diagnosis. Ten-year conditional OS was calculated using multivariable Cox regression. RS was estimated by dividing patient survival rates by those of the general Dutch population.

RESULTS

We included 7969 patients: 52.3% had T1N0, 15.3% T1N1, 19.9% T2N0 and 12.5% T2N1 stage. For T1N0, 10-year LR rates changed from 4.6% at diagnosis to 0.5% in year 10. RR rates changed from 2.3% to 0.2%, and DM rates changed from 7.8% to 0.6%. For T2N1 stage, the LR, RR and DM rates changed from 6.2% to 0.8%, 5.2%-0.4% and 19.6%-1.5%, respectively. For the luminal A subtype, LR, RR and DM rates changed from 3.9% to 0.4%, 1.7%-0.5% and 7.3%-1.1%, while for triple negative, these rates changed from 5.6% to 0.7%, 4.9%-0.2% and 16.7%-0%, respectively. Differences between subgroups attenuated over time, and all recurrence rates became ≤1.5% in year 10. Ten-year OS and RS, adjusted for confounding, showed declining risk differences between subgroups over time.

CONCLUSION

Differences in recurrence rates, OS and RS between prognostic subgroups declined as years passed by. These results highlight the importance of taking into account disease-free years to more accurately predict (ex-)breast cancer patients' prognosis over time.

Nationwide population-based study of trends and regional variation in breast-conserving treatment for breast cancer

Background

Landmark trials have shown breast-conserving surgery (BCS) combined with radiotherapy to be as safe as mastectomy in breast cancer treatment. This population-based study aimed to evaluate trends in BCS from 1989 to 2015 in nine geographical regions in the Netherlands.

Methods

All women diagnosed between 1989 and 2015 with primary T1–2 N0–1 breast cancer, treated with BCS or mastectomy, were identified from the Netherlands Cancer Registry. Crude and case mix-adjusted rates of BCS were evaluated and compared between nine Dutch regions for two time intervals: 1989–2002 and 2003–2015. The annual percentage change in BCS per region over time was assessed by means of Joinpoint regression analyses. Explanatory variables associated with the choice of initial surgery were evaluated using multivariable logistic regression.

Results

A total of 202 934 patients were included, 82 200 treated in 1989–2002 and 120 734 in 2003–2015. During 1989–2002, the mean rate of BCS was 50·6 per cent, varying significantly from 39·0 to 71·7 per cent between the nine regions. For most regions, a marked rise in BCS was observed between 2002 and 2003. During 2003–2015, the mean rate of BCS increased to 67·4 per cent, but still varied significantly between regions from 58·5 to 75·5 per cent. A significant variation remained after case-mix correction.

Conclusion

This large nationwide study showed that the use of BCS increased from 1989 to 2015 in the Netherlands. After adjustment for explanatory variables, a large variation still existed between the nine regions. This regional variation underlines the need for implementation of a uniform treatment and decision-making strategy.

DIEAP Flap Breast Reconstruction Followed by Local Recurrence of Breast Cancer

Local recurrence after an autologous breast reconstruction is uncommon. We describe 2 patients with local recurrence 3 and 9 years, respectively, after mastectomy with DIEAP (deep inferior epigastric artery perforator) flap breast reconstruction. Patients generally present with a palpable mass, pain, or other visible abnormalities. Various imaging techniques are helpful, always completed by biopsy to characterize the tumour. A repeated sentinel node procedure can be useful in staging. The treatment of the local recurrence needs to be determined in a multidisciplinary team consultation.

Assessment of HER2 status in breast cancer biopsies is not affected by accelerated tissue processing

AIMS

To establish whether core needle biopsy (CNB) specimens processed with an accelerated processing method with short fixation time can be used to determine accurately the human epidermal growth factor receptor 2 (HER2) status of breast cancer.

METHODS AND RESULTS

A consecutive case-series from two high-volume breast clinics was created. We compared routine HER2 immunohistochemistry (IHC) assessment between accelerated processing CNB specimens and routinely processed postoperative excision specimens. Additional amplification-based testing was performed in cases with equivocal results. The formalin fixation time was less than 2 h and between 6 and 72 h, respectively. Fluorescence in-situ hybridisation and multiplex ligation-dependent probe amplification were used for amplification testing. One hundred and forty-four cases were included, 15 of which were HER2-positive on the routinely processed excision specimens. On the CNB specimens, 44 were equivocal on IHC and required an amplification-based test. Correlation between the CNB specimens and the corresponding excision specimens was high for final HER2 status, with an accuracy of 97% and a kappa of 0.85.

CONCLUSIONS

HER2 status can be determined reliably on CNB specimens with accelerated processing time using standard clinical testing methods. Using this accelerated technology the minimum 6 h of formalin fixation, which current guidelines consider necessary, can be decreased safely. This allows for a complete and expedited histology-based diagnosis of breast lesions in the setting of a one-stop-shop, same-day breast clinic.

Can Gentamicin-collagen Sponges Prevent Seroma Formation Following Mastectomy?

BACKGROUND

The aim of this study was to investigate whether gentamicin-collagen (GC) sponges can lower the incidence of seroma and surgical site infections following breast cancer surgery.

PATIENTS AND METHODS

A retrospective cohort study was performed. Two consecutive cohorts of patients who underwent a mastectomy with or without an axillary lymph node dissection were compared. The first cohort was treated conventionally (n = 38), the second cohort received GC sponges (n = 39). Endpoints were the incidence of clinical significant seroma (CSS) and surgical site infections (SSI), the mean number of aspirations, and the mean aspirated volume.

RESULTS

GC sponges lowered the CSS incidence from 73.7% to 38.5% (P = .002). The mean number of aspirations and the mean aspirated volume were not affected. SSI incidence was 15.8% in the conventional cohort compared with 7.7% in the GC cohort (P = .23).

CONCLUSION

Application of GC sponges significantly lowered the incidence of CSS. The incidence of SSI was halved, although this was not significant.

Validation of the online prediction tool PREDICT v. 2.0 in the Dutch breast cancer population

BACKGROUND

PREDICT version 2.0 is increasingly used to estimate prognosis in breast cancer. This study aimed to validate this tool in specific prognostic subgroups in the Netherlands.

METHODS

All operated women with non-metastatic primary invasive breast cancer, diagnosed in 2005, were selected from the nationwide Netherlands Cancer Registry (NCR). Predicted and observed 5- and 10-year overall survival (OS) were compared for the overall cohort, separated by oestrogen receptor (ER) status, and predefined subgroups. A >5% difference was considered as clinically relevant. Discriminatory accuracy and goodness-of-fit were determined using the area under the receiver operating characteristic curve (AUC) and the Chi-squared-test.

RESULTS

We included 8834 patients. Discriminatory accuracy for 5-year OS was good (AUC 0.80). For ER-positive and ER-negative patients, AUCs were 0.79 and 0.75, respectively. Predicted 5-year OS differed from observed by -1.4% in the entire cohort, -0.7% in ER-positive and -4.9% in ER-negative patients. Five-year OS was accurately predicted in all subgroups. Discriminatory accuracy for 10-year OS was good (AUC 0.78). For ER-positive and ER-negative patients AUCs were 0.78 and 0.76, respectively. Predicted 10-year OS differed from observed by -1.0% in the entire cohort, -0.1% in ER-positive and -5.3 in ER-negative patients. Ten-year OS was overestimated (6.3%) in patients ≥75 years and underestimated (-13.%) in T3 tumours and patients treated with both endocrine therapy and chemotherapy (-6.6%).

CONCLUSIONS

PREDICT predicts OS reliably in most Dutch breast cancer patients, although results for both 5-year and 10-year OS should be interpreted carefully in ER-negative patients. Furthermore, 10-year OS should be interpreted cautiously in patients ≥75 years, T3 tumours and in patients considering endocrine therapy and chemotherapy.

Patterns and predictors of first and subsequent recurrence in women with early breast cancer

Purpose

Little is known about the occurrence, timing and prognostic factors for first and also subsequent local (LR), regional (RR) or distant (DM) breast cancer recurrence. As current follow-up is still consensus-based, more information on the patterns and predictors of subsequent recurrences can inform more personalized follow-up decisions.

Methods

Women diagnosed with stage I-III invasive breast cancer who were treated with curative intent were selected from the Netherlands Cancer Registry (N = 9342). Extended Cox regression was used to model the hazard of recurrence over ten years of follow-up for not only site-specific first, but also subsequent recurrences after LR or RR.

Results

In total, 362 patients had LR, 148 RR and 1343 DM as first recurrence. The risk of first recurrence was highest during the second year post-diagnosis (3.9%; 95% CI 3.5–4.3) with similar patterns for LR, RR and DM. Young age (<40), tumour size >2 cm, tumour grade II/III, positive lymph nodes, multifocality and no chemotherapy were prognostic factors for first recurrence. The risk of developing a second recurrence after LR or RR (N = 176) was significantly higher after RR than after LR (50 vs 29%; p < 0.001). After a second LR or RR, more than half of the women were diagnosed with a third recurrence.

Conclusions

Although the risk of subsequent recurrence is high, absolute incidence remains low. Also, almost half the second recurrences are detected in the first year after previous recurrence and more than 80% are DM. This suggests that more intensive follow-up for early detection subsequent recurrence is not likely to be (cost-)effective.

Electronic supplementary material

The online version of this article (doi:10.1007/s10549-017-4340-3) contains supplementary material, which is available to authorized users.

Clinically node negative breast cancer patients undergoing breast conserving therapy, sentinel lymph node procedure versus follow-up: a Dutch randomized controlled multicentre trial (BOOG 2013-08)

BACKGROUND

Studies showed that axillary lymph node dissection can be safely omitted in presence of positive sentinel lymph node(s) in breast cancer patients treated with breast conserving therapy. Since the outcome of the sentinel lymph node biopsy has no clinical consequence, the value of the procedure itself is being questioned. The aim of the BOOG 2013-08 trial is to investigate whether the sentinel lymph node biopsy can be safely omitted in clinically node negative breast cancer patients treated with breast conserving therapy.

METHODS

The BOOG 2013-08 is a Dutch prospective non-inferiority randomized multicentre trial. Women with pathologically confirmed clinically node negative T1-2 invasive breast cancer undergoing breast conserving therapy will be randomized for sentinel lymph node biopsy versus no sentinel lymph node biopsy. Endpoints include regional recurrence after 5 (primary endpoint) and 10 years of follow-up, distant-disease free and overall survival, quality of life, morbidity and cost-effectiveness. Previous data indicate a 5-year regional recurrence free survival rate of 99% for the control arm and 96% for the study arm. In combination with a non-inferiority limit of 5% and probability of 0.8, this result in a sample size of 1.644 patients including a lost to follow-up rate of 10%. Primary and secondary endpoints will be reported after 5 and 10 years of follow-up.

DISCUSSION

If the sentinel lymph node biopsy can be safely omitted in clinically node negative breast cancer patients undergoing breast conserving therapy, this study will cost-effectively lead to a decreased axillary morbidity rate and thereby improved quality of life with non-inferior regional control, distant-disease free survival and overall survival.

TRIAL REGISTRATION

The BOOG 2013-08 study is registered in ClinicalTrials.gov since October 20, 2014, Identifier: NCT02271828. https://clinicaltrials.gov/ct2/show/NCT02271828.

Interval breast cancer characteristics before, during and after the transition from screen-film to full-field digital screening mammography

Background

To determine the proportion of “true” interval cancers and tumor characteristics of interval breast cancers prior to, during and after the transition from screen-film mammography screening (SFM) to full-field digital mammography screening (FFDM).

Methods

We included all women with interval cancers detected between January 2006 and January 2014. Breast imaging reports, biopsy results and breast surgery reports of all women recalled at screening mammography and of all women with interval breast cancers were collected. Two experienced screening radiologists reviewed the diagnostic mammograms, on which the interval cancers were diagnosed, as well as the prior screening mammograms and determined whether or not the interval cancer had been missed on the most recent screening mammogram. If not missed, the cancer was considered an occult (“true”) interval cancer.

Results

A total of 442 interval cancers had been diagnosed, of which 144 at SFM with a prior SFM (SFM-SFM), 159 at FFDM with a prior SFM (FFDM-SFM) and 139 at FFDM with a prior FFDM (FFDM-FFDM). The transition from SFM to FFDM screening resulted in the diagnosis of more occult (“true”) interval cancers at FFDM-SFM than at SFM-SFM (65.4% (104/159) versus 49.3% (71/144), P < 0.01), but this increase was no longer statistically significant in women who had been screened digitally for the second time (57.6% (80/139) at FFDM-FFDM versus 49.3% (71/144) at SFM-SFM). Tumor characteristics were comparable for the three interval cancer cohorts, except of a lower porportion (75.7 and 78.0% versus 67.2% af FFDM-FFDM, P < 0.05) of invasive ductal cancers at FFDM with prior FFDM.

Conclusions

An increase in the proportion of occult interval cancers is observed during the transition from SFM to FFDM screening mammography. However, this increase seems temporary and is no longer detectable after the second round of digital screening. Tumor characteristics and type of surgery are comparable for interval cancers detected prior to, during and after the transition from SFM to FFDM screening mammography, except of a lower proportion of invasive ductal cancers after the transition.

Abstract P1-10-21: Influence of timing of radiation therapy following breast-conserving surgery on 10-year disease-free survival

Background

In the Netherlands, one of the indicators of quality of care is that radiation therapy (RT) should start within six weeks following breast-conserving surgery (BCS). However, there is still much controversy regarding timing of RT in literature. This study investigated the effect of timing of RT on disease-free survival (DFS) in a Dutch nationwide population-based cohort.

Methods

All women diagnosed with primary invasive stage I-IIIA breast cancer in 2003, treated with BCS plus RT, of whom the start date of RT was known, were included. Patients who received chemotherapy between surgery and RT were excluded, as this affects delay. Patients were categorised into three groups: &lt;42 days, 42-55 days and &gt;55 days, between surgery and start of RT. The primary outcome was 10-year DFS. Secondary outcomes were 10-year locoregional recurrence-free (LRRFS) and distant metastasis-free survival (DMFS). Multivariable Cox regression was used to correct for confounding. Since adjuvant systemic therapy largely influences DFS, all analyses were stratified for use of adjuvant systemic therapy (chemotherapy and/or endocrine therapy).

Results

In total, 2,759 patients were included. The median number of days between BCS and RT was 45 (IQR 37-54 days). The hazard ratio (HR) for 10-year DFS was 0.79 (95% CI: 0.65-0.96) for 42-55 days and 0.71 (95% CI: 0.56-0.90) for &gt;55 days, both compared to &lt;42 days. While no significant differences in 10-year LRRFS were found, 10-year DMFS (HR 0.64 [95% CI: 0.45-0.91]) was significantly higher for BCS-RT interval &gt;55 days compared to &lt;42 days. After stratification, no significant differences were found for any outcome in patients not treated with adjuvant systemic therapy, while in patients who were treated with adjuvant systemic therapy, 10-year DFS was significantly improved for 42-55 days (HR 0.70 (95% CI: 0.51-0.97) and &gt;55 days (HR 0.63 (95% CI: 0.42-0.96) compared to &lt;42 days. Significantly improved 10-year DMFS was confirmed after stratification for longer delays (HR 0.69 (95% CI: 0.47-1.00 for 42-55 days) and 0.59 (95% CI: 0.36-0.96) for &gt;55 days, compared to &lt;42 days)

10-year DFS, LRRFS and DMFS for different time intervals between BCS and RT, stratified for use of adjuvant systemic therapy Entire cohort (n=2,759)No adjuvant treatment (n=1,761)Adjuvant treatment (n=998)Time intervalHR [95% CI]*HR [95% CI]*HR [95% CI]*10-year DFS&lt;42 days11142-55 days0.79 [0.65-0.96]0.83 [0.65-1.05]0.70 [0.51-0.97]&gt;55 days0.71 [0.56-0.90]0.77 [0.57-1.03]0.63 [0.42-0.96]10-year LRRFS&lt;42 days11142-55 days0.74 [0.51-1.06]0.79 [0.52-1.21]0.55 [0.28-1.11]&gt;55 days0.90 [0.59-1.37]0.99 [0.61-1.60]0.67 [0.29-1.57]10-year DMFS&lt;42 days11142-55 days0.90 [0.69-1.17]1.13 [0.77-1.66]0.69 [0.47-1.00]&gt;55 days0.64 [0.45-0.91]0.73 [0.44-1.22]0.59 [0.36-0.96]* Corrected for all relevant confounders. HRs in bold are statistically significant (p&lt;0.05).

Conclusion and interpretation

In conclusion, patients treated with adjuvant systemic therapy following RT showed increasing 10-year DFS and DMFS with longer BCS-RT intervals, which was not the case for patients not receiving adjuvant systemic therapy. Possible explanations for these results have to be explored further.

Citation Format: van Maaren MC, Bretveld RW, Jobsen JJ, Veenstra R, Groothuis-Oudshoorn KCGM, Struikmans H, Maduro JH, Strobbe LJA, Poortmans P, Siesling S. Influence of timing of radiation therapy following breast-conserving surgery on 10-year disease-free survival [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-10-21.

Abstract P1-11-14: Breast conserving therapy and mastectomy revisited: overall and breast cancer-specific survival and the influence of age, stage, receptor status and comorbidities in 143,376 patients

This abstract was withdrawn by the authors.

Postoperative Complications After Breast Cancer Surgery are Not Related to Age

INTRODUCTION

Consensus about surgical treatment options for breast cancer in elderly patients remains elusive due to exclusion from clinical trials. Fear of complications due to increased age often is an important factor in the choice of treatment and might result in different treatment of the older patient.

METHODS

A total of 1258 female patients who underwent breast cancer surgery for primary diagnosed breast cancer in 2010-2014 were included. Incidence of postoperative complications (POCs) was compared between the younger (18-70 years, N = 1008) and older (≥71 years, N = 250) patients. Multivariate logistic regression was performed to identify the correlation between age and POCs.

RESULTS

POCs developed in 25.9% of the younger and 31.6% of the older patients (p = 0.042). In multivariable logistic regression analysis of the overall study population, age was no risk factor for POC (odds ratio 0.950, 95% confidence interval 0.640-1.410, p = 0.798). More extensive surgery (mastectomy and/or axillary lymph node dissection compared with single lumpectomy) and increased body mass index increased the odds of developing a POC. Analyses of the ≥71-year group separately revealed only type of surgery to be of influence.

CONCLUSIONS

Fear of increased risk of complications in the older patient is unjustified. Neither increased age nor high American Society of Anesthesiologists classification are predictors for developing POC. Type of surgery is the most important determinant. Choosing mastectomy while breast-conserving surgery is suitable should be discouraged, particularly in the older patient.

Modified Core Wash Cytology: A reliable same day biopsy result for breast clinics

BACKGROUND

Fine Needle Aspiration Biopsy (FNAB), Core Needle biopsy (CNB) and hybrid techniques including Core Wash Cytology (CWC) are available for same-day diagnosis in breast lesions. In CWC a washing of the biopsy core is processed for a provisional cytological diagnosis, after which the core is processed like a regular CNB. This study focuses on the reliability of CWC in daily practice.

METHODS

All consecutive CWC procedures performed in a referral breast centre between May 2009 and May 2012 were reviewed, correlating CWC results with the CNB result, definitive diagnosis after surgical resection and/or follow-up. Symptomatic as well as screen-detected lesions, undergoing CNB were included.

RESULTS

1253 CWC procedures were performed. Definitive histology showed 849 (68%) malignant and 404 (32%) benign lesions. 80% of CWC procedures yielded a conclusive diagnosis: this percentage was higher amongst malignant lesions and lower for benign lesions: 89% and 62% respectively. Sensitivity and specificity of a conclusive CWC result were respectively 98.3% and 90.4%. The eventual incidence of malignancy in the cytological 'atypical' group (5%) was similar to the cytological 'benign' group (6%).

CONCLUSION

CWC can be used to make a reliable provisional diagnosis of breast lesions within the hour. The high probability of conclusive results in malignant lesions makes CWC well suited for high risk populations.