Local relapse after breast-conserving therapy for ductal carcinoma in situ: a European single-center experience and external validation of the Memorial Sloan-Kettering Cancer Center DCIS nomogram

Efficacy of radiation therapy in Japanese patients with positive margins after breast-conserving surgery

BACKGROUND

Additional surgical resection is recommended after breast-conserving surgery if the surgical margin is pathologically positive. However, in clinical practice, radiation therapy is sometimes used instead for several reasons. Irradiation may be appropriate for some patients, but real-world data is still insufficient to establish it as standard treatment. We retrospectively investigated the status of local control in patients who received irradiation for positive margins.

METHODS

We investigated 85 patients with positive margins after curative partial mastectomy who were treated with irradiation instead of additional excision during the period 2006-2013. The patients received whole-breast irradiation (43.2-50 Gy) using photon beams and additional tumour-bed boost (8.1-16 Gy) using electron beams. Intrabreast tumour recurrence was defined as secondary cancer within the ipsilateral conserved breast. Surgical margin was defined as positive if tumour cell exposure was pathologically confirmed on the margin.

RESULTS

Seven patients (8.2%) developed intrabreast tumour recurrence during a mean observation period of 119 months. As to components of positive margin, 76 cases were positive for an intraductal component, of which seven (9.2%) developed intrabreast tumour recurrence. Meanwhile, all nine cases positive for an invasive component were free from intrabreast tumour recurrence. Two of the intrabreast tumour recurrence cases seemed to develop new lesions rather than recurrence, considering tumour location. The cumulative incidence of intrabreast tumour recurrence over 10 years was 6.1%. Limited to true recurrence, intrabreast tumour recurrence incidence was 4.9%.

CONCLUSION

Our real-world data supports irradiation as an alternative to additional surgical intervention for positive margins after breast-conserving surgery and offers a basis for further research.

Tools to Guide Radiation Oncologists in the Management of DCIS

Similar to invasive breast cancer, ductal carcinoma in situ is also going through a phase of changes not only from a technical but also a conceptual standpoint. From prescribing radiotherapy to everyone to personalized approaches, including radiotherapy omission, there is still a lack of a comprehensive framework to guide radiation oncologists in decision making. Many pieces of the puzzle are finding their place as high-quality data mature and are disseminated, but very often, the interpretation of risk factors and the perception of risk remain very highly subjective. Sharing the therapeutic choice with patients requires effective communication for an understanding of risks and benefits, facilitating an informed decision that does not increase anxiety and concerns about prognosis. The purpose of this narrative review is to summarize the current state of knowledge to highlight the tools available to radiation oncologists for managing DCIS, with an outlook on future developments.

Analysis of Local Recurrence Risk in Ductal Carcinoma In Situ and External Validation of the Memorial Sloan Kettering Cancer Center Nomogram

BACKGROUND

Adjuvant radiotherapy and hormonotherapy after breast-conserving surgery (BCS) in ductal carcinoma in situ (DCIS) have been shown to reduce the risk of local recurrence. To predict the risk of ipsilateral breast tumor relapse (IBTR) after BCS, the Memorial Sloan Kettering Cancer Center (MSKCC) developed a nomogram to analyze local recurrence (LR) risk in our cohort and to assess its external validation.

METHODS

A historical cohort study using data from 296 patients treated for DCIS at the Hospital Clínic of Barcelona was carried out. Patients who had had a mastectomy were excluded from the analysis.

RESULTS

The mean age was 58 years (42-75), and the median follow-up time was 10.64 years. The overall local relapse rate was 13.04% (27 patients) during the study period. Actuarial 5- and 10-year IBTR rates were 5.8 and 12.9%, respectively. The external validation of the MSKCC nomogram was performed using a multivariate logistic regression analysis on a total of 207 patients, which did not reach statistical significance in the studied population for predicting LR (p = 0.10). The expression of estrogen receptors was significantly associated with a decreased risk of LR (OR: 0.25; p = 0.004).

CONCLUSIONS

In our series, the LR rate was 13.4%, which was in accordance with the published series. The MSKCC nomogram did not accurately predict the IBTR in this Spanish cohort of patients treated for DCIS (p = 0.10).

Prediction Models and Decision Aids for Women with Ductal Carcinoma In Situ: A Systematic Literature Review

Simple Summary

Ductal carcinoma in situ (DCIS) is a potential precursor to invasive breast cancer (IBC). Although in many women DCIS will never become breast cancer, almost all women diagnosed with DCIS undergo surgery with/without radiotherapy. Several studies are ongoing to de-escalate treatment for DCIS. Multiple decision support tools have been developed to aid women with DCIS in selecting the best treatment option for their specific goals. The aim of this study was to identify these decision support tools and evaluate their quality and clinical utility. Thirty-three studies were reviewed, in which four decision aids and six prediction models were described. While some of these models might be promising, most lacked important qualities such as tools to help women discuss their options or good quality validation studies. Therefore, the need for good quality, well validated decision support tools remains unmet.

Abstract

Even though Ductal Carcinoma in Situ (DCIS) can potentially be an invasive breast cancer (IBC) precursor, most DCIS lesions never will progress to IBC if left untreated. Because we cannot predict yet which DCIS lesions will and which will not progress, almost all women with DCIS are treated by breast-conserving surgery +/− radiotherapy, or even mastectomy. As a consequence, many women with non-progressive DCIS carry the burden of intensive treatment without any benefit. Multiple decision support tools have been developed to optimize DCIS management, aiming to find the balance between over- and undertreatment. In this systematic review, we evaluated the quality and added value of such tools. A systematic literature search was performed in Medline(ovid), Embase(ovid), Scopus and TRIP. Following the PRISMA guidelines, publications were selected. The CHARMS (prediction models) or IPDAS (decision aids) checklist were used to evaluate the tools’ methodological quality. Thirty-three publications describing four decision aids and six prediction models were included. The decision aids met at least 50% of the IPDAS criteria. However, most lacked tools to facilitate discussion of the information with healthcare providers. Five prediction models quantify the risk of an ipsilateral breast event after a primary DCIS, one estimates the risk of contralateral breast cancer, and none included active surveillance. Good quality and external validations were lacking for all prediction models. There remains an unmet clinical need for well-validated, good-quality DCIS risk prediction models and decision aids in which active surveillance is included as a management option for low-risk DCIS.

Recurrence risk stratification based on a competing-risks nomogram to identify patients with esophageal cancer who may benefit from postoperative radiotherapy

BACKGROUND

A reliable model is needed to estimate the risk of postoperative recurrence and the benefits of postoperative radiotherapy (PORT) in patients with thoracic esophageal squamous cell cancer (TESCC).

METHODS

The study retrospectively reviewed 3652 TESCC patients in stage IB-IVA after radical esophagectomy, with or without PORT. In one institution as the training cohort (n = 1620), independent risk factors associated with locoregional recurrence (LRR), identified by the competing-risks regression, were used to establish a predicting nomogram, which was validated in an external cohort (n = 1048). Area under curve (AUC) values of receiver operating characteristic curves were calculated to evaluate discrimination. Risk stratification was conducted using a decision tree analysis based on the cumulative point score of the LRR nomogram. After balancing the baseline of characteristics between treatment groups by inverse probability of treatment weighting, the effect of PORT was evaluated in each risk group.

RESULTS

Sex, age, tumor location, tumor grade, and N category were identified as independent risk factors for LRR and added into the nomogram. The AUC values were 0.638 and 0.706 in the training and validation cohorts, respectively. Three risk groups were established. For patients in the intermediate- and high-risk groups, PORT significantly improved the 5-year overall survival by 10.2% and 9.4%, respectively (p < 0.05). Although PORT was significantly associated with reduced LRR in the low-risk group, overall survival was not improved.

CONCLUSION

The nomogram can effectively estimate the individual risk of LRR, and patients in the intermediate- and high-risk groups are highly recommended to undergo PORT.

Nomogram for the personalisation of radiotherapy treatments in breast cancer patients

Introduction

Numerous prospective studies have shown that the incorporation of genomic assays into clinical practice significantly impacts the choice of adjuvant treatments for patients with early-stage breast cancer. However, the same evidence does not exist for the treatment of locoregional recurrences.

Hypothesis and objectives

The main objective of this work was to identify the clinicopathological, molecular, and genetic parameters that allow patients to be more precisely categorised into risk groups, in order to create a locoregional recurrence riskclassification tool, the PersonalRT27.

Material and methods

To create PersonalRT27, we retrospective assessed the variables of patients with early breast cancer (stages I or II) who had undergone the OncotypeDx ® and MammaPrint ® genetic tests. These variables and factors included in the tests were categorised and weighted to obtain scores between 1 and 5 pointsto represent a lower or higher risk of relapse, respectively, based on these factors and as determined by the researchers.

Results

The mean follow-up time was 60.5 months (range 25–96 months); locoregional progression-free survival at the time of the analysis was 98.4%, and overall survival was 97.5%, of which 0.6% of the deaths had been cancer specific. The area under the curve for the PersonalRT27 was 0.76 (95% CI [0.70, 0.81]), sensitivity was 78%, and the specificity was 58.9%. We used these factors to create an inhospital web-based nomogram.

Conclusions

The PersonalRT27 is a novel tool that integrates clinical-pathological, molecular, and genetic parameters. External and independent validation will be required to implement its clinical use.

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Genomic assays impact the choice of adjuvant systemic treatment for patients with early-stage breast cancer.

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However, the same evidence does not exist for decision making regarding adjuvant locoregional therapy.

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In other words, can the clinically approved genomic assays predict the risk of locoregional recurrende as a primary event.

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The main objective of this work was to identify the clinicopathological, molecular, and genetic parameters that allow patients to be more precisely categorised into risk groups, in order to create a locoregional recurrence risk-classification tool, the PersonalRT27.

Advances and controversies in management of breast ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive breast cancer. It accounts for 25% of all breast cancers diagnosed, as a result of the expansion of breast cancer screening and is associated with a high survival rate. DCIS is particularly clinically challenging, due to its heterogeneous pathological and biological traits and its management is continually evolving towards more personalized and less aggressive therapies. This article suggests evidence-based guidelines for proper DCIS clinical management, which should be discussed within a multidisciplinary team in order to propose the most suitable approach in clinical practice, taking into account recent scientific studies. Here we include updated multidisciplinary treatment protocols and techniques in accordance with the most recent contributions published on this topic in the peer-reviewed medical literature, and we outline future perspectives.

Patterns of invasive recurrence among patients originally treated for ductal carcinoma in situ by breast-conserving surgery versus mastectomy

Purpose

Local recurrence after treatment of ductal carcinoma in situ (DCIS) with breast-conserving surgery (BCS) is more common than after mastectomy, but it is unclear if patterns of invasive recurrence vary by initial surgical therapy. Among patients with invasive recurrence after treatment for DCIS, we compared patterns of first recurrence between those originally treated with BCS vs. mastectomy.

Methods

From 2000 to 2016, women with an invasive recurrence occurring ≥ 6 months after initial treatment for DCIS were retrospectively identified. Clinicopathologic features and adjuvant treatment of the initial DCIS, as well as characteristics of first invasive recurrences, were compared between patients who had undergone BCS vs. mastectomy.

Results

452 patients with an invasive recurrence after surgery for DCIS were identified: 367 patients (81%) had initially undergone BCS and 85 patients (19%) mastectomy. Patients originally treated with mastectomy were younger and were more likely to have had high grade, necrosis, and multifocal or multicentric DCIS (p < 0.001) compared with the BCS group. A higher proportion of invasive recurrences were local after BCS (93%; 343/367), whereas 88% (75/85) of recurrences after mastectomy were regional or distant (p < 0.001). The median time to first invasive recurrence was not different between surgical groups (BCS: 6.4 years vs. mastectomy: 5.5 years; p = 0.12).

Conclusions

Among women who experienced a first invasive recurrence after treatment for DCIS, those who had originally undergone mastectomy more commonly presented with advanced disease compared to those treated with BCS, likely related to the absence of the breast and the higher risk profile of their initial DCIS.

Supplementary Information

The online version of this article (10.1007/s10549-021-06129-3) contains supplementary material, which is available to authorized users.

Comparison of Oncoplastic Breast-Conserving Therapy and Standard Breast-Conserving Therapy in Early-Stage Breast Cancer Patients

Background

The aim of this study was to compare the efficacy and safety of oncoplastic breast-conserving therapy (OBCT) and SBCT (standard breast-conserving therapy) in breast cancer surgery.

Material/Methods

We enrolled 192 breast cancer patients who underwent breast-conserving surgery during January 2015 to April 2018. The surgery strategies of OBCT and SBCT were performed according to the patients’ condition. For measurement of surgical cosmetic effects, the Harris scale, the modified objective scores, and the subjective evaluation were all used. The basic clinical characteristics, intraoperative indices, postoperative complications, metastasis, and recurrence during the 2-year follow-up were recorded.

Results

The mean surgical time was remarkably longer and the resected volume was markedly larger in the OBCT group than in the SBCT group. The excellent and good ratios of Harris scale, the modified objective scores, and the ratio of very satisfied and satisfied patients by subjective scale were all significantly higher in the OBCT group than in the SBCT group. The occurrence rates of seroma and poor incision healing were remarkably lower in the OBCT group. No significant difference was found for metastasis and recurrence.

Conclusions

OBCT had better cosmetic effects, fewer complications, and no adverse effects on metastasis and recurrence.

A Comparison of Predicted Ipsilateral Tumor Recurrence Risks in Patients With Ductal Carcinoma in Situ of the Breast After Breast-Conserving Surgery by Breast Radiation Oncologists, the Van Nuys Prognostic Index, the Memorial Sloan Kettering Cancer Center DCIS Nomogram, and the 12-Gene DCIS Score Assay

Purpose

To compare ipsilateral breast event (IBE) risks in patients with ductal carcinoma in situ of the breast (DCIS) post-lumpectomy, as estimated by breast radiation oncologists, the Van Nuys Prognostic Index, the Memorial Sloan Kettering Cancer Center (MSKCC) DCIS nomogram, and the 12-gene Oncotype DX DCIS score assay.

Methods and Materials

Consecutive DCIS cases treated with lumpectomy from November 2011 to August 2014 with available DCIS score results were identified. Three radiation oncologists independently estimated the 10-year IBE risk. The Van Nuys Prognostic Index and MSKCC nomogram 10-year IBE risk estimates were generated. Differences and correlations between the IBE estimates and clinicopathologic factors were evaluated.

Results

Ninety-one patients were identified for inclusion. Forty-eight percent would have been ineligible for the E5194 study. The mean risk of IBE from the DCIS score assay was 12.4%, compared with a range of 18.9% to 26.8% from other sources. The mean IBE risk from the DCIS score assay was lower regardless of E5194 eligibility. The MSKCC nomogram and DCIS score assay risk estimates were weakly correlated with each other (P = .23) and were each moderately correlated with the other risk estimates (P = .41-.56). When applying the radiation oncologists’ treatment recommendations based on their proposed risk cutoffs, evaluating risk according to the DCIS score assay led to the highest proportion of patients recommended excision alone.

Conclusions

IBE risk estimates for this general community cohort of DCIS cases vary significantly among commonly available clinical predictive tools and individual radiation oncologist estimates. Surgical margins and tumor size continue to factor prominently in radiation oncologist decision algorithms. The differences found between the IBE risk estimate methods suggests that they are not interchangeable and the methods that rely on clinicopathologic features may tend to overestimate risk.

Validation of a Ductal Carcinoma In Situ Biomarker Profile for Risk of Recurrence after Breast-Conserving Surgery with and without Radiotherapy

PURPOSE

A major challenge in ductal carcinoma in situ (DCIS) treatment is selection of the most appropriate therapeutic approach for individual patients. We conducted an external prospective-retrospective clinical validation of a DCIS biologic risk signature, DCISionRT, in a population-based observational cohort of women diagnosed with DCIS and treated with breast-conserving surgery (BCS).

EXPERIMENTAL DESIGN

Participants were 455 health plan members of Kaiser Permanente Northwest diagnosed with DCIS and treated with BCS with or without radiotherapy from 1990 to 2007. The biologic signature combined seven protein tumor markers assessed in formalin-fixed, paraffin-embedded tumor tissue with four clinicopathologic factors to provide a DCISionRT test result, termed decision score (DS). Cox regression and Kaplan-Meier analysis were used to measure the association of the DS, continuous (linear) or categorical (DS ≤ 3 vs. DS > 3), and subsequent total ipsilateral breast events and invasive ipsilateral breast events at least 6 months after initial surgery.

RESULTS

In Cox regression, the continuous and categorical DS variables were positively associated with total and invasive breast event risk after adjustment for radiotherapy. In a subset analysis by treatment group, categorical Kaplan-Meier analyses showed at least 2-fold differences in 10-year risk of total breast events between the elevated-risk and low-risk DS categories.

CONCLUSIONS

In this first external validation study of the DCISionRT test, the DS was prognostic for the risk of later breast events for women diagnosed with DCIS, following BCS.

Treatment of Ductal Carcinoma in Situ: Considerations for Tailoring Therapy in the Contemporary Era

Purpose of Review

Standard options for the treatment of ductal carcinoma in situ (DCIS) include breast-conserving surgery (BCS) alone; BCS with radiotherapy or endocrine therapy, or both; and mastectomy. Survival is excellent with all options, but rates of local recurrence (LR) vary, as do quality-of-life measures. Here we discuss treatment outcomes, risk factors for LR, and tools for risk estimation.

Recent Findings

After BCS, radiotherapy reduces the risk of LR by half, and endocrine therapy reduces the risk by a third. Young age, inadequate margins, and greater volume of disease are associated with higher risk of LR after BCS, while young age, high grade, and microinvasion are associated with higher risk of locoregional recurrence after mastectomy. Clinical tools, including the Memorial Sloan Kettering Cancer Center (MSKCC) DCIS nomogram, provide LR risk estimates after BCS that appear more accurate than current genomic assays. The safety of active surveillance for seemingly low-risk patients remains uncertain.

Summary

Estimation of LR risk, utilizing a multitude of clinicopathologic and treatment factors, can help a woman balance that risk with her values and priorities, and allow her to choose the optimal treatment option for her.

Prognostic significance of cathepsin V (CTSV/CTSL2) in breast ductal carcinoma in situ

AIMS

Cathepsin V (CTSV/CTSL2) is a lysosomal cysteine proteinase and plays a role in extracellular matrix degradation. It is associated with poor prognosis in invasive breast cancer (IBC), but its role in breast ductal carcinoma in situ (DCIS) remains unclear. In this study, we aimed to evaluate the prognostic significance of CTSV in DCIS.

METHODS

CTSV protein expression was immunohistochemically assessed in a well-characterised and annotated cohort of DCIS comprising pure DCIS (n=776) and DCIS coexisting with IBC (n=239). CTSV expression was analysed in tumour cells and surrounding stroma, including its association with clinicopathological parameters and outcome.

RESULTS

In pure DCIS, high CTSV expression was observed in 29% of epithelial tumour cells and 20% of surrounding stroma. High expression in both components was associated with features of poor prognosis including higher nuclear grade, hormone receptor negativity and HER2 positivity. In addition, stromal CTSV expression was associated with larger DCIS size, comedo-type necrosis and high proliferation index. DCIS associated with IBC showed higher CTSV expression than pure DCIS either within the epithelial tumour cells or surrounding stroma (p<0.0001 and p=0.001, respectively). In DCIS/IBC, CTSV expression was higher in the invasive component than DCIS component either in tumour cells or surrounding stroma (both p<0.0001). CTSV stromal expression was associated with invasive recurrence independent of other prognostic factors in patients treated with breast conserving surgery (HR=3.0, p=0.005).

CONCLUSION

High expression of CTSV is associated with poor outcome in DCIS and is a potential marker to predict DCIS progression to invasive disease.

Comparison of Local Recurrence Risk Estimates After Breast-Conserving Surgery for DCIS: DCIS Nomogram Versus Refined Oncotype DX Breast DCIS Score

BACKGROUND

A ductal carcinoma in situ (DCIS) Nomogram integrating 10 clinicopathologic/treatment factors and a Refined DCIS Score (RDS) that incorporates a genomic assay and three clinicopathologic factors (Oncotype DX DCIS Score) are available to estimate DCIS 10-year local recurrence risk (LRR). This study compared these estimates.

METHODS

Patients 50 years of age or older with DCIS size 2.5 cm or smaller and a genomic assay available were identified. An RDS within 1-2% of the range of Nomogram LRR estimates obtained by assuming use and non-use of endocrine therapy (Nomogram ± ET) was defined as concordant. Assuming a 10-year risk threshold of 10% for recommending radiation, Nomogram ± ET and RDS estimates were compared, and threshold concordance was determined.

RESULTS

For 54 (92%) of 59 patients, the RDS and Nomogram ± ET LRR estimates were concordant. For the remaining 5 (8%) of the 59 patients, the RDS LRR estimates were lower than the Nomogram + ET estimates, with an absolute difference of 3-8%, and thus were discordant. For these five patients, the RDS estimates of 10-year LRR were lower than 10% (range 5-8%) and the Nomogram + ET estimates were 10% or higher (range 11-14%). These five patients with both discordant and threshold-discordant estimates all had close margins (≤ 2 mm).

CONCLUSIONS

Among 92% of women 50 years of age or older with DCIS size 2.5 cm or smaller, free-of-charge online Nomogram 10-year LRR estimates were concordant with those obtained using the commercially available RDS (> $4600). Among the 8% with discordant risk estimates, the RDS appeared to underestimate the LRR and may lead to inappropriate omission of radiotherapy. Unless other data show a clinically significant advantage of the RDS (Oncotype DX DCIS Score), the study data suggest that for women 50 years of age or older with DCIS size 2.5 cm or smaller, its use is not warranted.

Ductal carcinoma in situ of the breast: an update for the pathologist in the era of individualized risk assessment and tailored therapies

Ductal carcinoma in situ (DCIS) is a neoplastic proliferation of mammary ductal epithelial cells confined to the ductal-lobular system, and a non-obligate precursor of invasive disease. While there has been a significant increase in the diagnosis of DCIS in recent years due to uptake of mammography screening, there has been little change in the rate of invasive recurrence, indicating that a large proportion of patients diagnosed with DCIS will never develop invasive disease. The main issue for clinicians is how to reliably predict the prognosis of DCIS in order to individualize patient treatment, especially as treatment ranges from surveillance only, breast-conserving surgery only, to breast-conserving surgery plus radiotherapy and/or hormonal therapy, and mastectomy with or without radiotherapy. We conducted a semi-structured literature review to address the above issues relating to "pure" DCIS. Here we discuss the pathology of DCIS, risk factors for recurrence, biomarkers and molecular signatures, and disease management. Potential mechanisms of progression from DCIS to invasive cancer and problems faced by clinicians and pathologists in diagnosing and treating this disease are also discussed. Despite the tremendous research efforts to identify accurate risk stratification predictors of invasive recurrence and response to radiotherapy and endocrine therapy, to date there is no simple, well-validated marker or group of variables for risk estimation, particularly in the setting of adjuvant treatment after breast-conserving surgery. Thus, the standard of care to date remains breast-conserving surgery plus radiotherapy, with or without hormonal therapy. Emerging tools, such as pathologic or biologic markers, may soon change such practice. Our review also includes recent advances towards innovative treatment strategies, including targeted therapies, immune modulators, and vaccines.

The prognostic significance of lysosomal protective protein (cathepsin A) in breast ductal carcinoma in situ

AIMS

Cathepsin A (CTSA) is a key regulatory enzyme for galactoside metabolism. Additionally, it has a distinct proteolytic activity and plays a role in tumour progression. CTSA is differentially expressed at the mRNA level between breast ductal carcinoma in situ (DCIS) and invasive breast carcinoma (IBC). In this study, we aimed to characterise CTSA protein expression in DCIS and evaluate its prognostic significance.

METHODS AND RESULTS

A large cohort of DCIS [n = 776 for pure DCIS and n = 239 for DCIS associated with IBC (DCIS/IBC)] prepared as a tissue microarray was immunohistochemically stained for CTSA. High CTSA expression was observed in 48% of pure DCIS. High expression was associated with features of poor DCIS prognosis, including younger age at diagnosis (<50 years), higher nuclear grade, hormone receptor negativity, HER2 positivity, high proliferative index and high hypoxia inducible factor 1 alpha expression. High CTSA expression was associated with shorter recurrence-free interval (RFI) (P = 0.0001). In multivariate survival analysis for patients treated with breast conserving surgery, CTSA was an independent predictor of shorter RFI (P = 0.015). DCIS associated with IBC showed higher CTSA expression than pure DCIS (P = 0.04). In the DCIS/IBC cohort, CTSA expression was higher in the invasive component than the DCIS component (P < 0.0001).

CONCLUSION

CTSA is not only associated with aggressive behaviour and poor outcome in DCIS but also a potential marker to predict co-existing invasion in DCIS.

Ductal carcinoma in situ current trends, controversies, and review of literature

Ductal carcinoma in situ (DCIS) is a non-obligate precursor, non-invasive malignancy confined within the basement membrane of the breast ductal system. There is a wide variation in the natural history of DCIS with an estimated incidence of progression to invasive ductal carcinoma being at least 13%-50% over a range of 10 or more years after initial diagnosis. Regardless of the treatment strategy, long-term survival is excellent. The controversy surrounding DCIS relates to preventing under-treatment, while also avoiding unnecessary treatments. In this article, we review the incidence, presentation, management options and surveillance of DCIS. Furthermore, we address several current controversies related to the management of DCIS, including margin status, sentinel node biopsy, hormonal therapy, the role of radiation in breast conservation surgery, and various risk stratification schemes.

Ductal Carcinoma In Situ

Ductal carcinoma in situ has been stable in incidence for a decade and has an excellent prognosis. Breast conservation therapy is safe and effective for most patients. Adjuvant whole breast radiation therapy is recommended to reduce the risk of local recurrence. Accelerated partial breast irradiation is a promising alternative to decrease toxicity and improve cosmetic results. Adjuvant hormonal therapy can reduce local recurrence, but should be used cautiously. Future directions in management include developing predictive tools for guidance for use of adjuvant therapy and selecting low-risk patients with ductal carcinoma in situ in whom surgery may be safely omitted.

Controversies in the Treatment of Ductal Carcinoma in Situ

Ductal carcinoma in situ (DCIS) accounts for 20% of all newly diagnosed breast cancers. Mastectomy was once the gold standard for the treatment of DCIS; however, breast-conserving surgery (BCS) has been adopted as the treatment of choice for patients with small, screen-detected lesions. Both adjuvant radiation and hormonal therapy following BCS have been demonstrated in randomized trials to reduce the risk of both invasive and DCIS recurrence, but neither affects survival. With the variety of surgical and adjuvant treatment options available, there has been great interest in tailoring the treatment to the individual, with the goal of optimizing the balance of risks and benefits according to the values and priorities of the woman herself. Prospective studies of women with "low-risk" DCIS treated with BCS alone have successfully identified women at lower than average risk but have not achieved the goal of identifying a subset of women with DCIS at minimal risk of recurrence after surgical excision alone. No studies have evaluated the safety of medical management alone.

Ductal Carcinoma In Situ Biology, Biomarkers, and Diagnosis

Ductal carcinoma in situ (DCIS) is an often-diagnosed breast disease and a known, non-obligate, precursor to invasive breast carcinoma. In this review, we explore the clinical and pathological features of DCIS, fundamental elements of DCIS biology including gene expression and genetic events, the relationship of DCIS with recurrence and invasive breast cancer, and the interaction of DCIS with the microenvironment. We also survey how these various elements are being used to solve the clinical conundrum of how to optimally treat a disease that has potential to progress, and yet is also likely over-treated in a significant proportion of cases.

Delay in radiotherapy is associated with an increased risk of disease recurrence in women with ductal carcinoma in situ

BACKGROUND

The current study was conducted to examine the association between ipsilateral breast tumor recurrence (IBTR) and the timing of radiotherapy (RT) in women with ductal carcinoma in situ (DCIS) undergoing breast-conserving surgery (BCS).

METHODS

Women with DCIS who were treated with BCS and RT from 1980 through 2010 were identified from a prospectively maintained database. IBTR rates, measured from the time of RT completion, were compared between those who initiated RT ≤8 weeks, >8 to 12 weeks, and >12 weeks after the completion of surgery. The association between RT timing and IBTR was evaluated by Kaplan-Meier and log-rank analyses; Cox modeling was used for multivariable analysis.

RESULTS

A total of 1323 women met the inclusion criteria. The median follow-up was 6.6 years, with 311 patients followed for ≥10 years. A total of 126 IBTR events occurred. Patients were categorized by RT timing: 806 patients (61%) with timing of ≤8 weeks, 386 patients (29%) with timing of >8 to 12 weeks, and 131 patients (10%) with timing >12 weeks. The 5-year and 10-year IBTR rates were 5.8% and 13.0%, respectively, for RT starting ≤8 weeks after surgery; 3.8% and 7.6%, respectively, for RT starting >8 to 12 weeks after surgery; and 8.8% and 23.0%, respectively, for an RT delay >12 weeks after surgery (P = .004). On multivariable analysis, menopause (hazard ratio [HR], 0.54; P = .0009) and endocrine therapy (HR, 0.45; P = .002) were found to be protective against IBTR, whereas a delay in RT >12 weeks compared with ≤8 weeks was associated with a higher risk of IBTR (HR, 1.92; P = .014). There was no difference in IBTR noted between RT initiation at ≤8 weeks and initiation at >8 to 12 weeks after BCS (P = .3).

CONCLUSIONS

A delay in RT >12 weeks is associated with a significantly higher risk of IBTR in women undergoing BCS for DCIS. Efforts should be made to avoid delays in starting RT to minimize the risk of disease recurrence. Cancer 2018;124:46-54. © 2017 American Cancer Society.

Outcomes for Women with Minimal-Volume Ductal Carcinoma In Situ Completely Excised at Core Biopsy

BACKGROUND

Overdiagnosis and overtreatment of ductal carcinoma in situ (DCIS) are concerns, especially for women with low-volume, screen-detected DCIS. This study aimed to evaluate the outcomes for such patients.

METHODS

Women who had minimal-volume DCIS (mDCIS, defined as DCIS diagnosed by core biopsy but with no residual disease on the surgical excision) treated with breast-conserving surgery from 1990 to 2011 were identified. Ipsilateral and contralateral breast events (IBE and CBE) were compared by competing-risk (CR) analysis. Kaplan-Meier (KM) estimates and log-rank tests were used to evaluate covariates.

RESULTS

The study identified 290 cases of mDCIS. The median age of the patients was 53 years. Radiation therapy (RT) was performed for 27.6% and endocrine therapy for 16.2% of the patients. The median follow-up period was 6.8 years. Overall, the IBE rates were 4.3% at 5 years and 12.3% at 10 years. Among the women not receiving RT, the 5- and 10-year IBE rates (5.4 and 14.5%) were higher than the CBE rates (1.8 and 2.7%). Among those receiving RT, the IBE rates (1.5 and 6.0%) were lower than the CBE rates (4.1 and 15.6%). The women receiving RT trended toward significantly lower IBE rates (p = 0.07). Age, grade, and endocrine therapy were not significantly associated with IBE risk.

CONCLUSIONS

Among the patients with mDCIS who did not receive RT, the IBE risk was substantially higher than the CBE risk, demonstrating that even DCIS of very low volume is associated with clinically relevant disease. The finding that the IBE risk was greater than the CBE risk supports current strategies that treat DCIS as a precursor rather than a risk marker. Women with mDCIS are not at negligible risk for IBE in the absence of adjuvant therapy.

Current treatment trends and the need for better predictive tools in the management of ductal carcinoma in situ of the breast

Ductal carcinoma in situ (DCIS) of the breast represents a group of heterogeneous non-invasive lesions the incidence of which has risen dramatically since the advent of mammography screening. In this review we summarise current treatment trends and up-to-date results from clinical trials studying surgery and adjuvant therapy alternatives, including the recent consensus on excision margin width and its role in decision-making for post-excision radiotherapy. The main challenge in the clinical management of DCIS continues to be the tailoring of treatment to individual risk, in order to avoid the over-treatment of low-risk lesions or under-treatment of DCIS with higher risk of recurring or progressing into invasion. While studies estimate that only about 40% of DCIS would become invasive if untreated, heterogeneity and complex natural history have prevented adequate identification of these higher-risk lesions. Here we discuss attempts to develop prognostic tools for the risk stratification of DCIS lesions and their limitations. Early results of a UK-wide audit of DCIS management (the Sloane Project) have also demonstrated a lack of consistency in treatment. In this review we offer up-to-date perspectives on current treatment and prediction of DCIS, highlighting the pressing clinical need for better prognostic indices. Tools integrating both clinical and histopathological factors together with molecular biomarkers may hold potential for adequate stratification of DCIS according to risk. This could help develop standardised practices for optimal management of patients with DCIS, improving clinical outcomes while providing only the amount of therapy required for each individual patient.

The Association of Surgical Margins and Local Recurrence in Women with Ductal Carcinoma In Situ Treated with Breast-Conserving Therapy: A Meta-Analysis

PURPOSE

There is no consensus on adequate negative margins in breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS). We systematically reviewed the evidence on margins in BCS for DCIS.

METHODS

A study-level meta-analysis of local recurrence (LR), microscopic margin status and threshold distance for negative margins. LR proportion was modeled using random-effects logistic meta-regression (frequentist) and network meta-analysis (Bayesian) that allows for multiple margin distances per study, adjusting for follow-up time.

RESULTS

Based on 20 studies (LR: 865 of 7883), odds of LR were associated with margin status [logistic: odds ratio (OR) 0.53 for negative vs. positive/close (p < 0.001); network: OR 0.45 for negative vs. positive]. In logistic meta-regression, relative to >0 or 1 mm, ORs for 2 mm (0.51), 3 or 5 mm (0.42) and 10 mm (0.60) showed comparable significant reductions in the odds of LR. In the network analysis, ORs relative to positive margins for 2 (0.32), 3 (0.30) and 10 mm (0.32) showed similar reductions in the odds of LR that were greater than for >0 or 1 mm (0.45). There was weak evidence of lower odds at 2 mm compared with >0 or 1 mm [relative OR (ROR) 0.72, 95 % credible interval (CrI) 0.47-1.08], and no evidence of a difference between 2 and 10 mm (ROR 0.99, 95 % CrI 0.61-1.64). Adjustment for covariates, and analyses based only on studies using whole-breast radiotherapy, did not change the findings.

CONCLUSION

Negative margins in BCS for DCIS reduce the odds of LR; however, minimum margin distances above 2 mm are not significantly associated with further reduced odds of LR in women receiving radiation.

Ductal carcinoma in situ - update on risk assessment and management

Ductal carcinoma in situ (DCIS) accounts for ~20-25% of breast cancers. While DCIS is not life-threatening, it may progress to invasive carcinoma over time, and treatment intended to prevent invasive progression may itself cause significant morbidity. Accurate risk assessment is therefore necessary to avoid over- or undertreatment of an individual patient. In this review we will outline the evidence for current management of DCIS, discuss approaches to DCIS risk assessment and challenges facing identification of novel DCIS biomarkers.

Women with Low-Risk DCIS Eligible for the LORIS Trial After Complete Surgical Excision: How Low Is Their Risk After Standard Therapy?

BACKGROUND

Identifying DCIS patients at low risk for disease progression could obviate need for standard therapy. The LORIS (surgery versus active monitoring for low-risk DCIS) trial is studying the safety of monitoring low-risk DCIS, although ipsilateral breast tumor recurrence (IBTR) rates in patients meeting enrollment criteria after complete surgical excision are unknown.

METHODS

Women with pure DCIS treated with breast-conserving surgery (BCS) with/without radiation therapy (RT) from 1/1996-1/2011 were included from a prospectively maintained database. IBTR rates were compared between those who did and did not meet LORIS eligibility criteria (age ≥ 46 years, screen-detected calcifications, nipple discharge absence, minimal family history, non-high-grade DCIS) after complete surgical excision.

RESULTS

A total of 2394 women were identified; 401 met LORIS criteria. Median follow-up was 5.9 years; 431 had ≥10 years follow-up. LORIS cohort median age was 61 years (range 46-86 years); 207 (52 %) underwent RT, 79 (20 %) received endocrine therapy. Of 401 patients, 24 experienced an IBTR. Overall 10-year IBTR rates were 10.3 % (LORIS) versus 15.4 % (non-LORIS) (p = 0.08); without RT, 12.1 versus 21.4 %, respectively (p = 0.06). The 10-year invasive-IBTR rates for women meeting LORIS criteria were: 5.3 % BCS overall, 6.0 % without RT.

CONCLUSIONS

Women meeting LORIS criteria (after complete surgical excision) are at somewhat lower risk for IBTR. Among such women undergoing excision without RT, the 10-year invasive-IBTR rate was 6 %. Given that approximately 20 % of women with core biopsy-proven non-high-grade DCIS have invasive cancer at excision, women managed without excision would be expected to incur higher invasive cancer rates. Additional criteria are needed to identify women not requiring intervention for DCIS.

Updates in the treatment of ductal carcinoma in situ of the breast

PURPOSE OF REVIEW

Ductal carcinoma in situ (DCIS) accounts for approximately 20% of mammographically diagnosed breast cancers. Currently, there is a trend to consider DCIS as a lesion for which treatment deescalation is advocated to avoid overtreatment, that is, radiotherapy in addition to breast-conserving surgery or even surgery at all.

RECENT FINDINGS

The long-term follow-up updates of the four first-generation randomized trials comparing lumpectomy with and without radiation therapy have confirmed that radiation halves the local failure rates. However, radiotherapy is not associated with a survival benefit just as affirmed by the recently published evaluation of the Surveillance, Epidemiology, and End Results registries database, including 108,196 women with DCIS. Nevertheless, the risk of dying of breast cancer increases about factor 18 after experience of an invasive local recurrence. That means at least some DCIS have the potential to progress to a life threatening disease. At the same time, none of the recently updated prospective trials that tested the outcome after excision alone in low-risk DCIS achieved a 10-year local failure rate below 10%.

SUMMARY

DCIS is not a uniform disease. Its clinical behaviour is heterogeneous, but up to date no citeria are available that allow a precise identification of patients with low or very low progression risk who do not need irradiation. Therefore, excision followed by radiotherapy is still the standard of care in patients undergoing breast conservation. Promising new approaches for risk estimation have to be validated prospectively before their use in daily practice can be recommended.

Breast-conserving treatment for ductal carcinoma in situ: Impact of boost and tamoxifen on local recurrences

PURPOSE

Ductal carcinoma in situ represents 15 to 20% of all breast cancers. Breast-conserving surgery and whole breast irradiation was performed in about 60% of the cases. This study reports local recurrence rates in patients with ductal carcinoma in situ treated by breast-conserving surgery and whole breast irradiation with or without boost and/or tamoxifen and compares different therapeutic options in two European countries.

PATIENTS AND METHODS

From 1998 to 2007, 819 patients with pure ductal carcinoma in situ were collected, both in France (266) and Italy (553). Median age was 56. All underwent breast-conserving surgery and whole breast irradiation; 391 (48%) received a boost (55% in France and 45% in Italy, P=0.017) and 173 (22.5%) tamoxifen (4.5% in France and 32% in Italy, P<0.0001).

RESULTS

With a 90-month median follow-up, there were 51 local recurrences (6.2%), including 27 invasive (53%). The 5- and 10-year local recurrence rates were 4% and 8.6%. Two patients developed axillary recurrence and 12 (1.5%) metastases (seven after invasive local recurrence); 41 (5%) patients had contralateral breast cancer. In the multivariate analysis, high nuclear grade and lack of tamoxifen are the most powerful predictors of local recurrence, with 2.6 (95% confidence interval [95% CI]: 1.74-3.89, P=0.0012) and 2.85 (95% CI: 1.42-5.72, P=0.04) odds ratio (OR) estimates, respectively. Age, margin status and boost did not influence local recurrence rates.

CONCLUSIONS

This study confirms the ductal carcinoma in situ treatment heterogeneity among countries and the unfavourable prognostic role of nuclear grade. Tamoxifen reduces local recurrence rates and might be considered for some subgroups of patients, but further confirmation is required. The boost usefulness still remains unclear.

Impact of Age on Risk of Recurrence of Ductal Carcinoma In Situ: Outcomes of 2996 Women Treated with Breast-Conserving Surgery Over 30 Years

BACKGROUND

Age is a known risk factor for recurrence in women with ductal carcinoma in situ (DCIS) treated with breast-conserving surgery (BCS). We explored the relationship between age, other risk factors, and recurrence.

METHODS

Using a prospectively maintained database of DCIS patients undergoing BCS from 1978 to 2010, the association of age and recurrence risk was analyzed using Kaplan-Meier estimates, multivariable analysis, and competing risk multivariable analysis.

RESULTS

Overall, 2996 cases were identified. Median follow-up for those without recurrence was 75 months; 732 were followed for ≥10 years, and 363 (12 %) had recurrence [192 (53 %) DCIS, 160 (44 %) invasive, 11 (3 %) unknown]. Risk of recurrence decreased with age, even after adjustment for eight clinicopathologic variables on multivariable analysis [hazard ratios (HR), with <40 years of age as the reference: 40-49 years, 0.82 (p = 0.36), 50-59 years, 0.46 (p = 0.0005), 60-69 years, 0.50 (p = 0.003), 70-79 years, 0.56 (p = 0.02), ≥80 years, 0.21 (p = 0.0015)]. This association persisted for cohorts with and without radiation therapy. Using competing risk multivariable analysis, the effect of age on invasive recurrence was empirically stronger than for DCIS recurrence. Ten-year invasive recurrence was 16 and 6.5 % in women <40 years of age and women ≥40 years of age, respectively. Only 0.6 % of the population ultimately developed distant disease; those <40 years of age constituted 4.7 % (141/2996) of the population, but 21 % (4/19) of those developed distant disease.

CONCLUSIONS

The risk of recurrence of DCIS decreases with age. This effect is particularly strong at the extremes of age and is independent of other clinicopathologic factors. The oldest women are at low risk of recurrence, while the youngest women have a higher overall, and especially invasive, recurrence rate, although mortality remains low. These findings should be incorporated into risk/benefit discussions of treatment options.

Comparison of ipsilateral breast tumor recurrence after breast-conserving surgery between ductal carcinoma in situ and invasive breast cancer

Background

We aimed to evaluate the differences in the rates and predictive factors for ipsilateral breast tumor recurrence (IBTR) after breast-conserving surgery (BCS) between ductal carcinoma in situ (DCIS) and invasive breast cancer. And, we evaluated the impact of IBTR on overall survival and distant metastasis.

Methods

We retrospectively reviewed 322 consecutive patients with DCIS or invasive breast cancer who underwent BCS between 2004 and 2010. We evaluated the rates of IBTR of DCIS and invasive breast cancer. Univariate and multivariate analyses were performed to determine the predictive factors for IBTR, and survival rates were analyzed with Kaplan-Meier estimates.

Results

With a median follow-up period of 57 months, 5 (10 %) out of 50 DCIS patients and 14 (5.1 %) out of 272 invasive cancer patients had developed IBTR. Factors associated with IBTR on univariate and multivariate analyses were positive resection margin status in DCIS and omission of radiotherapy in invasive cancer, respectively. The hormone receptor negativity was strong independent predictive factors for IBTR in both DCIS and invasive breast cancer. Although the differences of survival curve did not reach statistical significance, the 5-year overall survival and distant metastasis-free survival of invasive cancer patients who suffered IBTR were inferior to those without (84 vs. 98 % and 63.3 vs. 96.5 %, respectively). Advanced initial stage, lymph node metastasis and experience of IBTR were associated with poor overall survival and distant metastasis on univariate and multivariate analyses.

Conclusions

The hormone receptor negativity was revealed as independent predictive factor for IBTR after BCS in both DCIS and invasive cancer. Experience of IBTR was independent prognostic factor for poor overall outcome in patients with invasive breast cancer. Aggressive local control and adjuvant therapy should be made in hormone receptor-negative patients who receive treatment with BCS.

Relationship Between Margin Width and Recurrence of Ductal Carcinoma In Situ: Analysis of 2996 Women Treated With Breast-conserving Surgery for 30 Years

OBJECTIVE

Our goal was to investigate, in a large population of women with ductal carcinoma in situ (DCIS) and long follow-up, the relationship between margin width and recurrence, controlling for other characteristics.

BACKGROUND

Although DCIS has minimal mortality, recurrence rates after breast-conserving surgery are significant, and half are invasive. Positive margins are associated with increased risk of local recurrence, but there is no consensus regarding optimal negative margin width.

METHODS

We retrospectively reviewed a prospective database of DCIS patients undergoing breast-conserving surgery from 1978 to 2010. Univariate and Cox proportional hazard models were used to investigate the association between margin width and recurrence.

RESULTS

In this review, 2996 cases were identified, of which 363 recurred. Median follow-up for women without recurrence was 75 months (range 0-30 years); 732 were studied for ≥10 years. Controlling for age, family history, presentation, nuclear grade, number of excisions, radiotherapy (RT), endocrine therapy, and year of surgery, margin width was significantly associated with recurrence in the entire population. Larger negative margins were associated with a lower hazard ratio compared with positive margins. An interaction between RT and margin width was significant (P < 0.03); the association of recurrence with margin width was significant in those without RT (P < 0.0001), but not in those with RT (P = 0.95).

CONCLUSIONS

In women not receiving RT, wider margins are significantly associated with a lower rate of recurrence. Obtaining wider negative margins may be important in reducing the risk of recurrence in women who choose not to undergo RT and may not be necessary in those who receive RT.

Decreasing Recurrence Rates for Ductal Carcinoma In Situ: Analysis of 2996 Women Treated with Breast-Conserving Surgery Over 30 Years

BACKGROUND

Randomized trials of radiation after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS) found substantial rates of recurrence, with half of the recurrences being invasive. Decreasing local recurrence rates for invasive breast carcinoma have been observed and are largely attributed to improvements in systemic therapy. In this study, we examine recurrence rates after BCS for DCIS over 3 decades at one institution.

METHODS

We retrospectively reviewed a prospectively maintained database of DCIS patients undergoing BCS from 1978 to 2010. Cox proportional hazard models were used to investigate the association between the treatment period and recurrence, controlling for other variables.

RESULTS

Overall, 363 (12%) recurrences among 2996 cases were observed. Median follow-up for patients without recurrence was 75 months (range 0-30 years); 732 patients were followed for ≥10 years. The 5-year recurrence rate for the period 1978-1998 was 13.6 versus 6.6% for the period 1999-2010 [hazard ratio (HR) 0.62, p < 0.0001]. Controlling for age, family history, presentation, nuclear grade, necrosis, number of excisions, margin status, radiation, and endocrine therapy, treatment period remained significantly associated with recurrence, with later years associated with a lower HR (0.74, p = 0.02) compared to earlier. After stratification by radiation use, association of recurrence with treatment period persisted in those treated without radiation (HR 0.62, p = 0.003).

CONCLUSIONS

Recurrence rates for DCIS have fallen over time, with increases in screen detection, negative margins, and use of adjuvant therapies only partially explaining this decrease. The unexplained decline persists in women not receiving radiation, suggesting it is not due to changes in radiation efficacy but may be due to improvements in radiologic detection and pathologic assessment.

Risk Prediction for Local Breast Cancer Recurrence Among Women with DCIS Treated in a Community Practice: A Nested, Case-Control Study

BACKGROUND

Various patient, treatment, and pathologic factors have been associated with an increased risk of local recurrence (LR) following breast-conserving therapy (BCT) for ductal carcinoma in situ (DCIS). However, the strength and importance of individual factors has varied; whether combining factors improves prediction, particularly in community practice, is uncertain. In a large, population-based cohort of women with DCIS treated with BCT in three community-based practices, we assessed the validity of the Memorial Sloan-Kettering Cancer Center (MSKCC) DCIS nomogram, which combines clinical, pathologic, and treatment features to predict LR.

METHODS

We reviewed slides of patients with unilateral DCIS treated with BCT. Regression methods were used to estimate risks of LR. The MSKCC DCIS nomogram was applied to the study population to compare the nomogram-predicted and observed LR at 5 and 10 years.

RESULTS

The 495 patients in our study were grouped into quartiles and octiles to compare observed and nomogram-predicted LR. The 5-year absolute risk of recurrence for lowest and highest quartiles was 4.8 and 33.1 % (95 % CI 3.1-6.4 and 24.2-40.9, respectively; p < 0.0001). The overall correlation between 10-year nomogram-predicted recurrences and observed recurrences was 0.95. Compared with observed 10-year LR rates, the risk estimates provided by the nomogram showed good correlation, and reasonable discrimination with a c-statistic of 0.68.

CONCLUSIONS

The MSKCC DCIS nomogram provided good prediction of the 5- and 10-year LR when applied to a population of patients with DCIS treated with BCT in a community-based practice. This nomogram, therefore, is a useful treatment decision aid for patients with DCIS.

Validation of a nomogram in the prediction of local recurrence risks after conserving surgery for Asian women with ductal carcinoma in situ of the breast

AIMS

At our centre, ductal carcinoma in situ (DCIS) was commonly treated with breast-conservation therapy (BCT). Local recurrence after BCT is a major concern. The aims of our study were to review the outcomes of DCIS treatment in our patients and to evaluate a nomogram from Memorial Sloan Kettering Cancer Centre (MSKCC) for predicting ipsilateral breast tumour recurrence (IBTR) in our Asian population.

MATERIALS AND METHODS

Chart reviews of 716 patients with pure DCIS treated from 1992 to 2011 were carried out. Univariable Cox regression analyses were used to evaluate the effects of the 10 prognostic factors of the MSKCC nomogram on IBTR. We constructed a separate National Cancer Centre Singapore (NCCS) nomogram based on multivariable Cox regression via reduced model selection by applying the stopping rule of Akaike's information criterion to predict IBTR-free survival. The abilities of the NCCS nomogram and the MSKCC nomogram to predict IBTR of individual patients were evaluated with bootstrapping of 200 sets of resamples and the NCCS dataset, respectively. Harrell's c-index was calculated for each nomogram to evaluate the concordance between predicted and observed responses of individual subjects.

RESULTS

Study patients were followed up for a median of 70 months. Over 95% of patients received adjuvant radiotherapy. The 5 and 10 year actuarial IBTR-free survival rates for the cohort were 95.5 and 92.6%, respectively. In the multivariate analysis, independent prognostic factors for IBTR included use of adjuvant endocrine therapy, presence of comedonecrosis and younger age at diagnosis. These factors formed the basis of the NCCS nomogram, which had a similar c-index (NCCS: 0.696; MSKCC: 0.673) compared with the MSKCC nomogram.

CONCLUSION

The MSKCC nomogram was validated in an Asian population. A simpler NCCS nomogram using a different combination of fewer prognostic factors may be sufficient for the prediction of IBTR in Asians, but requires external validation to compare for relative performance.