Local recurrence in women with stage I breast cancer: declining rates over time in a large, population-based cohort

Estimated incidence of disruptions to event-free survival from non-metastatic cancers in New South Wales, Australia - a population-wide epidemiological study of linked cancer registry and treatment data

Introduction

Population cancer registries record primary cancer incidence, mortality and survival for whole populations, but not more timely outcomes such as cancer recurrence, secondary cancers or other complications that disrupt event-free survival. Nonetheless, indirect evidence may be inferred from treatment data to provide indicators of recurrence and like events, which can facilitate earlier assessment of care outcomes. The present study aims to infer such evidence by applying algorithms to linked cancer registry and treatment data obtained from hospitals and universal health insurance claims applicable to the New South Wales (NSW) population of Australia.

Materials and methods

Primary invasive cancers from the NSW Cancer Registry (NSWCR), diagnosed in 2001-2018 with localized or regionalized summary stage, were linked to treatment data for five common Australian cancers: breast, colon/rectum, lung, prostate, and skin (melanomas). Clinicians specializing in each cancer type provided guidance on expected treatment pathways and departures to indicate remission and subsequent recurrence or other disruptive events. A sample survey of patients and clinicians served to test initial population-wide results. Following consequent refinement of the algorithms, estimates of recurrence and like events were generated. Their plausibility was assessed by their correspondence with expected outcomes by tumor type and summary stage at diagnosis and by their associations with cancer survival.

Results

Kaplan-Meier product limit estimates indicated that 5-year cumulative probabilities of recurrence and other disruptive events were lower, and median times to these events longer, for those staged as localized rather than regionalized. For localized and regionalized cancers respectively, these were: breast - 7% (866 days) and 34% (570 days); colon/rectum - 15% (732 days) and 25% (641 days); lung - 46% (552 days) and 66% (404 days); melanoma - 11% (893 days) and 38% (611 days); and prostate - 14% (742 days) and 39% (478 days). Cases with markers for these events had poorer longer-term survival.

Conclusions

These population-wide estimates of recurrence and like events are approximations only. Absent more direct measures, they nonetheless may inform service planning by indicating population or treatment sub-groups at increased risk of recurrence and like events sooner than waiting for deaths to occur.

Incorporating Tumor Biology to Select Patients for the Omission of Radiation Therapy

Although adjuvant breast radiotherapy has long been a universal component of breast conservation therapy (BCT), it is now clear that "breast cancer" is a broad class of many disparate diseases with varying natural histories and risk profiles. In turn, some breast conservation patients enjoy exceedingly favorable outcomes following surgery alone. Ongoing trials seek to identify such low-risk patient populations, hypothesizing that some may safely forego radiotherapy. Whereas prior-generation trials focused on clinicopathologic features for risk stratification, contemporary studies are employing molecular biomarkers to identify those patients who are unlikely to benefit significantly from radiotherapy.

Ten-year results of hypofractionated whole breast radiotherapy and intraoperative electron boost in premenopausal women

AIM

To evaluate outcome of intraoperative electron boost (IOERT) and hypofractionated whole breast irradiation (HWBI) for breast cancer (BC) in young women.

METHODS AND MATERIALS

Women aged ≤ 48 with pT1-2 N0-1 BC received 12 Gy IOERT boost during conservative surgery followed by 3-dimensional conformal HWBI in 13 fractions (2.85 Gy/die). Local relapses (LR) and survival (disease-free, DFS; specific, BCSS; overall, OS) were analyzed.

RESULTS

481 consecutive BC patients, mostly node negative, with median age of 42 were treated between 2004 and 2014. Median tumor size was 1.48 cm and median IOERT collimator was 4 cm. After 25-day mean interval, HWBI was delivered. At a median follow-up of 9.6 years, there were 23 LRs (4.8 %, 9 of which were in the boost region). Ten-year LR cumulative incidence was 4.1 % (95 %CI, 2.5-6.3). Over time, local control rate decreased for Luminal A and HER2 positive with negative hormonal receptors, while remained steady for triple negative. At multivariate analysis, LR predictors included age < 40, extensive intraductal component and the use of 4-cm IOERT collimator size. Ten-year survival outcomes were as follows: DFS 80.0 % (95 % CI, 75.8-83.5), BCSS 97.5 % (95 % CI, 95.5-98.6 %), OS 96.5 % (95 % CI, 94.3-97.9). Luminal B HER2 negative had the worse survival outcomes. Perioperative complications were uncommon (16.4 %), acute toxicity was mild (<2% Grade 3), but moderate/severe fibrosis was described in 40.8 % of the cases. Cosmesis was scored as excellent/good in 86 % of the cases.

CONCLUSIONS

ELIOT boost and HWBI achieved an excellent local control at the cost of tumor bed fibrosis. IOERT boost dose lower than 12 Gy is advisable.

Long-term oncological outcomes of organ-sparing treatment of patients with early breast cancer aged 65 years and older who had no postoperative radiation therapy

Postoperative radiation therapy after breast-conserving surgery is a standard method of treating breast cancer, but recently the issue of its de-escalation in patients older than 65 due to concomitant pathology, lower life expectancy and possible development of post-radiation complications has been discussed. The results of some foreign studies prove the absence of a statistically significant difference in relapse-free and overall survival in patients with early breast cancer older than 65 years with relatively favorable clinical and morphological characteristics without postoperative radiation therapy. We analyzed the long-term oncological results in patients with breast cancer older than 65 years after breast-conserving surgery without postoperative radiation therapy. The results of the study showed that postoperative radiation therapy in patients over 65 years of age with stage IA pT1N0M0 breast cancer of luminal immunophenotype A does not improve long-term oncological indicators. Thus, the exclusion of postoperative radiation therapy from the treatment plan of this group of patients is oncologically safe and economically justified.

Nipple-sparing mastectomy for breast cancer close to the nipple: a single institution's 11-year experience

BACKGROUND

This study aimed to analyze our 11-year experience using NSM with immediate breast reconstruction in breast cancer.

METHODS

Between January 2007 and December 2015, 251 NSMs were performed on 251 women with breast cancer for therapeutic purpose at Pusan National University Hospital.

RESULTS

The clinical and pathologic mean tumor size was 3.1 cm. Based on preoperative imaging, mean distance between tumor and nipple was 2.5 cm. Among 251 tumors, 119 cases (47.4%) and 69 cases (27.5%) with a distances ≤ 2 cm and ≤ 1 cm, respectively, were detected. There were 11 patients (4.4%) with locoregional recurrences during the mean follow-up period of 68.0 months. Of these 11 cases, one (0.4%) had local recurrence in the retained NAC, and the others had recurrence in the chest wall or skin.

CONCLUSION

Unless clinical and histological evidence of nipple involvement, NSM can be an oncologically safe surgical option for breast cancer, even if the tumor is located close to the nipple.

Contemporary Issues in Breast Cancer Radiotherapy

A series of landmark studies have increasingly emphasized the role of adjuvant radiotherapy for the definitive management of breast cancer. Although regional nodal irradiation, including the internal mammary nodes, was typically reserved for high-risk patients, there is now evidence of benefit to this approach even for those with a limited nodal disease burden. Similarly, low-risk disease has historically been treated with whole-breast tangents, although contemporary studies now support accelerated partial breast irradiation or the omission of radiotherapy in select cases. This article presents recent data informing these contemporary developments in the radiotherapeutic management of breast cancer.

Tumor Resection Margin Definitions in Breast-Conserving Surgery: Systematic Review and Meta-analysis of the Current Literature

Worldwide, various guidelines recommend what constitutes an adequate margin of excision for invasive breast cancer or for ductal carcinoma-in-situ (DCIS). We evaluated the use of different tumor resection margin guidelines and investigated their impact on positive margin rates (PMR) and reoperation rates (RR). Thirteen guidelines reporting on the extent of a positive margin were reviewed along with 31 studies, published between 2011 and 2016, reporting on a well-defined PMR. Studies were categorized according to the margin definition. Pooled PMR and RR were determined with random-effect models. For invasive breast cancer, most guidelines recommend a positive margin of tumor on ink. However, definitions of reported positive margins in the clinic vary from more than focally positive to the presence of tumor cells within 3 to 5 mm from the resection surface. Within the studies analyzed (59,979 patients), pooled PMRs for invasive breast cancer ranged from 9% to 36% and pooled RRs from 77% to 99%. For DCIS, guidelines vary between no DCIS on the resection surface to DCIS cells found within a distance of 2 mm from the resection edge. Pooled PMRs for DCIS varied from 4% to 23% (840 patients). Given the differences in tumor margin definition between countries worldwide, quality control data expressed as PMR or RR should be interpreted with caution. Furthermore, the overall definition for positive resection margins for both invasive disease and DCIS seems to have become more liberal.

Tumour bed boost radiotherapy for women after breast-conserving surgery

BACKGROUND

Breast-conserving therapy, involving breast-conserving surgery followed by whole-breast irradiation and optionally a boost to the tumour bed, is a standard therapeutic option for women with early-stage breast cancer. A boost to the tumour bed means that an extra dose of radiation is applied that covers the initial tumour site. The rationale for a boost of radiotherapy to the tumour bed is that (i) local recurrence occurs mostly at the site of the primary tumour because remaining microscopic tumour cells are most likely situated there; and (ii) radiation can eliminate these causative microscopic tumour cells. The boost continues to be used in women at high risk of local recurrence, but is less widely accepted for women at lower risk. Reasons for questioning the boost are twofold. Firstly, the boost brings higher treatment costs. Secondly, the potential adverse events are not negligible. In this Cochrane Review, we investigated the effect of the tumour bed boost on local control and side effects.

OBJECTIVES

To assess the effects of tumour bed boost radiotherapy after breast-conserving surgery and whole-breast irradiation for the treatment of breast cancer.

SEARCH METHODS

We searched the Cochrane Breast Cancer Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (January 1966 to 1 March 2017), Embase (1980 to 1 March 2017), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov on 1 March 2017. We also searched the European Society of Radiotherapy and Oncology Annual Meeting, the St Gallen Oncology Conferences, and the American Society for Radiation Oncology Annual Meeting for abstracts.

SELECTION CRITERIA

Randomised controlled trials comparing the addition and the omission of breast cancer tumour bed boost radiotherapy.

DATA COLLECTION AND ANALYSIS

Two review authors (IK and CW) performed data extraction and assessed risk of bias using Cochrane's 'Risk of bias' tool, resolving any disagreements through discussion. We entered data into Review Manager 5 for analysis and applied GRADE to assess the quality of the evidence.

MAIN RESULTS

We included 5 randomised controlled trials analysing a total of 8325 women.Local control appeared to be better for women receiving a tumour bed boost compared to no tumour bed boost (hazard ratio (HR) 0.64, 95% confidence interval (CI) 0.55 to 0.75; 5 studies, 8315 women, low-quality evidence). Overall survival did not differ with or without a tumour bed boost (HR 1.04, 95% CI 0.94 to 1.14; 2 studies, 6342 women, moderate-quality evidence). Disease-free survival did not differ with or without a tumour bed boost (HR 0.94, 95% CI 0.87 to 1.02; 3 studies, 6549 women, low-quality evidence). Late toxicity scored by means of percentage of breast retraction assessment did not differ with or without a tumour bed boost (mean difference 0.38, 95% CI -0.18 to 0.93; 2 studies, 1526 women, very low-quality evidence). Cosmesis scored by a panel was better (i.e. excellent or good compared to fair or poor) in the no-boost group (odds ratio (OR) 1.41, 95% CI 1.07 to 1.85; 2 studies, 1116 women, low-quality evidence). Cosmesis scored by a physician did not differ with or without a tumour bed boost (OR 1.58, 95% CI 0.93 to 2.69; 2 studies, 592 women, very low-quality evidence).We excluded two studies in a sensitivity analysis of local recurrence (because the biological equivalent dose (BED) to the tumour bed was lower, in situ tumours were included, or there was a high risk of selective reporting bias or blinding of outcome assessment bias), which resulted in a HR of 0.62 (95% CI 0.52 to 0.73; 3 studies, 6963 women, high-quality evidence). Subgroup analysis including women older than 40 years of age yielded a HR of 0.65 (95% CI 0.53 to 0.81; 2 studies, 5058 women, high-quality evidence).We found no data for the outcomes of acute toxicity, quality of life, or costs.

AUTHORS' CONCLUSIONS

It appears that local control rates are increased with the boost to the tumour bed, but we found no evidence of a benefit for other oncological outcomes. Subgroup analysis including women older than 40 years of age yielded similarly significant results. Objective percentage of breast retraction assessment appears similar between groups. It appears that the cosmetic outcome is worse with the boost to the tumour bed, but only when measured by a panel, not when assessed by a physician.

Trend in Age and Racial Disparities in the Receipt of Postlumpectomy Radiation Therapy for Stage I Breast Cancer: 2004-2009

OBJECTIVES

Significant effort has been expended over the past decade to reduce racial disparities in breast cancer care. Whether disparities in receipt of appropriate radiotherapy care for breast cancer persisted despite these efforts is unknown, as is the impact of being eligible for Medicare. We therefore investigated trends in racial differences by age in postbreast lumpectomy radiation therapy (PLRT) from 2004 to 2009.

MATERIALS AND METHODS

We analyzed the Surveillance, Epidemiology and End Results registry database for women aged 40 to 85 years who underwent lumpectomy for stage I breast cancer and were eligible for PLRT. We examined variables potentially associated with the receipt of PLRT, including year of diagnosis, race, and examined women separately by age group.

RESULTS

Among 67,124 women aged 40 to 85 years undergoing lumpectomy, receipt of PLRT decreased from 80.7% in 2004 to 76.8% by 2009 (P<0.001). There remained a persistent disparity in PLRT among African American women (in 2004, 80.6% white vs. 78.9% African American and in 2009, 77.5% white vs. 72.0% African American). In multivariable logistic regression, African American race (odds ratio [OR], 0.82; 95% confidence interval [CI]. 0.76-0.89) and being diagnosed more recently were associated with lower odds of PLRT (OR for 2009 vs. 2004: 0.74; 95% CI, 0.69-0.79), whereas older women typically covered by public health insurance (aged 65 to 69 y) were more likely to receive PLRT (OR, 1.09; 95% CI, 1.02-1.15).

CONCLUSIONS

PLRT decreased by a significant percentage of 3.9% among all women in recent years, and racial disparities in PLRT receipt have persisted. Medicare eligibility increased the likelihood of PLRT receipt.

Prognostic assessment and systemic treatments of invasive local relapses of hormone receptor-positive breast cancer

The rate of local recurrences, after breast-conserving surgery or mastectomy for hormone receptor-positive (HR+) breast cancer, has dramatically changed in last decades, due to advances in surgical and radiation techniques and a more extensive use of adjuvant systemic treatments. However, the occurrence of local recurrences remains a major predictor for distant metastasis and is responsible for increased cancer-specific death. It has been estimated that 1 in 4 HR+ and HR-ipsilateral breast recurrences leads to widespread metastatic disease, with an annual mortality rate of 10% in the first 5 years. Nevertheless, very few studies have been conducted to evaluate the optimal care of purely HR+ local relapses of breast cancer, after surgical removal. In this review we have highlighted the available knowledge on prognostic assessment and systemic treatment for women experiencing local relapses of HR+ breast cancers, underlying unsolved questions and controversial clinical aspects.

Adjuvant intraoperative radiotherapy for selected breast cancers in previously irradiated women: Evidence for excellent feasibility and favorable outcomes

BACKGROUND

The present report provides preliminary outcomes with intraoperative radiotherapy delivered to women with breast cancer included in a re-irradiation program.

MATERIALS AND METHODS

From October 2010 to April 2014, thirty women were included in a re-irradiation protocol by exploiting IORT technique. The median time between the two irradiations was 10 years (range 3-50). All patients underwent conservative surgery, sentinel lymph node excision and IORT with electron beam delivered by a mobile linear accelerator. Primary endpoint was esthetic result and consequential/late toxicity; secondary endpoints were local control (LC), disease free survival (DFS) and overall survival (OS).

RESULTS

With a median follow up of 47 months (range 10-78), we analyzed 29 patients (1 lost at follow up). Twenty-seven patients (90%) had presented breast cancer local relapse or a new primary cancer in the same breast after a previous conservative surgery plus radiation treatment; three patients (10%) had previously received irradiation with mantle field for Hodgkin Lymphoma. Esthetic result was excellent in 3 pts (10%), good in 12 pts (41%), fair in 8 pts (28%) and poor in 6 pts (21%). 12 (41%) patients showed subcutaneous fibrosis at the last follow-up. LC, DFS and OS at five years was 92.3%, 86.3% and 91.2%, respectively.

CONCLUSION

Although we analyzed a small number of patients, our results are satisfactory and this approach is feasible even if it could not be considered the standard treatment. Further clinical trials exploring IORT are needed to identify possible subgroups of patients that might be suitable for this type of approach.

The changing landscape in radiotherapy for breast cancer: Lessons from long term follow-up in some European breast cancer trials

This review describes the developments in the radiation treatment of breast cancer based on some randomized European trials during the past decades. It will focus on the relevance of long term follow-up in breast cancer patients, starting with the surprising and important change in treatment results during follow-up shown in a locally advanced breast cancer trial. Breast conserving therapy (BCT) in stage I and II breast cancer was explored and tested in a randomized trial to prove equivalence between BCT and mastectomy. The positive outcome led to trials in breast conserving therapy with lower doses and partial breast irradiation. Finally the need for finding genetic profiles for predicting treatment response will be addressed in a trial with preoperative partial breast irradiation.

Validation of the Web-Based IBTR! 2.0 Nomogram to Predict for Ipsilateral Breast Tumor Recurrence After Breast-Conserving Therapy

PURPOSE

To evaluate the IBTR! 2.0 nomogram, which predicts 10-year ipsilateral breast tumor recurrence (IBTR) after breast-conserving therapy with and without radiation therapy for breast cancer, by using a large, external, and independent cancer center database.

METHODS AND MATERIALS

We retrospectively identified 1898 breast cancer cases, treated with breast-conserving therapy and radiation therapy at the University Hospital Leuven from 2000 to 2007, with requisite data for the nomogram variables. Clinicopathologic factors were assessed. Two definitions of IBTR were considered where simultaneous regional or distant recurrence were either censored (conform IBTR! 2.0) or included as event. Validity of the prediction algorithm was tested in terms of discrimination and calibration. Discrimination was assessed by the concordance probability estimate and Harrell's concordance index. The mean predicted and observed 10-year estimates were compared for the entire cohort and for 4 risk groups predefined by nomogram-predicted IBTR risks, and a calibration plot was drawn.

RESULTS

Median follow-up was 10.9 years. The 10-year IBTR rates were 1.3% and 2.1%, according to the 2 definitions of IBTR. The validation cohort differed from the development cohort with respect to the administration of hormonal therapy, surgical section margins, lymphovascular invasion, and tumor size. In univariable analysis, younger age (P=.002) and a positive nodal status (P=.048) were significantly associated with IBTR, with a trend for the omission of hormonal therapy (P=.061). The concordance probability estimate and concordance index varied between 0.57 and 0.67 for the 2 definitions of IBTR. In all 4 risk groups the model overestimated the IBTR risk. In particular, between the lowest-risk groups a limited differentiation was suggested by the calibration plot.

CONCLUSIONS

The IBTR! 2.0 predictive model for IBTR in breast cancer patients shows substandard discriminative ability, with an overestimation of the risk in all subgroups.

Evaluation of a breast cancer nomogram to predict ipsilateral breast relapse after breast-conserving therapy

BACKGROUND AND PURPOSE

A nomogram to predict for the 10-year ipsilateral breast relapse (IBR) after breast-conserving therapy (BCT) for breast cancer (BC) was developed based on the 'boost-no-boost'-trial with a concordance probability estimate (CPE) of 0.68. The aim of our study was to validate that algorithm.

MATERIAL AND METHODS

We retrospectively identified 1787 BC cases, treated with BCT and radiotherapy at the University Hospitals Leuven from 2000 to 2007, without missing data of the nomogram variables. Clinicopathologic factors were assessed. Validity of the prediction model was tested in terms of discrimination and calibration.

RESULTS

Median follow-up time was 10.75years. The validation cohort differed with respect to the administration of a radiation boost, chemo- or hormonal therapy, age, tumour diameter or grade, ductal carcinoma in situ and hormone receptor positivity. On multivariable analysis, the omission of the boost was a significant prognosticator of IBR (p<0.01). The 10-year IBR-rate was 1.4%. The nomogram demonstrated suboptimal discrimination (CPE 0.54) and calibration, with an overestimation of the IBR-risk in general.

CONCLUSIONS

The predictive model for IBR in BC is imperfect in this more recent study population.

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.

Expanded Indications and Improved Outcomes for Nipple-Sparing Mastectomy Over Time

BACKGROUND

Demand for nipple-sparing mastectomy (NSM) has increased. The authors' initial NSM guidelines included risk reduction and cancers 2 cm or smaller located more than 2 cm from the nipple. The relative contraindications included obesity, large and/or ptotic breasts, and prior radiation. This study aimed to evaluate changes over time in NSM indications, surgical approach, and early outcomes.

METHODS

After institutional review board approval, the study identified 354 patients scheduled for 588 NSMs, 341 (96%) of whom underwent 566 NSMs. Changes across time [early (2009-2010), mid (2011-2012), and recent (2013-6/2014)] were assessed using tests for linear trend.

RESULTS

For patients undergoing reconstruction, NSMs increased from 24% (early) to 40% (recent) (p = 0.004). Among the NSM patients, average body mass index, proportion with bra cup sizes of C or larger, and prior radiation increased significantly over time. Performance of NSM for tumors 2 cm or less from the nipple increased from 5 to 18%, and after neoadjuvant therapy, from 8 to 21.5% (p = 0.02). Use of inframammary, radial, and reduction-type incisions increased over time, together with intraoperative laser angiography (both p < 0.0001). Concomitantly, the overall complication rate, complications requiring treatment, and postoperative nipple loss decreased. During a median follow-up period of 19 months, five locoregional recurrences (LRR) were observed, for an estimated 2-year LRR rate of 1.7% [95% confidence interval (CI), 0-3.9%].

CONCLUSIONS

Over time, the indications for NSM expanded in terms of patient characteristics, tumor stage, and prior therapy, whereas the complication rates decreased. Excellent short-term outcomes suggest that NSM is a reasonable approach for many risk-reduction and cancer patients without disease in the nipple-areolar complex. Further study is needed to assess long-term aesthetics, patient satisfaction, and oncologic safety.

Gene expression profiling to predict the risk of locoregional recurrence in breast cancer: a pooled analysis

The 70-gene signature (MammaPrint) has been developed to predict the risk of distant metastases in breast cancer and select those patients who may benefit from adjuvant treatment. Given the strong association between locoregional and distant recurrence, we hypothesize that the 70-gene signature will also be able to predict the risk of locoregional recurrence (LRR). 1,053 breast cancer patients primarily treated with breast-conserving treatment or mastectomy at the Netherlands Cancer Institute between 1984 and 2006 were included. Adjuvant treatment consisted of radiotherapy, chemotherapy, and/or endocrine therapy as indicated by guidelines used at the time. All patients were included in various 70-gene signature validation studies. After a median follow-up of 8.96 years with 87 LRRs, patients with a high-risk 70-gene signature (n = 492) had an LRR risk of 12.6% (95% CI 9.7-15.8) at 10 years, compared to 6.1% (95% CI 4.1-8.5) for low-risk patients (n = 561; P < 0.001). Adjusting the 70-gene signature in a competing risk model for the clinicopathological factors such as age, tumour size, grade, hormone receptor status, LVI, axillary lymph node involvement, surgical treatment, endocrine treatment, and chemotherapy resulted in a multivariable HR of 1.73 (95% CI 1.02-2.93; P = 0.042). Adding the signature to the model based on clinicopathological factors improved the discrimination, albeit non-significantly [C-index through 10 years changed from 0.731 (95% CI 0.682-0.782) to 0.741 (95% CI 0.693-0.790)]. Calibration of the prognostic models was excellent. The 70-gene signature is an independent prognostic factor for LRR. A significantly lower local recurrence risk was seen in patients with a low-risk 70-gene signature compared to those with high-risk 70-gene signature.

Identification of patients at very low risk of local recurrence after breast-conserving surgery

PURPOSE

To identify clinical and pathological factors that identify groups of women with stage I breast cancer with a 5-year risk of local recurrence (LR) ≤1.5% after breast-conserving therapy (BCS) plus whole-breast radiation therapy (RT).

METHODS AND MATERIALS

Study subjects were 5974 patients ≥50 years of age whose cancer was diagnosed between 1989 and 2006, and were referred with pT1 pN0 invasive breast cancer treated with BCS and RT. Cases of 5- and 10-year LR were examined using Kaplan-Meier methods. Recursive partitioning analysis was performed in patients treated with and without endocrine therapy to identify combinations of factors associated with a 5-year LR risk ≤1.5%.

RESULTS

The median follow-up was 8.61 years. Median age was 63 years of age (range, 50 to 91). Overall 5-year LR was 1.5% (95% confidence interval [CI], 1.2%-1.9%) and 10-year LR was 3.4% (95% CI, 2.8%-4.0%). Of 2830 patients treated with endocrine therapy, patient subsets identified with 5-year LR ≤1.5% included patients with grade 1 histology (n=1038; LR, 0.2%; 95% CI, 0%-0.5%) or grade 2 histology plus ≥60 years of age (n=843; LR, 0.5%; 95% CI, 0%-1.0%). Ten-year LR for these groups were 0.8% (95% CI, 0.1%-1.6%) and 0.9% (95% CI, 0.2%-1.6%), respectively. Of 3144 patients treated without endocrine therapy, patients with grade 1 histology plus clear margins had 5-year LR ≤1.5% (n=821; LR, 0.6%; 95% CI, 0.1%-1.2%). Ten-year LR for this group was 2.2% (95% CI, 1.0%-3.4%).

CONCLUSIONS

Histologic grade, age, margin status, and use of endocrine therapy identified 45% of a population-based cohort of female patients over age 50 with stage I breast cancer with a 5-year LR risk ≤1.5% after BCS plus RT. Prospective study is needed to evaluate the safety of omitting RT in patients with such a low risk of LR.