International Journal of Radiation Oncology*Biology*Physics
Clinical InvestigationLocal Recurrence in Women With Stage I Breast Cancer: Declining Rates Over Time in a Large, Population-Based Cohort
Introduction
Breast-conserving therapy is the standard of care for most women with early stage breast cancer. After breast-conserving surgery, whole-breast radiation therapy (RT) has been shown in randomized trials and meta-analyses to improve local control and provide survival rates similar to those of mastectomy 1, 2, 3, 4. Advances in breast cancer screening, surgical techniques, and adjuvant therapy have improved local control and survival in patients with early-stage breast cancer. Increased awareness and use of mammographic screening have contributed to earlier diagnoses of smaller tumors. Improved surgical technique and pathologic evaluation have led to more accurate margin assessments and assignment of pathologic stages (5).
Prospective trials 6, 7 and single-institution series 8, 9 have emerged with reports of declining local recurrence (LR) rates after breast-conserving therapy in women with early stage breast cancer. In a United Kingdom trial examining 1410 women with T1-3 N0-1 M0 breast cancer treated with breast-conserving surgery and radiation therapy between 1986 and 1998, 5-year LR was 8% (95% confidence interval [CI], 6.5%-9.5%) (6). In contrast, a more contemporary UK trial testing fractionation regimens in 4451 women between 1998 and 2002 reported a lower 5-year LR rate of 3.1% (95% CI, 2.6%-3.7%) (7). While these findings suggest that LR risks may be diminishing over time, comparisons among different studies are limited by variations in diagnostic, surgical, pathologic or stage distribution that could influence LR risk trends.
This study examined whether local recurrence risk has changed over time among women consecutively diagnosed with stage I breast cancer treated with breast-conserving surgery and RT, using population-based data from a Canadian provincial cancer institution.
Section snippets
Study subjects
An institutional database with prospectively collected information on demographics, treatment, and outcomes in referred patients was used to identify the subjects of this analysis. The study cohort included 5974 women aged ≥50 years diagnosed with pT1N0 invasive breast cancer between 1989 and 2006. All patients were treated with breast-conserving surgery and adjuvant breast RT. The study excluded patients with in situ breast cancer, node-positive disease, unknown nodal status, distant
Results
The median follow-up time was 8.6 years. Table 1 summarizes data comparing clinicopathologic characteristics among the 4 time periods. The mean age at diagnosis was similar in the 4 cohorts. The mean tumor size was similar among cohorts. Among patients diagnosed in 1989 to 1993, 1994 to 1998, 1999 to 2002, and 2003 to 2006, the proportions of grade 1 tumors increased over time (16% vs 29% vs 40% vs 39%, respectively, P<.001). Rates of LVI declined over the 4 time periods (20% vs 10% vs 7% vs
Discussion
This longitudinal outcomes study provides documentation that at the population level, LR rates are declining in women with pT1N0 breast cancer treated with breast-conserving therapy. Other institutional series have reported declining LR rates over time. Investigators from the William Beaumont Hospital evaluated patterns of disease recurrence over time from 1981 to 1996 in 607 patients with stages I to II breast cancer treated with breast-conserving surgery and RT. Reduced 5-year and 12-year LR
Conclusions
Significant changes in tumor characteristics, surgical techniques, and adjuvant systemic therapy for breast cancer have occurred over the past 2 decades. This has resulted in the diagnoses of more favorable risk tumors, higher rates of margin clearance, and increased systemic therapy use. These changes contribute to the observed declining rates of LR at the population level among women with early stage breast cancer treated with breast-conserving surgery and radiation therapy.
References (35)
- et al.
Local relapse rates are falling after breast conserving surgery and systemic therapy for early breast cancer: Can radiotherapy ever be safely withheld?
Radiother Oncol
(2009) - et al.
Comparison of clinical-pathologic characteristics and outcomes of true interval and screen-detected invasive breast cancer among participants of a Canadian breast screening program: A nested case-control study
Clin Breast Cancer
(2011) - et al.
Meta-analysis of the impact of surgical margins on local recurrence in women with early-stage invasive breast cancer treated with breast-conserving therapy
Eur J Cancer
(2010) - et al.
Patients with early stage invasive cancer with close or positive margin treated with conservative surgery and radiation have increased risk of breast recurrence that is delayed by adjuvant systemic therapy
Int J Radiat Oncol Biol Phys
(1999) - et al.
Predictors of re-excision findings and recurrence after breast conservation
Int J Radiat Oncol Biol Phys
(2003) - et al.
Subsets of women with close or positive margins after breast-conserving surgery with high local recurrence risk despite breast plus boost radiotherapy
Int J Radiat Oncol Biol Phys
(2011) - et al.
Histological grading of breast carcinomas: A study of interobserver agreement
Hum Pathol
(1995) - et al.
The impact of hypofractionated whole breast radiotherapy on local relapse in patients with grade 3 early breast cancer: A population-based cohort study
Int J Radiat Oncol Biol Phys
(2012) - et al.
Comparison of the diagnostic accuracy of lymphatic endothelium markers: Bayesian approach
Mod Pathol
(2005) Favourable and unfavourable effects on long-term survival of radiotherapy for early breast cancer: an overview of the randomised trials
Lancet
(2000)
Effects of radiotherapy and of differences in the extent of surgery for early breast cancer on local recurrence and 15-year survival: An overview of the randomised trials
Lancet
Twenty-year follow-up of a randomized study comparing breast-conserving surgery with radical mastectomy for early breast cancer
N Engl J Med
Twenty-year follow-up of a randomized trial comparing total mastectomy, lumpectomy, and lumpectomy plus irradiation for the treatment of invasive breast cancer
N Engl J Med
The UK Standardisation of Breast Radiotherapy (START) trial B of radiotherapy hypofractionation for treatment of early breast cancer: A randomised trial
Lancet
The UK Standardisation of Breast Radiotherapy (START) trial A of radiotherapy hypofractionation for treatment of early breast cancer: A randomised trial
Lancet Oncol
Changes in management techniques and patterns of disease recurrence over time in patients with breast carcinoma treated with breast conserving therapy at a single institution
Cancer
Improving local control with breast conserving therapy: A 27 year single-institution experience
Cancer
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Conflict of interest: none.