Breast Cancer Symposium: Recurrence Rates for Ductal Carcinoma in Situ Treated Between 1978–2010
A new retrospective analysis explored local recurrence rates for women with ductal carcinoma in situ (DCIS) treated between 1978 and 2010. In the research (Abstract 32) by Van Zee et al, to be presented September 25 at the 2015 Breast Cancer Symposium, in San Francisco, investigators evaluated a prospectively maintained database of 2,996 women who underwent breast-conserving surgery (lumpectomy) at Memorial Sloan Kettering Cancer Center.
Study Background
Randomized trials of radiation after breast-conserving surgery for DCIS found substantial rates of recurrence, with half of recurrences invasive. Decreasing local recurrence rates for invasive breast carcinoma have been observed, and are largely attributed to systemic therapy improvements. Researchers examined recurrence rates after breast-conserving surgery for DCIS over 3 decades at one institution.
Investigators retrospectively reviewed a prospectively maintained database of DCIS patients undergoing breast-conserving surgery between 1978 and 2010. Cox proportional hazard models were used to investigate the association between treatment period and recurrence, controlling for other variables.
Analysis Findings
A total of 363 (12%) recurrences among 2,996 cases were observed. Median follow-up for patients without recurrence was 75 months (range = 0–30 years); 732 were followed for ≥ 10 years. The 5-year recurrence rate for those treated between 1978–1998 was 13.6%, vs 6.6% for the group treated between 1999–2010 (hazard ratio [HR] = 0.62, P < .0001).
After controlling for age, family history, presentation (radiologic vs clinical), nuclear grade (non-high vs high grade), necrosis, number of excisions (≤ 2 vs ≥ 3), margin status (positive/close vs negative), radiation, and endocrine therapy, treatment period remained significantly associated with recurrence, with later years associated with a lower HR (0.74, P = .02) compared to earlier years.
After stratification by radiation use and adjustment for seven other factors, the decrease in recurrence rates was limited to those without radiation (HR = 0.62, P = .003); there was no decline in recurrence rates among those receiving radiation (HR = 1.13, P = .6).
Patients with DCIS who were treated in between 1999 and 2010 had a 40% lower risk of cancer recurrence than those treated between 1978 and 1998.
Recurrence rates for DCIS have clearly fallen over time. Increases in screen-detection, negative margins, and use of adjuvant therapies only partially explain the decrease. The unexplained decline is limited to women not receiving radiation, suggesting it is not due to changes in radiation efficacy, but may be due to improvements in mammography quality, radiologic detection, and pathologic assessment. The lower recurrence risk observed for DCIS patients treated in more recent years is important for patient education, especially in view of the widely reported recent increase in use of mastectomy.
ASCO Expert Harold J. Burstein, MD, PhD, FASCO, said, “Over the past 3 decades, substantial progress has been made in lowering the risk of breast cancer recurrence after treatment. This study demonstrates that multidisciplinary care, combined with advances in management and detection, is making a tangible difference for women with DCIS.”
Study author Monica Morrow, MD, reported honoraria from Genomic Health. Disclosure information for all authors is available here.
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