Trends in Treatment Patterns and Outcomes for Ductal Carcinoma In Situ

Abstract

Background: Impact of contemporary treatment of pre-invasive breast cancer (ductal carcinoma in situ [DCIS]) on long-term outcomes remains poorly defined. We aimed to evaluate national treatment trends for DCIS and to determine their impact on disease-specific (DSS) and overall survival (OS).

Methods: The Surveillance, Epidemiology, and End Results (SEER) registry was queried for patients diagnosed with DCIS from 1991 to 2010. Treatment pattern trends were analyzed using Cochran-Armitage trend test. Survival analyses were performed using inverse probability weights (IPW)-adjusted competing risk analyses for DSS and Cox proportional hazard regression for OS. All tests performed were two-sided.

Results: One hundred twenty-one thousand and eighty DCIS patients were identified. The greatest proportion of patients was treated with lumpectomy and radiation therapy (43.0%), followed by lumpectomy alone (26.5%) and unilateral (23.8%) or bilateral mastectomy (4.5%) with significant shifts over time. The rate of sentinel lymph node biopsy increased from 9.7% to 67.1% for mastectomy and from 1.4% to 17.8% for lumpectomy. Compared with mastectomy, OS was higher for lumpectomy with radiation (hazard ratio [HR] = 0.79, 95% confidence interval [CI] = 0.76 to 0.83, P < .001) and lower for lumpectomy alone (HR = 1.17, 95% CI = 1.13 to 1.23, P < .001). IPW-adjusted ten-year DSS was highest in lumpectomy with XRT (98.9%), followed by mastectomy (98.5%), and lumpectomy alone (98.4%).

Conclusions: We identified substantial shifts in treatment patterns for DCIS from 1991 to 2010. When outcomes between locoregional treatment options were compared, we observed greater differences in OS than DSS, likely reflecting both a prevailing patient selection bias as well as clinically negligible differences in breast cancer outcomes between groups.

Figure 1.

Time trends of treatment and survival among ductal carcinoma in situ (DCIS) patients diagnosed from 1991 to 2010. A) Trends of breast locoregional treatment. B) Trends of axillary surgery procedures grouped by mastectomy and lumpectomy. C) Trend of five-year disease-specific survival overall and for patients undergoing mastectomy, lumpectomy with/without radiation therapy. 95% confidence interval provided for “All Treatments” only. ALND = axillary lymph node dissection (≥ 5 LNs), if no nodes were indicated, case coded as having had no lymph node surgery; DSS = disease-specific survival; LN = lymph node; SLNB = sentinel lymph node biopsy (1–4 LN); XRT = radiation therapy.

Figure 2.

Adjuvant radiation rates per Surveillance, Epidemiology, and End Results (SEER) registry among patients undergoing lumpectomy: A) 1991–1995 (SEER 9 and 13); B) 1996–2000 (SEER 13 and 18); C) 2001–2005 (SEER 18); D) 2006–2010 (SEER 18). Registries: SEER 9: Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, San Francisco, Seattle, Utah. SEER 13: SEER 9 plus Alaska Natives, Los Angeles, Rural Georgia, San Jose-Monterey. SEER 18: SEER 13 plus California, Greater Georgia, Kentucky, Louisiana, New Jersey. XRT = Radiation Therapy.

Figure 3.

Overall and breast cancer–specific survival by locoregional treatment, overall group, and stratified by three age groups based on inverse probability weight (IPW)–adjusted survival data. All P values based on IPW-adjusted, two-sided log-rank test. Left column, overall survival: A) entire cohort, B) 18–49 years, C) 50–69 years, D) ≥70 years. Right column, breast cancer–specific mortality: E) entire cohort, F) 18–49 years, G) 50–69 years, H) ≥70 years. XRT = Radiation Therapy.