Facility Mammography Volume in Relation to Breast Cancer Screening Outcomes.
OBJECTIVE
To clarify the relationship between facility-level mammography interpretive volume and breast cancer screening outcomes.


METHODS
We calculated annual mammography interpretive volumes from 2000-2009 for 116 facilities participating in the U.S. Breast Cancer Surveillance Consortium (BCSC). Radiology, pathology, cancer registry, and women's self-report information were used to determine the indication for each exam, cancer characteristics, and patient characteristics. We examined the effect of annual total volume and percentage of mammograms that were screening on cancer detection rates using multinomial logistic regression adjusting for age, race/ethnicity, time since last mammogram, and BCSC registries. "Good prognosis" tumours were defined as screen-detected invasive cancers that were <15 mm, early stage, and lymph node negative at diagnosis.


RESULTS
From 3,098,481 screening mammograms, 9,899 cancers were screen-detected within one year of the exam. Approximately 80% of facilities had annual total interpretive volumes of >2,000 mammograms, and 42% had >5,000. Higher total volume facilities were significantly more likely to diagnose invasive tumours with good prognoses (odds ratio [OR] 1.32; 95% confidence interval [CI] 1.10-1.60, for total volume of 5,000-10,000/year v. 1,000-2,000/year; p-for-trend <0.001). A concomitant decrease in tumours with poor prognosis was seen (OR 0.78; 95%CI 0.63-0.98 for total volume of 5,000-10,000/year v. 1,000-2,000/year).


CONCLUSIONS
Mammography facilities with higher total interpretive volumes detected more good prognosis invasive tumours and fewer poor prognosis invasive tumours, suggesting that women attending these facilities may be more likely to benefit from screening.
Department of Biomedical Data Science, Department of Epidemiology, The Dartmouth Institute for Health Policy and Clinical Practice, Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH Tracy.L.Onega@dartmouth.edu.
Tracy
T
Onega
Department of Medicine, University of California, San Francisco, CA.
L Elizabeth
LE
Goldman
Group Health Research Institute, Group Health Cooperative, Seattle, WA.
Rod L
RL
Walker
Group Health Research Institute, Group Health Cooperative, Seattle, WA Department of Public Health Sciences, University of California, Davis, CA.
Diana L
DL
Miglioretti
Group Health Research Institute, Group Health Cooperative, Seattle, WA.
Diana Sm
DS
Buist
National Cancer Institute, Rockville, MD.
Stephen
S
Taplin
Department of Radiology and Office of Health Promotion Research, University of Vermont, Burlington, VT.
Berta M
BM
Geller
Department of Internal Medicine, University of New Mexico, Albuquerque, NM.
Deirdre A
DA
Hill
Department of Radiology, University of California, San Francisco, CA.
Rebecca
R
Smith-Bindman
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D002277:Carcinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D055088:Early Detection of Cancer; D005260:Female; D006268:Health Facilities / Q000706:statistics & numerical data; D061847:Hospitals, High-Volume / Q000706:statistics & numerical data*; D061846:Hospitals, Low-Volume / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008327:Mammography / Q000706:statistics & numerical data*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D016017:Odds Ratio; D011379:Prognosis; D011871:Radiology; D012042:Registries; D047368:Tumor Burden; D014481:United States
Cancer detection; breast cancer screening; mammography; volume