A main goal of the San Francisco Mammography Registry’s (SFMR) is to better understand how breast imaging tests (mammograms, breast ultrasound, breast MRI) contribute to breast cancer detection. The large data source in the SFMR allows us to examine the relationship between imaging tests and detection for various characteristics of women and breast cancer types. The following figures display the distributions of race/ethnicity, age, breast imaging tests, estrogen receptor status of invasive tumors, and breast cancer stage. For figures 1-5, women that did not indicate a category or labeled themselves as “Unknown” were not included in the calculation of proportions.
Figure 1: Distribution of Women, by Race/Ethnicity
Patient Characteristics
About half (48.7%) of participants have indicated White as their race/ethnicity category while approximately a quarter of participants indicated either Chinese (16.5%) or Hispanic (11.7%). In comparison, we see that less than <1% of the women in the SFMR are American Indian (0.2%) or Vietnamese (0.7%). Japanese and Other Non-Asian patients make up about 1.3% and 1%, respectively, of all women in the SFMR.
Figure 2: Distribution of Examinations, by Age
Approximately 79% of all exams are performed in women between the ages of 40-69 years. The greatest proportion is represented in the 50-59 (29.4%) age group while the lowest is represented in the >90 (0.3%) age group.
Figure 3: Distribution of Invasive Tumors, by Estrogen Receptor Status
Figure 4: Distribution of Breast Cancer, by Stage
Cancer Characteristics
Figures 3 and 4 display the distribution of invasive tumors by estrogen receptor (ER) status (Figure 3) and by AJCC cancer stage (Figure 4). In both figures, unknown receptor status and unknown stage were not used in the calculation of proportions.
A total of 82.9% of tumors are ER- positive, 17% ER-negative, and 0.1% have a borderline status (Figure 3). Additionally, Figure 4 shows the highest proportion of breast cancers are stage I (40.7%) while stage IV cancers are the lowest (2.2%). The majority of all cancers at the SFMR are in either stage 0 or I (64.7%), which means that they are early stage.
Figure 5: Type of Imaging Test, by Indication for Test
Examination Trends and Proportions
The five different types of imaging tests collected are film, digital, and tomosynthesis (3D) mammograms; magnetic resonance imaging (MRI); and ultrasound. For all imaging tests except ultrasound, the screening indication is the highest proportion for each type. Screening mammograms comprise more than 80% of each film, digital and tomosynthesis test and screening MRI comprise about 50% of all MRIs. In contrast, diagnostic ultrasounds make up the majority of all ultrasounds (87.3%).
Figure 6: Distribution of Mammograms, by Year
Over the years, new mammography technologies have been introduced into clinical care. Film mammograms were offered as early as 1985 and were both the majority and their highest volume during the period 2000-2004 (42%). With the rise and use of digital mammograms, the proportion of film mammograms dropped to 25% in 2005-2009, 5% in 2010-2014. While only 2% of digital mammograms were performed during the 2000-2004 period, there was a steady increase to 31% in 2005-2009 and even larger increase during 2010-2014 with approximately 50% of digital mammograms occurring during this time period. By 2015-present, there was a sharp decline in digital mammograms as the popularity in tomosynthesis increased. From 2015-present, the proportion of mammograms is the highest for tomosynthesis (77%).