Mammography screening and mortality by risk status in the California teachers study

Abstract

Background The debate continues among medical professionals regarding the frequency, starting age, and stopping age for mammography screening. Some experts suggest tailoring recommendations based on individuals’ personal breast cancer risk. Previous studies have not compared the impact of annual versus biennial mammography stratified by age group and risk category. The purpose of this study was to examine the relationship between mammography frequency and mortality by age group and risk category in the California Teachers Study. Methods Using data from study questionnaires from 93,438 women between the ages of 40 and 85 and linkages to the California Cancer Registry and other indices, overall and breast cancer-specific mortality by mammography frequency were estimated using multivariable Cox proportional hazards models, stratified by age group and risk category at baseline as determined by the Gail breast cancer risk model. Results During the follow-up period of 20 years, overall mortality risk was lower in women who had annual or biennial mammography compared to less frequent or no mammography in all age groups. Annual mammography was associated with lower overall mortality risk compared to biennial mammography among women age 50–85. This difference was especially apparent in women age 60–74, regardless of estimated Gail risk category at baseline. Breast cancer-specific mortality was lower among women who had annual mammography compared to biennial or less frequent mammography among women age 60–74, regardless of their baseline risk. Conclusions Our findings suggest that at least biennial mammography is beneficial to most women age 40–85 and that annual mammography is more beneficial than biennial mammography to most women age 50–85 in terms of overall mortality.

Health benefits and harms of mammography screening in older women (75+ years)—a systematic review

“…Of the 27 observational studies, 18 studies followed up women after screening and/or diagnosis; [ 4 , 16 , 21 , 23 , 26 , 32 , 33 , 35 – 37 , 40 – 43 , 45 , 48 – 50 ] follow-up times in these studies ranged from 4 months to 20 years. Three studies did not include any comparison group and provided only descriptive statistics [ 22 , 24 , 27 ] and three studies compared groups by detection methods in those with breast cancer [ 32 , 33 , 36 ].…”

“…Three studies did not include any comparison group and provided only descriptive statistics [ 22 , 24 , 27 ] and three studies compared groups by detection methods in those with breast cancer [ 32 , 33 , 36 ]. One study had multiple comparisons (by age and screening history) [ 35 ]; the remaining studies compared mammography screening outcomes in women aged 75 years and older with screening outcomes in women: of other ages (ten studies) [ 4 , 16 , 18 , 20 , 21 , 23 , 25 , 38 , 43 , 48 ]; differing screening histories (three studies) [ 44 – 46 ]; differing screening intervals (three studies) [ 37 , 40 , 41 ] or historical unscreened women (one study) [ 49 ]; women who did not screen (one study) [ 42 ] and women who stopped screening (two studies) [ 26 , 50 ]. (Table 1 ).…”

“…Median across all models Annual: 8%, Biennial: 7% Difference in breast cancer deaths averter per 1000 women— stopping at 79 vs 69. Median across all models Annual: 2, Biennial: 2 McCarthy [ 35 ] Non-users compared to regular users Breast cancer mortality (assuming lead time of 1.25 years for regular users) - HR: 75–84: 2.47 (1.70– 3.58) 85 +: 1.45 (0.63– 3.32) Park [ 37 ] Never/less frequent v biennial v annual screening Breast cancer specific mortality rates never/less frequent as referent (multivariable analysis) HR (95%CI) - Biennial: 0.67 (0.31–1.44) Annual: 0.76 (0.38–1.53) Richman [ 50 ] Subsequent screen v no subsequent screen Breast cancer mortality per 100 women (95%CI) 0.36 (0.29–0.46) v 0.42 (0.28-0.64) Breast cancer mortality HR 0.87 (0.55–1.37) Schousboe [ 39 ] Stopping screening at 75 years compared to 80 years, 85 years and 90 years—by CCS, biennial mammography Breast cancer deaths averted per 1000 women CCS0: 80y: 1.7 (1.2–2.2) 9.5% 85 y: 2.8 (2.0–3.6) 15.6% 90 y: 3.5 (2.5–4.4) 3.5% CCS1: 80 y: 1.4 (0.9–1.9) 10.4% 85 y: 2.3 (1.5–2.9) 16.9% 90 y: 2.7 (1.9–3.5) 20.3% CCS > = 2; 80 y: 1.0 (0.7–1.4) 11.0% 85 y: 1.7 (1.1–2.1) 17.5% 90 y: 2.0 (1.4–2.5) 20.5% Simon [ 40 ] Mammography interval - <2 years, 2–5 years, 5+ years or none Death from breast cancer (<2 ys reference group) HR 2–5 years mamm HR: 1.87 (1.10–3.19) 5+ or no mamm HR: 3.17 (1.68-5.96) p-trend = 0.0001 Simon [ 41 ] Mammography interval - <2 years, 2–5 years, 5+ years or none Death from Breast cancer (<2 ys reference group) 2-5years HR = 1.62 (1.03–2.54) 5+ years or none HR: 2.80 (1.57–5.00) ptrend = 0.0002 Subdistribution HR for breast cancer death taking competing causes into account SHR for 2–5 years: 1.60 (1.02–2.52), 5+years or none: 2.74 (1.50–5.03) Van Dijck [ 44 ] Attended last screen or n...…”

“…Aged 69 years and older Cohort study Cancer detected between 1987 and 1993 linked to Medicare records which indicated pattern of screening Non-user (none in past 2 years), single user (once in the last 2 years), regular user (at least 2 screening mammograms at least 11 months apart in past 2 years) i) Age at diagnosis ii) Non-users v regular users 67–74 n = 4609 75–84 n = 4072 85+ n = 1086 Screen-usage 67-74: Reg 29%; Non 18% 75–84: Reg 23%; Non 21% 85+: Reg 10%; Non 33% Follow-up: 1–8 years Collection period: 1987–1993 Serious McPherson [ 36 ] USA Caucasian women aged 65–101 diagnosed with invasive breast cancer from 1986 to 1994 Cohort study Cancer detected between 1986 and 1994 identified from records in the Upper Midwest Oncology Registry System. Method of detection extracted Mammography but no further details Mammography detected v clinically detected cancers 75–79: 599 v 546; 80–84: 473 v 313; 85+: 451 v 148 Follow-up: not stated, but reports 8–9 years post diagnosis data Collection period: 1986–1994 Serious Park [ 37 ] USA 40–85 years at baseline Cohort study Women enroled in the California Teachers study (1995–1996) followed up with data linkage up until Dec 31 2015 Routine screening Never/less frequent v biennial v annual screening 8024 women aged 75-85 at baseline Follow-up: 20 years Collection period: 1995–2015 Serious Randolph [ 38 ] USA All women in the SEER database wo received a diagnosis of incident breast cancer in 1995 or 1996 and were linked with Medicare data. Aged 69 years and older Cross-sectional study Cancer detected between 1995 and 1996 linked to Medicare records which indicated pattern of screening Nonuser (no screening in past 2 years), single user (once in the last 2 years), regular user (at least 2 screening mammograms at least 11 months apart in past 2 years) 65–74 v 75 and older Total 11,039.…”

Comparison of Characteristics of Breast Cancer Detected through Different Imaging Modalities in a Large Cohort of Hong Kong Chinese Women: Implication of Imaging Choice on Upcoming Local Screening Program

“…At the same time, adherence to a screening program is a key to achieving a sustainable result with mortality improvement. A study by Park et al found that overall mortality risk was lower for patients with annual compared with biennial mammography [ 19 ]. Further investigation is required to see if similar results would apply to ultrasound-based screening.…”