Of the 1471 eligible women sent a baseline Personal History and Screening Questionnaire
, 1309 (89.0%) were contacted, 1071 (81.8%) agreed to participate and 69 women were ineligible (n
37 had a breast cancer diagnosis and n
32 did not have a first-degree relative with breast and/or ovarian cancer). Of the 1002 women sent a Year 1 Follow-up Personal History and Screening Questionnaire
, 942 (94.0%) were interviewed. Of the 936 women without breast cancer sent a Year 2 Follow-up Personal History and Screening Questionnaire
, 856 (91.5%) were interviewed. Women who reported having a mammogram (817 at baseline, 558 at year 1 and 540 at year 2) were asked to provide written consent for access to their medical imaging report. In total, 776 (95.0%), 536 (96.0%) and 511 (94.6%) consented to share their mammogram report after completing the baseline, year 1 and year 2 questionnaires, respectively; and of these, 774 (99.7%), 453 (84.6%) and 497 (97.3%) reports were received.
Of the 646 eligible women with a baseline screening mammogram (Figure
), 420 reported a screening mammogram at year 1 (291 within 18
months and 129 beyond 18
months). Of the remaining 226 women with no screening mammogram at year one, 99 reported a screening mammogram at their second year interview (9 within 18
months and 90 beyond 18
months) and 127 did not report one. There were 65 women reporting no baseline screening mammogram but screening mammograms at year 1 and 2, 29 of which returned within 18
months and 36 beyond 18
months. Overall, 711 women reported at least two screening mammograms, of which 329 (46.3%) were adherers and 382 (53.7%) were late-screeners. There were 147 women who reported having no mammogram at all three interviews (baseline, year 1 and year 2) and these women were considered never-screeners.
Tree diagram of women included in the study.
The final sample size included 858 women from 569 unique families of which 381 (67.0%) had one family member, 121 (21.3%) had two family members and 67 (11.7%) had three to seven family members. The majority of adherers and late-screeners were aged 50
years or older (74.1% and 57.1%, respectively) whereas the majority of never-screeners were under age 50 (87.8%) (Table
). For adherers, a similar distribution was found of women in the low, moderate and high familial risk groups, whereas, nearly 50% of the late-screeners and more than 70% of the never-screeners were at low familial risk. Moderate (OR: 1.55; 95% CI: 1.06-2.27) or high (OR: 1.48; 95% CI: 1.04-2.12) versus low familial risk was significantly associated with a woman returning for screening within 18
months versus beyond 18
months. Similarly, moderate (OR: 2.47; 95% CI: 1.38-4.41) and high (OR: 2.01; 95% CI: 1. 06-3.80) versus low familial risk were significantly associated with women returning within 18
months versus never being screened. A majority of the women had more than a high school education, were married and had visited a health professional three times or less per year in all three screening groups.
Table 1 Adjusted odds ratios (ORs) with 95% confidence intervals (CI) for adherence to annual breast screening by demographic, family history risk and visits to health professionals for female relatives from the Ontario site of the Breast Cancer Family Registry (more ...)
Women who indicated a belief in annual mammogram screening were significantly more likely to be screening adherent (OR: 5.02; 95% CI: 2.97-8.49 for adherers versus late-screeners and OR: 6.82; 95% CI: 3.29-14.16 for adherers versus never-screeners) than women who believed in a lesser frequency (Table
). When adherers were compared with never-screeners, women who believed mammography should start for higher risk women before age 50 were significantly more likely to adhere than those who thought it should start at
years (OR: 9.72; 95% CI: 3.26-29.02). Screening adherence was not associated with beliefs about breast cancer risk factors or beliefs about the likeliness of a mammogram finding breast cancer when adherers were compared with late-screeners or never-screeners.
Adjusted odds ratios (ORs) with 95% confidence intervals (CI) for adherence to annual breast screening by breast screening belief factors for female relatives from the Ontario site of the Breast Cancer Family Registry