Two-view mammography at the incident round has improved the rate of screen-detected breast cancer in Wales

Cohort profile of the Sloane Project: methodology for a prospective UK cohort study of >15 000 women with screen-detected non-invasive breast neoplasia

PURPOSE

The introduction of breast screening in the UK led to an increase in the detection of non-invasive breast neoplasia, predominantly ductal carcinoma in situ (DCIS), a non-obligatory precursor of invasive breast cancer. The Sloane Project, a UK prospective cohort study of screen-detected non-invasive breast neoplasia, commenced in 2003 to evaluate the radiological assessment, surgical management, pathology, adjuvant therapy and outcomes for non-invasive breast neoplasia. Long-term follow-up and accurate data collection are essential to examine the clinical impact. Here, we describe the establishment, development and analytical processes for this large UK cohort study.

PARTICIPANTS

Women diagnosed with non-invasive breast neoplasia via the UK National Health Service Breast Screening Programme (NHSBSP) from 01 April 2003 are eligible, with a minimum age of 46 years. Diagnostic, therapeutic and follow-up data collected via proformas, complement date and cause of death from national data sources. Accrual for patients with DCIS ceased in 2012 but is ongoing for patients with epithelial atypia/in situ neoplasia, while follow-up for all continues long term.

FINDINGS TO DATE

To date, patients within the Sloane cohort comprise one-third of those diagnosed with DCIS within the NHSBSP and are representative of UK practice. DCIS has a variable outcome and confirms the need for longer-term follow-up for screen-detected DCIS. However, the radiology and pathology features of DCIS can be used to inform patient management. We demonstrate validation of follow-up information collected from national datasets against traditional, manual methods.

FUTURE PLANS

Conclusions derived from the Sloane Project are generalisable to women in the UK with screen-detected DCIS. The follow-up methodology may be extended to other UK cohort studies and routine clinical follow-up. Data from English patients entered into the Sloane Project are available on request to researchers under data sharing agreement. Annual follow-up data collection will continue for a minimum of 20 years.

An observational study to evaluate the performance of units using two radiographers to read screening mammograms

AIM

To examine the performance of screening units in which a proportion of mammograms were double read using "non-discordant radiographer only (double) reading" (NDROR).

MATERIALS AND METHODS

NDROR was used by seven pilot units between 2006 and 2009, and six further units in 2009 only. There were 51 comparison units. Screening performance outcome measures were calculated, and logistic regression was used to compare performance between the pilot and comparison units.

RESULTS

Phase 1 pilot units read between on average 15 and 48% of mammograms per year using NDROR between 2006 and 2009 (median, 33%) and in 2009, phase 2 pilot units used NDROR to read between 4 and 77% of mammograms (median, 34%). The results showed an increase in recall rates in the phase 1 pilot units relative to the comparison units at both prevalent and incident screens (adjusted OR 1.09, 95% CI 1.05, 1.14; and adjusted OR 1.10, 95% CI 1.07, 1.14, respectively). There were also increases in the phase 2 pilot units relative to the comparison units; adjusted OR 1.08 (95% 1.00, 1.17) at prevalent screens, and adjusted OR 1.07 (95% CI 1.02, 1.14) at incident screens. There was no evidence to suggest a difference in cancer-detection rates between the pilot units and the comparison units.

CONCLUSIONS

Evidence from the present study suggests that recall rates may increase as a result of units using radiographers to double read a proportion of their mammograms. However, there is little evidence to suggest that NDROR, as practiced by the pilot units in the present study, is likely to have major impacts on performance in the UK National Health Service Breast Screening Programme (NHSBSP), particularly if it is fully supported and closely monitored (particularly recall rates).

Comparison of interval breast cancer rates for two-versus single-view screening mammography: a population-based study

OBJECTIVE

To determine whether the implementation of two-view mammography was followed by a reduction in the rates of interval cancers.

MATERIAL AND METHOD

We analyzed the data concerning women aged 50-69 who attended the breast cancer screening program between January 1, 1994 and December 31, 2006 in Isère, France. We performed Poisson regressions to estimate age-adjusted rate ratios of women being recalled, cancer detection, and interval cancer for two-view compared to single-view mammography.

RESULTS

After adjusting for age, two-view mammography was associated with a higher risk of cancer detection (1.37 [95% CI, 1.16-1.62]) and with a decreased risk of 12-month (0.46 [95% CI, 0.23-0.92]) and 24-month (0.64 [95% CI, 0.46-0.88]) interval cancer.

CONCLUSION

Two-view mammography for first and subsequent screens is associated with lower rates of interval breast cancer. This is at the expense of an increased number of women being recalled for further assessment after subsequent screens.