Towards evidence-based follow-up intervals for breast cancer survivors: Estimates of the preclinical detectable phase of contralateral second breast cancer.

Purpose: Follow-up schemes in breast cancer survivors are predominantly consensus-based. To determine evidence-based follow-up intervals, estimates of sensitivity of the screening test(s) and duration of the preclinical detectable phase (PCDP) are key. We estimated the sensitivity and the duration of the PCDP of clinical breast examination (CBE) and mammography for the detection of contralateral second breast cancers (CBC) in breast cancer survivors.

Methods: Women with a CBC (N = 589) diagnosed in Florence between 1980 and 2005 were included. Test sensitivity and the duration of PCDP were estimated using a simple exponential model of PCDP duration. Analyses were stratified by follow-up period (0-5 vs. >5 years after primary diagnosis) and age at CBC diagnosis (<50 vs. ≥50 years).

Results: For CBE, test sensitivity was 55% and the duration of the PCDP 16 months. Mammography sensitivity was 91% and duration of the PCDP 35 months. Stratified analyses showed a higher test sensitivity for CBE for women aged <50 (70% vs. 51%). No difference in the duration of PCDP of CBE was found. For mammography, test sensitivity and the duration of the PCDP were higher for women with longer follow-up and in older women.

Conclusions: Poor test sensitivity for CBE with a shorter duration of the PCDP compared with mammography were observed. Mammography had high test sensitivity and the potential to detect CBCs early. The estimated duration of the PCDP (35 months) was considerably longer than the recommended follow-up interval (12 months). Future studies are needed to determine whether a longer follow-up interval is appropriate.