Breast cancer follow-up strategies in randomized phase III adjuvant clinical trials: a systematic review

The effectiveness of different breast cancer follow-up procedures to decrease breast cancer mortality are still an object of debate, even if intensive follow-up by imaging modalities is not recommended by international guidelines since 1997. We conducted a systematic review of surveillance procedures utilized, in the last ten years, in phase III randomized trials (RCTs) of adjuvant treatments in early stage breast cancer with disease free survival as primary endpoint of the study, in order to verify if a similar variance exists in the scientific world. Follow-up modalities were reported in 66 RCTs, and among them, minimal and intensive approaches were equally represented, each being followed by 33 (50%) trials. The minimal surveillance regimen is preferred by international and North American RCTs (P = 0.001) and by trials involving more than one country (P = 0.004), with no relationship with the number of participating centers (P = 0.173), with pharmaceutical industry sponsorship (P = 0.80) and with trials enrolling > 1000 patients (P = 0.14). At multivariate regression analysis, only geographic location of the trial was predictive for a distinct follow-up methodology (P = 0.008): Western European (P = 0.004) and East Asian studies (P = 0.010) use intensive follow-up procedures with a significantly higher frequency than international RCTs, while no differences have been detected between North American and international RCTs. Stratifying the studies according to the date of beginning of patients enrollment, before or after 1998, in more recent RCTs the minimal approach is more frequently followed by international and North American RCTs (P = 0.01), by trials involving more than one country (P = 0.01) and with more than 50 participating centers (P = 0.02). It would be highly desirable that in the near future breast cancer follow-up procedures will be homogeneous in RCTs and everyday clinical settings.