Increase in response rate by prolonged treatment with neoadjuvant letrozole.

The aim of this study was to investigate the potential benefits of prolonged treatment with neoadjuvant letrozole. About 182 consecutive patients have been treated in Edinburgh with neoadjuvant letrozole for 3 months or longer and 63 patients have continued on letrozole beyond 3 months. Outcomes are reported. Of the 63 patients who continued on letrozole, 38 patients took letrozole for more than 1 year and 23 took letrozole for more than 24 months. The median reduction in clinical volume in the first 3 months in these 63 patients was 52%. Similar reductions in median clinical volume were seen between three to 6 months (50%), 6-12 months and 12-24 months (medians 37 and 33%, respectively). At 3 months 69.8% of the 182 patients had a partial or complete response. The response rate increased to 83.5% with prolonged letrozole treatment. Continuing letrozole beyond 3 months increased the number of women who initially required mastectomy or had locally advanced breast cancer who were subsequently suitable for breast conserving surgery from 60% (81/134) at 3 months to 72% (96/134). Thirty-three women remain on letrozole alone (man age at diagnosis 83 years) and at 3 years the median time to treatment failure has not been reached. Continuing letrozole in responding patients beyond 3-4 months achieves further clinical reduction in tumour size. For elderly women with a short life expectancy letrozole alone may provide long-term disease control.