The definition of the 'no change' category in patients treated with endocrine therapy and chemotherapy for advanced carcinoma of the breast.

In the criteria used for assessment of response to treatment for advanced breast cancer the definition of no change (NC) is clear; however, there is no indication of the duration of stabilization required for patients to qualify for this category of response. We have made the assumption that NC is a worthwhile category of response if the overall time to progression (TTP) and survival of this group is not significantly different from patients with partial remissions (PR). Two hundred and sixty-three evaluable patients treated with endocrine therapy and 302 evaluable chemotherapy-treated patients were studied and the TTP and survival curves for PR and periods of NC from 1 to 6 months compared. For the endocrine-treated patients the TTP and survival curves for NC became non-significantly different from the PR curves after 4 and 5 months respectively. For chemotherapy-treated patients the TTP curves became non-significantly different from PR at 4 months and for survival the period was 3 months. In order to define NC as a useful category of response and to eliminate the possibility that NC taken for a shorter period could simply represent a slowly progressive tumour, we suggest that the minimum period of disease stabilization be taken as 5 months for both endocrine- and chemotherapy-treated patients.