This is an exploratory analysis of a subgroup of patients that were included in the MINDACT study which was a phase III study including overall 6,693 patients and has concluded and reported results last year. This analysis, in fact, looked at the outcome of patients with small tumours, meaning less than 1cm, node negative breast cancer.
Were there any differences in terms of aggressiveness?
The striking finding of this analysis, the first striking finding, was that we identified 24% of these patients of these tumours that they have an aggressive biology based on the 70-gene signature. These tumours usually are considered to be of low clinical risk and thus in the past they were excluded from adjuvant chemotherapy trials. This was the first striking finding because we identified that the biology of these tumours is aggressive and we should not consider all of these tumours innocent.
The next finding of this work was that we compared the outcome results of those patients that had discordant findings between the clinical risk assessment which was done per modified version of Adjuvant! Online, as in the main MINDACT study, and the genomic risk assessment. Those patients that had discordant results and received chemotherapy, it seems that they went better than those that did not receive chemotherapy. Of course I need here to add that this analysis was an exploratory analysis, the whole sample size was 826 patients so you can understand that we are talking about a small number of patients, small number of events and hence an under-powered analysis. However, we got a signal of the clinical utility of the 70-gene signature in identifying more aggressive tumours within the whole subset of this subset of node negative breast cancers.
How can we successfully identify patients at risk?
Of course we have to repeat the fact that the analysis was exploratory and we cannot extrapolate robust conclusions based on this analysis for the clinical practice. We have to stick on the classical ways of defining adjuvant chemotherapy administration in early breast cancer, taking into account all the clinical parameters, meaning the age of the patient, the performance stats of the patient, the tumour characteristics, ER status, HER2, node positivity or negativity, the grade of the tumour. All this should be taken into account. The genomic test could provide additional information in cases that are in the grey zone of our decision.
So I would say that the decision should be a case by case discussion with the patient and, of course, taking into account the patient’s preferences. The fact that the MINDACT study overall was a huge effort to be conducted and completed successfully so we should be grateful to the two organisations, EORTC and BIG, that supported the study and conducted the study and, of course, to all our academic partners that contributed and believed in the concept. And, of course, many, many thanks to the patients and their families that supported the general idea.