Public engagement in health technology assessment (HTA) is increasing worldwide. There are several forms of public engagement and it is not always possible to determine which stakeholders participate in the HTA process and how they contribute. Our objective was to investigate which types of social representatives contributed to the public consultation on the incorporation of Trastuzumab for early-stage breast cancer treatment within the public health system in Brazil, held in 2012 by the National Committee for Health Technology Incorporation (CONITEC). A mixed methods approach was used to analyze social representativeness and the composition of the corpus from the public consultation, which consisted of 127 contributions. Three types of analysis were performed using IRaMuTeQ software: classic lexical analysis, descending hierarchical classification and specificities analysis. The contributions were clustered according to the main categories of discourse observed, into four social representation categories: 1) patient representation/advocacy; 2) pharmaceutical industry/advocacy; 3) healthcare professionals; and 4) individual contributions. Category 1 contained words related to increased survival due to use of the drug and a low score for words pertaining to studies on Trastuzumab. The word "safety" obtained a positive score only in category 2, which was also the only category that exhibited a negative score for the word "risk". Category 3 displayed the lowest scores for "diagnosis" and "safety". The word "efficacy" had a negative score only in category 4. Each category exhibited different results for words related to health systems and to key concepts linked to HTA. Our analysis enabled the identification of the most prominent contributions for each category. Despite the promising results obtained, further research is needed to validate this software for use in analyzing public contributions.