ObjectiveThis study aimed to test the psychometric properties of the Portuguese Supportive Care Needs Survey-Short Form-34 (SCNS-SF34-Pt) and its breast cancer-specific complementary module (SCNS-BR8-Pt). A further aim was to characterize Portuguese Breast Cancer Survivors (BCS) unmet supportive care needs, using these measures.MethodsA convenient sample of BCS was recruited from five hospitals in Portugal and invited to complete SCNS-SF34-Pt and SCNS-BR8-Pt, EORTCQLQC30 and QLQBR23, the Generalized Anxiety Disorder, and the Patient Health-Questionnaire. The validity (i.e. convergent, discriminant and convergent validity) and reliability of SCNS-SF34-Pt and SCNS-BR8-Pt were statistically evaluated. BCS unmet supportive care needs were descriptively assessed.Findings336 BCS participated in the study. A four-factor solution was produced for SCNS-SF34-Pt. This solution included the Physical and daily living needs, Psychological needs, Sexuality needs, and Health system, information, and patient support needs dimensions (73% of the total variance; Cronbachs alpha=.82 to .97). SCNS-SF34-Pt demonstrated good convergent validity. It could also discriminate between known-groups regarding age, disease staging, treatment performed, and ECOG performance status. SCNS-BR8-Pt revealed a single-factor structure (62% of the total variance; Cronbachs alpha=.91).Portuguese BCS most prevalent unmet supportive care needs were associated with the Psychological, and Physical and daily living domains. Fear of cancer spreading, the inability to do things as usual, and lack of energy/tiredness were perceived as issues requiring further supportive care.Findings336 BCS participated in the study. A four-factor solution was produced for SCNS-SF34-Pt. This solution included the Physical and daily living needs, Psychological needs, Sexuality needs, and Health system, information, and patient support needs dimensions (73% of the total variance; Cronbachs alpha=.82 to .97). SCNS-SF34-Pt demonstrated good convergent validity. It could also discriminate between known-groups regarding age, disease staging, treatment performed, and ECOG performance status. SCNS-BR8-Pt revealed a single-factor structure (62% of the total variance; Cronbachs alpha=.91).Portuguese BCS most prevalent unmet supportive care needs were associated with the Psychological, and Physical and daily living domains. Fear of cancer spreading, the inability to do things as usual, and lack of energy/tiredness were perceived as issues requiring further supportive care.ConclusionsSCNS-SF34-Pt and the SCNS-BR8-Pt are valid and reliable tools to assess Portuguese BCS unmet supportive care needs. Fear of cancer spreading and lack of energy/tiredness concerns should be a target of supportive care services.