Multifocal, multicentric, and bilateral breast tumours are either benign, precursor lesions or malignant neoplasms.A multidisciplinary review of these entities can offer clinicians a practical guidance for diagnostic and treatment procedures. Multiple synchronous (multifocal or multicentric) ipsilateral breast cancers (MSIBC) with heterogeneous histopathology require particular attention, since MSIBC tends toward more aggressive biology and higher rates of nodal positivity. Being independent of laterality, domination of the invasive carcinoma was observed in the bilateral and multifocal disease type. The TNM staging system for breast cancer does not include multifocality and multiplicity. Only the tumour with the largest diameter is considered for the pT category, neglecting the secondary foci which can make the treatment decision more difficult. MSIBC has a similar prognosis to unifocal cancers, but sometimes they might be negative prognostic parameters. Likewise, in comparison with unifocal breast cancer, MSIBC presents a different genetic pathway.
Part of the book: Breast Cancer