How does one classify breast cancer after chemotherapy? Is pTpN appropriate?
“In those cases in which classification is performed during or following initial multimodality therapy, the TNM or pTNM categories are identified by a y prefix” (TNM 6th ed., p. 14). For example, yT1N0M0 or ypT1pN0M0. 2.8.11 The TNM Classification of Breast Tumours states: The clinical T1 category is further subclassified into T1mic, T1a, T1b, T1c. There was a discussion among physicians here as to why this was included in the clinical description as microscopic invasion can only be defined pathologically. Histologic examination is required on all clinical classifications for “confirmation of the disease”. Pathologic classification, pT, requires more than histologic examination. It “requires the examination of the primary tumour with no gross tumour at the margins of resection”. (See TNM 6th ed., p. 136.
