Breast Cancer Management: Should We Treat Our Patients According to the TNM or the Molecular Classification?

Abstract

It is the merit of a French surgeon, Pierre Denoix, the former director of the Gustave Roussy Institute, to have created two major concepts in the breast cancer management: 1) the TNM classification and 2) the multidisciplinary “committees”. The TNM classification described four (in fact five) clinical T classes from T0 (non palpable tumor), T1 (0-2cm), T2 (2-5cm), T3 (over 5cm) and T4 (chest wall or cutaneous invasion). During the years, this initial classification improved separating the main classes in subclasses (T1a or T1b for example) and adding the pos t -opera t ive classification (pTNM) according to the size in the permanent section of the operative specimen in pathology report. This classification also included the clinical axillary nodal status N0, 1a, 1b, 2 and 3. The lymph node status in the TNM classification has also been recently upgraded by adding micro-metastatic and IHC characteristics of the lymph node according to post operative assessments. The M status is not any more clinical but is diagnosed on the workup on common metastatic sites. Initially, it was just according to the findings on the radiological analysis of the chest X-ray and the bone scan examination of the ribs, sternum, pelvis, and other common sites. Nowadays, it has become more and more sophisticated by searching the metastatic lesions in other organs, especially visceral organs, and PET scan is becoming a standard approach in some teams. The immense merit of this classification was first to exist, in order to communicate between surgeons and other physicians about the patients. Moreover, it was useful particularly to schematically separate the operable breast cancer from the metastatic ones and to decide which patients were the best candidates for breast conserving therapy. As all classifications, TNM suffers from its own limitations. As an example, the significance of a small T1 in a large breast is quite different from a T2 lesion in a small breast. Actually, one can discuss the exact significance of a 1.9 cm versus a 2.1 cm lesion which are in different T status, but is there really a great difference between them (T1 or T2)? Then, if we go back to the beginning of this paper, Pierre Denoix also created the concept of multidisciplinary committees. In these meetings, next to the surgeons were sitting radiologists, pathologists, and radiation therapists. When he practiced, medical oncologists were not really concerned about breast cancer. Most of them were issued from hematology and used to consider breast cancer as a minor subject until papers by G. Bonadonna demonstrated the benefits of CMF adjuvant medical treatment on survival in the end of the 70’s. We all know the 1