The epoch of the pioneers began in 1929 with Keynes and then Baclesse in Paris. The time of the large studies coincided, in 1960, with the first cobalt treatment instruments (Pierquin-Spitallier-Papillon-Calle). The randomized studies carried out by Véronesi, I.G. Roussy and the NSABP, showed during the 1970s that conservative treatments and mastectomy had the same long-term efficacy in small breast cancers. In 1990, the standard treatment for T1-T2 less than or equal to 3 cm N0-N1 of the breast is tumorectomy curage followed by irradiation. Surgical and X-ray techniques have clearly improved and now give good aesthetic results in most cases. Women are better informed and consult earlier, screening is being developed and 1 out of 2 women, or perhaps even more, now receive conservative treatment. By the year 2000, we will know the identity of the risk factors of local relapse and how to distinguish these as well as when and how to prescribe adjuvant medication. We will doubtless know that most in situ cancers can be treated like T1 cancers. We may know whether conservative treatment can be proposed for tumors measuring 4 cm and more (primary chemotherapy or radiotherapy, mastectomy and immediate reconstruction). Women have changed little between 1960 and 1990, there has been little change in bistouries and cobalt treatment, and yet mastectomy has disappeared from the treatment of small breast cancers. It has thinking that has changed in the past 30 years. Time is gradually having its effects on medical mentalities.