[To boost the tumor bed: the age of reason].

It is well known that the conservative reference treatment of infiltrative carcinoma of the breast, after en bloc complete excision, should be completed by irradiation of the whole breast delivering 50 Gy in 25 fractions. The discussion related to the validity and the procedures of delivery of the boost of the tumor bed has to be adjusted with our knowledge of specific prognostic factors of local recurrence. Through the two phase III randomized trials published in the literature, the young age of the patient, palpable tumor and negative receptor to progesterone may be recognized as statistically linked to a higher risk of local recurrence. Tumor size and palpable tumor remain unquestionable factors of bad prognosis. The true level of significativeness of age remains controversial as well as peri-tumoral characteristics such as ductal carcinoma in situ. Treatment technique should be rigorous either in terms of prescription of external radiation therapy or for the boost. They have a major impact on the cosmetic result and the fibrosis rate. Improvement of the results is expected through careful analysis of genic and molecularly prognostic factors of the tumor in order to select patients amenable to this type of technique.