Partial breast irradiation: Why, how?

摘要

Radiation therapy represents a very important part of breast conservative treatment. The classic schedule consists in delivering a total dose of 50 Gy in 25 fractions on 5 weeks, sometimes associated with a 10 to 16 Gy boost. For elderly women with difficulties to move or for younger women having professional activity or with young children in charge, a 5 to 6 weeks radiation therapy with long and frequent transportations is sometimes difficult to achieve. The aim of partial breast irradiation (PBI) is to prevent, in a short period (5 to 8 days) and less transportations, the risk of local recurrence into the tumor bed. Different techniques have been described, using either interstitial brachytherapy (low or high dose rate) or intra-operative radiation therapy (IORT photons or electrons) or external beam radiation therapy. Phase II PBI trials using interstitial brachytherapy showed a local control rate of 0 to 4% with a follow-up of 20 to 75 months. The rate of good/excellent cosmetic results is 67 to 100%. Results analysis of trials using very new PBI techniques (MammoSite((R)), IORT) remains more difficult. If phase III randomized trials could confirm that PBI achieved, for selected patients, local controls equivalent to those obtain with whole breast irradiation, PBI could improve quality of life during radiation therapy, and maybe contribute to have a cost effective breast cancer conservative treatment.