Partial breast irradiation: revolution or evolution?

It is well established that there is no significant difference in terms of overall survival between mastectomy and radio-surgical conservative treatment (RSCT). Ten to fifteen years have been needed to change from the "standard" to the "new" breast cancer treatment. At the end of the 1990s, a few authors published preliminary results of phase II trials using partial breast irradiation (PBI) as sole post-operative treatment based on interstitial low or high dose rate brachytherapy techniques. Currently, phase III randomized trials comparing whole breast irradiation versus PBI are ongoing in the USA and in EU.

The authors reviewed the literature regarding issues in the irradiation of breast cancer and the potential role of PBI to prevent local recurrence in the ipsilateral breast. Furthermore, potential advantages of PBI were discussed as well as the limits of such a procedure. Finally, we tried to determine the characteristics of a subgroup of patients who would receive benefit from this radiation technique.

Phase II and III trials have been analyzed concerning feasibility, efficacy and toxicity. PBI may be delivered through low or high dose rate brachytherapy or intraoperative/external beam radiation therapy. PBI satisfies the control quality criteria. The majority of the teams provide PBI recurrence rates lower than 5% (0-4.4%) with a median follow-up varying between 8 and 72 months, and associated with cosmetic results comparable to those achieved with conventional external beam.

RSCT does not replace mastectomy; mastectomy and RSCT are used together to treat different subgroups of patients. PBI furnished encouraging preliminary results in terms of local control and cosmetic results. However, caution in interpreting the results is required along with longer follow-up. PBI should not replace CT, but could be considered as a new therapeutic strategy for breast cancer dedicated to a very well defined subgroup of patients with a low risk of local recurrence.