Partial breast irradiation and intraoperative radiotherapy
© BioMed Central Ltd 2007
Received: 23 May 2007
Published: 19 June 2007
Over the past few years an increasing number of papers have appeared in peer-reviewed journals detailing various partial breast irradiation (PBI) approaches, utilizing high-precision external beam radiation therapy, single-dose intraoperative radiation therapy or brachytherapy. The concept of PBI has been associated with the use of accelerated schedules of fractionation. More recently, several preliminary clinical reports of retrospective series and the 5-year results of the only randomized study from Budapest using brachytherapy have produced significant discussion and confirmed the widespread interest toward PBI. The comparison between the current standard with early data coming from PBI techniques poses a dilemma as to when preliminary results are sufficiently mature to consider a new treatment approach as safe.
PBI allows reducing the radiation field to only the initially involved quadrant of the breast and significantly shortens the duration of radiation therapy. This may represent the possibility of overcoming constraints such as accessibility to the radiation therapy centres, and the socioeconomic impact on the working life and on the personal habits of the patient. PBI seems to have a positive impact on patients' quality of life. Another important advantage is the avoidance of interactions with systemic therapy that may determine delays in the initiation or in the carrying out of the conventional treatment.
These possible benefits must be balanced with the potential risk of recurrence within the untreated tissue in the breast receiving PBI as well as the unknown long-term cosmetic results with the accelerated techniques. Significant practical considerations also include the choice of technique, interstitial brachytherapy (high dose-rate versus low dose-rate), balloon-based brachytherapy (MammoSite®), external beam (3D-conformal versus intensity modulated radiation therapy), and intra-operative irradiation (electrons versus low-energy X-ray device). The choice of the technique has an impact on the schedules and dose-rate that can be used, on the volume that can be irradiated and on the dose homogeneity achievable.
Patient selection also remains uncertain, including questions regarding age exclusions, applicability with various primary tumour sizes, hystopathological features, the tumour-free margin and amount of tumour near the margins, and negative (including micrometastasis) or positive axillary lymph node status (up to three or more).
For this reason, data coming from the multicentric or unicentric large phase III ongoing trials in the United States and Europe comparing standard irradiation with the different PBI schedules and techniques will hopefully support the movement of PBI into routine clinical practice. Issues of patient selection, target volume definition, total dose, fractionation, and the quality assurance programme should be addressed and defined from analysing the results of such randomized trials.
The authors thank the support of the American Italian Cancer Foundation and Associazione Italiana Ricerca sul Cancro to the research programme of the division.