Trial Information

Randomized Clinical Trial: Comparison Between Quadrantectomy Followed by External Fractionated Radiotherapy and Quadrantectomy Associated With Intraoperative Radiotherapy in Women >= 48 Years of Age Affected by Early-stage Breast Carcinoma.

The ELIOT trial is a prospective single center randomised phase III trial which compared
intraoperative radiotherapy with electrons to the tumor bed with conventional scheme of
whole breast external beam radiotherapy. Patients were randomly allocated to intraoperative
radiotherapy group or external radiotherapy group in a 1:1 ratio.

The rationale for providing partial breast irradiation to the tumor bed lies on the patterns
of ipsilateral breast tumor relapse reported in Literature. In fact, the majority of
recurrences occur close to the tumor bed. Several randomized trials of breast conserving
surgery with or without whole breast radiotherapy showed that in 75-90% of cases
recurrences were at the site of original primary tumor. In this context, limiting
irradiation to the tumor bed may result in a similar local control as whole breast
irradiation, provided that patients are properly selected.

The intraoperative treatment was delivered with a mobile miniaturized accelerator, located
in the operating room, while for external radiotherapy a 6 MV linear accelerator was used.
The surgical technique to perform ELIOT has been standardized in every step. The breast
gland is prepared by separating it from the subcutaneous tissue and the underlying
pectoralis muscle and by restoring the continuity of the surgical breach after having
protected the thoracic wall by lead and aluminium disks to optimize the delivered dose. The
linear accelerator delivers electrons at variable energy, ranging from 3 to 9 MeV: the
proper electron energy is chosen according to the target thickness. Collimation is achieved
by hard-docking system, consisting of 5 mm thick high- quality polymethyl methacrylate round
applicators of 4 to 10 -cm diameter.

For radiation protection a primary beam stopper and mobile 1.5 cm thick lead shields are
provided. The prescribed dose was 21 Gy at the 90% isodose. After delivery of the radiation
dose, the applicator and the disk were removed and the gland is reconstructed again.

In the conventional arm of the study, the external beam radiotherapy is given after the full
recovery from the surgical excision. All patients undergo virtual simulation including a
treatment-planning CT scan. The clinical target volume is defined to extend to 5 mm below
the skin surface and include breast parenchyma down to the deep fascia, but not including
the underlying muscle and rib cage. The irradiated volume should extend medially to the
midline, laterally to the mid axillary line and inferiorly to 1-2 cm below the level of
intra-mammary fold and superiorly to the suprasternal notch. Using BEV, the blocks are used
to shield as much heart and lung as possible without compromising the PTV.

Treatment is delivered by a pair of tangential fields with wedges as necessary. The
prescribed dose to the whole-breast was 50 Gy delivered in 2 Gy fraction over 5 weeks with
a 6 -megavolt linear accelerator followed by a sequential boost of 10 Gy to the tumor bed
with electrons. A PTV dose homogeneity of -5% + 7% as recommended by ICRU (International
Commission on Radiation Units and Measurements) report no 50.

Patients were followed up with at least 6-month clinical examination up to 5 years and then
every 8 months thereafter. Annual mammogram was performed .