Impact of the boost dose of 10 Gy versus 26 Gy in patients with early stage breast cancer after a microscopically incomplete lumpectomy: 10-year results of the randomised EORTC boost trial.
OBJECTIVE
To assess the impact of the boost dose in patients with involved surgical margins.


METHODS
In the EORTC "boost versus no boost" trial, 251 patients with a microscopically incomplete tumour excision were randomised to receive either a low boost dose of 10 Gy (126 patients) or a high boost dose of 26 Gy (125 patients). Overall survival and the cumulative incidence of local recurrence as first event were compared by Logrank and Gray test, respectively (2-sided alpha=0.05), with a median follow-up of 11.3 years. The planned sample size was 660 patients, but only 251 were recruited.


RESULTS
The median age at randomisation was 54 years. Thirty-seven patient initially relapsed locally. At 10 years, the cumulative incidence of local recurrence was 17.5% (95% CI: 10.4-24.6%) versus 10.8% (95% CI: 5.2-16.4%) for the low and high boost dose groups, respectively (HR=0.83, 95% CI: 0.43-1.57, Gray p>0.1). Overall, 64 patients have died (25.5%), 47 of them of breast cancer, without a difference in duration of survival between the two groups (HR=0.97, 95% CI=0.59-1.5, p>0.1). Severe fibrosis was palpated in the breast in 1% versus 5% and in the boost area in 3% versus 13% in the low and high boost dose groups, respectively.


CONCLUSIONS
There was no statistically significant difference in local control or survival between the high boost dose of 26 Gy and the low boost dose of 10 Gy in patients with microscopically incomplete excision of early breast cancer. Fibrosis, however, was noted significantly more frequently in cases treated with the high boost dose.
Poortmans
Philip M
PM
Department of Radiation Oncology, Dr. Bernard Verbeeten Instituut, Tilburg, The Netherlands. poortmans.ph@bvi.nl
Collette
Laurence
L
Horiot
Jean-Claude
JC
Van den Bogaert
Walter F
WF
Fourquet
Alain
A
Kuten
Abraham
A
Noordijk
Evert M
EM
Hoogenraad
Willem
W
Mirimanoff
René-Olivier
RO
Pierart
Marianne
M
Van Limbergen
Erik
E
Bartelink
Harry
H
D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008207:Lymphatic Metastasis; D015412:Mastectomy, Segmental / Q000379:methods*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D011879:Radiotherapy Dosage; D015996:Survival Rate; D016896:Treatment Outcome