Higher toxicity with 42 Gy in 10 fractions as a total dose for 3D-conformal accelerated partial breast irradiation: results from a dose escalation phase II trial.
OBJECTIVE
Recent recommendations regarding indications of accelerated partial breast irradiation (APBI) have been put forward for selected breast cancer (BC) patients. However, some treatment planning parameters, such as total dose, are not yet well defined. The Institut Gustave Roussy has initiated a dose escalation trial at the 40 Gy/10 fractions/5 days and at a further step of total dose (TD) of 42 Gy/10 fractions/ 5 days. Here, we report early results of the latest step compared with the 40 Gy dose level.


METHODS
From October 2007 to March 2010, a total of 48 pT1N0 BC patients were enrolled within this clinical trial: 17 patients at a TD of 42 Gy/10f/5d and 31 at a TD of 40 Gy/10f/5d. Median follow-up was 19 months (min-max, 12-26). All the patients were treated by APBI using a technique with 2 minitangents and an "enface" electrons delivering 20% of the total dose. Toxicities were systematically assessed at 1; 2; 6 months and then every 6 months.


RESULTS
Patients' recruitment of 42 Gy step was ended owing to persistent grade 3 toxicity 6 months after APBI completion (n = 1). Early toxicities were statistically higher after a total dose of 42 Gy regarding grade ≥2 dry (p = 0.01) and moist (p = 0.05) skin desquamation. Breast pain was also statistically higher in the 42 Gy step compared to 40 Gy step (p = 0.02). Other late toxicities (grade ≥2 fibrosis and telangectasia) were not statistically different between 42 Gy and 40 Gy.


CONCLUSIONS
Early toxicities were more severe and higher rates of late toxicities were observed after 42 Gy/10 fractions/5 days when compared to 40 Gy/10 fractions/5 days. This data suggest that 40 Gy/10 fractions/ 5 days could potentially be the maximum tolerance for PBI although longer follow-up is warranted to better assess late toxicities.
Department of Radiation Oncology, Institut Gustave Roussy, 114 rue Edouard Vaillant, 94 805, Villejuif, France. bourgier@igr.fr
Celine
C
Bourgier
Catalina
C
Acevedo-Henao
Ariane
A
Dunant
Christine
C
Rossier
Antonin
A
Levy
Mohamed
M
El Nemr
Isabelle
I
Dumas
Suzette
S
Delaloge
Marie-Christine
MC
Mathieu
Jean-Remi
JR
Garbay
Alphonse
A
Taghian
Hugo
H
Marsiglia
D000368:Aged; D001940:Breast / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000532:radiotherapy*; D002278:Carcinoma in Situ / Q000532:radiotherapy; D018270:Carcinoma, Ductal, Breast / Q000532:radiotherapy*; D015331:Cohort Studies; D019583:Dose Fractionation, Radiation; D004890:Erythema / Q000209:etiology; D005218:Fat Necrosis / Q000209:etiology; D005260:Female; D005355:Fibrosis; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D015412:Mastectomy, Segmental; D008875:Middle Aged; D010146:Pain / Q000209:etiology; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011881:Radiotherapy, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D011882:Radiotherapy, High-Energy; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis; D012867:Skin / Q000528:radiation effects; D012871:Skin Diseases / Q000209:etiology; D013684:Telangiectasis / Q000209:etiology
D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; C508053:ERBB2 protein, human