Accelerated partial breast irradiation with interstitial implants: risk factors associated with increased local recurrence.
OBJECTIVE
To analyze patient, disease, and treatment-related factors regarding their impact on local control after interstitial multicatheter accelerated partial breast irradiation (APBI).


METHODS
Between November 2000 and April 2005, 274 patients with early breast cancer were recruited for the German-Austrian APBI Phase II trial (ClinicalTrials.gov identifier: NCT00392184). In all, 64% (175/274) of the patients received pulsed-dose-rate (PDR) brachytherapy and 36% (99/274) received high-dose-rate (HDR) brachytherapy. Prescribed reference dose for HDR brachytherapy was 32 Gy in eight fractions of 4 Gy, twice daily. Prescribed reference dose in PDR brachytherapy was 49.8 Gy in 83 consecutive fractions of 0.6 Gy each hour. Total treatment time was 3 to 4 days.


RESULTS
The median follow-up time was 64 months (range, 9-110). The actuarial 5-year local recurrence free survival rate (5-year LRFS) was 97.7%. Comparing patients with an age <50 years (49/274) vs. ≥50 years (225/274), the 5-year LRFS resulted in 92.5% and 98.9% (exact p = 0.030; 99% confidence interval, 0.029-0.032), respectively. Antihormonal treatment (AHT) was not applied in 9% (24/274) of the study population. The 5-year LRFS was 99% and 84.9% (exact p = 0.0087; 99% confidence interval, 0.0079-0.0094) in favor of the patients who received AHT. Lobular histology (45/274) was not associated with worse local control compared with all other histologies (229/274). The 5-year LRFS rates were 97.6% and 97.8%, respectively.


CONCLUSIONS
Local control at 5 years is excellent and comparable to therapeutic successes reported from corresponding whole-breast irradiation trials. Our data indicate that patients <50 years of age ought to be excluded from APBI protocols, and that patients with hormone-sensitive breast cancer should definitely receive adjuvant AHT when interstitial multicatheter APBI is performed. Lobular histology need not be an exclusion criterion for future APBI trials.
Ott
Oliver J
OJ
University Hospital Erlangen, Department of Radiation Oncology, Erlangen, Germany. oliver.ott@uk-erlangen.de
Hildebrandt
Guido
G
Pötter
Richard
R
Hammer
Josef
J
Hindemith
Marion
M
Resch
Alexandra
A
Spiegl
Kurt
K
Lotter
Michael
M
Uter
Wolfgang
W
Kortmann
Rolf-Dieter
RD
Schrauder
Michael
M
Beckmann
Matthias W
MW
Fietkau
Rainer
R
Strnad
Vratislav
V
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001317:Austria; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D005858:Germany; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011446:Prospective Studies; D012307:Risk Factors; D018709:Statistics, Nonparametric