Tumor location, interval between surgery and radiotherapy, and boost technique influence local control after breast-conserving surgery and radiation: retrospective analysis of monoinstitutional long-term results.
OBJECTIVE
To obtain long-term data on local tumor control after treatment of invasive breast cancer by breast-conserving surgery and adjuvant radiotherapy (RT), in consideration of the interstitial high-dose-rate boost technique.


METHODS
A total of 263 women with 268 mammary carcinomas (International Union Against Cancer Stage I-IIB) who had undergone breast-conserving surgery and adjuvant RT between 1990 and 1994 were included. The potential risk factors for local recurrence-free survival were investigated.


RESULTS
During a median follow-up period of 94 months, 27 locoregional recurrences, 25 of which were in breast, were diagnosed. The cumulative rate of in-breast recurrence was 4.1% +/- 1.4% at 5 years of follow-up and 9.9% +/- 2.4% at 10 years. The multivariate analysis identified medial tumor location and delayed RT (defined as an interval of >2 months between surgery and the start of RT) as significant risk factors for in-breast recurrence in the overall study population. Medial tumor location vs. lateral/central location (hazard ratio, 2.48; 95% confidence interval, 1.06-5.84) resulted in a cumulative in-breast recurrence rate of 22.5% +/- 8.3% vs. 6.9% +/- 2.3% at 10 years. Delayed RT (hazard ratio, 2.84; 95% confidence interval, 1.13-7.13) resulted in a cumulative in-breast recurrence rate of 18.5% +/- 6.2% vs. 6.8% +/- 2.4% at 10 years. The multivariate analysis also showed that the risk of in-breast recurrence was lower after high-dose-rate boost therapy than after external beam boost therapy in patients with laterally/centrally located tumors (hazard ratio, 3.25; 95% confidence interval, 0.91-11.65).


CONCLUSIONS
Tumor location, interval between surgery and RT, and boost technique might influence local control of breast cancer treated by breast-conserving surgery and RT.
Knauerhase
Hellen
H
Department of Radiation Therapy, University of Rostock, Rostock, Germany.
Strietzel
Manfred
M
Gerber
Bernd
B
Reimer
Toralf
T
Fietkau
Rainer
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000628:therapy*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000517:prevention & control*; D017063:Outcome Assessment, Health Care; D018714:Radiotherapy, Adjuvant / Q000706:statistics & numerical data; D020266:Radiotherapy, Conformal / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D016879:Salvage Therapy / Q000706:statistics & numerical data; D013997:Time Factors; D016896:Treatment Outcome