Sole brachytherapy of the tumor bed after conservative surgery for T1 breast cancer: five-year results of a phase I-II study and initial findings of a randomized phase III trial.
OBJECTIVE
The objectives of this study were to test the feasibility of sole interstitial high-dose-rate brachytherapy (HDR-BT) after breast-conserving surgery (BCS) for T1 breast cancer in a phase I-II study, and to present the initial findings of a phase III trial comparing the efficacy of tumor bed radiotherapy (TBRT) alone with conventional whole breast radiotherapy (WBRT).


METHODS
Forty-five prospectively selected patients with T1 breast cancer undergoing BCS were enrolled into a phase I-II study of TBRT alone, using interstitial HDR implants. HDR-BT of 7 x 4.33 Gy (n = 8) and 7 x 5.2 Gy (n = 37) was delivered to the tumor bed. Based on the results of this phase I-II study, a further 126 patients were randomized to receive 50 Gy WBRT (n = 63) or TBRT alone (n = 63); the latter consisted of either 7 x 5.2 Gy HDR-BT (n = 46) or 50-Gy wide-field electron irradiation (n = 17). Breast cancer related events and side effects were assessed.


RESULTS
In the phase I-II study, at a median follow-up of 57 months, 2 (4.4%) local, 3 (6.7%) axillary, and 3 (6.7%) distant failures were observed. Two patients (4.4%) died of breast cancer. The 5-year probability of cancer-specific, relapse-free and local recurrence-free survival was 90.0%, 85.9%, and 95.6%, respectively. The cosmetic results were judged to be excellent in 44 of 45 patients (97.8%). Severe (higher than grade 2) skin sequelae or fibrosis was not found. Symptomatic fat necrosis occurred in one patient (2.2%). In the phase III study, at a median follow-up of 30 months, the locoregional tumor control was 100% in both arms. The 3-year probability of cancer-specific and relapse-free survival was 98.1% and 98.4% in the WBRT group and 100% and 94.4% in the TBRT group, respectively (P = NS). There was no significant difference between the two treatment arms regarding the incidence of radiation side effects.


CONCLUSIONS
Five-year results of our phase I-II study prove that sole HDR-BT of the tumor bed with careful patient selection and adequate quality assurance is a feasible alternative to WBRT. However, long-term results of phase III trials are required to determine the equivalence of TBRT alone, compared with WBRT in the management of selected patients with early breast cancer.
Polgár
Csaba
C
Department of Radiotherapy, National Institute of Oncology, Budapest, Hungary. polgar@oncol.hu
Sulyok
Zoltán
Z
Fodor
János
J
Orosz
Zsolt
Z
Major
Tibor
T
Takácsi-Nagy
Zoltán
Z
Mangel
László C
LC
Somogyi
András
A
Kásler
Miklós
M
Németh
György
G
D000328:Adult; D000368:Aged; D001918:Brachytherapy / Q000401:mortality; D001943:Breast Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D015412:Mastectomy, Segmental; D008875:Middle Aged; D011879:Radiotherapy Dosage; D015996:Survival Rate