Weekly concomitant boost in adjuvant radiotherapy for patients with early breast cancer: preliminary results on feasibility.
OBJECTIVE
Recent advances in the management of patients with breast cancer are focused toward the reduction of overall treatment time of radiotherapy by delivering a dose biologically equivalent to a standard schedule. The aim of the present study was to evaluate the feasibility and preliminary toxicity of a moderately hypofractionated whole breast irradiation schedule with the addition of a concomitant boost delivered to the tumor bed once-a-week in patients with early breast cancer submitted to conservative surgery.


METHODS
We selected patients with pT1c and pT2 N0/N+ M0 carcinoma of the breast with negative surgical margins. The basic course consisted of 4600 cGy prescribed to the ICRU 50 reference point dose and delivered in 20 fractions, 4 times a week for 5 weeks. Once a week, immediately after whole breast irradiation, a concomitant photon boost of 120 cGy was delivered to the lumpectomy area. Overall, according to the linear-quadratic model, the schedule provides a biologically equivalent dose of 87 Gy for breast tumor (assuming alpha/beta = 4 Gy), of 66 Gy for acute responding normal tissues (assuming alpha/beta = 10 Gy), and 99 Gy for late responding normal tissues (assuming alpha/beta = 3 Gy). Biologically, the schedule compares favorably with the 6-week conventional regimen consisting of 50 Gy, 2 Gy/fraction, followed by a 10 Gy boost (BED(tumor), 90 Gy; BED(acute effects), 72 Gy, and BED(late effects), 100 Gy).


RESULTS
From November 2004 to April 2007, we tested this radiotherapy schedule in 176 patients. All enrolled patients had achieved a minimum follow-up of 6 months and were considered in detail for the evaluation of feasibility. Three clinical examinations were performed by a group of independent physicians at treatment end, after 1 month and after 6 months. According to the RTOG/EORTC Toxicity Criteria, of the 176 assessable patients at the end of radiotherapy, 58% showed grade 0-1 skin toxicity, 30% grade 2 and 12% grade 3. At one month of follow-up, grade 0 toxicity was observed in 47% of cases, grade 1 in 46% and grade 2 in 7%. At 6 months, late (skin and subcutaneous tissue) toxicity was assessed with the following scores: grade 0 in 68%, grade 1 in 26% and grade 2 in 6% of the patients. At 6 months, cosmesis was excellent, good and fair in 71%, 24% and 5% of patients, respectively.


CONCLUSIONS
The explored adjuvant schedule planned to intensify the radiotherapy course for patients with early breast cancer by adding a weekly concomitant boost appears to be feasible and provides low local toxicity and excellent to good short-term cosmetic results.
Corvò
Renzo
R
National Institute for Cancer Research and University, Genoa, Italy. renzo.corvo@unige.it
Giudici
Stefania
S
Maggio
Francesca
F
Bevegni
Monica
M
Sampietro
Chiara
C
Lucido
Maria Rosaria
MR
Orsatti
Marco
M
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D019583:Dose Fractionation, Radiation; D004954:Esthetics; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009367:Neoplasm Staging; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects; D012867:Skin / Q000528:radiation effects*; D016896:Treatment Outcome