Effect of external boost volume in breast-conserving therapy on local control with long-term follow-up.
OBJECTIVE
To determine the effects of boost volume (BV) in relation to margin status and tumor size on the development of local recurrence with breast-conserving therapy.


METHODS
Between 1983 and 1995, 1,073 patients with invasive breast cancer underwent 1,101 breast-conserving therapies. Of these 1,101 BCTs, 967 were eligible for analysis. The BV was categorized into tertiles: <66 cm(3) (n = 330), 66-98 cm(3) (n = 326), and >98 cm(3) (n = 311). The median follow-up was 141 months. Separate analyses were done for women < or =40 years and >40 years.


RESULTS
No significant difference in local recurrence was shown between the tertiles and the recurrence site. The 15-year local recurrence-free survival rate was 87.9% for the first tertile, 88.7% for the second, and 89% for the third. For women < or =40 years old, the corresponding 15-year local recurrence-free survival rate was 80%, 74.5%, and 69.2%. For women >40 years old, the corresponding rate was 88.7%, 89.5%, and 90.9%. At 5 years, women >40 years old had significantly more local failures in the first tertile; this difference disappeared with time. A test for trend showed significance at 5 years (p = 0.0105) for positive margins for ductal carcinoma in situ in women >40 years of age.


CONCLUSIONS
The results of this study have shown that the size of the external BV has no major impact on local control. For women >40 years old, positive margins for ductal carcinoma in situ showed a trend with respect to BV at 5 years. The BV had no influence on local control in the case of positive margins for invasive carcinoma.
Jobsen
Jan J
JJ
Department of Radiation Oncology, Medisch Spectrum Twente, Enschede, The Netherlands. J.Jobsen@ziekenhuis-mst.nl
van der Palen
Job
J
Ong
Francisca
F
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D002278:Carcinoma in Situ / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D012044:Regression Analysis; D047368:Tumor Burden