Intervals Longer Than 20 Weeks From Breast-Conserving Surgery to Radiation Therapy Are Associated With Inferior Outcome for Women With Early-Stage Breast Cancer Who Are Not Receiving Chemotherapy

Ivo A. Olivotto, Mary L. Lesperance, Pauline T. Truong, Alan Nichol, Tanya Berrang, Scott Tyldesley, François Germain, Caroline Speers, Elaine Wai, Caroline Holloway, Winkle Kwan, Hagen Kennecke

From the British Columbia Cancer Agency–Vancouver Island Centre, Vancouver Centre, Centre for the Southern Interior; and Fraser Valley Centre, Radiation Therapy Program, Systemic Therapy Program, and Breast Cancer Outcomes Unit, University of British Columbia; and the Department of Mathematics and Statistics, University of Victoria, British Columbia, Canada

Corresponding author: Ivo A. Olivotto, BSc, MD, FRCPC, BC Cancer Agency–Vancouver Island Centre, 2410 Lee Ave, Victoria, British Columbia, Canada, V8R 6V5; e-mail: iolivott@bccancer.bc.ca

Purpose: To determine the interval from breast-conserving surgery (BCS) to radiation therapy (RT) that affects local control or survival.

Patients and Methods: The 10-year Kaplan-Meier (KM) local recurrence-free survival (LRFS), distant recurrence-free survival (DRFS), and breast cancer–specific survival (BCSS) were computed for 6,428 women who had T1 to 2, N0 to 1, M0 breast cancer that was diagnosed in British Columbia between 1989 and 2003, and who were treated with BCS and RT without chemotherapy. Intervals from BCS to RT were grouped by weeks as follows: 4 (n = 83), greater than 4 to 8 (n = 2,288; reference group); greater than 8 to 12 (n = 2,606); greater than 12 to 16 (n = 961); greater than 16 to 20 (n = 358); and greater than 20 weeks (n = 132). Cox proportional hazards models and matching were used to control for confounding variables.

Results: The median follow-up time was 7.5 years. The 10-year KM outcomes were as follows: LRFS, 95.4%; DRFS, 90.5%; and BCSS, 92.5%. Compared with the greater than 4 to 8 weeks group, hazard ratios (HR) were not significantly different for any outcome among patients who were treated up to 20 weeks after BCS. However, LRFS (hazard ratio [HR], 2.00; P = .15), DRFS (HR, 1.86; P = .02) and BCSS (HR, 2.15; P = .009) were inferior for women with BCS-to-RT intervals greater than 20 weeks compared with those greater than 4 to 8 weeks. The matched analysis yielded similar results.

Conclusion: Outcomes were statistically similar for BCS-to-RT intervals up to 20 weeks, but they were inferior for intervals beyond 20 weeks. Time can be reasonably allowed for the breast to heal and for patients to consider treatment options, but RT should start within 20 weeks of BCS.

published online ahead of print at www.jco.org on November 17, 2008.

Ivo A. Olivotto has provided expert testimony on the effects of time between surgery and radiation therapy on breast cancer outcomes.

Presented in part at the 30th San Antonio Breast Cancer Symposium, Dec 13-16, 2007, San Antonio, TX.

Authors’ disclosures of potential conflicts of interest and author contributions are found at the end of this article.