SAN ANTONIOIn the treatment of early-stage breast
cancer, postoperative radiation therapy after sector resection
(breast-conserving surgery) reduces recurrences but does not influence
survival, according to a Swedish study presented at the 23rd Annual San Antonio
Breast Cancer Symposium.
Investigators from the Swedish Breast Cancer Group, Lund,
Sweden, presented findings based on 1,188 women with stage I and II
node-negative breast cancer treated between 1991 and 1997 with radical
Patients were randomized to postoperative radiotherapy, 50 Gy
in 25 fractions over 5 weeks (n = 593), or no postoperative irradiation (n =
595). Median age was 60 and median tumor size was
12 mm; 65% of cases were detected by mammographic screening.
Per Olof Malmstrom, MD, PhD, of Lund University Hospital,
reported no significant difference in survival according to whether or not
patients received radiotherapy in addition to surgery. Overall survival at 5
years was 94% among patients receiving radiotherapy and 93% in the control
group (follow-up of patients alive was 6.5 years). Deaths from breast cancer
occurred in 4% of the control patients and 3% of radiotherapy-treated patients.
Event-free survival at 5 years, however, was more favorable in
the radiotherapy group: 85% vs 75% in the control group (P = .001). Ipsilateral
breast recurrence as a first event occurred in 14% of controls (78 patients)
and 4% of radiotherapy patients (26 patients), for a statistically significant
threefold difference (P < .0001).
Other first events that were not significant included the
following for the control group and radiotherapy group, respectively: axillary
recurrence in 6 and 3; distant metastases, 25 and 23; contralateral breast
cancer, 17 and 17; and non-breast-cancer deaths, 18 and 20.
Regarding recurrence, the best prognostic factors were age 50
and older in the irradiated group (P = .07) and age 50 and older plus detection
by mammographic screening in the nonirradiated group (P = .001).
"Radiotherapy after resection decreases ipsilateral breast recurrences rates, but there is no influence on
breast cancer mortality or overall survival. In patients not getting
radiotherapy, there is a lower risk of recurrence among patients over age 50
whose tumors are detected by screening," he concluded.