Background: Randomized clinical trials have clearly demonstrated that the use of radiation therapy (RT) following breast-conserving surgery (CS) substantially reduces the risk of local recurrence. However, the low rate of local recurrence after CS and RT for patients without known risk factors, and the recent increase in the detection of smaller cancers due to mammographic screening have led to the speculation that a subgroup of patients who have a low risk of local recurrence without RT might be identified. In 1986, we initiated a one-arm, prospective clinical trial of CS alone for treatment of highly selected breast cancer patients without known risk factors for local recurrence.
Methods: The study had a sequential design with a planned accrual of 90 patients. Criteria for entry into the trial were: a unicentric, clinical TI infiltrating ductal, mucinous or tubular carcinoma without an extensive intraductal component or lymphatic vessel invasion; a wide excision with a pathologically-documented negative margin of at least 1 cm; and histologically negative axillary lymph nodes. No adjuvant RT or systemic therapy was administered. Seventy-six per cent of the lesions were detected by mammography alone. The median gross pathologic tumor size was 0.9 cm. The median patient age was 67 years.
Results: Eighty-seven patients were enrolled in the trial before it closed prematurely in 1992 because the predefined stopping boundary was crossed (i.e., the sixth local recurrence was observed). At that time, the average annual local recurrence rate was 4.2%. With a median follow-up of 56 months, there are now 14 patients (16%) with local recurrence as their site of first failure (average annual local recurrence rate: 3.6%). Four patients without local recurrence developed distant metastases. Three patients have died, one of metastatic breast cancer and two of unrelated causes.
Conclusions: Even in a highly selected group of patients with early-stage breast cancer, there is a substantial risk of early local recurrence for those treated with wide excision alone.