Factors affecting recurrence in lumpectomy without irradiation for breast cancer. Between 1980 and 1988, 122 women with operable invasive breast cancers underwent wide excision and axillary dissection without subsequent irradiation. During the follow-up period of 1 to 8 years (median, 4 years), recurrences were observed in 23 patients (19%), 22 occurring in the breast and one in the axilla. This is a significant rate of recurrence and supports the need for breast irradiation after conservative surgery. The incidence of recurrence in the breast did not appear to be related to the presence or absence of axillary nodal metastasis. No recurrences were noted in 20 patients whose primary tumors were smaller than 1 cm. The incidence of recurrence was directly correlated to the increasing size of the tumor, but it also appeared to decrease with advancing age. In 31 patients over 70 years of age, only one (3%) recurrence was observed. If these early findings are confirmed, it is likely that patients with tumors smaller than 1 cm or patients over 70 years of age may be spared breast irradiation after wide excision. 