OBJECTIVE To study the local recurrence and the role of whole breast radiotherapy for early breast cancer treated by conservative surgery.METHODS From April 1990 to December 2000, 49 patients with early primary breast cancer were treated by conservative surgery in our hospital. The cases were comprised of Stage 0, 1; Stage Ⅰ, 31; and Stage Ⅱa,17. Forty cases underwent quadrantectomy plus axillary lymph node dissection, and the other 9 cases had lumpectomy alone. Irradiation, which was received by 39 patients, was administered by using low tangential half fields with 6 MV X-ray to decrease the pulmonary irradiative volume.The dose to the whole breast was 45 Gy/22～23f/4.5W, then a 15 Gy boost dose was delivered to the tumor bed by an electron beam. The other patients underwent an irradiated regional field according to postoperative pathology.RESULTS All patients were followed-up for 10 years or more. The 10year local recurrence rates, distant metastasis rates and survival rates were 6.1%, 4.1% and 98.0% respectively. All of the 3 patients who had a local recurrence had infiltrative carcinomas and negative lymph nodes.The 10-year local recurrence rate was higher (2.6% vs. 20.0%) with nonpostoperative whole breast radiotherapy, but the statistical difference was not marked because of the low number of cases. All of the recurrent lesions localized within 3 cm of the primary lesion.CONCLUSION Original recurrence of the tumor was the main type of local recurrence. Radiotherapy after conservative surgery is very essential.After conservative surgery it is feasible that irradiation can be delivered alone to the neighboring region of the tumor bed. Partial breast radiotherapy can substitute for whole breast radiotherapy.