Breast conservation in the treatment of early breast cancer. A 20-year follow-up.

Two hundred sixty-three patients with unilateral primary breast cancer, treated by local excision of the primary tumor and radical radiation therapy between 1954 and 1969, were followed up for a minimum of 10 years and a maximum of 20 years. The treatment plan delivered 4500 rad in fractions of orthovoltage irradiation to five fields: tangential breast fields, axilla with posterior axillary field, parasternal and supraclavicular, with a subsequent boost of 1000 rad to the primary tumor site, axilla, and supraclavicular fossa. Patients were clinically staged using the TNM (UICC) system; 115 patients had tumors less than 2 cm in diameter and a clinically negative axilla (T1N0N1a), 96 had tumors 2 to 5 cm in diameter with a clinically negative axilla (T2N0N1a), and 52 had tumors less than 5 cm in diameter and clinical axillary lymph node metastases (T1T2N1b). The actuarial relapse-free survival of patients with T1N0N1a tumors was 72% at 5 years, 59% at 10 years, and 47% at both 15 and 20 years. The relapse-free survival of patients with T2N0N1a tumors was not statistically different (P greater than 0.05). A significantly worse survival was observed in patients with clinical axillary lymph node metastases (T1T2N1b), with a survival of 37% at 5 years, 29% at 10 years, 23% at 15 years, and 22% at 20 years, when compared with patients with clinically negative lymph nodes (P less than 0.01). Locoregional relapse occurred in 22%, at 10 years, of those patients with T1 or T2N0N1a tumors and 52% of the patients with T1T2N1b tumors. The pattern of locoregional relapses indicated that approximately 50% occur at least 5 years after treatment; this contrasts with the pattern of early locoregional relapse after mastectomy. The commonest sites of relapse were in the breast in 19% and axilla in 6% of patients with T1 or T2N0N1a tumors. There was no attenuation of the radiation dose administered at the site of a subsequent relapse. Surgery for radiation failure produced a 42% crude relapse-free survival at 5 years after salvage mastectomy in those patients originally treated for T1 or T1N0N1a tumors. The results of this study suggest that a significant proportion of patients relapse locally over a prolonged period after breast conservation. The evolution of new radiation techniques may provide better locoregional control and early salvage surgery may result in improved long-term survival.