Local relapse and contralateral tumor rates in patients with breast cancer treated with conservative surgery and radiotherapy (Institut Gustave Roussy 1970-1982). IGR Breast Cancer Group.

Background: Breast conservation is now established treatment for patients with small breast cancers. The authors reviewed a large series of patients with long term follow-up who underwent conservative treatment. Clinical and pathologic factors were analyzed to identify patients at an increased risk of relapse in the breast (local relapse) or development of a contralateral tumor.

Methods: Seven hundred fifty-seven patients with unilateral invasive breast cancer (T0-2, N0-1, M0) were treated conservatively (wide local excision and radiotherapy) at the Institut Gustave-Roussy between 1970 and 1982. The median follow-up was 9 years. The risk of local relapse or development of a contralateral tumor (as first event) was studied by univariate analysis for the main clinical, pathologic, and treatment factors. Those found to be significant were entered into a Cox proportional regression analysis.

Results: Fifty-one patients relapsed in the treated breast (actuarial local relapse rates at 5 and 10 years were 5% and 8%, respectively) and 34 in the contralateral breast (actuarial contralateral tumor rates at 5 and 10 years were 3% and 6%, respectively). Multivariate analysis of the risk factors for local relapse showed that only age younger than 40 years (P < 0.02) or inadequate surgical excisioin (P < 0.02) were significant. No particular risk factors for contralateral tumor development were identified.

Conclusions: Overall, for most patients, the risk of local relapse or of developing a contralateral tumor was low. A small number of young patients with inadequately excised tumors are at higher risk of local relapse, need more meticulous surgery, and may merit higher dose radiotherapy.