Local recurrences and distant metastases after conservative breast cancer treatments: partly independent events.

BACKGROUND: Local disease recurrences are a concern in conservative breast cancer surgery, and many studies have attempted to identify risk factors for these events. It is important to distinguish local recurrences linked to increased risk of distant spread from those due to inadequate local treatment.
PURPOSE: We evaluated the incidence of local and distant recurrences according to demographic, biological, and pathologic variables in a large series of women who were conservatively and uniformly treated for breast cancer, with the aim of identifying women in whom local failure is predictive for distant metastases and who are therefore candidates for aggressive systemic treatment.
METHODS: Medical records of 2233 women who had been hospitalized at the Milan Cancer Institute from 1970 to 1987 were analyzed. All women received quadrantectomy and axillary lymph node dissection followed by radiotherapy for the breast. Quadrantectomy is breast-conserving removal of most of the affected quadrant by a radial incision that includes part of the skin. The end points considered were local failures (including local recurrences and new ipsilateral carcinomas) and distant metastases. Statistical analysis employed the competing risks and multiple failures approaches.
RESULTS: There were 119 local recurrences, 32 new ipsilateral carcinomas, and 414 distant metastases as first events. The timing of local failures and distant metastases differed: The yearly probability for local failures was approximately 1% up to the 10th year and for distant metastases was 5% in the 2nd year and decreased progressively until the 8th year. Young age was an important risk factor, with peritumoral lymphatic invasion also predictive for local and distant recurrences. Tumor size and axillary lymph node involvement were not related to local recurrence but were important predictors of distant metastases. Extensive intraductal component was only a risk factor for local recurrence. Early (< 2 years) local failure predicted for distant metastases compared with later failure. In local failure patients, the 5-year survival rate was 69% from failure.
CONCLUSIONS: Local recurrences and distant metastases are partially independent events that occur at different times; several predicting factors also differ. However, women with local recurrences have increased risk of distant metastases. In particular, women 35 years old or younger at first diagnosis who had initial peritumoral lymphatic invasion and local recurrence within 2 years are at high risk for distant spread. For recurrence in cases with an extensive intraductal component or where initial local surgery was possibly inadequate, women are at lower risk.