Purpose: To determine which clinical, biological, or treatment-related factors of the first and second primary breast cancers influenced the outcome following contralateral breast carcinoma (CBC).
Methods and materials: By August 1994, 319 of 6406 patients with clinical Stage 0 to III breast carcinoma treated between 1981 and 1987 at Institut Curie had developed a second breast cancer that was diagnosed more than 6 months following ipsilateral breast cancer. Of these 319 patients, 235 had a CBC as the first recurrent event and constitute the study population. Comparisons of first and second breast tumor characteristics were done using Fisher's exact test. Survival distributions from the date of CBC were compared by the log-rank test. Prognostic factors for local relapses, distant relapses, and survival after CBC were assessed by univariate and multivariate analysis using the Cox proportional hazards model.
Results: The diagnosis of CBC was more frequently guided by mammographies than for ipsilateral tumors (p < 0.0001). The proportion of early stage tumors < or = T1 was significantly higher in the opposite breast as compared to the the first primary tumor (p < 0.0001). A greater rate of noninvasive tumors was observed in CBCs (p = 0.0003). Median follow-up time from the diagnosis of CBC was 54 months (1-137). Five-year survival following CBC was 79% (+/- 6). Five-year local (CBC breast or chest wall) and distant failure rates were 15 and 24%, respectively. Time interval to the occurrence of CBC (< 2 years, 2-5 years, > 5 years) had no influence on survival. Cox model analysis showed that the risk factors for distant metastases were stage and progesterone receptor levels of the contralateral tumor. The risk of distant failure in CBC was not influenced by the extent of surgery.
Conclusions: In this selected population of CBCs as first recurrent events, a follow-up policy based on clinical examination and annual mammography enabled the detection of CBCs at an earlier stage than the primary ipsilateral cancer. The outcome after CBC was determined only by the characteristics of the contralateral tumor. Breast-conserving treatment should be recommended when it is feasible. Adjuvant chemotherapy should be delivered according to the same criteria as the primary tumor.