Patterns of metastasis in women with metachronous contralateral breast cancer

BACKGROUND: The understanding of metastatic patterns after metachronous contralateral breast cancer (CBC) may help determine the biological nature of CBC. METHODS: A cohort of 8478 women with breast cancer treated at Guy's and St Thomas' NHS Foundation Trust between 1975 and 2006 were studied. Organ-specific 5-year cumulative incidence and incidence rate ratios were assessed for women diagnosed with unilateral breast cancer (UBC), CBC within 5 years and CBC more than 5 years of the initial diagnosis. RESULTS: Women diagnosed with CBC within 5 years had a higher incidence of metastases in all organs compared with UBC. Women with a short interval time to CBC developed metastasis more rapidly and were more likely to develop visceral and distant cutaneous metastases compared with bone metastasis. CONCLUSION: These findings explain poor prognosis of women with early occurring CBC and suggest that some of these CBCs are indicators of aggressive and/or systemic disease

Tumor Stage Affects Risk and Prognosis of Contralateral Breast Cancer: Results From a Large Swedish-Population–Based Study

Purpose The number of breast cancer survivors at risk of developing contralateral breast cancer (CBC) is increasing. However, ambiguity remains regarding risk factors and prognosis for women with CBC. Patients and Methods In a cohort of 42,670 women with breast cancer in the Uppsala/Örebro and Stockholm regions in Sweden in 1992 to 2008, we assessed risk factors for and prognosis of metachronous CBC by using survival analysis. Breast cancer–specific survival for women with CBC was evaluated and compared with results for women with unilateral breast cancer (UBC) by using time-dependent Cox-regression modeling. Results An increased risk for CBC was observed among women who had primary breast cancer with ≥ 10 involved lymph nodes compared with node-negative women (adjusted hazard ratio [HR], 1.8; 95% CI, 1.2 to 2.7). The prognosis was poorer in women with CBC than with UBC. The hazard of dying from breast cancer was especially high for women with a short interval time to CBC (adjusted HR, 2.3; 95% CI, 1.8 to 2.8 for CBC diagnosed ≤ 5 years v UBC) and gradually decreased with longer follow-up time but remained higher than the hazard originating from the primary tumor for ≥ 10 years. Conclusion Women with advanced-stage primary breast cancer had an increased risk of developing CBC. CBC is associated with an increased risk of dying from breast cancer throughout a long period of follow-up after the primary tumor. Our findings suggest that the event of CBC marks a new clinical situation in terms of investigations for metastases, treatment considerations, and follow-up strategy. </jats:sec