Comparing survival rates in women diagnosed with cancer in one or both breasts

This study compared survival rates of patients who developed cancer in both breasts (called contralateral breast cancer or CBC) and patients who had cancer in one breast (unilateral breast cancer or UBC).

Breast cancer is the most common cancer among women. Breast cancer survivors are 3.5 times more likely to develop a second cancer in the opposite breast compared to women who have never had breast cancer. This is referred to as contralateral breast cancer (CBC). Most cases of CBC develop within the first few years after the diagnosis of the initial breast cancer. Discovering who would benefit most from frequent checkups for CRC is an important aspect of research aimed at increasing survival for these patients.

Medical records of over 191,000 women diagnosed with breast cancer between 1989 and 2008 were reviewed in this study. Overall, women with UBC had a better survival than with CBC. For women under the age of 50 with UBC, the 5 year overall survival (defined as the percentage of patients who survived 5 years after the diagnosis) was 86%, while women with CBC showed a 72% 5 year survival rate. For women over 50, the 5 year survival rates were 85% and 80% for patients with UBC and CBC respectively. Increased cancer size and lymph node involvement (cancer spread to the nearby lymph nodes) were also associated with decreased survival in women with CBC. Moreover, patients diagnosed with CBC in less than 5 years after the initial cancer diagnosis had a lower survival compared to those whose CBC was diagnosed after more than 5 years from the first cancer.

In this study, CBC was associated with decreased overall survival, especially among women under the age of 50. It is recommended that women diagnosed with breast cancer at a young age receive frequent and thorough checkups of the opposite breast, particularly during the first 5 years after diagnosis.

This trial failed to address the risk factors in developing CBC. Also, this was a retrospective study (it followed patients who have been diagnosed and treated in the past, rather than following patients throughout their treatment and determining their outcomes). Retrospective studies are known to provide weak statistical information.

Consult with your doctor regarding a follow up plan to detect any recurrences of your cancer.