Approximately 30% of women who present with early breast cancer undergo mastectomy. The results of randomized clinical trials have shown that post mastectomy radiotherapy {PMRT} (radiation to the chest wall, nodes in the neck and nodes under the arm) reduces the risk of local (chest wall) and regional (nodes of the neck and under the arm) recurrence and possibly improves survival. Recurrence under the arm can be particularly symptomatic with swelling of the arm and pain from invasion of the nerves, which can have a devastating impact on quality of life. Unfortunately, even with PMRT, some patients remain at an increased risk of recurrence and it is not clear why these patients are more likely to recur.
In the current study led by a radiation oncology resident, Dr. Lynn Chang, a historical cohort study was performed to identify tumor and patient factors which predict for local regional recurrence following PMRT. The records of the Juravinski Cancer Centre were searched to identify patients who received PMRT between January 1997 and December 2008. Information regarding the patient and their breast cancer disease factors, such as tumor size, estrogen receptor status, number of lymph nodes involved, etc., were collected. The goal was to identify patients who had a local regional recurrence after receiving PMRT, to determine if there were any specific risk factors associated with recurrence. If such risk factors can be identified, there is the potential to perform further research evaluating novel radiation regimens in patients with this type of breast cancer.
800 patients were identified as eligible for this study. The research team collected the study specified information from the case records of these patients and has identified those who have had a local regional breast cancer recurrence. A biostatistician has analyzed the data and results have been presented nationally. The results showed that patients with lymphovascular invasion positive or hormone (estrogen/progesterone) receptor negative disease appear to be at higher risk of locoregional recurrence despite PMRT and may be candidates for more intensive treatment.
