Breast cancer may return despite the best care and treatment. When this happens, it is called a recurrence or relapse. A relapse may occur when some of the original cancer cells survive the initial treatment, or when cancer cells spread to other parts of the body while being undetected. Some of the more common risk factors that may affect the chances of breast cancer returning include: Tumour size – Large tumours usually point towards a greater chance of cancer recurrence. Cancer spread – Breast cancer is more likely to recur if it had spread to the lymph nodes. Cancer subtypes – Some breast cancer subtypes like HER2-positive breast cancer are more likely to recur.