Second malignancies and recurrences happen when there is a secondary tumour growing in addition to the primary one or when the primary tumour grows back after treatment. Secondary malignancies can also occur after treatment for a primary cancer. Unfortunately, chemotherapy and radiation can sometimes cause tissues that have been damaged to turn cancerous. In these cases, the same treatment that was used to treat the primary tumour may not be effective, so additional therapy options have to be considered, including clinical trials.
Cancer may recur in the same location as the primary tumour, called a local recurrence, or it can occur nearby, which is called a regional recurrence, or it can recur in another part of the body in which case it is called metastasis. This happens when the primary cancer is treated but it comes back after treatment.
Metastatic or stage IV cancer occurs when the cancer has spread to another part of the body. Metastatic cancer can happen before diagnosis is made, or after treatment. Metastases most commonly develop when cancer cells travel through the blood stream or the lymphatic system to distant parts of the body and create tumours replicating the primary cancer. One of the most common sites for metastasis is in the bones. Treatment for these cancers depends on the type of cancer, how large the tumour is, how fast it is growing and how it responds to treatment. If you have been diagnosed with metastatic bone cancer, caution is necessary when lifting, twisting, exercising, participating in high impact activities, or coughing, etc. People can live for years with bone mets. However, there is little information available regarding patient assessment and education about how to live with bone mets. Some research shows that physical activity is beneficial for people with metastatic cancer.
Treatment for mets includes systemic therapy, one that impacts the entire body. This may include chemotherapy, targeted therapy, hormone therapy and/or immunotherapy, which aim at reducing the side effects of the cancer, but are not curative. In these cases, doctors treat metastatic cancer as a chronic condition.
 Eileen Dahl, RP, MDiv, CT, Breast cancer patient with bone metastases. Presented at the All Parties Cancer Caucus Meeting, November 22nd, 2017.