Based on my understanding, Ki-67 represents the percentage of cells that are dividing meaning the speed at which the cancer is growing. Lower numbers are better. 1% would mean only 1% of the cancer cells are dividing. 100% would mean all cancer cells are dividing. 93% is aggressive. My original breast cancer had a Ki-67 in the teens so moderate. My recurrent breast cancer is Ki-67 50% so it’s considered aggressive this time. I did surgery, radiation and have been on Kisqali and Letrozole for 4 years now and doing well. My neuroendocrine lung cancer (NETs) is Ki-67 2% so very very slow growing. Based on symptoms and old scans I’ve likely had lung NETs for at least 30 years and it still hasn’t spread outside my lungs. Higher Ki-67 is likely to spread faster.

Sorry to hear about your breast cancer. Good that you are starting treatment soon to squash your cancer. You’re going to see better days. You’ll get through this. Prayers for you.