Can endometriosis be cancerous?

No. There are endometrial cancers. Endometriosis is a non cancerous diagnosis, .
Sometimes. The old answer was no. Recent studies have shown an increased risk of a specific type of ovarian cancer in women who have endometriosis. We don't know yet whether this is a cause and effect thing or whether treating the endometriosis decreases your risk. This type of cancer accounts for 10-20% of ovarian cancer and mainly affects women age 60-70.