hello there.. You are right in saying that breast and ovarian cancer are related in familial inheritance from first degree relatives like mother, sister, daughter. SO your are at risk of breast cancer and ovarian cancer if the cause of breast cancer was genetic and not sporadic in your mother. The familial inheritance is known through studying genes like BRCA1 and BRCA2 , both of which predispose to ovarian and breast cancers. The risk of your cyst being cancerous depends on the ultrasound features of your cyst. Cysts with thick walls, irregular margins with solid areas and echoes and calcifications with associated fluid collection in abdomen (ascites) are more likely to be cancerous. Other marker which is likely to be high in ovarian cancers is CA-125 which if high is not diagnostic of cancer but has a prognostic value ( the outcome of your tumor). Your query about cancer cervix and HPV infection associated with ovarian cancer is not true. They dont lead to ovarian cancers unless when metastasis (blood spread) occurs in advanced stages. Ultrasound and CA125 are not absolute indicators of ovarian cancer. To be asolutely sure ovarian cystectomy and histopathology( tissue study of ovary) is a must which is done on staging laparotomy (surgical procedure). But since your cyst is only 3cm , you can still follow up it with a repeat ultrasound after a month. If there is a rapid increase in size or it gets more than 4cm, it needs to be surgically operated for histopathology.