Ovarian Cysts and Tumours

Epidemiology and Risk Factors

Ovarian cancers are thought to arise partly through repeated surface epithelial irritation during ovulation, meaning factors that increase the total number of ovulations over a woman’s lifetime are associated with higher risk. Key risk and protective factors are summarised below.

There is also a significant genetic component to ovarian cancer risk. BRCA1 mutations carry a lifetime risk of ovarian cancer of 36 to 53% and BRCA2 of 11 to 25%. Both are also associated with increased breast cancer risk, and risk-reducing bilateral salpingo-oophorectomy may be offered. Lynch syndrome carriers (MLH1, MSH2, or MSH6 variants) have an estimated lifetime ovarian cancer risk of 6 to 13%.

Classification of Ovarian Cysts

Ovarian tumours are broadly classified as non-neoplastic (no malignant potential) or neoplastic (with potential for malignancy). A simple cyst contains fluid only; a complex cyst may contain solid material, blood, or septations.

Clinical Features

Ovarian Cysts

Many ovarian cysts are asymptomatic, discovered incidentally on ultrasound. When symptomatic, presentation depends on the size and nature of the cyst.

• Chronic pelvic pain: pressure on the bladder or bowel may cause urinary frequency, constipation, or dyspareunia.
• Acute pain: may indicate bleeding into the cyst, rupture, or ovarian torsion.
• Menstrual disturbance or postmenopausal bleeding.
• Abdominal distension or a palpable mass.

Ovarian Cancer

The presentation of ovarian cancer is frequently non-specific, often causing delay in diagnosis. Clinicians should maintain a low threshold for investigation, particularly in postmenopausal women presenting with:

• Persistent bloating
• Change in bowel habit
• Increased urinary frequency or urgency
• Unexplained weight loss
• Persistent pelvic or abdominal pain

On examination, look for abdominal masses arising from the pelvis, ascites, or adnexal masses on pelvic examination. Cervical excitation suggests pelvic inflammatory disease rather than a simple cyst.

Investigations

The Risk of Malignancy Index (RMI) is an internationally validated scoring system used to stratify the risk of malignancy in ovarian cysts and guide referral decisions. It combines three variables – ultrasound features, menopausal status, and CA125 – and is calculated as:

A worked example: a postmenopausal patient (M = 3) with a CA125 of 100 and bilateral lesions with solid areas on ultrasound (U = 3) gives an RMI of 3 x 3 x 100 = 900. Patients with an RMI >250 should be referred to a specialist gynaecological oncology centre.

The referral thresholds described in this article reflect UK practice. Thresholds vary internationally: the Society of Obstetricians and Gynaecologists of Canada (SOGC) uses a threshold of >200, and the American College of Obstetricians and Gynecologists (ACOG) uses a clinical criteria-based approach rather than a single RMI cutoff, incorporating CA125, ultrasound findings, and family history.

Additional Investigations

All women with a suspected ovarian malignancy should have basic blood tests including FBC, U&E, LFTs, and albumin. Further imaging and staging investigations include:

• Abdominal and pelvic ultrasound: first-line imaging.
• CT abdomen and pelvis: for staging of confirmed or suspected malignancy.
• Chest X-ray: for staging and to assess for metastatic disease.
• Lactate dehydrogenase (LDH), alpha-fetoprotein (AFP), and hCG: should be measured in all women under 40 due to the possibility of germ cell tumours.

Management

Premenopausal Women

In premenopausal women, CA125 is not routinely measured for simple ovarian cysts, as many benign conditions (endometriosis, menstruation, pelvic infection) can elevate it.

• Rescan the cyst at 6 weeks. If persistent, monitor with ultrasound and CA125 every 3 to 6 months and calculate the RMI.
• If the cyst persists or exceeds 5 cm, consider laparoscopic cystectomy or oophorectomy.
• LDH, AFP, and hCG should be measured in women under 40 to screen for germ cell tumours.

Postmenopausal Women

Management is guided by RMI score:

• Low RMI (<25): follow up for one year with ultrasound and CA125 if the cyst is <5 cm.
• Moderate RMI (25 to 250): bilateral oophorectomy; if malignancy is confirmed, staging is required (hysterectomy, omentectomy ± lymphadenectomy).
• High RMI (>250): referral to a specialist gynaecological oncology centre for staging laparotomy.

Ovarian Cancer Management

The most common malignant ovarian tumours are epithelial subtypes, principally serous cystadenocarcinoma (characterised by Psammoma bodies) and mucinous cystadenocarcinoma (characterised by mucin vacuoles). Treatment comprises:

• Surgery: staging laparotomy with tumour debulking for high-RMI cases.
• Adjuvant chemotherapy: platinum-based chemotherapy is recommended for all patients except those with early, low-grade disease.
• Follow-up: clinical examination and CA125 monitoring for five years, with intervals extending according to recurrence risk.

Complications

Ovarian cysts may cause significant complications, most commonly presenting as acute pelvic pain. Key complications include:

• Ovarian torsion: rotation of the ovary on its pedicle, compromising blood supply. Presents with sudden-onset severe unilateral pelvic pain, often with nausea and vomiting. It is a surgical emergency; delay risks irreversible ischaemia.
• Cyst rupture: presents with sudden acute pain and may cause peritonism if the cyst contents are irritant (e.g. a ruptured dermoid). Usually managed conservatively unless there is significant haemorrhage.
• Haemorrhage into the cyst: causes acute or subacute pain. Most cases resolve spontaneously.
• Malignant transformation: uncommon in benign neoplastic cysts but a key long-term concern.

Follow-up for confirmed ovarian cancer involves clinical examination and CA125 monitoring every three months for the first two years, extending to every six months thereafter, for a total period of five years.

Equity, Safety and Professionalism

Access to gynaecological cancer services can be inequitable. Women from ethnic minority backgrounds and those living in areas of socioeconomic deprivation have been shown to present at a more advanced stage and may face barriers to timely investigation and referral. Shared decision-making is essential when discussing surveillance, surgery, and genetic testing options, particularly for women with BRCA mutations considering risk-reducing surgery.

All women presenting with a pelvic mass should be offered appropriate genetic counselling if there is a personal or family history suggesting an inherited syndrome. Clinicians should be aware that symptom delay is common in ovarian cancer and that persistent non-specific symptoms in postmenopausal women should prompt investigation rather than reassurance.

Recent Changes and Controversies

Population-level screening for ovarian cancer remains controversial. The UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) did not demonstrate a significant reduction in ovarian cancer mortality at long-term follow-up, and routine population screening is not currently recommended by NICE or NHS England.

Access to BRCA testing has expanded through mainstreaming of genomic testing, meaning clinicians across specialties may now initiate testing without specialist genetic referral. NICE guidelines support BRCA1/2 testing in women with ovarian cancer and cascade testing for at-risk family members.

References

1. National Institute for Health and Care Excellence. Ovarian cancer: recognition and initial management. Clinical guideline CG122. London: NICE; 2011 [updated 2023]. Available from: https://www.nice.org.uk/guidance/cg122 [Accessed May 2026].

2. National Institute for Health and Care Excellence. Ovarian cysts in postmenopausal women. Clinical Knowledge Summary. London: NICE; 2023. Available from: https://cks.nice.org.uk/topics/ovarian-cysts-postmenopausal-women/ [Accessed May 2026].

3. Jacobs I, Oram D, Fairbanks J, Turner J, Frost C, Grudzinskas JG. A risk of malignancy index incorporating CA125, ultrasound and menopausal status for the accurate preoperative diagnosis of ovarian cancer. Br J Obstet Gynaecol. 1990;97(10):922-929.

4. NHS Genomics Education Programme. Ovarian cancer. GeNotes Knowledge Hub. NHS England. Available from: https://www.genomicseducation.hee.nhs.uk/genotes/knowledge-hub/ovarian-cancer/ [Accessed May 2026].

Recommended Reading

• NICE CG122 – Ovarian cancer: recognition and initial management (2011, updated 2023)
• RCOG Green-top Guideline No. 62 – Management of Suspected Ovarian Masses in Premenopausal Women (2011)
• Cancer Research UK – Ovarian cancer statistics