What Is Ovarian Cancer?
Ovarian cancer refers to malignant tumours arising from the ovary, fallopian tube, or primary peritoneum. These three sites share embryological origin and are treated as a single diagnostic category under current guidelines. Epithelial ovarian cancer accounts for roughly 90% of cases, and within this group, high-grade serous carcinoma (HGSOC) is the most common and most lethal subtype.
In Australia, approximately 1,800 women are diagnosed with ovarian cancer each year. It is the most lethal gynaecological malignancy — not because it is uniquely aggressive, but because it is typically diagnosed at an advanced stage, when treatment is harder. The lifetime risk for an average woman is approximately 1.4%.
Key Points
- Ovarian cancer symptoms are non-specific; the key warning sign is persistence — new symptoms that occur most days for 3+ weeks.
- There is no proven population screening test — CA-125 and ultrasound have not reduced mortality in trials and are not recommended for routine screening.
- ~75% of cases are diagnosed at Stage III or IV, when cancer has spread within the abdomen.
- BRCA1/2 pathogenic variants confer a 10–46% lifetime risk; genetic testing is warranted in affected women and appropriate family members.
- Standard treatment is cytoreductive surgery followed by platinum-based chemotherapy; PARP inhibitors have transformed maintenance therapy.
- Five-year survival for Stage I disease exceeds 90%; survival falls sharply with advanced stage.
- Symptoms should prompt GP evaluation — persistent bloating, abdominal discomfort, early satiety, or urinary changes in a woman over 40 warrant assessment.
Types of Ovarian Cancer
| Type | Proportion | Key Features |
|---|---|---|
| High-grade serous carcinoma (HGSOC) | ~70% of epithelial | Most common; often BRCA-related; chemotherapy-sensitive; usually advanced at diagnosis |
| Low-grade serous carcinoma | ~5% | Slower-growing; less chemotherapy-sensitive; often younger women |
| Endometrioid | ~10% | Associated with endometriosis; Lynch syndrome link |
| Clear cell | ~10% | Associated with endometriosis; lower platinum sensitivity |
| Mucinous | ~3% | Often early stage; CA-125 often not elevated |
| Borderline (low malignant potential) | Variable | Not invasive; generally excellent prognosis; surgery often curative |
| Germ cell tumours | ~5% | Young women; highly curable; fertility often preserved |
| Sex cord-stromal tumours | ~5% | Include granulosa cell tumours; may produce hormones |
Knowing the histological type matters because it influences treatment sensitivity, surveillance approach, and genetic risk implications.
Symptoms
Ovarian cancer symptoms are non-specific — they overlap with common benign conditions, including irritable bowel syndrome, bladder conditions, and functional gastrointestinal problems. This is the main reason for late diagnosis, not that women ignore symptoms.
The most common symptoms:
- Persistent bloating — a feeling of fullness or abdominal distension
- Abdominal or pelvic pain
- Difficulty eating or feeling full quickly (early satiety)
- Urinary urgency or frequency
Less common but notable:
- Unexplained weight loss or gain
- Changes in bowel habits (new constipation or diarrhoea)
- Abnormal vaginal bleeding (postmenopausal bleeding; intermenstrual bleeding)
- Back pain
- Fatigue
What makes symptoms clinically significant:
- They are new (not a lifelong pattern)
- They are persistent — occurring most days for 3 or more weeks
- They represent a change from a woman’s normal baseline
Most women with bloating or abdominal discomfort do not have ovarian cancer. However, persistent new symptoms in a woman — particularly over 40 — warrant GP evaluation. A pelvic examination, CA-125 blood test, and transvaginal ultrasound are standard first steps.
Why Diagnosis Is Often Delayed
Several factors converge to delay ovarian cancer diagnosis:
- Non-specific symptoms — early symptoms mimic common benign conditions
- No reliable screening test — unlike cervical or bowel cancer, there is no population programme
- Anatomical location — the ovaries lie deep in the pelvis; early tumours do not cause palpable masses
- Peritoneal spread — HGSOC often spreads early across the peritoneal surface; by the time symptoms emerge, disease may be widespread
- Normalisation — bloating and abdominal discomfort are common symptoms that women and clinicians may attribute to other causes
The International Ovarian Tumour Analysis (IOTA) group and UK symptom awareness research have both demonstrated that improving recognition of persistent symptoms can help shift the stage at diagnosis.
Diagnosis
Initial Assessment
Women presenting with suspicious symptoms should have:
- Pelvic examination
- CA-125 blood test
- Transvaginal ultrasound (TVUS)
CA-125
CA-125 is elevated in 80% of epithelial ovarian cancers overall, but in only ~50% of Stage I disease. It has important limitations:
- Elevated in benign conditions: endometriosis, uterine fibroids, pelvic inflammatory disease, pregnancy, liver disease
- Not elevated in some cancers: mucinous and clear cell carcinomas often have normal CA-125
- Not useful for population screening — large trials (UKCTOCS) failed to show mortality reduction
CA-125 is most valuable as a monitoring tool after treatment (tracking response) and for combining with ultrasound to risk-stratify a pelvic mass (e.g., using the Risk of Malignancy Index or IOTA ADNEX model).
Imaging
- Transvaginal ultrasound is the first-line imaging tool; experienced operators can characterise ovarian masses with high accuracy
- CT scan — used for staging once malignancy is suspected; assesses peritoneal disease, lymph nodes, and upper abdominal involvement
- MRI — used for problem-solving when ultrasound findings are equivocal; not for staging
Tissue Diagnosis
Definitive diagnosis requires histological confirmation — usually obtained at surgery. Unlike most cancers, ovarian cancer biopsy is often deferred until surgical staging, because tumour spill can upstage disease. For women who are not immediately surgical candidates, image-guided biopsy of peritoneal deposits may be used to establish histology before neoadjuvant chemotherapy.
Staging
Ovarian cancer is staged surgically using the FIGO classification:
| Stage | Description | Approx. 5-year survival |
|---|---|---|
| I | Confined to ovary/fallopian tube | 90%+ |
| II | Pelvic extension | ~70% |
| III | Peritoneal spread within abdomen / retroperitoneal nodes | 29–40% |
| IV | Distant metastases (pleural effusion, liver, spleen parenchyma) | ~17% |
Approximately 75% of women are diagnosed at Stage III or IV. This accounts for ovarian cancer’s high mortality relative to other gynaecological cancers.
Treatment
Surgery
Cytoreductive surgery (debulking) is the cornerstone of treatment. The goal is complete resection — no visible residual disease (R0). Surgical procedures may include bilateral salpingo-oophorectomy, total hysterectomy, omentectomy, appendectomy, peritoneal stripping, and bowel resection where necessary.
The extent of residual disease after surgery is the strongest predictor of overall survival.
For women whose disease is considered surgically difficult to resect upfront, neoadjuvant chemotherapy (3 cycles before surgery) followed by interval debulking surgery is an acceptable alternative with equivalent survival outcomes.
Chemotherapy
Standard first-line chemotherapy is intravenous carboplatin and paclitaxel, given every 3 weeks for 6 cycles. Intraperitoneal chemotherapy is used in some centres but is associated with higher toxicity. Response rates exceed 80% in platinum-sensitive HGSOC.
Recurrence is common — approximately 70–80% of women with advanced disease will relapse within 3 years.
PARP Inhibitors
A major advance in ovarian cancer treatment. PARP inhibitors (olaparib, niraparib, rucaparib) exploit deficiencies in DNA repair pathways — particularly homologous recombination deficiency (HRD), which is characteristic of BRCA-mutated tumours.
Indications:
- Maintenance therapy after response to first-line platinum chemotherapy (olaparib ± bevacizumab for BRCA-mutated; niraparib for HRD+ tumours)
- Maintenance therapy at recurrence after platinum-sensitive relapse
- Third-line treatment in BRCA-mutated, platinum-sensitive recurrence
PARP inhibitors have significantly extended progression-free survival and transformed the treatment landscape, particularly for BRCA-mutated disease.
Bevacizumab
An anti-angiogenic agent (targets VEGF) used in combination with first-line chemotherapy and as maintenance, particularly in Stage III/IV and in high-risk or HRD-positive disease.
Genetics and Family Risk
BRCA1 and BRCA2
Pathogenic variants in BRCA1 or BRCA2 are identified in approximately 15–20% of all ovarian cancer cases — making ovarian cancer more heritable than almost any other solid tumour.
| Gene | Lifetime ovarian cancer risk | Population risk |
|---|---|---|
| BRCA1 | ~40–46% | ~1.4% |
| BRCA2 | ~10–27% | ~1.4% |
BRCA testing is recommended for all women diagnosed with epithelial ovarian cancer, regardless of family history, because:
- It identifies family members who may benefit from testing and risk reduction
- BRCA-mutated tumours respond better to PARP inhibitors
- Risk-reducing surgery can be offered to at-risk relatives
Lynch Syndrome
Lynch syndrome (mismatch repair gene deficiency: MLH1, MSH2, MSH6, PMS2) confers a 6–13% lifetime ovarian cancer risk and a substantially elevated endometrial cancer risk. Ovarian cancers in Lynch syndrome are typically endometrioid or clear cell subtype.
Risk-Reducing Surgery
For BRCA1/2 carriers who have completed childbearing, risk-reducing bilateral salpingo-oophorectomy (RRSO) reduces ovarian cancer risk by ~80–95% and is recommended at age 35–40 for BRCA1 and 40–45 for BRCA2. It also reduces breast cancer risk in BRCA2 carriers who have not yet had breast cancer.
Prognosis
Prognosis depends primarily on stage at diagnosis, histological type, extent of surgical debulking, and whether there is a BRCA/HRD mutation (which predicts treatment response). Improvements in surgical technique and the introduction of PARP inhibitors have improved progression-free survival substantially in recent years, though long-term cure rates in Stage III/IV disease remain challenging.
Progress is ongoing — clinical trials in immunotherapy and targeted agents continue to expand options.
Further Reading
- Ovarian Cancer Australia — Patient Resources — Australian patient support and clinical information
- NHS — Ovarian Cancer — UK national guidance
- Cancer Australia — Ovarian Cancer — Australian clinical guidelines
- Cancer Council Australia — Ovarian Cancer Overview — plain-language resource
Related Guides
- Breast Cancer: Understanding the Diagnosis and Treatment Options
- Mammography and Breast Cancer Screening: What You Need to Know
- Genetic Testing: What It Can and Can’t Tell You
- Endometriosis: Symptoms, Diagnosis, and Treatment Options
- Cervical Cancer: Causes, Screening, Prevention, and Treatment
Last updated: May 2026