Introduction

Definition of ovarian cancer

Ovarian cancer occurs within the ovaries, which are two small organs located on either side of the uterus,⁷ and make up part of the female reproductive system.^1,2 The ovaries are responsible for forming eggs during reproductive years and releasing estrogen and progesterone hormones involved in the menstrual cycle and pregnancy.³ Ovarian cancer is characterised by the abnormal growth of cells in the ovaries that often present vague or nonspecific symptoms, which lead to challenges in early detection and diagnosis.¹⁵ Ovarian cancer typically affects women over the age of 50,² with the median age at diagnosis of 63 years old.⁴

Brief statistics 

As the eighth most common cancer ⁵, ovarian cancer is the number one cause of female cancer deaths globally.⁶ Approximately 314,000 women are affected by ovarian cancer each year, with over 207,000 deaths annually.⁵  The incidence and mortality rates of ovarian cancer vary between countries; however, in the UK, approximately 7400 individuals are diagnosed each year.⁷  Nagle et al. 2025 state that although ovarian cancer survival rates have improved over recent years with earlier screening, the overall 5-year survival rates remain below 50%.⁶

Importance of early detection

Most ovarian cancer cases are diagnosed at the later stages of the disease,^2,8 as the signs and symptoms are non-specific, which can result in the delayed diagnosis of ovarian cancer.⁸ The early detection of ovarian cancer is important, as when diagnosed early and the individual is provided with treatment, the five-year survival rate can increase to 90%.⁹

Types of ovarian cancer

Ovarian cancer is an umbrella term used for the grouping of three different types of cancer: 

• Epithelial ovarian cancer¹⁰
• Germ cell tumours¹¹
• Stromal tumours¹²

Germ cell tumours form in ovarian cells that develop into eggs (known as germ cells).¹¹ Stromal tumours (known as sex cord tumours) are rare tumours that develop in the stroma.¹² The stroma is made up of tissue, blood vessels, nerves and lymphatic vessels that support the ovary by providing nutrients and removing waste.^12,13  

According to Cancer Research UK, approximately 90% of ovarian tumours are of the epithelial form.¹⁴ Epithelial ovarian cancer develops in the epithelial cells, which line the outer surface layer of the ovaries.¹⁴ Epithelial ovarian cancer can be subdivided into high-grade serous (grows and spreads quickly), low-grade serous (less common and slower to progress), clear cell, endometrioid and mucinous ovarian cancer.¹⁵ According to Macmillan Cancer Support, 80% of epithelial ovarian cancers are serous cancers.⁷ The methods of diagnostic assessment, treatment, and patient outcomes can vary based on the subtype of epithelial ovarian cancer.¹⁵

Risk factors

The risk of being diagnosed with ovarian cancer increases with age;¹⁶ however, multiple risk factors may increase an individual's chance of diagnosis, including reproductive and family genetic history, alongside the use of hormone replacement therapy (HRT).^4,17 These risk factors are:

• Obesity 
• Starting your period at a young age
• Having a baby later in life (after 35 years old)
• Not having a full-term pregnancy
• Not using hormonal contraception, e.g. the contraceptive pill¹⁶
• Experiencing menopause after 55 years old
• Taking hormone replacement therapy (shown to increase the risk of developing ovarian cancer by 22% for oestrogen-only therapy and 10% for combined oestrogen and progesterone therapy)⁴
• Previously using fertility treatment (in vitro fertilisation/IVF)¹⁷
• Family history and genetics (BRCA genetic mutations, resulting in alterations to the BRCA1 and BRCA2 tumour suppressor genes)⁴
• Previously having breast or bowel cancer¹⁶
• Smoking

Symptoms

According to Cancer Research UK, the signs and symptoms of ovarian cancer are typically vague and can be common to a range of less serious medical conditions, thus making the diagnosis of ovarian cancer difficult.¹⁸ These include:

• Bloating
• Abdominal pain
• Loss of appetite
• Urinary changes (urinating more frequently or urgently)
• Bowel function changes
• Unexplained tiredness or fatigue¹⁹
• Indigestion
• Weight loss
• Nausea

Diagnosis

Due to the vagueness of ovarian cancer symptoms, signs may be initially dismissed.⁴ Therefore, ovarian cancer is typically diagnosed when the cancer has reached a late stage (e.g. stage III or IV; see stages and grades section of this article) because symptoms become more severe and require medical intervention.⁴ Several diagnostic assessments can be conducted to determine if an individual presents ovarian cancer:

• Physical and pelvic examination
• Blood tests (looking for the CA125 marker)
• Imaging tests (ultrasound or a CT scan)
• Biopsy - taking a small amount of tissue to be tested in a laboratory²⁰

Physical and pelvic examination

Individuals experiencing symptoms would contact their local general practitioner (GP) for an initial physical examination. This would involve applying gentle pressure to the abdomen and pelvic region to look for swelling or areas that may not appear normal.²⁰ The GP would perform a pelvic examination (also known as a vaginal examination), using a small speculum inserted into the vagina²⁰, similar to the smear test for cervical cancer. The pelvic examination involves looking for potential abnormalities within the vagina, cervix and rectum.²⁰ 

Blood test

A blood test can be used to check the levels of a protein circulating in the blood called Cancer Antigen 125 (CA125).²¹ CA125 is known as a tumour marker (an indication that cancerous cells may be present), and has been the primary tumour marker of ovarian cancer for 40 years.²¹ Most females demonstrate a low or normal level of CA125 (less than 35U/mL; units per millilitre)²¹, and a higher level of the tumour marker may indicate inflammation around the pelvis.²⁰ However, the CA125 blood test is not completely reliable, as approximately 80% of patients with ovarian cancer exhibit elevated CA125 levels,²¹ while some individuals with ovarian cancer may experience normal CA125 levels.²⁰

Imaging tests

Ovarian cancer can be detected using imaging techniques such as an ultrasound or a CT scan.²⁰ An ultrasound scan uses high-frequency sound waves to create a picture of the ovaries and reproductive structure.²⁰ The ultrasound can be a transvaginal scan (scanning device inserted into the vagina) or an abdominal scan (external scan over the stomach area).²²  A CT (computed tomography) scan is a form of X-ray medical imaging, using X-rays rotated around the abdomen, to produce computer-generated 3D images of the ovaries, pelvis and abdomen.²³

Stages and grades

The severity of ovarian cancer can be determined by the stage (how large the cancerous tumour is and the possibility of it spreading) and the grade (how abnormal the cells look under a microscope).²⁴ 

Stages 

There are four stages of ovarian cancer:

• Stage I - the cancer is present in the ovaries
• Stage II - the cancer has grown outside the ovaries and spread to the pelvis
• Stage III - the cancer has spread beyond the pelvis to the abdominal cavity
• Stage IV - the cancer has spread to various parts of the body, such as the lungs

Grades

There are three grades of ovarian cancer,²⁵ these are:

• Grade 1 - low-grade, as the cancer cells look like normal cells and grow slowly
• Grade 2 - cancer cells start to look different to normal cells and grow a little faster than grade 1
• Grade 3 - high-grade, as the cancer cells look abnormal and tend to grow very quickly

Treatment

Treatment options for ovarian cancer vary depending on the stage and grade of the cancer, and the individual's general health and preferences.²⁶ These are:

• Surgery - to remove as much of the cancer as possible by the removal of affected ovaries, fallopian tubes, womb, etc .²⁶
• Chemotherapy - to reduce the number of cancerous cells before surgery or treat any cells that could not be removed during surgery²⁶
• Targeted cancer therapy drugs - using PARP inhibitors.²⁷ These cancer drugs are usually provided after the patient has received chemotherapy for stages III and IV ovarian cancer. The mechanism works by restricting a protein in the body called PARP, which prevents the ovarian cancer cells from repairing themselves. This results in the death of cancerous cells, therefore allowing the generation of normal, cancer-free cells²⁸

FAQ’s

How can I prevent ovarian cancer?

There are no specific ways to prevent ovarian cancer; however, there are factors that have been shown to decrease risk, such as maintaining a healthy weight, quitting smoking and taking oral contraceptives.¹⁶ A recent study showed that taking oral contraceptives for an average of five years showed a reduction in ovarian cancer of 0.54%.⁴ The Society of Gynecologic Oncology recommends that all women diagnosed with invasive ovarian cancer undergo genetic screening to assess for the BRCA gene mutations that could lead to an increased risk of family members being diagnosed with ovarian cancer.⁴

What is the survival rate for ovarian cancer?

The overall 5-year survival rate is approximately 50%; however, survival rates can vary depending on the stage and grade of ovarian cancer.⁶

What are the early signs of ovarian cancer?

Early warning signs can include abdominal pain, bloating and changes in urination. However, these symptoms can be common in less serious medical conditions.¹⁸ If you are experiencing any of these ongoing symptoms, it is important to consult a GP.

Summary

Ovarian cancer occurs within the ovaries and encompasses three cancer types, with epithelial ovarian cancer as the most common. Ovarian cancer affects women over the age of 50 and presents general, non-specific symptoms, e.g. abdominal pain and bloating. Ovarian cancer occurrence can be linked to lifestyle habits and family genetic history.

Ovarian cancer is challenging to diagnose early and is the leading cancer of death from cancer in females globally each year. The main diagnostic methods are pelvic examinations, blood tests to look for the CA125 marker, imaging tests and biopsies. Ovarian cancer presents a range of stages and grades, determining the type of treatment an individual may receive. Common forms of treatment are surgery, chemotherapy and targeted cancer drugs.