1.1 Structure and function of ovaries
The ovaries are located within the pelvic cavity, on either side of the uterus. Each ovary is in close proximity to its corresponding fallopian tube, which connects to the left and right sides of the uterus.
The ovaries are composed of different types of cells. The outermost layer consists of epithelial cells. Below the epithelial layer are germ cells, which have the role of developing into eggs for reproduction. During each menstrual cycle, one of the ovaries releases a mature egg in a process called ovulation. The egg then travels through the fallopian tube and into the uterus. If the egg is not fertilized, it is expelled from the uterus along with menstrual blood.
In addition to germ cells, the ovaries also contain cells called sex-cord stromal cells, which are responsible for secreting female hormones. These hormones include estrogen and progesterone. Estrogen and progesterone play crucial roles in regulating various physiological changes in females and control the functions of multiple organs, including the reproductive organs.
1.2 About ovarian cancer
According to the Hong Kong Hospital Authority’s Cancer Registry, in 2016, there were 1,050 cases of ovarian cancer and 133 deaths related to ovarian cancer in Hong Kong. Ovarian cancer ranked sixth among the top ten cancers in Hong Kong and seventh in terms of mortality rate.
Ovarian cancer occurs when cells in the ovaries undergo malignant transformation, leading to uncontrolled cell growth. The tumor can invade surrounding normal tissues, making it an invasive cancer. Ovarian cancer can be classified into several major types based on pathological results:
- Epithelial Ovarian Cancer: This type, also known as epithelial ovarian cancer, originates from the surface epithelial cells of the ovaries. Approximately 90% of ovarian cancers belong to this category.
- Germ Cell Ovarian Cancer: Germ cell ovarian cancer develops from the cells responsible for producing eggs within the ovaries. This type of ovarian cancer is relatively rare and predominantly affects younger patients, usually under the age of 30.
- Sex-Cord Stromal Cancer: Sex-cord stromal cancer arises from the cells within the ovaries that produce female hormones. This type of cancer is relatively rare.
- Borderline Tumors: Borderline tumors refer to tumors with minimal potential for spreading or recurrence. They do not qualify as cancerous tumors. Borderline tumors commonly occur in younger women.
1.3 Cause of ovarian cancer
At present, the medical community has not reached a definitive conclusion on the formation of ovarian cancer, but the following risk factors increase the risk of developing ovarian cancer:
- Age: Women over 45 are more susceptible to ovarian cancer.
- Nulliparity or infertility increases the risk compared to the general population.
- Early onset of menstruation (before age 12) or late menopause (after age 55) is associated with a higher chance of developing ovarian cancer.
- Family history: Having close relatives with ovarian cancer increases the risk.
- Hereditary cancers: Patients inherit cancer-causing genes from their parents, and they also have a higher risk of developing other cancers, such as: BRCA2 hereditary breast and ovarian cancer.
Hereditary non-polyposis colorectal cancer (HNPCC).
1.4 Symptoms of ovarian cancer
The early symptoms of ovarian cancer are often not apparent, leading to frequent neglect. By the time patients experience noticeable symptoms, the disease has often progressed to an advanced stage, significantly impacting their prognosis. Therefore, doctors advise patients to seek medical attention early and undergo thorough examinations if they feel unwell to avoid delays in diagnosis.
Common symptoms of ovarian cancer include:
- Abdominal bloating or swelling: The growth of ovarian tumors can cause bloating in the lower abdomen, which may not be easily noticed by patients.
- Abdominal pain or discomfort in the lower abdomen.
- Frequent urination: Ovarian tumors can exert pressure on the bladder and urethra, leading to increased frequency of urination, with patients feeling the need to urinate frequently.
- Gastrointestinal discomfort, such as heartburn, acid reflux, nausea, and indigestion.
- Unexplained weight loss.
- Loss of appetite.
- Changes in menstrual cycle or unexpected vaginal bleeding after menopause.
- Pain during sexual intercourse.
1.5 Diagnosis of ovarian cancer
If you experience the above-mentioned symptoms, doctors will arrange different tests to establish a diagnosis and gain further understanding of your condition, assisting them in formulating a treatment plan.
Physical Examination
Doctors will conduct a detailed clinical examination, beginning with palpation of your abdomen to identify any abdominal masses or fluid accumulation (ascites). If fluid is detected during the examination, the doctor may recommend inserting a needle into the abdomen to extract the fluid for analysis, aiding in the diagnostic process.
Pelvic Ultrasound
Following the clinical examination, the doctor will perform a gynecological examination, inspecting your vagina and reproductive organs, and then proceed with a pelvic ultrasound. Pelvic ultrasound can be conducted using two methods: trans-abdominal ultrasound and trans-vaginal ultrasound. Ultrasound imaging converts the structures within the pelvic region into real-time images displayed on a screen, allowing the doctor to examine the ovaries for any suspicious masses in detail.
Blood Tests
The cancer marker CA125 is commonly used to diagnose and monitor ovarian cancer. CA125 is a substance naturally present in ovarian cells, and when there is a tumor in the ovary, the uncontrolled proliferation of cancer cells causes this substance to enter the bloodstream, resulting in elevated levels of CA125 in the blood. By measuring CA125 levels through a blood test, doctors can assess the risk of ovarian cancer in patients. However, it should be noted that conditions other than ovarian cancer, such as endometriosis or uterine fibroids, may occasionally cause an increase in CA125 levels. Therefore, the results of the CA125 test need to be considered in conjunction with clinical examination and other tests.
Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) Scans
CT scans and MRI scans are advanced imaging techniques that provide detailed cross-sectional images of the abdominal and pelvic organs and structures. They enable doctors to clearly visualize any abnormalities or shadows in the organs, including the ovaries, as well as detect tumor invasion or involvement of nearby tissues. Contrast agents may be used during the scans to enhance the visibility of abnormal areas, especially regions with abnormal blood vessel growth.
1.6 Staging of ovarian cancer
After a detailed examination and confirmation of ovarian cancer, doctors will determine the stage of the tumor based on its severity. Staging aims to determine the extent of tumor invasion, assist in devising a treatment plan, and evaluate the patient’s prognosis. The following is the most commonly used staging system for ovarian cancer:
- Stage 1: Cancer cells are present in one or both ovaries.
- Stage 2: The tumor has spread beyond the ovaries and has invaded nearby pelvic structures.
- Stage 3: The tumor has spread to the peritoneal surfaces within the abdomen, the lymph nodes in the abdomen or pelvis, or both.
- Stage 4: The tumor has spread to distant organs outside the abdominal cavity, such as the liver, lungs, or other distant lymph nodes.