Ovarian Cancer (Small Cell Carcinoma)

Ovarian cancer is a type of carcinoma that causes one or more tumours to develop in the ovaries. The ovaries are a pair of small, walnut shaped organs that are responsible for the release of eggs (ovum) during the female reproductive cycle. In general, ovarian cancers are broadly classified into one of three categories depending on the type of cells they develop from – epithelial, germ-cell or stromal-cell.

Small cell ovarian cancer (SCOC) is a very rare and aggressive subtype of this disease. Because it is so rare, it is unclear whether it is defined as a type of epithelial, stromal or germ-cell ovarian cancer.

SCOCs are generally diagnosed in children, adolescents, and young adults; however, it can affect almost anyone with ovaries – including women, transgender men, non-binary individuals, and intersex people – at any age.

Types of Ovarian Small Cell Carcinoma

There are two primary subtypes of SCOC that have been identified, which are categorised by the types of cells present in the cancer and specific characteristics of the disease.

Hypercalcaemic Type (SCOCHT)

Hypercalcaemic type SCOC (SCOCHT) is the most common subtype of this disease, and is characterised by hypercalcaemia. Most patients with this subtype tend to be diagnosed at a later stage of disease, and may not respond as well to chemotherapy treatment. SCOCHT is generally diagnosed around the age of 22, and may not have as good of a prognosis as other types of ovarian cancer.

Pulmonary Type (SCOCPT)

Pulmonary type SCOC (SCOCPT) is a rare subtype of this disease, and is characterised by a cellular appearance that is very similar to small cell carcinoma of the lung. Most patients with this subtype tend to be diagnosed at a later stage of disease, and may respond better to chemotherapy compared to patients with SCOCHT. Unlike SCOCHT, SCOCPT is commonly diagnosed in older women (generally around 50 years old), and may not have as good of a prognosis.

Treatment

If an ovarian cancer is detected, it will be staged and graded based on size, metastasis, and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.

Ovarian cancers can be staged using the Federation of Gynaecology and Obstetrics (FIGO) system from stage I to IV.

  • Stage I: cancer cells are confined to one or both ovaries only. This stage is also known as early-stage cancer.
  • Stage II: cancer cells have grown deeper into nearby organs in the pelvis, such as the uterus, fallopian tubes, bladder and/or bowel. This is also known as localised cancer.
  • Stage III: the cancer has become larger and has spread beyond the pelvis into the lining of the abdomen (peritoneum). Lymph nodes are also often affected. This is also known as advanced or metastatic cancer.
  • Stage IV: the cancer has spread to more distant organs, such as the lungs or the liver. This is also known as advanced or metastatic cancer.

Cancers can also be graded based on the rate of growth and how likely they are to spread:

  • Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
  • Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
  • Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.

Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. In particular, they may look for mutations in the hereditary breast cancer genes (BRCA1 and BRCA2), which can cause an increased risk in developing ovarian cancer. They will then discuss the most appropriate treatment option for you.

Treatment is dependent on several factors, including fertility, type, stage of disease and overall health.

Treatment options for the SCOCs may include:

  • Surgery, potentially including:
    • Hysterectomy.
    • Bilateral salpingo-oophorectomy.
    • Unilateral salpingo-oophorectomy.
    • Lymphadenectomy.
    • Removal of other organs (only required in some cases where the cancer has spread beyond the pelvis).
  • Chemotherapy (more common in SCOCPT patients).
  • Radiation therapy.
  • Clinical trials.
  • Palliative care.

Ovarian Cancer Treatment and Fertility

Treatment for ovarian cancer may make it difficult to become pregnant. If fertility is important to you, discuss your options with your doctor prior to the commencement of treatment.

Risk factors

While the cause of ovarian cancer remains unknown, the following factors may increase your risk of developing the disease:

  • Having a family history of ovarian, breast, uterine and/or bowel cancer.
  • A mutation in the BRCA 1 and BRCA 2 genes.
  • Having Lynch syndrome.
  • Having certain medical conditions such as endometriosis.
  • Use of hormone replacement therapy (HRT).
  • Having a history of tobacco smoking.
  • Being obese.
  • Reproductive history, including:
    • Women who have never had children.
    • Women who have had assisted reproduction.
    • Women who have had children over the age of 35.
  • Having early puberty.
  • Having late menopause.
  • Having Ashkenazi Jewish ancestry.
  • Having rhabdoid tumour predisposition syndrome 2 (RTPS2).

Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.

Symptoms

Early-stage SCOCs may be asymptomatic. As the cancer progresses, some of the following symptoms may appear:

  • Abdominal bloating/swelling.
  • Abdominal/pelvic/lower back pain and/or pressure.
  • Changes in appetite, such as feeling full quickly or not feeling hungry.
  • Urinary changes, such as changes in frequency and urgency.
  • Changes in bowel habits, such as constipation and diarrhoea.
  • Unexplained weight loss or weight gain.
  • Unexplained fatigue.
  • Indigestion and/or heartburn.
  • Changes in menstrual periods, such as irregular periods, unusual vaginal bleeding, or vaginal bleeding post menopause.
  • Pain during sex.
  • Hypercalcaemia, which may produce its own set of symptoms:
    • Polyuria.
    • Polydipsia.
    • Abdominal discomfort and/or pain.
    • Nausea and/or vomiting.
    • Constipation.
    • Bone weakness and/or pain.
    • Muscle weakness.
    • Difficulties concentrating.
    • Confusion.
    • Drowsiness.
    • Fatigue.
  • Nausea and/or vomiting.

Not everyone with the symptoms above will have cancer, but see your GP if you are concerned.

Diagnosis

If your doctor suspects you have ovarian cancer, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment:

  • Pelvic examination.
  • Imaging tests, potentially including:
    • Pelvic ultrasound.
    • Transvaginal ultrasound.
    • CT (computed tomography) scan.
    • PET (positron emission tomography) scan.
  • Blood tests.
  • Biopsy.

References

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