What is the most aggressive type of uterine cancer?
In Australia, uterine cancer is the most common type of gynaecological cancer with more than 3,000 women diagnosed every year. Most typically it is a disease of postmenopausal women and its main symptoms are postmenopausal bleeding or spotting.
There are different types of uterine cancer, some more aggressive than others. While the majority of cancers arising in the womb are slow growing and innocuous, others are more aggressive which means that it may grow or spread quickly into other organs, or recur quicker.
There are two main types of uterine cancer:
- Endometrial cancers which start in the inner lining of the uterus (the endometrium) and is the most common type accounting for about 90% of all cases. The endometrium is part of the uterus, so endometrial cancer is often referred to as uterine cancer.
- Uterine sarcomas, which develop in the muscle tissue of the uterus (the myometrium). This type is rare, but is also the most aggressive form of uterine cancer.
- Mixed tumours (carcinosarcomas) that arise from both the muscle tissue and the endometrium. These tumours are also aggressive,
Diagnosing endometrial cancer involves a transvaginal ultrasound, examination of the lining of the uterus (hysteroscopy) and tissue sampling (biopsy).
Endometrial cancers can be further divided into 2 types:
Type 1 cancers are the most common endometrial cancers. They are usually endometrioid cancers, which start in the glandular cells of the endometrium. They are reported to be linked to an excess of oestrogen. Type 1 cancers are likely to be slow growing and are less likely to spread to other parts of the body. They typically require less intensive treatment and patients normally can expect a good prognosis. Conservative treatment of endometrial cancer should be offered to young patients with early stage endometrial cancer who wish to preserve fertility.
Type 2 cancers are less common. They include cancers of serous and clear cell type. The causes of type 2 are unknown. They grow faster than type 1 cancers and are more likely to spread due to symptoms presenting at later stages, resulting in the need for more aggressive treatment. Treatment involves surgery, often followed by radiation therapy, chemotherapy, or a combination of both. Carcinosarcomas also belong to this group of cancers.
Uterine sarcoma is a term to describe cancers that start from tissues such as muscle, fat, bone, and fibrous tissue. Uterine sarcomas are aggressive tumours arising from the myometrium (muscle tissue) or other tissues that support the uterus. There are three types: endometrial stromal sarcoma is a low-grade, slow-growing tumour, while leiomyosarcoma and undifferentiated sarcoma are usually faster growing and may be more likely to spread to other parts of the body.
At the Queensland Centre for Gynaecological Cancer we see approximately 30 patients with uterine sarcomas every year with the incidence increasing.
It is not known what causes uterine sarcomas, however certain risk factors have been identified. Increasing age, long-term use of tamoxifen (e.g. for breast cancer), previous pelvic radiation treatment (e.g. for rectal cancer) and genetic mutations (hereditary kidney cancer) are associated with an increased risk for uterine sarcomas.
Symptoms of uterine sarcomas are unspecific. However, the majority of patients present with abnormal uterine bleeding, pain and abdominal swelling. Unfortunately, these symptoms are also shared with common and benign gynaecological conditions such as fibroids.
As a rule, all patients with abnormal uterine bleeding need to have some tissue taken from the uterus to be examined under a microscope. This can be done by endometrial sampling in the clinic or by dilation and curettage (D&C) as a surgical day procedure. Unfortunately, removing tissue from the uterine cavity will still fail to diagnose rare cancers of the womb in up to 50% of patients.
Diagnosis by medical Imaging (for e.g. CT, MRI), blood tests, and pelvic exams are unreliable. Unfortunately, a significant percentage of uterine sarcomas are diagnosed incidentally following a hysterectomy or a myomectomy due to lack of any reliable screening options.
Due to the unspecific symptoms and because medical imaging is unreliable, unfortunately, only half of all uterine sarcomas will be diagnosed prior to surgery. Uterine sarcomas do not respond well to any type of adjuvant treatment (chemotherapy or radiation). Patients will solely rely on surgery for treatment.
Being diagnosed with an aggressive cancer can be a distressing process—speaking to a gynaecological oncologist will help you to be informed on how to effectively treat the disease.
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