Serous endometrial carcinoma is a rare and aggressive type of endometrial (uterine) cancer. Compared to other forms, this subtype tends to grow and spread faster. Because of this, people diagnosed with serous endometrial carcinoma often have a poorer prognosis (expected outcome).

Keep reading to learn more about serous endometrial carcinoma and what it could mean to you or a loved one.

1. Serous Endometrial Carcinoma Makes Up About 1 in 10 Cases

Serous endometrial carcinoma is the second most common type of endometrial cancer, but it’s still considered relatively rare. About 10 percent of endometrial cancer cases are the serous type, yet it accounts for around 40 percent of deaths from this disease.

Doctors classify endometrial cancers by histologic type — based on how the cells look under a microscope. Endometrioid carcinoma, the most common type, makes up 85 percent to 90 percent of cases. Less common histologic subtypes include carcinosarcoma, undifferentiated carcinoma, clear cell carcinoma, and squamous cell carcinoma.

2. The Serous Type Doesn’t Rely on Hormones To Grow

For most types of endometrial cancer, higher lifetime exposure to estrogen increases the risk. That’s because this hormone encourages growth in the cells that line the uterus (called the endometrium), which can sometimes lead to cancer. Factors that raise estrogen levels include having a higher body weight, starting menstruation early, and taking tamoxifen after menopause. However, serous endometrial carcinoma doesn’t depend on estrogen to grow. As a result, people without these common risk factors can develop this type of cancer.

3. Diagnosis Often Happens at Later Stages

Like other types of endometrial cancer, serous endometrial carcinoma often causes abnormal vaginal bleeding and discharge as the first symptoms. However, people with serous endometrial carcinoma are 2.5 times more likely to be diagnosed at a more advanced stage.

About half of people diagnosed with serous endometrial carcinoma have stage 3 or 4 cancer. At stage 3, the cancer has spread beyond the uterus to nearby tissues or pelvic lymph nodes. Symptoms at this stage may include pelvic pain or discomfort and bloating.

At stage 4, the cancer has spread outside the pelvis to other parts of the body, such as distant lymph nodes, the bladder, or the rectum. Additional symptoms may include:

• Painful urination
• Changes in bowel habits
• Unexplained weight loss
• A swollen stomach
• Cough

4. Serous Endometrial Carcinoma Tends To Grow and Spread Faster

Doctors assign a grade to endometrial cancer cells based on how different they look from normal cells. Grades range from 1 to 3, with 1 and 2 considered low-grade cancers — they usually grow more slowly and are less likely to spread. Grade 3 tumors are considered high grade, meaning the cells look more abnormal and the cancer is usually more aggressive. Serous endometrial carcinoma is typically classified as a high-grade cancer.

5. Genetic Mutations Drive the Cancer’s Aggressive Behavior

If you’re diagnosed with endometrial cancer, your oncologist (cancer doctor) may check your cancer cells for genetic mutations (changes). These mutations can help doctors understand how the cancer behaves and which treatments might work best. Mutations typically found in serous endometrial carcinomas are linked to faster growth and a higher risk of spreading.

6. Surgery May Be More Extensive

Surgery to remove the uterus is usually the main treatment for early-stage endometrial cancer, including serous endometrial carcinoma. However, because the serous type is more aggressive, the surgery may need to be more extensive and involve additional biopsies.

Treatment typically involves a hysterectomy plus bilateral salpingo-oophorectomy (radical hysterectomy) — removal of the uterus, cervix, ovaries, and fallopian tubes.

Your surgeon may also remove nearby lymph nodes to check for cancer spread. They may take a biopsy from the omentum (the layer of fat that surrounds the abdominal organs). Biopsies help determine cancer stage and whether cancer has spread to other parts of the body.

7. More Treatment May Be Needed After Surgery

The term “adjuvant therapy” refers to treatments given after surgery to help reduce the risk of recurrence (cancer returning). Although some people with low-grade, stage 1 endometrial cancer may not need more treatment, adjuvant therapy is usually recommended for the serous type because it’s considered high grade.

Radiation Therapy

A few weeks after surgery, you may start radiation therapy, such as:

• Brachytherapy — A small container of radioactive material is placed inside the vagina.
• External beam radiation therapy — Radiation is directed at the pelvis from a machine outside the body.

Clinical trials (studies that test therapies’ safety and effectiveness in humans) show that radiation therapy can improve outcomes for people with serous endometrial carcinoma.

Chemotherapy

Chemotherapy (chemo) uses drugs that prevent cancer cells from growing and dividing.

Adding chemotherapy to radiation therapy may also help lead to better outcomes for people with serous endometrial carcinoma. Common chemo drugs used for endometrial cancer include carboplatin, cisplatin, and paclitaxel.

Immunotherapy and Targeted Therapy

Immunotherapy is often among the first treatments for serous endometrial carcinoma. These treatments help the immune system find and attack cancer cells by blocking immune checkpoints — natural “brakes” that cancer cells can use to hide from the body’s defenses.

Treatment with a single immune checkpoint inhibitor usually isn’t effective for people with serous endometrial carcinoma. However, some may benefit from a combination of pembrolizumab (Keytruda) and lenvatinib (Lenvima), a targeted therapy. Two other checkpoint inhibitors, dostarlimab-gxly (Jemperli) and durvalumab (Imfinzi), are also approved by the U.S. Food and Drug Administration (FDA) for certain types of endometrial cancer.

Researchers are continuing to study the effectiveness of possible drug combinations. Ask your cancer care team about new treatments for endometrial cancer.

8. Earlier Diagnosis Can Improve Outcomes

The five-year survival rate for people with stage 1 or 2 serous endometrial carcinoma is about 74 percent. Advanced serous endometrial cancer has a worse prognosis. Because serous endometrial cancer is more likely to spread quickly and return after treatment, it’s harder to treat in later stages. The five-year survival rate for stage 3 or 4 serous endometrial cancer is around 33 percent.

Ongoing research is leading to better ways to detect and treat serous endometrial carcinoma. Talk with your care team about what’s available today and what may be on the horizon.

Find Your Team

On MyEndometrialCancerTeam, the social network for people with endometrial cancer and their loved ones, members come together to ask questions, give advice, and share their stories with those who understand life with endometrial cancer.

Are you living with serous endometrial carcinoma? What advice do you have for others recently diagnosed with this aggressive type of cancer? Share your experience in the comments below, or start a conversation by posting on your Activities page.