What Is the Main Idea?

The endometrium is the inner lining of the uterus. Endometrial cancer occurs when malignant cells grow in the tissue of the endometrium. This post deals with some of the information you might need to understand this type of cancer.

What Else Can You Learn?

The open access case report “Exceptional Response to Pembrolizumab for Treatment of Metastatic Chemorefractory Endometrial Carcinoma in a Patient with Lynch Syndrome: A Case Report”, published in the journal Case Reports in Oncology, focuses on a patient whose endometrial cancer responded well to treatment with pembrolizumab. This post summarizes the case study.

What Is the Endometrium?

The endometrium is the inner lining of the uterus. It contains epithelial tissue (tightly packed cells that usually have a protective function), connective tissue, and stem cells. The functional layer of the endometrium thickens during the menstrual cycle, readying itself for a fertilized egg. If a fertilized egg doesn’t implant itself in the endometrium, the functional layer is completely shed. This is what causes menstrual bleeding. The basal layer is not shed: Its function is to protect the uterus and regenerate the functional layer.

There are a few endometrial conditions that warrant medical attention. If the endometrium is too thin or too thick, this can affect the chances of a fertilized egg implanting successfully. It can also lead to rejection of the embryo at some point after implantation. If the endometrium grows outside the uterus or grows into the muscular layer of the uterus (the myometrium), this can cause pain and other problems. Polyps growing from the endometrium can also interfere with pregnancy and cause discomfort.

In this post, the focus is endometrial cancer.

What Are the Symptoms of Endometrial Cancer?

Endometrial cancer occurs when malignant cells grow in the tissue of the endometrium. It is crucial to diagnose it early and start treatment. With early treatment, it has a high five-year survival rate (81%) but if it reaches advanced stages, few treatment options exist.

People are advised to consult a doctor if they experience:

  • Bleeding or bloody discharge that is not related to menstruation
  • Bleeding or a white vaginal discharge after the end of menopause
  • Pain or cramping in the pelvic area
  • A lump or mass in the pelvic area
  • Difficulty urinating or pain while urinating
  • Pain during sexual intercourse

A computed tomography (CT) or magnetic resonance imaging (MRI) scan, ultrasound, endometrial biopsy, or certain blood tests (e.g., measuring the CA-125 level in the blood) are used to diagnose endometrial cancer.

Is There a Difference between Endometrial Cancer and Uterine Cancer?

Uterine cancer is often used interchangeably with endometrial cancer. However, technically there is a difference. Uterine cancer can mean endometrial cancer or uterine sarcoma, which is a cancer that forms in the muscles of the uterus, under the endometrium. Uterine sarcoma is very rare, making up less than 5% of uterine cancer diagnoses. The symptoms of uterine sarcoma are very similar to those of endometrial cancer.

What Are the Treatments for Endometrial Cancer?

Surgery is generally the first choice for dealing with endometrial cancer. Chemotherapy is usually chosen for more advanced endometrial cancers (stage III or IV), where metastasis has already occurred. Surgery followed by chemotherapy is common in such cases. Radiation therapy is similarly used when the surgery alone cannot guarantee removal of the cancer tissues.

The surgery is a hysterectomy, which means the removal of the uterus and cervix, although in some cases the ovaries and fallopian tubes must also be removed. If the ovaries are removed, menopause will occur.

What Is the Case Study about?

The case study “Exceptional Response to Pembrolizumab for Treatment of Metastatic Chemorefractory Endometrial Carcinoma in a Patient with Lynch Syndrome: A Case Report” looks at a 46-year old cisgender woman with advanced endometrial cancer. She had gone through chemotherapy with two commonly used drugs: carboplatin and paclitaxel. She was still experiencing progression of the disease. The doctors then treated her with pembrolizumab. The response is described as exceptional, with a decrease in the mass of the tumor and a reduction in the swelling of her lymph nodes.

There are two important pieces of information about this patient. They may contribute to understanding why she had such a strong positive response to the pembrolizumab. One is that she had Lynch syndrome: a genetic predisposition to certain cancer types, including colorectal cancer, stomach cancer, endometrial cancer, and ovarian cancer. The other is that her endometrial cancer was a type with high microsatellite instability (MSI; related to mutations in part of the DNA). Around 30% of endometrial cancers are the high-MSI type, and people with Lynch syndrome often develop this type.

The authors mention the theory that patients with Lynch syndrome and endometrial cancer may respond well to pembrolizumab chemotherapy. Another way of saying this is MSI-high endometrial cancer may be susceptible to pembrolizumab.

This is a case study of a single patient, so it shouldn’t be taken as proof that pembrolizumab alone will treat advanced endometrial cancer. However, adding to the body of evidence for a treatment is important — and it’s important for oncologists to be aware of the possibilities of using a particular drug in difficult cases.

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