Uterine polyps, also known as endometrial polyps, are growths that form on the inner lining of the uterus, known as the endometrium. These growths are extremely common, especially in women aged 40 to 50, and the vast majority are non-cancerous, or benign. However, a small percentage of uterine polyps can harbor malignant cells or represent a localized area of endometrial cancer. Understanding the potential for malignancy is important, as early detection of these rare cancerous polyps significantly improves treatment outcomes.
Understanding Malignant Uterine Polyps
Uterine polyps develop from an overgrowth of the endometrial lining, often due to hormonal stimulation, particularly estrogen. While most consist of normal endometrial tissue, a small fraction, estimated to be around 2.73% across all patient populations, will contain malignant cells. The risk of a polyp being cancerous increases significantly after menopause, rising to nearly 5% to 6% in postmenopausal women.
The spectrum of concern ranges from pre-malignant changes to fully developed cancer. Pre-malignant lesions, such as atypical endometrial hyperplasia, involve abnormal cell growth and architecture that has the potential to progress to cancer. A true malignant polyp means that endometrial carcinoma, the most common type of uterine cancer, has either arisen directly within the polyp or is confined to it.
Malignancy within a polyp is typically classified as either endometrioid adenocarcinoma, which is hormone-sensitive, or less common and more aggressive types like serous or clear cell carcinoma. Pathological analysis looks for specific cellular features, such as nuclear atypia and disorganized glandular structure, to determine if the growth is benign, pre-malignant, or malignant. Identifying these specific cellular changes ultimately determines the patient’s cancer risk and guides management.
Recognizing Suspicious Signs
The presence of a uterine polyp often announces itself through abnormal uterine bleeding (AUB), which is the most frequent symptom. This symptom indicates that the polyp needs evaluation, especially because the risk of malignancy is higher in symptomatic polyps compared to asymptomatic ones. The most concerning type of bleeding is any vaginal bleeding that occurs after a woman has gone through menopause.
For women who are still having menstrual cycles, suspicious signs include bleeding or spotting between periods (intermenstrual bleeding). Abnormally heavy menstrual periods (menorrhagia) can also be a symptom. Less common indications include unusual or persistent vaginal discharge or chronic pelvic pain.
Confirming Diagnosis and Determining Extent
Diagnosis begins with imaging, typically a transvaginal ultrasound, to visualize the uterine lining and identify growths. A specialized technique called sonohysterography, where sterile fluid is instilled into the uterus during the ultrasound, provides clearer images of the polyp’s structure. While imaging suggests a polyp, a tissue sample is necessary to definitively rule out cancer.
The gold standard for diagnosis and initial treatment is hysteroscopy with polypectomy. This minimally invasive procedure involves inserting a thin, lighted scope through the cervix into the uterine cavity, allowing the physician to directly visualize and remove the polyp entirely. The removed tissue is sent for pathological analysis, where a pathologist examines the cells to determine if they are benign, pre-malignant, or cancerous.
If cancer is confirmed, the pathologist determines the tumor grade, which describes how abnormal the cancer cells look. Determining the extent, or staging, of the cancer is performed surgically using the International Federation of Gynecology and Obstetrics (FIGO) system. Staging confirms whether the cancer is confined to the polyp, has invaded the underlying uterine muscle (myometrium), or has spread to other sites.
Intervention Strategies and Follow-Up Care
The intervention strategy for a cancerous uterine polyp depends heavily on the pathological findings and the stage of the disease. If the cancer is a low-grade endometrioid type and is confirmed to be entirely confined to the removed polyp with clear margins, a simple polypectomy may be considered curative, especially in younger patients. However, the standard definitive treatment when cancer is confirmed is a hysterectomy, which involves the surgical removal of the entire uterus.
For cancers that have invaded the deeper tissue of the uterus or are of a more aggressive type, the surgical plan often includes a hysterectomy along with the removal of the fallopian tubes and ovaries, known as a total hysterectomy with bilateral salpingo-oophorectomy. Lymph nodes near the uterus may also be sampled or removed during the operation to check for any microscopic spread of the disease.
Depending on the final surgical staging and tumor grade, adjuvant therapies may be recommended after surgery to reduce the risk of recurrence. These treatments can include radiation therapy, which uses high-energy rays to kill any remaining cancer cells in the pelvic area, or chemotherapy if the cancer is high-grade or has spread beyond the uterus.
Long-term follow-up care monitors for recurrence. This typically involves a schedule of regular physical exams, pelvic exams, and possibly imaging or blood tests. The frequency and duration of this surveillance are tailored to the individual patient’s cancer stage and grade.