Serous ovarian cancer is a subtype of cancer that originates in the ovaries, characterized by the uncontrolled growth of abnormal cells. It is a form of epithelial ovarian cancer, accounting for 85% to 90% of all ovarian cancer cases. Serous ovarian cancer is the most common among these epithelial types.
Understanding Serous Ovarian Cancer
Serous ovarian cancer primarily arises from epithelial cells that line the outer surface of the ovaries, and increasingly, are understood to originate from the fallopian tubes. High-grade serous ovarian carcinoma (HGSC), the most common and aggressive form, is believed to frequently begin in the fimbriated ends of the fallopian tubes.
Serous ovarian carcinoma is classified into two main categories: low-grade serous ovarian carcinoma (LGSC) and high-grade serous ovarian carcinoma (HGSC). HGSC makes up approximately 70-80% of ovarian cancer deaths and is characterized by rapid growth and widespread peritoneal metastases at diagnosis. LGSC is less common and tends to grow more slowly, often progressing in a stepwise fashion from benign or borderline tumors.
Molecularly, HGSC often presents with widespread genetic instability and a high frequency of TP53 gene mutations, occurring in over 96% of cases. In contrast, LGSC is more genetically stable and typically involves mutations in genes such as KRAS, BRAF, or ERBB2.
Recognizing the Signs and Risk Factors
The symptoms of serous ovarian cancer are often vague, making early detection challenging. Common signs include abdominal bloating or swelling, quickly feeling full when eating, weight loss, and discomfort in the pelvic area. Other symptoms may involve changes in bowel habits, such as constipation, or a frequent need to urinate.
These subtle symptoms can easily be attributed to more common, less serious conditions, leading to diagnoses often occurring at advanced stages. If these symptoms persist for four weeks or longer, particularly if they are unusual, frequent, or worsening, medical investigation is advised.
Several factors can increase an individual’s risk of developing serous ovarian cancer. Age is a factor, with the risk increasing after menopause, particularly for women over 60. Genetic predispositions, such as inherited mutations in the BRCA1 or BRCA2 genes, are strongly linked to an increased risk, found in approximately one in five individuals with high-grade serous ovarian cancer. A family history of ovarian, fallopian tube, breast, pancreatic, or prostate cancer can also elevate risk. Conditions like endometriosis, a history of never having been pregnant, or the use of postmenopausal hormone replacement therapy may also contribute to an increased risk.
Diagnosis and Staging
Diagnosing serous ovarian cancer involves examinations and tests to confirm the presence of cancer and determine its extent. A physical exam, including a pelvic examination, is among the initial steps. Imaging tests, such as transvaginal ultrasound and CT scans, are commonly used to visualize any abnormalities in the ovaries or surrounding areas. CT scans are useful for staging.
Blood tests, specifically for cancer antigen 125 (CA-125), are also part of the diagnostic process. While elevated CA-125 levels can suggest ovarian cancer, they are not exclusive to it and can be raised in other benign or malignant conditions, and may even be normal in early-stage disease. Therefore, CA-125 testing is used in conjunction with other diagnostic methods.
The definitive diagnosis of serous ovarian cancer is made through a biopsy, which involves surgical removal of tissue samples for microscopic examination by a pathologist. Once cancer is confirmed, surgical staging is performed using the International Federation of Gynecology and Obstetrics (FIGO) staging system. This system classifies the cancer into stages I through IV, based on the extent of tumor spread, involvement of nearby lymph nodes, and metastasis to distant sites. For instance, Stage I indicates cancer confined to one or both ovaries or fallopian tubes, while Stage IV signifies spread to distant organs like the liver or lungs. This staging process guides subsequent treatment decisions and understanding the prognosis.
Treatment Approaches
Treatment for serous ovarian cancer begins with surgical intervention. This involves debulking surgery, aiming to remove as much of the cancerous tissue as possible, ideally achieving no visible residual tumor. The extent of surgery depends on the cancer’s spread, but may include removal of one or both ovaries and fallopian tubes, the uterus (hysterectomy), and other affected tissues in the abdomen.
Following surgery, chemotherapy is a standard systemic treatment, often involving platinum-based drugs like carboplatin combined with taxane-based agents such as paclitaxel. This combination is administered to target any remaining cancer cells and reduce the risk of recurrence. Chemotherapy regimens are tailored to the individual patient, considering the cancer’s stage and overall health.
Newer therapies have expanded treatment options, particularly for advanced or recurrent disease. Poly (ADP-ribose) polymerase (PARP) inhibitors, such as olaparib, niraparib, and rucaparib, are targeted therapies that interfere with DNA repair mechanisms in cancer cells, especially effective in patients with BRCA gene mutations or homologous recombination deficiency (HRD). These inhibitors are used as maintenance therapy after chemotherapy to prolong remission. Immunotherapy, which helps the body’s immune system fight cancer, is also used, sometimes in combination with PARP inhibitors, although its success in ovarian cancer has been less consistent compared to other targeted therapies. Anti-angiogenic agents, such as bevacizumab, which inhibit the formation of new blood vessels that feed tumors, are also used in some cases, often in combination with chemotherapy or PARP inhibitors.
Outlook and Ongoing Care
Despite advancements, serous ovarian cancer often presents at advanced stages, which can pose challenges for prognosis. However, continuous progress in treatment strategies has improved outcomes. The optimal treatment includes upfront or intermediate complete cytoreduction combined with platinum and taxane-based chemotherapy, often incorporating targeted therapies.
Even with aggressive initial treatment, most patients with stages III-IV high-grade serous ovarian cancer will experience recurrence. The time to recurrence is an important factor in guiding subsequent management. Follow-up care is a continuous process, involving regular monitoring for signs of recurrence.
Monitoring for recurrence includes physical exams, blood tests for biomarkers like CA-125, and imaging as needed. While CA-125 is a reliable biomarker for detecting recurrence, its levels can be normal even with recurrence. Managing long-term side effects from treatment and providing supportive care are also aspects of ongoing care, helping patients maintain their quality of life.