Ovarian cancer

 Ovarian cancer

After cancer of the lung, breast, and colon, primary ovarian cancer ranks as the most common cause of cancer deaths among American women. In women with previously treated breast cancer, metastatic ovarian cancer is more common than cancer at any other site.

The prognosis varies with the histologic type and stage of the disease but is generally poor because ovarian tumors produce few early signs and are usually advanced at diagnosis.

Three main types of ovarian cancer exist:

• Primary epithelial tumors account for 90% of all ovarian cancers and include serous cystoadenocarcinoma, mucinous cystoadenocarcinoma, and endometrioid and mesonephric malignancies. Serous cystoadenocarcinoma is the most common type and accounts for 50% of all cases.
• Germ cell tumors include endodermal sinus malignancies, embryonal carcinoma (a rare ovarian cancer that appears in children), immature teratomas, and dysgerminoma.
• Sex cord (stromal) tumors include granulosa cell tumors (which produce estrogen and may have feminizing effects), granulosa-theca cell tumors, and the rare arrhenoblastomas (which produce androgen and have virilizing effects).

Causes

The exact cause of ovarian cancer is unknown, but its incidence is noticeably higher in women of upper socioeconomic levels between the ages of 20 and 54. However, it can occur during childhood. Certain genes, including BRCA1 and BRCA2, may increase risk. Other contributing factors include age at menopause; infertility; celibacy; high-fat diet; exposure to asbestos, talc, and industrial pollutants; nulliparity; familial tendency; and history of breast or uterine cancer.

Primary epithelial tumors arise in the müllerian epithelium; germ cell tumors, in the ovum itself; and sex cord tumors, in the ovarian stroma (the ovary's supporting framework).

Ovarian tumors spread rapidly intraperitoneally by local extension or surface seeding and, occasionally, through the lymphatics and the bloodstream. Generally, extraperitoneal spread is through the diaphragm into the chest cavity, which may cause pleural effusions. Other types of metastasis are rare.

Signs and symptoms

Typically, symptoms vary with the size of the tumor. Occasionally, in the early stages, ovarian cancer causes vague abdominal discomfort, dyspepsia, and other mild GI disturbances. As it progresses, it causes urinary frequency, constipation, pelvic discomfort, abdominal distention, and weight loss.

Tumor rupture, torsion, or infection may cause pain, which, in young patients, may mimic appendicitis. Granulosa cell tumors have feminizing effects (such as bleeding between periods in premenopausal women); conversely, arrhenoblastomas have virilizing effects. Advanced ovarian cancer causes ascites, rarely postmenopausal bleeding and pain, and symptoms relating to metastatic sites (most commonly pleural effusions).

Diagnosis

With ovarian cancer, diagnosis requires clinical evaluation, a complete patient history, surgical exploration, and histologic studies. Preoperative evaluation includes a complete physical examination, including pelvic examination with Papanicolaou smear (not clinically useful for ovarian cancer but helpful in diagnosing cervical dysplasia, cervical cancer, and some endometrial cancers) and the following special tests:

• abdominal ultrasonography, computed tomography scan, or magnetic resonance imaging (may delineate tumor size)
• complete blood count and blood chemistries
• chest X-ray for distant metastasis and pleural effusions
• barium enema (especially in patients with GI symptoms) to reveal obstruction and size of tumor
• mammography to rule out primary breast cancer
• liver function studies or a liver scan in patients with ascites
• laboratory tumor marker studies, such as CA-125, carcinoembryonic antigen, and human chorionic gonadotropin (the last two are mainly for suspected germ cell tumors).
• Despite extensive testing, accurate diagnosis and staging are impossible without exploratory laparotomy, including lymph node evaluation and tumor resection.

Treatment

Depending on the stage of the disease and the patient's age, treatment of ovarian cancer requires varying combinations of surgery, chemotherapy and, in some cases, radiation. Cytoreductive surgery, in which the tumor nodules are reduced to as small a size as possible, may increase survival time.

Conservative treatment

Occasionally, in girls or young women with a unilateral encapsulated tumor who wish to maintain fertility, the following conservative approach may be appropriate:

• resection of the involved ovary
• biopsies of the omentum and the uninvolved ovary
• peritoneal washings for cytologic examination of pelvic fluid
• careful follow-up, including periodic chest X-rays to rule out lung metastasis.

Aggressive treatment

Ovarian cancer usually requires more aggressive treatment, including total abdominal hysterectomy and bilateral salpingo-oophorectomy with tumor resection, omentectomy, appendectomy, lymph node biopsies with lymphadenectomy, tissue biopsies, and peritoneal washings.

Complete tumor resection is impossible if the tumor has matted around other organs or if it involves organs that can't be resected. Bilateral salpingo-oophorectomy in a prepubertal girl necessitates hormone replacement therapy, beginning at puberty, to induce the development of secondary sex characteristics.

Chemotherapy extends survival time in most ovarian cancer patients. Unfortunately, it's largely palliative in advanced disease, but some patients are achieving prolonged remissions and even cures.

Chemotherapeutic drugs may be used alone; however, they're usually given in combination. They may be administered intraperitoneally. The preferred first-line regimen is paclitaxel and cisplatin (or carboplatin).

Radiation therapy is generally not used for ovarian cancer because the resulting myelosuppression would limit the effectiveness of chemotherapy. It also has limited efficacy.

Other treatments

Radioisotopes have been used as adjuvant therapy, but they cause small-bowel obstructions and stenosis.

In addition, I.V. administration of biological response modifiers—interleukin-2, interferon, and monoclonal antibodies—may be attempted.

Special considerations

Because the treatment of ovarian cancer varies widely, so must the care of the patient.

Before surgery:

• Thoroughly explain all preoperative tests, the expected course of treatment, and surgical and postoperative procedures.
• In premenopausal women, explain that bilateral oophorectomy artificially induces early menopause, so they may experience hot flashes, headaches, palpitations, insomnia, depression, and excessive perspiration.

After surgery:

• Monitor vital signs frequently, and check I.V. fluids often. Monitor intake and output, while maintaining good catheter care. Check the dressing regularly for excessive drainage or bleeding, and watch for signs of infection.
• Provide abdominal support, and watch for abdominal distention. Encourage coughing and deep breathing. Reposition the patient often, and encourage her to walk shortly after surgery.
• Monitor the patient, and treat any adverse reactions of radiation and chemotherapy.