Cancers of the ovary include celomic epithelial
carcinomas, germ cell neoplasms, and stromal tumors. Celomic epithelial
carcinomas, however, account for 90% of these lesions and for most of
the clinical research into the management of ovarian cancer.
Etiology and risk factors
The etiology of ovarian carcinoma is not known, although certain factors
associated with a higher risk of developing the disease have been
identified. There is an association between uninterrupted ovulation and the
disease.There is also an association between family history and increased
risk. Data now suggest that women with one first-order relative with ovarian
carcinoma have a risk 3.6-fold higher than that of the
general population. For those who have two or more relatives with ovarian
carcinoma, at least one of whom is a first-order relative, risk is estimated
to be at least 4.6-fold higher. For those with true familial syndromes by
genetic testing (BRCA1) or genetic linkage studies, risk is considerably
higher, with estimates as great as 50% reported but not necessarily
substantiated. These hereditary syndromes include hereditary breast-ovarian
cancer syndrome, hereditary ovarian cancer syndrome, and the Lynch II
syndrome (associated with colon cancer). These syndromes typically appear at
a younger age than sporadic ovarian carcinoma and appear to be vertically
transmitted by an autosomal dominant mode with incomplete penetrance.
The practical implications of these observations are not clear. Insufficient
data exist to justify prophylactic oophorectomy because not all of the
tissue at risk (the celomic epithelial lining of the peritoneal cavity)
would be removed by this procedure. Similarly, no screening techniques of
proven efficacy are available, although serum CA 125 levels and transvaginal
sonography are under investigation.
Initial presentation and approach
Patients with celomic epithelial carcinomas initially have feelings of
fullness or heaviness in the pelvis or increasing abdominal girth. These
symptoms unfortunately reflect advanced disease. Efforts to detect the
disease earlier have been unsuccessful. Initial evaluation of patients with
suspected ovarian carcinoma, after obtaining the patient history, a physical
examination, laboratory testing, and CA 125 levels, should include a
detailed assessment of the abdominal cavity. Various imaging techniques for
the abdomen are now available, but none provides the detail necessary to
accurately stage ovarian carcinoma. Nevertheless, CT scanning of the
abdominal cavity, chest roentgenography, and bone scanning should be done.
Unless these measures reveal disease outside the abdominal cavity,
exploratory laparotomy is essential. The laparotomy should be done through
an incision adequate to evaluate the entire peritoneal surface, including
the undersurface of the diaphragm and the right paracolic gutter as well as
the para-aortic lymph nodes. If there is no evidence of gross disease
outside the pelvis, multiple biopsies of the peritoneal surface should be
performed. Accurate staging of the disease will direct urther management.
Prognostic factors
The most significant prognostic factors for ovarian carcinoma are age,
histologic type and grade, extent of disease (stage), and volume of residual
disease. The most important among these is the extent of disease (stage) at
diagnosis. Almost 75% of patients will present with advanced (stage III or
IV) disease, most with disease confined to the peritoneal cavity (stage
III), reflecting intraperitoneal dissemination as the most common route of
spread.
Management
Advanced disease
Exploratory laparotomy, in addition to establishing the extent of disease,
also affords the first step in therapy. In addition to the diagnostic
measures described earlier, the procedure should include an aggressive
attempt at surgical cytoreduction. Patients who complete surgery with
small-volume residual disease (nodules < 2 cm in diameter) have a higher
response rate to chemotherapy and improved survival. The mainstay of
treating advanced disease is chemotherapy. Several chemotherapeutic agents
are active against ovarian carcinoma, the most important of which are the
platinum compounds, paclitaxel (Taxol), and the alkylating agents. The
standard of care for first-line therapy is a combination of paclitaxel plus
a platinum compound. In patients with large-volume advanced disease, this
combination yields a response rate of 73%-77%, a clinically complete
response rate of 50%-51%, no gross residual disease at second-look
laparotomy in 40%, progression-free survival of 16.6 to 18 months (median),
and overall survival of more than 35-38 months (median). In patients with
small-volume residual disease, results should be even better. Another
combination that has been used with somewhat less success is an alkylating
agent plus a platinum compound with or without doxorubicin
Limited disease
Exploratory laparotomy is essential to determine whether disease is confined
to the ovaries and pelvis and permits the classification of low-risk and
high-risk patients. Patients at low risk have a cure rate exceeding 90% with
total abdominal hysterectomy, bilateral salpingo-oophorectomy, and
omentectomy; they require no further therapy. Patients at high risk have a
recurrence rate of 40% and should receive adjuvant platinum-based
chemotherapy.
Salvage Therapy
For patients with disease recurrence after initial therapy, appropriate
management is determined by response to initial treatment. Patients who
first respond to platinum-based chemotherapy and have a recurrence more than
6 months after treatment are clinically platinum sensitive. Repeated
platinum-based therapy yields response rates as high as 60%. In contrast,
patients with progressive disease despite platinum-based treatment, with
persistent disease at the conclusion of platinum-based therapy, or with
recurrence less than 6 months after initial treatment are clinically
platinum resistant. Treatment should consist of paclitaxel or, in those who
received paclitaxel as initial therapy, oral etoposide, topotecan, tamoxifen
or, in some instances, gemcitabine, liposomal doxorubicin (Doxil)
vinorelbine tartrate (Navelbine) or ifosfamide. These seven agents all have
a demonstrated ability to induce responses in patients with platinum- or
paclitaxel-resistant disease. |