Photo by Clay Eals
Women at highest risk for ovarian cancer receive less screening and report less worry about getting the disease than women with a lower yet somewhat elevated risk, according to researchers in the Public Health Sciences Division.
Dr. Robyn Andersen, an investigator in the Cancer Prevention Research Program, led the study, which appeared in the April issue of Gynecologic Oncology.
Sue Peacock, Judy Nelson, Dr. Martin McIntosh and Dr. Nicole Urban, also of PHS, and Dr. Charles Drescher of the Marsha Rivkin Center for Ovarian Cancer Research were co-authors.
"Women most likely to report high levels of perceived risk and to get screening for ovarian cancer are those at elevated risk with a single relative affected with ovarian cancer, as compared to high-risk women with multiple family members affected by breast and/or ovarian cancer," Andersen said.
"These results suggest that many women need additional education about ovarian-cancer risk. We found that the majority of women overestimate their risk, and yet a significant percentage of those at highest risk fail to get the recommended screening."
The findings were based on a survey of 3,257 women designed to measure the relationship between perceived ovarian-cancer risk, worry and screening use. The participants averaged 48 years of age and were well educated; nearly 70 percent had graduated from college.
Of those surveyed, 142 were at high risk due to a strong family history of breast or ovarian cancer, and 144 women were at elevated risk due to a single, first-degree relative with ovarian cancer. The remaining 2,971 women were considered average risk.
The survey revealed significant differences in screening rates between women at high and elevated risk.
While more than 60 percent of those at elevated risk reported having undergone screening, fewer than half (47 percent) of the high-risk women said they had been tested for ovarian cancer.
"Most of the highest-risk women for ovarian cancer are at very high risk because their relatives have had breast cancer, not ovarian cancer," Andersen said. "However, it appears that many of these women don't make the association between a family history of breast cancer and increased ovarian-cancer risk. The connection isn't as obvious as it would be if their mother or sister, for example, had ovarian cancer."
In addition, the researchers found 32 percent of those at average risk of ovarian cancer had undergone screening, which reflects an overestimation of danger by this group.
"Most women appear to have unrealistic beliefs about their risks for ovarian cancer," Andersen said. "Only 11 percent and 27 percent of those in the elevated and average-risk groups, respectively, correctly estimated their risk of getting the disease."
The two most hopeful screening tools sunder in vestigation for high-risk women are the CA125 blood test and/or transvaginal ultrasound. CA125 is a protein found in the blood that in large amounts can signal the presence of ovarian cancer.
Transvaginal ultrasound is a radiologic imaging procedure that can detect small tumors as well as benign structural irregularities in the ovaries often associated with menstruation. Typically, the blood test is used in conjunction with ultrasound.
A Consensus Conference on Ovarian Cancer held in 1994 by the National Institutes of Health recommended ovarian-cancer screening for high-risk women because such women may carry a genetic mutation for inherited breast or ovarian cancer called BRCA1 or BRCA2.
While only 5 percent to 10 percent of all ovarian cancers are hereditary, such mutations increase the likelihood of a woman developing ovarian cancer by between 16 percent (one in seven women) and 40 percent (two in five women).
"On the other hand, if a woman with a strong family history gets tested for these mutations and is found to be negative, her risk of ovarian cancer is thought to be approximately average," Andersen said. One in 57 women of average risk develop the disease.
In the absence of genetic screening for BRCA1 and BRCA2, those with a prominent family history of breast and/or ovarian cancer are encouraged to see a gynecological oncologist for ovarian-cancer surveillance at least annually, if not every six months, Andersen said.
Such women also are encouraged to be vigilant about breast-cancer surveillance (mammograms and clinical breast checkups every six months, as well as self-exams at least weekly), as these mutations increase the lifetime risk of breast cancer to between 45 percent and 85 percent.
Ovarian-cancer screening for women at elevated risk - those with a single affected family member - is not officially endorsed, Andersen said.
That's because the long-term benefit of screening has not been established in terms of reducing death rates from the disease.
Women in this category face an increased lifetime risk of between 5 percent and 7 percent (one in 20 women and one in 14 women, respectively.)
"The risk for these women is considerably lower than that of women with a genetic mutation but still considerably higher than that of average-risk women," the researchers wrote.
"These women are encouraged to discuss the possibility of screening with their physicians and to pursue screening if they feel that their risk of ovarian cancer is sufficient to warrant it, even in the absence of evidence for its effectiveness."
The facts about ovarian cancer
Incidence and mortality
- About one in 56 women will develop ovarian cancer.
- Ovarian cancer is the fifth most common cancer in women and ranks as the fifth highest cause of cancer death in women.
- This year, an estimated 13,900 American women died from ovarian cancer and 23,300 new cases were diagnosed.
- In Washington state, about 300 women will die from ovarian cancer this year.
- Ovarian cancer often does not produce distinctive symptoms.
- There is no known way to prevent ovarian cancer, and the screening tests for the disease are not always reliable.
- Possible warning signals include bloating, a feeling of fullness or gas, abdominal distention, frequent or urgent urination, nausea, indigestion, constipation, diarrhea, fatigue and backaches.
- When ovarian cancer is detected before it has spread beyond the ovaries, 92 percent of women survive longer than five years, and most are cured of the disease.
- Only 24 percent of ovarian cancer cases are diagnosed in the beginning stages.
- When diagnosed in the late stages, the chance of survival is only 20 to 25 percent.
Factors that increase risk
Although some risk factors have been identified, the overwhelming majority of women who get ovarian cancer do not have any of the known risk factors, which include:
- Never giving birth (nulliparity).
- Previous diagnosis of breast cancer.
- Family history of ovarian and/or breast cancer.
- Being over age 60, as risk increases with age.
Factors that reduce risk:
- Early menopause.
- The use of oral contraceptives.
- Surgical treatment usually involves the removal of one or both ovaries, the uterus and the fallopian tubes. If the cancer is detected early, especially in younger women, it is possible that only the cancerous ovary will be removed.
- Chemotherapy is available to prevent or slow the recurrence of ovarian cancer or the spread of the cancer to other parts of the body after surgery.
More research, education needed
- No one knows what causes ovarian cancer or how to prevent it.
- Ovarian-cancer diagnostic tests are less useful than tests for detecting breast and cervical cancer.
- Little is known about key scientific aspects of the disease.
- American Cancer Society - Cancer Facts & Figures 2002.
- American Cancer Society - Cancer Facts 1995.
- Ovarian Cancer National Alliance - Facts about Ovarian Cancer.
Participants needed for national ovarian-cancer early-detection study
What's the study?
Participants are needed for a nationwide, multicenter study of women with a strong family history of ovarian cancer and/or early onset breast cancer.
The goal of the investigation, named the Ovarian Cancer Early-Detection Study, is to determine if CA125 (a biomarker found in the blood) is useful for early detection of ovarian cancer.
The study, funded by the National Cancer Institute, is conducted locally by the Pacific Ovarian Cancer Research Consortium and the Northwest Cancer Genetics Network, both of which are based at Fred Hutchinson. This study is conducted in collaboration with the Marsha Rivkin Center for Ovarian Cancer Research.
How does it work?
Participants initially will be asked to complete a questionnaire about their health history. This information will help researchers better understand which factors change their risk of disease.
Along with a short questionnaire, every three months a blood test will be taken to measure the CA125 blood level. Participants also will have an ovarian ultrasound examination once a year.
All information obtained from this study will be handled in a confidential manner according to strict guidelines of the National Institutes of Health.
Women may choose to discontinue the study at any time; doing so will not affect the quality of their standard care. It is the participant's right as a patient to make the decision that best suits her needs.
Who can enroll?
- Have a family history of two or more blood relatives with breast or ovarian cancers.
- Have tested positive for BRCA1 or BRCA2, a genetic marker, or have a close relative who has tested positive for BRCA1 or BRCA2.
- Are of Ashkenazi Jewish ethnicity and have personally had breast cancer, or have at least one close family member with breast or ovarian cancer.
- Are healthy, with no personal history of ovarian cancer.
The advantage of participating in this study is having one's gynecological health closely monitored.
Knowledgeable specialists who routinely work with women at high risk for developing ovarian cancer will monitor participants' CA125 results.
This monitoring may benefit participants through early cancer detection. However, there is no certainty of early detection of ovarian cancer prior to detection from standard clinical care.