Patterns of inheritance of ovarian cancer. An analysis from an ovarian cancer screening program

Prophylactic oophorectomy: a continuing controversy

Prophylactic oophorectomy remains a controversial issue among gynecological surgeons. A woman's history of hereditary ovarian cancer syndrome is currently considered the most important indication for prophylactic oophorectomy. This is because of the high risk of ovarian cancer developing in these women and the poor prognosis that is generally associated with ovarian cancer. The purpose of prophylactic oophorectomy in women with no family history of hereditary ovarian cancer syndrome who present for hysterectomy because of other gynecological indications is, however, less clear. The attitude of the patients toward removal of normal ovaries deserves special consideration when counseling for prophylactic oophorectomy in this group of women. Knowledge about the risk of ovarian cancer in the conserved ovaries, cancer phobia, possible psychological effects of prophylactic oophorectomy, and the need for long-term hormone replacement therapy if prophylactic oophorectomy is carried out, are all important considerations in the counseling process.

Segregation analysis of epithelial ovarian cancer in Finland

Epithelial ovarian cancer is known to aggregate in families. The dominantly inherited ovarian cancer predisposing genes, BRCA1, BRCA2 and genes involved in the hereditary non-polyposis colorectal cancer (HNPCC) syndrome, have recently been identified. However, in the majority of families with more than one case of ovarian cancer, dominant inheritance cannot be recognized. We investigated familial clustering of epithelial ovarian cancer in a population-based sample of 663 Finnish ovarian cancer patients. A segregation analysis with the POINTER software was conducted on the 937 nuclear families from these 663 pedigrees. The major gene model was favoured, and the sporadic and multifactorial models were strongly rejected. In the studied population, the best fitting model was a recessive mode of inheritance, and 8% of ovarian cancer patients were estimated to be homozygous for the deleterious genotype. This evidence for recessively inherited ovarian cancer predisposition should be interpreted cautiously, as the analysis is subject to certain errors, which are discussed in the article. Results of this analysis, however, strongly emphasize the role of genetic factors in all familial aggregation of epithelial ovarian cancer.

Family history: a comprehensive genetic risk assessment method for the chronic conditions of adulthood

Targeting individuals with increased risk for common, chronic disease can improve the efficiency and efficacy of preventive efforts by improving the predictability of screening tests and participant compliance. Individuals with the greatest risk for these disorders are those with a genetic susceptibility. The purpose of this study was to determine the feasibility of using a single, comprehensive family history as a method for stratifying risk for many preventable, common genetic disorders. Family histories obtained in a prenatal diagnostic clinic were reviewed regarding cardiovascular diseases, diabetes and several cancers; 42.5% of individuals reported a family history for at least one of the disorders under study. Familial coronary artery disease was most commonly reported (29% of participants), followed by noninsulin-dependent diabetes (14%). Qualitative characterization of disease susceptibility was also accomplished using family history data. For example, occurrence of different cancers within pedigrees was suggestive of familial cancer syndromes, and clustering of noninsulin-dependent diabetes and cardiovascular disease suggested an insulin resistance syndrome. Depending on the specific disease, 5 to 15% of at-risk individuals had a moderately increased risk (2 to 5 times the population risk), and approximately 1 to 10% had a high risk (absolute risks approaching 50%). Family history reports of common, chronic disease are prevalent among the population at large, and collection and interpretation of comprehensive family history data is a feasible, initial method for risk stratification for many preventable, chronic conditions. These findings may have important implications for disease prevention and management.

Immunohistochemically detected p53 and HER-2/neu expression and nuclear DNA content in familial epithelial ovarian carcinomas

BACKGROUND

Some epithelial ovarian carcinomas tend to occur more frequently in certain families. This clustering may be due to a genetic predisposition, but the role of inherited susceptibility in all families with multiple cases of ovarian carcinoma is currently unresolved. Studies characterizing familial ovarian carcinomas are few.

METHODS

From a population-based study of 559 patients with epithelial ovarian carcinoma, 27 families with 2 or more ovarian carcinoma cases occurring in first-degree relatives were identified. Histopathology, ploidy, and immunohistochemically detected p53 and HER-2/neu expression in these tumors were examined.

RESULTS

The mean age of the patients with familial ovarian carcinoma was 56.7 years. Approximately 67% of the tumors were either serous or undifferentiated adenocarcinomas. The percentage of aneuploid tumors was 46%, that of p53 positive tumors was 51%, and that of HER-2/neu positive tumors was 69%. When the families were divided into families with cases of breast carcinoma in addition to ovarian carcinoma cases and/or ovarian carcinoma in 2 consecutive generations (12 families) and families with ovarian carcinoma occurring in sisters only without cases of breast carcinoma (15 families), no differences were noted in the frequency of any of the studied variables.

CONCLUSIONS

Familial ovarian carcinomas do not appear to differ from sporadic ovarian carcinomas with regard to patient age at presentation, histopathology, ploidy, and immunohistochemically detected p53 expression. Immunohistochemically detected HER-2/neu expression was found to occur more frequently in familial ovarian carcinomas than has been reported in sporadic ovarian carcinomas.

Early detection of familial ovarian cancer

When ovarian cancer is detected at an early stage, prognosis is good, which has led to discussion of a screening programme. The aim of this study was to identify and examine women at high risk of familial ovarian cancer, and to evaluate the inclusion criteria and the diagnostic methods for early detection of ovarian cancer. We report the first round screening findings in a prospective study of 180 women (mean age 43.4 years) considered to be at high risk of ovarian cancer based on family history. They were subjected to gynaecological examination with transvaginal ultrasound (TVU), CA125 and breast examination. Of these, 13 women with oestrogen receptor positive breast cancer had therapeutic oophorectomy and the ovaries were histologically examined. Among 180 women examined, nine ovarian cancers (among them two found at oophorectomy because of breast cancer) (mean age 49.0 years), seven benign tumours of the ovary (mean age 48.1 years), one cancer of the cervix, and four breast cancers were diagnosed. The prevalence of ovarian cancers (5%) was significantly more than in any previous series. TVU as a diagnostic method proved useful and detected 7/9 cancers, whereas CA125 was elevated in 4/9 cancers. To our knowledge, this is the first programme which has successfully delineated a high risk group and prospectively demonstrated their high prevalence of ovarian cancer. Possible biases are discussed.

Cancer incidence in the first-degree relatives of ovarian cancer patients

Cancer incidence was studied among 3072 first-degree relatives of 559 unselected ovarian cancer patients. Among cohort members there were 306 cancer cases. The overall cancer incidence was not increased: the standardised incidence ratio (SIR) in males was 0.9 (95% confidence interval 0.8-1.1) and in females 1.0 (0.8-1.1). The female relatives had a significantly increased risk for ovarian cancer (SIR 2.8, 1.8-4.2). The excess was attributable to sisters only (SIR 3.7, 2.3-5.7). The relative risk for ovarian cancer among sisters decreased both by increasing age of the sister and by increasing age at diagnosis of the index patient: the SIRs were 7.3 (1.5-21.4), 4.5 (1.6-9.8) and 3.1 (1.7-5.4) for sisters of index patients diagnosed in age < 45, 45-54 and 55-75 years respectively. The age dependency of the risk supports the role of genetic factors in familial ovarian cancer. Although the risk of ovarian cancer among sisters from families with breast cancer (SIR 9.2, 3.7-19.0) was significantly higher than among sisters from families with no breast cancer patients (SIR 2.9, 1.6-4.8, rate ratio 3.1, P < 0.05), the excess was not solely attributable to coaggregation of breast and ovarian cancer. Among the 27 families with two or more ovarian cancers, only sisters were affected in 24 families, which might implicate recessive inheritance or shared environmental factors influencing ovarian cancer risk in sisters.

Family history in ovarian cancer referral population

In order to determine the incidence of familial and hereditary ovarian cancer in a referral patient population, we conducted a retrospective study of 44 patients from a consecutive set of 62 patients treated for ovarian carcinoma at the Gynecologic Oncology Clinic at the Richland Memorial Hospital Center for Cancer Treatment and Research between January 1, 1993 and December 31, 1993. In our study of the referred patients, only two (4.55%) reported a history of at least one first-degree relative also being affected with ovarian cancer. However, 13 patients (29.55%) reported a family history consistent with one of the hereditary ovarian cancer syndromes. In addition to having a suggestive family history, these 13 families demonstrated several cardinal features of hereditary cancer syndromes including early onset, bilaterality, multiple primary tumors, and transmission. Race was the only significantly different demographic factor between the hereditary and sporadic ovarian cancer groups. All 13 patients who appeared to have a hereditary form of cancer were Caucasian.

Ovarian carcinoma. A review of the significance of familial risk factors and the role of prophylactic oophorectomy in cancer prevention

Women with a family history of ovarian cancer are at increased risk of ovarian cancer. Prophylactic oophorectomy (PO) remains the only effective method of ovarian cancer prevention. This study reviewed current data on the significance of family history and how prophylactic oophorectomy should be used in different risk groups. Approximately 7% of ovarian cancer patients have a positive family history of whom 3-9% may eventually manifest certain hereditary cancer syndromes. Women in direct genetic lineage of family cancer syndromes have up to a 50% lifetime risk of ovarian cancer. Because of the high risk, PO is indicated for women with familial cancer syndromes after childbearing or between the ages of 35-40 at the latest. The majority of women with a positive family history of ovarian cancer do not have one of the recognized syndromes. Women with one or two affected relatives have an increased lifetime risk of ovarian cancer from a baseline of 1.6 to 5-7%. This risk is not high enough to warrant PO for a large number of women. After being properly informed, the patient still chooses surgical prevention, she then receives PO. For women without a family history of ovarian cancer, the role of PO remains controversial. Assuming an annual incidence of 22,000 new cases of ovarian cancer, it is estimated that at least 1000 may be prevented if PO is diligently practiced during hysterectomy. Despite ovarian and breast cancer prevention, PO would lead to shorter life expectancy if estrogen therapy compliance were less than perfect. Thus, the decision on PO as a concurrent procedure should depend on the individual patient and her ability to comply with lifelong estrogen therapy.