Risk of prostate, ovarian, and endometrial cancer among relatives of women with breast cancer

Genetic epidemiology of breast cancer

It has been recognized for some time that a family history of breast cancer is associated rather strongly with a woman's own risk of developing the disease. Recent segregation analyses of population-based data on familial patterns provide evidence for a rare autosomal dominant allele that increases a carrier's susceptibility to breast cancer. The estimated proportion of breast cancer patients who carry this allele declines sharply with age at diagnosis. Empirical estimates of the risk associated with particular patterns of family history of breast cancer indicate the following: (1) having any first-degree relative with breast cancer increases a woman's risk of breast cancer 1.5-3-fold, depending on age, (2) having multiple first degree relatives affected is associated with particularly elevated risks, (3) having a second-degree relative affected increases the risk by approximately 50%, (4) affected family members on the maternal side and the paternal side contribute similarly to the risk, (5) a family history of breast cancer is associated with bilateral disease, and (6) breast cancer in males is associated with breast cancer in female relatives in much the same way as is breast cancer in women. Ovarian cancer clearly has been shown to be associated with breast cancer in families, and genetic linkage has provided strong evidence for a breast-ovarian cancer gene located somewhere on chromosome 17q. At the population level, having a first degree relative with ovarian cancer may be at least as predictive of a woman's risk for developing breast cancer as is having a second-degree relative with breast cancer. Considerably weaker evidence points to a possible familial relationship between breast and endometrial cancer and between breast cancer in women and prostatic cancer in males. The clinical applications of the genetic epidemiology of breast cancer are complicated by uncertainty as to the efficacy of mammographic screening in women under the age of 50. For the vast majority of women with a positive family history, the epidemiologic evidence does provide the basis for offering considerable reassurance in that risks are not extremely high. For that rather small subgroup at exceptionally high risk, realistic estimates of the magnitude of absolute risk over the next 10-20 years may be more informative and less alarming than lifetime probabilities.

Somatic allelic loss at the DCC, APC, nm23-H1 and p53 tumor suppressor gene loci in human prostatic carcinoma

We present a restriction fragment length polymorphism (RFLP) analysis of 29 benign and 30 malignant prostatic tumors, using polymorphic DNA probes to the putative tumor suppressor genes DCC (Deleted in Colorectal Carcinoma; chromosome 18q21.3), nm23-H1 (17q21.3), APC (Adenomatous Polyposis Coli; 5q21) and p53 (17p13). Six of 23 evaluable cancers (26%) showed loss of heterozygosity (LOH) at DCC; 5 were advanced stage and one was clinically localized (p < 0.05). Mapping 18q deletions, another (advanced) cancer showed LOH at a locus distal to DCC (18q22), but no LOH at DCC. Three of 15 evaluable cancers (20%), all advanced, showed LOH at APC. Three of eight (38%) cancers, of which 2 were advanced, showed LOH at p53. One high grade/stage cancer of 21 (5%) showed LOH at nm23-H1 (and also at DCC). Combining data, allelic losses at either DCC, APC, or p53 genes were seen in 13% of localized cancers, but in 71% of advanced cancers (p < 0.002). Allelic loss involving nm23-H1 is rare in prostatic carcinoma. We suggest that loss of tumor suppressor genes DCC and/or an unidentified gene located distally on chromosome 18q, APC, or p53 may influence progression in prostatic carcinoma.

Familial effects of prostate and other cancers on lifetime breast cancer risk

Lifetime probabilities of developing breast cancer were calculated for first-degree female relatives of three groups of breast cancer patients: 114 with bilateral cancer, 186 unselected, and 88 males. The patients were classified according to whether they had a family history of prostate, endometrial, or ovarian cancer, or no family history of these cancers. In families of unselected female and male patients with no family history of prostate, endometrial, or ovarian cancer, the lifetime probability of developing breast cancer was 11.4%. The risk increased slightly to 13.5% when these other cancers may or may not have present (i.e., they were ignored, which is the usual method in computing risks) and increased further to 25.5% when prostate, endometrial, or ovarian cancer was present in the family. In families of patients with bilateral cancer the respective risks were 10.9%, 17.3%, and 34.4%. A family history of prostate cancer increased lifetime risk consistently in each of the groups, to 29.0% in the unselected and male groups and to 38.2% in the bilateral group. Endometrial cancer increased risk only in the bilateral group (to 41.8%) as did ovarian cancer (to 54.6%). Increased risk of breast cancer with a family history of endometrial or ovarian cancer appeared to be influenced by families with hereditary breast-ovarian cancer or the cancer family syndrome. The results indicate that prostate cancer, and endometrial and ovarian cancers in some families, can significantly increase breast cancer risk and should be taken into account when counseling women about their breast cancer risk.

Familial breast cancer risks. Effects of prostate and other cancers

BACKGROUND

Previous studies have provided conflicting results concerning the effects of a family history of prostate and other cancers on breast cancer risks.

METHODS

Three groups of families were studied to determine the effects of a family history of prostate cancer on breast cancer risks. Also considered were the effects of a family history of melanoma, colon, lung, ovarian, and endometrial cancers. Included were 422 first-degree female relatives of 114 patients with bilateral breast cancer, 320 first-degree relatives of 88 male patients with breast cancer, and 633 relatives of 186 unselected female patients. For estimating relative risks, observed numbers of breast cancers in relatives were compared with expected numbers based on population incidence data. Multiple logistic-regression also provided odds ratios of relatives affected with breast cancer.

RESULTS

A family history of prostate cancer increased the breast cancer risks in each of the groups, compared with families without prostate cancer. Ovarian cancer in a family increased the breast cancer risks only in the bilateral breast cancer group, and endometrial cancer increased the risks in the bilateral and unselected groups. These increases in risk appeared to be the consequence of families with multiple cancers, including those with hereditary breast-ovarian cancers and the cancer family syndrome. A family history of melanoma, lung, or colon cancer did not increase breast cancer risks.

CONCLUSIONS

A family history of prostate cancer, as well as endometrial and ovarian cancer, significantly increases the risk of breast cancer.

Linkage analysis of chromosome 17q markers and breast-ovarian cancer in Icelandic families, and possible relationship to prostatic cancer

Seven families, selected for breast cancer segregation, have been analyzed for chromosome 17q12-q23 linkage to breast and ovarian cancer. In two of them, linkage is seen with most markers tested, increasing toward the most proximal region, but without informative recombinations above NM23. In the remaining families, no linkage is observed. Families with 17q linkage are not easily distinguished by clinical characteristics such as early onset (mean age at diagnosis < or = 45 years) or organs involved. In fact, the family with the highest lod scores (> or = 2.3) belongs to the "later onset" (> 45 years) category of families. Interestingly, prostatic cancer is the most frequent malignancy, after breast cancer, in the families that we studied (13 cases total, all metastasizing) and is especially prevalent in males presumed to carry the trait. Of 16 paternal carriers, 7 (44%) had developed prostatic cancer. Haplotype analysis in families with 17q linkage reveals two further prostatic cases as potential carriers. We propose that breast cancer genes may predispose to prostatic cancer in male carriers.

The search for the familial breast/ovarian cancer gene

Familial breast cancer is a very common autosomal dominant disorder in women. A predisposing gene for breast and ovarian cancer (BRCA1) has been mapped by linkage analysis to the long arm of chromosome 17. In almost all families with breast and ovarian cancer and half of those with only breast cancer, the disease is linked to this gene. The BRCA1 gene, which is also believed to be involved in sporadic breast and ovarian cancer, should soon be identified.