Cancer risks in women with 2 breast or ovarian cancers: clues to genetic cancer susceptibility

A common environmental carcinogen unduly affects carriers of cancer mutations: carriers of genetic mutations in a specific protective response are more susceptible to an environmental carcinogen

One way an inherited cancer gene mutation may target specific tissues for cancer is by increasing susceptibility when a tissue is exposed to environmental carcinogens. An example of this may be the increased susceptibility of BRCA1 or BRCA2 mutation carriers to the carcinogen formaldehyde. Formaldehyde is now a proven cause of human myeloid leukemias. Yet millions of tons of formaldehyde are produced every year and it is everywhere. High formaldehyde levels can overwhelm normal enzyme detoxification systems and cause DNA damage. It is known that some types of formaldehyde-associated DNA damage require error-free DNA repairs mediated by pathways containing BRCA1 and BRCA2 proteins. Otherwise some formaldehyde-related DNA damage cannot be properly repaired so mutations may occur. Therefore, carriers of BRCA1 and BRCA2 gene defects should be unduly susceptible to myeloid leukemia. Studies show that inherited biallelic BRCA2 gene defects dramatically increase risks for myeloid leukemia. Heterozygous BRCA1 or BRCA2 mutations also increase risks for myeloid leukemias in 11 of 12 relevant studies. BRCA1/2 mutation carriers may reduce risks for myeloid leukemias by using available precautions to lower their exposure to formaldehyde.

The BRCA1/2 pathway prevents hematologic cancers in addition to breast and ovarian cancers

BACKGROUND

The present study was designed to test the hypothesis that inactivation of virtually any component within the pathway containing the BRCA1 and BRCA2 proteins would increase the risks for lymphomas and leukemias. In people who do not have BRCA1 or BRCA2 gene mutations, the encoded proteins prevent breast/ovarian cancer. However BRCA1 and BRCA2 proteins have multiple functions including participating in a pathway that mediates repair of DNA double strand breaks by error-free methods. Inactivation of BRCA1, BRCA2 or any other critical protein within this "BRCA pathway" due to a gene mutation should inactivate this error-free repair process. DNA fragments produced by double strand breaks are then left to non-specific processes that rejoin them without regard for preserving normal gene regulation or function, so rearrangements of DNA segments are more likely. These kinds of rearrangements are typically associated with some lymphomas and leukemias.

METHODS

Literature searches produced about 2500 epidemiology and basic science articles related to the BRCA pathway. These articles were reviewed and copied to a database to facilitate access. Meta-analyses of statistical information compared risks for hematologic cancers vs. mutations for the components in a model pathway containing BRCA1/2 gene products.

RESULTS

Deleterious mutations of genes encoding proteins virtually anywhere within the BRCA pathway increased risks up to nearly 2000 fold for certain leukemias and lymphomas. Cancers with large increases in risk included mantle cell lymphoma, acute myeloid leukemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, and prolymphocytic leukemia. Mantle cell lymphoma is defined by a characteristic rearrangement of DNA fragments interchanged between chromosomes 11 and 14. DNA translocations or rearrangements also occur in significant percentages of the other cancers.

CONCLUSION

An important function of the BRCA pathway is to prevent a subgroup of human leukemias and lymphomas that may involve non-random, characteristic gene rearrangements. Here, the genetic defect in BRCA pathway deficiencies is a chromosomal misrepair syndrome that may facilitate this subgroup of somatic cancers. Inactivation of a single gene within the pathway can increase risks for multiple cancers and inactivation of a different gene in the same pathway may have similar effects. The results presented here may have clinical implications for surveillance and therapy.

Prognostic value of BRCA1 mutations in familial breast cancer patients affected by a second primary cancer

The aim of this prospective study is to assess the prognostic value of BRCA1 mutations in familial breast cancer patients affected by a second primary cancer. The study group comprised 19 women having multiple primary breast cancers (breast-breast, breast-other primary) who were either BRCA1 mutation carriers, or not. Appearance of a second primary cancer was recognised as the event and survival and second primary free cancer survival was calculated from the date of diagnosis to the secondary primary cancer. The results of this study show that the event free survival of women with familial breast cancer affected by a second primary cancer, who are BRCA1 mutation carriers is better, compared with women from the general population with breast cancer selected for second primary cancer sites and all second primary sites -- P = 0.009 and P = 0.0078 respectively. In contrast, the event free survival of women with breast cancer affected by a second primary cancer, without a breast cancer family history, who are not BRCA1 mutation carriers is the same, as for women from the general population with breast cancer selected for second primary cancer sites and all second primary sites -- P = 0.6417 and P = 0.4859 respectively. The median time from diagnosis of the first to second primary cancer in the mutation carrying, and non-carrying, groups was 8,7 and 1,9 years respectively. In the study group, the highest event free survival rates had been observed among those carrying the said mutations -- 66.7% at 5 years, and 33.3% at 10 years -- in contrast with those not carrying the mutations, with rates of 30.8% and 15.4% respectively.

Hereditary breast and ovarian cancer: review and future perspectives

Breast cancer (BC) is the most frequent carcinoma in women. The cumulative risk for the disease is 10% up to the age of 80 years. A familial history of BC and ovarian cancer (OC) is a significant risk factor. Some 5-10% of all cases of BC and 25-40% of cases in patients under the age of 35 years have a hereditary origin. BRCA1/BRCA2 mutations are responsible for 3-8% of all cases of BC and 30-40% of familial cases. Ten percent of patients with OC have a genetic predisposition. About 80% of families with a history of OC have BRCA1 mutations, while 15% have BRCA2 mutations. Women at risk can receive counseling from interdisciplinary cancer genetics clinics, while those at high risk can receive genetic testing. Risk calculation programs can define the risks and assist in decision making for genetic testing and clinical options. Clinical options require information on the risks of the disease and its mutation status. Chemoprevention is currently a controversial topic, while the use of oral contraceptives can be regarded as reducing the risk for OC. Prophylactic mastectomy and bilateral ovariectomy are the only options that lead to a demonstrable reduction in risk, but they do, of course, affect the patient's physical integrity. It is not currently known whether intensified early cancer detection is individually beneficial, but this is currently the option that is the least invasive and least burdensome to the patient. Although hereditary BC has different pathological characteristics and the BRCA mutation is an independent negative prognostic factor, there are currently no special treatment guidelines. Without adjuvant hormone therapy or chemotherapy, the overall survival in BRCA mutation carriers is reduced. Chemotherapy regimens involving platinum are particularly beneficial in the treatment of hereditary BC.

What is new in melanoma research: genetics and epidemiology of melanoma in 2003? Review of a workshop held in Milan in May 2003

The various papers that were presented during this symposium touched on two of the most important aspects concerning melanoma because they dealt with epidemiology and genetics. Secondary prevention represents the most important step to cure melanoma patients once the disease has presented on a patient. It is clear that educational campaigns lead to greater awareness of the public and hence better prevention and earlier diagnosis. A second item is becoming more and more important in the field of prevention and early diagnosis, which is to understand the genetic basis of melanoma etiology and development. Studies concerning the familial clustering, for example, can lead to more careful monitoring of patients for other tumours and also lead to a basis for further research.

Germline 657del5 mutation in the NBS1 gene in patients with malignant melanoma of the skin

In this study we determined in what proportion of consecutive malignant melanoma (MM) cases the 657del5 mutation of exon 6 of the NBS1 gene can be detected and whether it is associated with the occurrence of MM. Two groups of patients were studied: a series of 80 consecutive patients with histologically confirmed MM of the skin diagnosed in the city of Szczecin, Poland, and a series of 530 consecutive individuals selected at random by family doctors from the city of Szczecin. Molecular examination included an allele-specific polymerase chain reaction assay for the NBS1 founder mutation (657del5), genomic sequencing, loss of heterozygosity analysis using CA-repeat microsatellite markers, and haplotype analysis. The NBS1 founder mutation was detected in two of the 80 (2.5%) MM cases and in three of the 530 individuals (0.6%) from the general population. The difference was not statistically significant. However, examination of tumorous DNA from the patients with MM and NBS1 mutation revealed loss of heterozygosity in both cases. Haplotype analysis revealed that allellic loss affects wild-type alleles. Breast cancer was found in second-degree relatives of both MM probands with NBS1 mutations. One of these probands was simultaneously affected with breast cancer. It seems that the 657del5 mutation of exon 6 of NBS1 gene may be responsible for the occurrence of a small proportion of MM patients, characterized by the occurrence of breast cancer among their relatives.

Increased risk of breast cancer in relatives of malignant melanoma patients from families with strong cancer familial aggregation

The aim of this study was to evaluate the risk of occurrence of malignancies of different site of origin in patients with malignant melanoma (MM) of the skin and their first-degree relatives from families with cancer familial aggregations with unknown pathogenetic background (CFA). We analysed tumour spectrum and age at diagnosis of malignancies in 51 families with MM/CFA. In addition, we evaluated observed frequency (OF); expected frequency (EF); and relative risk (RR) of occurrence of malignancies in these families. In all cases peripheral blood examination of common Polish founder BRCA1 mutations was performed. In 25 families, we analysed loss of heterozygosity of BRCA1 and BRCA2 genes. We identified two subgroups of cases: 22 MM/CFA families with MM diagnosed before 55 years (< or =55 MM/CFA) and 29 MM/CFA families with MM diagnosed after 55 (>55 MM/CFA). In these families we observed increased proportion of breast cancers: 17.52% in the first subgroup (mean age of diagnosis 48.5) and 12.15% in the second subgroup. The odds ratio for breast tumours occurring before 50 in < or =55 MM/CFA families was 3.71. We also observed increased numbers of liver cancers, CSU and leukaemias. OF and EF analyses revealed increased risk of occurrence of cancers of breast (OF 10.4%, EF 4.5%) and liver (OF 1.9%, EF 0.8%) in women from MM/CFA families, RR for breast tumours was approximately 3.3 in < or =55 MM/CFA families. Molecular examination of MM/CFA families revealed no alterations within the BRCA2 gene and one germline mutation of the BRCA1 gene. In conclusion, it seems to be justified to consider systematic breast surveillance beginning at the age around 35-40 years as an option in women from < or =55 MM/CFA families.