Mutations in the BRCA1 gene: implications of inter-population differences for predicting the risk of radiation-induced breast cancers

Exposure to low-dose radiation and the risk of breast cancer among women with a familial or genetic predisposition: a meta-analysis

BACKGROUND

Women with familial or genetic aggregation of breast cancer are offered screening outside the population screening programme. However, the possible benefit of mammography screening could be reduced due to the risk of radiation-induced tumours. A systematic search was conducted addressing the question of how low-dose radiation exposure affects breast cancer risk among high-risk women.

METHODS

A systematic search was conducted for articles addressing breast cancer, mammography screening, radiation and high-risk women. Effects of low-dose radiation on breast cancer risk were presented in terms of pooled odds ratios (OR).

RESULTS

Of 127 articles found, 7 were selected for the meta-analysis. Pooled OR revealed an increased risk of breast cancer among high-risk women due to low-dose radiation exposure (OR = 1.3, 95% CI: 0.9- 1.8). Exposure before age 20 (OR = 2.0, 95% CI: 1.3-3.1) or a mean of ≥5 exposures (OR = 1.8, 95% CI: 1.1-3.0) was significantly associated with a higher radiation-induced breast cancer risk.

CONCLUSION

Low-dose radiation increases breast cancer risk among high-risk women. When using low-dose radiation among high-risk women, a careful approach is needed, by means of reducing repeated exposure, avoidance of exposure at a younger age and using non-ionising screening techniques.

Radiotherapy and genetic predisposition to breast cancer

Cancer genetics is becoming increasingly integrated into oncological care; particularly in breast cancer management. The recognition of monogenic breast cancer predisposition syndromes, such as BRCA, is critical as there is also a risk of other cancers in addition to a markedly elevated risk of contralateral breast cancer. In individuals with breast cancer due to some predisposition genes, radiation should be avoided, e.g. the ATM and TP53 genes, but there is still controversy as to whether radiation should be used in BRCA1/2 mutation carriers and more follow-up is needed. There are some radiation-sensitive genetic conditions where, if breast cancer occurs (as it may occur in any individual, not necessarily due to an increased risk associated with the condition), radiation should be avoided. These conditions are often associated with dysmorphic features. If such features are noticed then the advice of a geneticist should be sought urgently prior to giving radiation.

Psychosocial aspects of genetic counseling and testing

OBJECTIVES

To highlight areas where persons who undergo BRCA1/2 mutation testing may benefit from psychosocial or behavioral support and intervention.

DATA SOURCES

Published scientific literature, cal, and research experiences.

CONCLUSION

Key psychosocial areas that deserve attention by clinicians and researchers include: indeterminate or inconclusive test results, selection of risk management strategies in unaffected BRCA1/2 mutation carriers, and genetic testing in minority communities.

IMPLICATIONS FOR NURSING PRACTICE

By addressing the psychosocial issues faced by patients undergoing genetic testing for cancer, nurses have the potential to maximize opportunities for prevention, early detection, and healthy coping.

Breast cancer: genetic predisposition and exposure to radiation

The identification of breast cancer susceptibility genes, such as BRCA1, BRCA2, ATM, and p53, has been accompanied by the examination of the effects of radiation in combination with genetic mutations at these loci. Women at high risk for developing breast cancer may respond differently than the general population to low- and high-dose radiation exposures associated with screening and treatment. Epidemiologic studies are being performed to investigate the effects of radiation on subsequent breast cancer development in genetically predisposed individuals. Mouse strains with specific genetic modifications are being created to study the consequence of both inherited mutations and radiation on mammary gland carcinogenesis. Finally, studies investigating DNA damage-response pathways after radiation exposure are being performed. Recent work on the effects of several known or suspected breast cancer susceptibility genes, alone or in combination with radiation, is presented here, and directions for future research are considered.