Patients with BRCA1- or BRCA2-mutated ovarian cancer may have a lower risk of developing breast cancer following treatment, according to a recent study published by Evans et al in Genetics in Medicine.
Background
Previous research has estimated that the risk of developing breast cancer by the age of 80 years may be 72% and 69% among patients with BRCA1 and BRCA2 mutations, respectively. However, the research did not specifically assess the risk of breast cancer following a diagnosis of ovarian cancer.
In addition, two prior studies addressed the risk of breast cancer following ovarian cancer, but had a follow-up period limited to 10 years and had no breakdown by gene. These studies estimated the risk of breast cancer to be 11% in 79 female patients and 7.8% in 509 female patients who had been diagnosed with ovarian cancer.
Study Methods and Results
In the recent study, the researchers analyzed the history of breast cancer among 701 female patients with BRCA1- and BRCA2-mutated ovarian cancer who had visited specialist genetics clinics. They assessed the annual incidence of breast cancer by age group for up to 15 years following ovarian cancer diagnoses.
The researchers discovered that the likelihood of developing breast cancer within 5 years of an ovarian cancer diagnosis was lower among the patients with BRCA1 and BRCA2 mutations compared with those without ovarian cancer.
Among patients with BRCA2-mutated ovarian cancer, the low rate of breast cancer continued through 10 years of follow-up. Their breast cancer risk after ovarian cancer diagnosis was 3.3% at 2 years, 6.2% at 5 years, 10.4% at 10 years, and 20.3% at 15 years. Among those with BRCA1-mutated ovarian cancer, the incidence of breast cancer was lower between 0 and 5 years after diagnosis, but the risk increased between 5 and 10 years. These patients had a breast cancer risk of 2.1% at 2 years, 5.0% at 5 years, 15.0% at 10 years, and 29.1% at 15 years.
The researchers emphasized that female patients should be aware of the increased risk of breast cancer after 10 years.
“For those with BRCA2 [mutations], lower rates of breast cancer continue until 10 years of follow-up, as this gene is more sensitive to chemotherapy than BRCA1 [mutations]. In [patients] with good long-term life expectancy, the higher risks of breast cancer after 10 years—particularly in BRCA1 [mutations]—should be discussed with their clinicians. This includes presenting all the available options such as [magnetic resonance imaging] screening and risk-reducing mastectomy,” underscored lead study author Gareth Evans, MD, FRCP, a consultant in Medical Genetics and Cancer Epidemiology at the Manchester University National Health Service Foundation Trust and the University of Manchester as well as Co-Theme Lead of Cancer Prevention and Early Detection at the National Institute for Health and Care Research Manchester Biomedical Research Centre.
Conclusions
“Many [patients] we speak to who have a new diagnosis of ovarian cancer immediately ask about bilateral mastectomy as an option to manage their cancer risk. Many are upset to hear they need to delay this to the required 2-year point of disease-free survival from ovarian cancer,” stressed Dr. Evans. “Our findings mean we can reassure [patients] that their risk of breast cancer in the first 2 years after diagnosis is relatively low at around 2% to 2.5%. This is likely because of the effects of platinum-based chemotherapy, which is widely used to treat ovarian cancer, resulting in control and potentially complete eradication of breast cancers that otherwise could have occurred in the first 5 years,” he concluded.
Disclosure: The research in this study was supported by the National Institute for Health and Care Research Manchester Biomedical Research Centre. For full disclosures of the study authors, visit gimjournal.org.
