By Billy Candra 
Cambridge, UK – A landmark study conducted by researchers at the University of Cambridge, in collaboration with the National Disease Registration Service (NDRS) in NHS England, has provided compelling evidence that bilateral salpingo-oophorectomy (BSO) – the surgical removal of the ovaries and fallopian tubes – not only drastically reduces the risk of ovarian cancer but also significantly lowers the risk of early death and secondary cancers in women diagnosed with breast cancer who carry particular BRCA1 and BRCA2 genetic variants. Published today in The Lancet Oncology, this large-scale investigation addresses long-standing uncertainties surrounding the overall impact of BSO, particularly for women who have already faced a breast cancer diagnosis. The findings offer crucial reassurance regarding the safety and profound benefits of this prophylactic procedure, affirming its role as a vital intervention in cancer prevention strategies.
Understanding the Genetic Predisposition: BRCA1 and BRCA2
The BRCA1 and BRCA2 genes are integral to the human body’s DNA repair mechanisms. They are classified as tumor suppressor genes, meaning their normal function is to prevent cells from growing and dividing uncontrollably. When these genes carry specific pathogenic variants (PVs), their ability to repair damaged DNA is compromised, leading to an increased risk of various cancers, most notably breast and ovarian cancer. Approximately 1 in 400 to 1 in 800 individuals in the general population carry a BRCA gene mutation, though prevalence can be higher in certain ethnic groups, such as Ashkenazi Jewish individuals.
For women inheriting a BRCA1 or BRCA2 mutation, the lifetime risk of developing breast cancer can range from 45% to 85%, significantly higher than the general population’s average of about 13%. The risk of ovarian cancer is also dramatically elevated: BRCA1 carriers face a lifetime risk of 40-60%, while BRCA2 carriers have a 10-30% risk, compared to approximately 1-2% in the general population. These cancers often manifest at younger ages and can be more aggressive, with BRCA1 mutations, in particular, being strongly associated with triple-negative breast cancer.
Given these stark statistics, medical guidelines have long recommended risk-reducing strategies for BRCA mutation carriers. For ovarian cancer prevention, BSO has been the primary surgical option, based on its proven efficacy in reducing the risk of developing the disease itself. However, the comprehensive impact of this surgery on overall survival, especially for women already contending with a breast cancer diagnosis, had remained a subject of ongoing debate and concern.
The Historical Context of BSO and Unanswered Questions
Bilateral salpingo-oophorectomy involves the removal of both ovaries and fallopian tubes, typically performed laparoscopically. This procedure is recommended at specific ages to pre-empt the development of ovarian cancer, which is notoriously difficult to detect early and often diagnosed at advanced stages, leading to poor prognoses. For BRCA1 carriers, the recommended age range for BSO is typically between 35 and 40 years, while for BRCA2 carriers, it is between 40 and 45 years, reflecting the differing average ages of ovarian cancer onset associated with each mutation.
Previous research had firmly established that BSO could lead to an impressive 80% reduction in the risk of developing ovarian cancer among these high-risk women. This substantial protective effect has made BSO a cornerstone of prophylactic care. However, the removal of the ovaries, which are the body’s primary source of oestrogen, inevitably induces early menopause. This sudden hormonal shift can bring about a range of challenging symptoms, including hot flashes, night sweats, sleep disturbances, mood changes, and vaginal dryness. More significantly, it raises concerns about long-term health consequences such as increased risks of cardiovascular disease, osteoporosis, and cognitive decline.
For women with a prior history of breast cancer, these concerns are amplified. Many breast cancers are hormone-receptor positive, meaning their growth is stimulated by oestrogen. Consequently, hormone replacement therapy (HRT), which is commonly used to manage menopausal symptoms in the general population, is often contraindicated for breast cancer survivors due to the potential risk of recurrence. This ethical and medical dilemma meant that the overall balance of benefits and risks of BSO in BRCA1 and BRCA2 carriers with a history of breast cancer was not fully understood, leaving patients and clinicians navigating a complex decision-making landscape with incomplete information.
Navigating the Ethical Imperative: An Innovative Research Approach
Traditionally, the "gold standard" for evaluating the efficacy and safety of medical interventions is the randomised controlled trial (RCT). In an RCT, participants are randomly assigned to either receive the intervention (e.g., BSO) or a control (e.g., no BSO), allowing researchers to rigorously compare outcomes between the groups and minimise bias. However, applying an RCT design to assess BSO in BRCA1 and BRCA2 carriers would be ethically untenable. Randomly assigning women with a known, significantly elevated risk of a deadly cancer to a control group without a proven risk-reducing surgery would expose them to substantially greater harm and is therefore deemed unethical.
To overcome this formidable challenge, the Cambridge research team, led by Professor Antonis Antoniou, adopted an innovative methodology. They leveraged the vast resources of electronic health records and genetic testing laboratory data collected and meticulously curated by the National Disease Registration Service (NDRS) in NHS England. This approach allowed them to conduct a large-scale, real-world observational study, examining the long-term outcomes of BSO among BRCA1 and BRCA2 pathogenic variant (PV) carriers who had been diagnosed with breast cancer. This methodology, while not an RCT, provided a powerful means to analyse outcomes in a retrospective cohort, drawing robust conclusions from existing clinical data.
Groundbreaking Findings: Reduced Mortality and Secondary Cancer Risk
The study identified a substantial cohort of 3,400 women carrying either a BRCA1 or BRCA2 cancer-causing variant, with approximately 1,700 women in each variant group. Among these, around 850 BRCA1 carriers and 1,000 BRCA2 carriers had undergone BSO surgery. The median follow-up period for the study was 5.5 years, providing sufficient time to observe significant long-term outcomes.
The results were striking and profoundly reassuring. Women who underwent BSO were found to be approximately half as likely to die from cancer or any other cause during the follow-up period. This dramatic reduction in early mortality underscores the broader, systemic benefits of the procedure beyond just ovarian cancer prevention. The survival advantage was particularly pronounced in BRCA2 carriers, who experienced a 56% reduction in mortality risk, compared to a still significant 38% reduction in BRCA1 carriers.
Beyond overall survival, the study also revealed another critical benefit: women who had BSO were about 40% less likely to develop a second primary cancer. This finding is particularly important for breast cancer survivors, who already face an elevated risk of subsequent cancers. While the researchers acknowledge that observational studies cannot definitively prove causation with 100% certainty, the strength and consistency of the evidence strongly point towards BSO being the direct cause of these reductions in risk. The mechanism behind the reduced risk of secondary cancers and overall mortality is likely multifactorial, involving the removal of the primary source of oestrogen, which can drive hormone-sensitive cancers, and potentially other complex biological pathways influenced by ovarian hormones.
Crucially, the study also meticulously investigated the long-term safety profile of BSO. In contrast to some earlier studies in the general population that had suggested potential links between BSO and increased risks of conditions like heart disease, stroke, or depression, the Cambridge team found no such association in their high-risk cohort. This finding is immensely reassuring for both patients and clinicians, alleviating concerns about unintended adverse health consequences arising from early menopause induced by the surgery.
Expert Commentary and Reassurance for Patients
Hend Hassan, a PhD student at the Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, and Wolfson College, Cambridge, and the study’s first author, articulated the significance of these findings: "We’ve always known that removing the ovaries and fallopian tubes dramatically reduces the risk of ovarian cancer. However, a persistent question mark has hung over the potential unintended consequences stemming from the sudden onset of menopause this procedure causes. Our research, thankfully, provides robust evidence that for women with a personal history of breast cancer and a BRCA mutation, BSO delivers clear, substantial benefits in terms of survival and a lower risk of other cancers, crucially without the adverse side effects such as heart conditions or depression that have been a concern in the past. This offers immense reassurance."
Professor Antonis Antoniou, from the Department of Public Health and Primary Care and the study’s senior author, emphasised the clinical utility of the research: "Our findings are poised to be absolutely crucial for counselling women with cancer linked to one of the BRCA1 and BRCA2 variants. They will empower these women to make truly informed decisions about whether or not to opt for this operation, armed with the most comprehensive evidence yet regarding its overall impact." He further highlighted the broader scientific implications, adding, "The study also powerfully underscores the immense value and potential of exceptional NHS datasets in driving impactful, clinically relevant research that can directly translate into improved patient outcomes."
Patient advocacy groups are expected to welcome these findings warmly. Organisations like Breast Cancer Now, Ovarian Cancer Action, and Macmillan Cancer Support frequently champion informed decision-making and access to preventative care for high-risk individuals. The study’s results will likely strengthen their messaging, providing concrete evidence to support the recommendation of BSO for this specific cohort.
Addressing Health Equity: Disparities in BSO Uptake
Despite the clear benefits identified, the study also brought to light concerning disparities in the uptake of BSO. The researchers observed that most women undergoing BSO in their cohort were white. Black and Asian women were found to be approximately half as likely to have BSO compared to white women. Furthermore, socioeconomic factors played a role, with women residing in less deprived areas being more likely to undergo BSO than those in the most-deprived categories.
These findings highlight significant health equity challenges. Hend Hassan expressed concern: "Given the clear and substantial benefits that this procedure provides for at-risk women, it is deeply concerning that certain groups of women are less likely to undergo it. We have a moral imperative to understand the underlying reasons for these disparities – whether they relate to access to genetic testing, communication barriers, cultural considerations, socioeconomic factors, or systemic biases within the healthcare system – and then actively work to encourage equitable uptake among all eligible women."
Addressing these disparities will require a multi-faceted approach, potentially involving targeted outreach programmes, culturally sensitive patient education materials, enhanced communication strategies, and a critical examination of healthcare pathways to ensure equitable access to genetic counselling and prophylactic surgery for all women at risk, regardless of their ethnicity or socioeconomic background.
Broader Implications for Clinical Practice and Future Research
The findings of this Cambridge study are set to have a profound impact on clinical practice. They provide robust, evidence-based support for recommending BSO to BRCA1 and BRCA2 carriers who have previously been diagnosed with breast cancer. This evidence will be instrumental in updating clinical guidelines, refining patient counselling protocols, and fostering more confident shared decision-making between clinicians and patients. The reassurance that BSO does not appear to increase the risk of cardiovascular disease, stroke, or depression in this specific population removes a significant barrier to informed consent.
Beyond immediate clinical applications, the study also underscores the immense potential of utilising large-scale, real-world health data for medical research. The collaboration between the University of Cambridge and the NDRS exemplifies how leveraging existing NHS datasets can yield clinically impactful results that would be impossible to obtain through traditional trial designs. This approach paves the way for future research to address other complex questions in cancer prevention and treatment.
Future research directions might include longer-term follow-up studies to assess the impact of BSO over decades, particularly regarding bone health and cognitive function. Investigating the precise biological mechanisms by which BSO reduces the risk of secondary cancers beyond ovarian cancer would also be valuable. Furthermore, studies focused on understanding and mitigating the observed health disparities in BSO uptake are urgently needed to ensure that the benefits of this life-saving procedure are accessible to all eligible women.
The research was generously funded by Cancer Research UK, a leading charity dedicated to cancer research, with additional crucial support from the National Institute for Health and Care Research (NIHR) Cambridge Biomedical Research Centre. The University of Cambridge, in partnership with Cambridge University Hospitals NHS Foundation Trust and Addenbrooke’s Charitable Trust (ACT), is actively fundraising for a new state-of-the-art Cambridge Cancer Research Hospital. This facility is envisioned to transform cancer diagnosis and treatment for patients across the East of England, with its research extending its impact to cancer patients throughout the UK and globally.
In conclusion, the Cambridge study marks a pivotal moment in the care of women with BRCA1 and BRCA2 mutations and a history of breast cancer. By definitively demonstrating a significant reduction in early mortality and secondary cancer risk without serious adverse long-term effects, it provides invaluable clarity and reassurance. This robust evidence will empower women and their healthcare providers to make more confident, informed decisions, ultimately saving lives and improving health outcomes for a vulnerable population.
