Hereditary Risk Assessment Beyond BRCA
Reviewed by Ann Dietrich, MD, FAAP, FACEP
For years, hereditary evaluation in breast cancer often was treated as a synonym for breast cancer gene (BRCA)1 and BRCA2 testing. That no longer is enough. The current American Society of Clinical Oncology (ASCO)-Society of Surgical Oncology (SSO) guideline recommends BRCA1/2 testing for all patients with newly diagnosed stage I to III or de novo stage IV/metastatic breast cancer who are 65 years of age or younger, and for selected patients older than 65 years of age based on poly (ADP-ribose) polymerase (PARP) inhibitor candidacy, triple-negative disease, personal or family history, male sex at birth, or founder-population ancestry. The same guideline also states that testing for high-penetrance genes beyond BRCA, including PALB2, TP53, PTEN, STK11, and CDH1, should be offered to appropriate patients because the results can influence therapy, surgical decision-making, estimates of second primary risk, and family risk assessment.
Many referrals still begin with a simple question about the BRCA gene, but the real clinical question is broader: Which inherited pathogenic variant best explains the phenotype, and what changes today because of that answer? Multigene testing increases the yield of clinically meaningful findings outside BRCA. In an unselected breast cancer population, the National Cancer Institute’s (NCI) Physician Data Query (PDQ) summary reports BRCA1/2 pathogenic variants in 6.1% of patients and pathogenic variants in other breast and ovarian cancer predisposition genes in 4.6% of patients. In a series of 35,409 women tested with a 25-gene panel, 9.3% had a pathogenic variant, and just under half of those positive results were BRCA1/2.
Why beyond BRCA matters now
The practical reason for going beyond BRCA is that hereditary breast cancer is not one syndrome. The NCI classifies PALB2, TP53, PTEN, CDH1, and STK11 as relatively high-penetrance breast cancer susceptibility genes, while CHEK2 and ATM are moderate-penetrance genes associated with increased breast cancer risk. These genes do not carry identical biology, identical cancer spectra, or identical management implications, which means a positive genetic test is only the beginning of decision-making, not the end of it.
That distinction matters because the result can chang0e several parts of care at once. A pathogenic variant may affect eligibility for targeted systemic therapy, the conversation about bilateral or risk-reducing surgery, the estimated risk of contralateral breast cancer, the need for surveillance of other organs, and the urgency of cascade testing for relatives. It also changes how clinicians should interpret a negative BRCA test. In women who previously tested negative for BRCA1/2, reflex multigene testing still has identified additional pathogenic variants in 8% to 11% of cases, underscoring how much clinically relevant hereditary risk can be missed when the workup stops at BRCA alone.
Which patients should trigger hereditary risk assessment
At a minimum, a breast cancer diagnosis should prompt familiarity with current germline testing criteria. The ASCO-SSO guideline recommends BRCA1/2 testing for all newly diagnosed stage I to III or de novo stage IV/metastatic breast cancer in patients age 65 years or younger, and for selected older patients with features that raise the probability of an actionable germline finding. The guideline also recommends BRCA1/2 testing for patients with recurrent disease who may be candidates for PARP inhibition and for patients with a second primary breast cancer. In other words, hereditary assessment no longer is reserved for the most dramatic pedigrees.
However, family history still matters, especially when deciding whether the evaluation should extend beyond BRCA. The NCI highlights several pedigree features that increase suspicion for inherited breast cancer susceptibility: a large number of affected relatives, relatives diagnosed at young ages, bilateral breast cancers, multiple ipsilateral primaries, and male breast cancer in the family. The NCI also emphasizes broader hereditary red flags such as multiple cancers within a family and two or more primary cancers in a single individual. Those patterns should move the clinician from a binary “test or do not test” mindset toward a more precise “which syndrome best fits this family” approach.
Tumor phenotype also helps. Triple-negative disease, especially at younger ages, remains a strong hereditary signal. Lobular histology should raise the index of suspicion for CDH1-associated disease when the family history includes diffuse gastric cancer. Very early onset breast cancer or a history of multiple primaries should bring TP53 into sharper focus. Tumor genomic profiling also can create germline follow-up questions, which is one reason the ASCO panel-selection guideline explicitly addresses when germline testing is indicated after tumor profiling.
Risk models are increasingly helpful after the initial history is obtained. The NCI notes that Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA)/CanRisk now incorporates not only BRCA1/2 but also non-BRCA genes such as CHEK2, ATM, and PALB2, along with a polygenic component. That matters because the absolute risk attached to a moderate-risk gene often is heavily influenced by pedigree structure, age, tumor markers, and the rest of the family history. In practice, model-based assessment is one of the most useful ways to avoid both under calling and overcalling hereditary risk in breast cancer clinics.
High-penetrance genes beyond BRCA
The high-penetrance genes beyond BRCA deserve special attention because they are the non-BRCA results most likely to alter management in a meaningful way. The ASCO-SSO guideline specifically names PALB2, TP53, PTEN, STK11, and CDH1 as genes whose testing may change medical therapy, surgery, risk estimates for second primary cancer, and family counseling. These are not incidental additions to a panel. They often are the reason a broad hereditary assessment becomes clinically useful rather than merely descriptive.
PALB2
PALB2 is the clearest example of why hereditary risk assessment in breast cancer no longer can be framed as BRCA or nothing. PALB2 interacts with BRCA1 and BRCA2 in homologous recombination repair, and the NCI notes that the breast cancer risk range for PALB2 overlaps with that of BRCA2. In PALB2 carriers, absolute breast cancer risk has been estimated at 16.9% by age 50 years and 52.8% by age 80 years. Earlier work found risk by age 70 years of 33% in carriers without a family history of breast cancer and 58% in carriers with two or more first-degree relatives with early onset breast cancer. That is high enough to change how many clinicians think about surveillance, surgical prevention, and family counseling.
PALB2 also matters after the first diagnosis. The NCI reports a 10-year cumulative contralateral breast cancer risk of 7.9% overall in PALB2 carriers and 19.7% in those with estrogen receptor (ER)-negative disease, and the ASCO-SSO breast cancer guideline notes that small single-arm studies have shown high response rates to PARP inhibitors in metastatic breast cancer with germline PALB2 variants. Even so, current Food and Drug Administration (FDA) breast cancer approvals for olaparib and talazoparib remain limited to germline BRCA-mutated HER2-negative disease. That gap between biologic plausibility, emerging evidence, and current label status is exactly why clinicians need to understand PALB2 on its own terms rather than folding it into a generic “non-BRCA” bucket.
TP53
TP53-associated Li-Fraumeni syndrome is one of the most management-altering hereditary findings in breast oncology. The NCI lists TP53 among the high-penetrance genes associated with breast cancer and reports that among 127 female TP53 carriers with breast cancer, 31% developed contralateral breast cancer. The NCI also notes that annual breast magnetic resonance imaging (MRI) with and without contrast is recommended in this population. Therefore, a TP53 result affects much more than simple recurrence counseling. It changes the intensity of surveillance, sharpens concern for multiple malignancies, and can change the balance of local therapy decisions in a way that moderate-risk genes generally do not.
Radiation considerations are especially important in TP53 carriers. The NCI cites a series in which 19 of 64 carriers who received radiation for treatment of their first tumor developed 26 secondary tumors within a radiation field, a 30% rate in that cohort. That does not mean radiation is categorically impossible, but it does mean TP53 status should materially change the local therapy discussion. When hereditary evaluation is delayed until after surgery and radiation planning, clinicians may lose the chance to integrate one of the most important pieces of biologic context into treatment selection.
PTEN, CDH1, and STK11
PTEN-associated syndromes are less common than BRCA-associated hereditary breast cancer, but they are easy to miss if the clinician only asks about breast and ovarian cancer. GeneReviews describes PTEN hamartoma tumor syndrome as carrying an approximately 85% lifetime breast cancer risk, with an average age at diagnosis between 38 and 46 years, and the NCI highlights clinical clues such as macrocephaly and other syndromic features. The NCI also notes that multigene panel testing increasingly is identifying PTEN carriers who do not meet older, classical diagnostic criteria. That is important because a patient who looks atypical for Cowden syndrome still can have a result with major implications for breast, thyroid, kidney, and endometrial cancer surveillance.
CDH1 and STK11 illustrate a second reason to think beyond the breast. The NCI identifies CDH1 as a high-penetrance gene associated with diffuse gastric and lobular breast cancer syndrome, meaning that lobular histology plus a family history of diffuse gastric cancer should immediately broaden the hereditary differential. STK11, the gene implicated in Peutz-Jeghers syndrome, also is high-penetrance; the NCI estimates cumulative breast cancer risk in this setting at 32% to 54%, alongside broader gastrointestinal, pancreatic, and gynecologic cancer risks. These are the kinds of results that transform hereditary testing from an explanation of breast cancer risk into a roadmap for multisystem surveillance across a family.
Moderate-penetrance genes require calibrated interpretation
If high-penetrance genes change management by force, moderate-penetrance genes change it by calibration. The NCI classifies CHEK2 and ATM as moderate-penetrance breast cancer genes, but moderate should not be mistaken for trivial. These genes often sit in the gray zone where a result is meaningful, yet the final clinical recommendation depends heavily on age at diagnosis, ER tatus, family history, prior breast cancer, and formal risk modeling. The danger is overreaction in one direction and dismissal in the other.
CHEK2
CHEK2 is one of the most common examples of this calibration problem. The NCI reports an approximately 1.5- to 3-fold increased risk of female breast cancer associated with CHEK2 pathogenic variants, with a pooled analysis showing a significant 2.3-fold excess risk and a meta-analysis of CHEK2 1100delC heterozygotes showing an odds ratio of 2.75. Those are clinically relevant numbers, but they do not justify treating all CHEK2 carriers as if they were BRCA carriers. Instead, a CHEK2 result should push the clinician to refine absolute risk using family history and model-based tools, especially when making surveillance and surgical prevention recommendations after a breast cancer diagnosis.
CHEK2 also matters after cancer diagnosis because contralateral risk is not negligible. In the prospective CARRIERS study, women with breast cancer and germline CHEK2 pathogenic variants had a significantly elevated risk of contralateral breast cancer. That does not mean contralateral mastectomy should be routine, but it does mean that a CHEK2 result belongs in the shared decision-making conversation about future breast events, especially in younger patients or those with a strong family history.
ATM
ATM similarly is important, and similarly easy to oversimplify. The NCI reports an odds ratio of 1.82 for breast cancer in ATM heterozygotes in a large U.S. study, along with an association with ER-positive disease, and cites meta-analytic cumulative risk estimates of 6.02% by age 50 years and 32.83% by age 80 years. Those numbers make ATM clinically relevant, especially when layered onto a strong pedigree, but they do not place ATM in the same management category as TP53, PALB2, or BRCA1/2.
Radiation and contralateral risk are two places where nuance matters. The NCI states there is insufficient evidence to recommend against radiation therapy in carriers of a single ATM pathogenic variant, and the CARRIERS study found that ATM carriers did not have a significantly increased risk of contralateral breast cancer. This is the kind of gene-specific distinction that prevents overly aggressive local therapy. A TP53 carrier is not the same as an ATM carrier, and hereditary reports that flatten those differences do more harm than good.
How to choose the right multigene panel
After the decision to test has been made, the next question is what to order. ASCO’s panel-selection guidance emphasizes choosing genes that have established or potential value in the context of a patient’s personal and family history, rather than reflexively defaulting to the broadest available panel. The goal is not simply to maximize the number of genes interrogated. The goal is to include the most relevant genes for the phenotype in front of you. That usually produces higher-value results and fewer distracting findings.
In breast cancer, that means panel design should reflect actual clues. Lobular histology with gastric cancer in the family argues for CDH1 attention. Very early onset disease or multiple primaries raises TP53 concern. Polyposis, mucocutaneous findings, or macrocephaly should widen the net toward PTEN or STK11. A family history rich in pancreatic cancer can increase the relevance of PALB2 and other genes. Tumor genomic profiling also may surface variants or patterns that justify germline follow-up. Therefore, a good panel is not big or small. It is phenotype-driven.
Pretest counseling is part of the test
Hereditary testing is not just a specimen order. The NCI defines comprehensive cancer risk assessment and counseling as a consultative service that includes clinical assessment, genetic testing when appropriate, and risk-management recommendations delivered in the context of counseling sessions. The NCI also emphasizes that pretest counseling is an important part of the process because it helps patients understand their testing options and potential outcomes. That point remains essential even in high-volume breast cancer clinics where the pressure to streamline ordering is intense.
The consent discussion should cover more than the possibility of finding BRCA. The NCI notes that informed consent is an integral part of pretest counseling, and patients should understand that results may come back as pathogenic or likely pathogenic, negative, or a variant of uncertain significance (VUS). A VUS is not a rare administrative nuisance. It is a predictable outcome of broader testing, especially as panels expand into genes with less settled penetrance data or less consistent phenotype correlations. Setting that expectation before testing reduces confusion and helps prevent overreaction when ambiguous results return.
How to interpret results without overcalling them
Pathogenic or likely pathogenic result
A pathogenic result should trigger gene-specific thinking, not just relief that the test found something. In breast cancer, the actionable domains usually include systemic therapy, surgical decision-making, contralateral breast cancer risk, surveillance for other cancers, and cascade testing. The ASCO-SSO guideline is explicit that high-penetrance genes beyond BRCA can inform medical therapy, surgery, second-primary risk estimates, and family risk assessment. The result has to be translated into a management plan that reflects the biology of that specific gene.
A negative result is not the end of risk assessment
A negative hereditary test does not automatically place a patient back at average risk. The NCI’s risk-assessment framework remains anchored in personal and family history, and the NCI’s breast genetics summary continues to highlight how family structure, young ages at diagnosis, bilateral disease, and other pedigree features can materially change breast cancer risk even when a clearly actionable pathogenic variant is not identified. Model-based assessment remains useful, especially when clinicians are deciding whether screening intensity or preventive discussions still should exceed population norms.
Variant of uncertain significance
A VUS should be understood for what it is: an indeterminate result. The NCI notes that a VUS often reflects limited penetrance evidence, discordant findings, or a variant in a gene whose relationship to the patient’s phenotype is unclear. Clinically, that means the result should not carry the weight of a pathogenic finding when decisions are being made about irreversible surgery or gene-specific surveillance. Management should continue to rest on the personal and family history until the variant is clarified or reclassified.
How looking beyond BRCA changes treatment and surgical planning
Systemic therapy is one of the clearest places where inherited findings matter immediately. FDA approvals in breast cancer currently remain BRCA-specific: Olaparib is approved for germline BRCA-mutated HER2-negative metastatic breast cancer and for high-risk early stage HER2-negative germline BRCA-mutated disease after chemotherapy, while talazoparib is approved for germline BRCA-mutated HER2-negative locally advanced or metastatic breast cancer. That means clinicians cannot assume that every homologous-recombination gene carries the same label-based therapeutic consequence, even when the underlying biology appears related.
Local therapy decisions also are gene-dependent. The ASCO-SSO guideline notes that testing beyond BRCA can refine estimates of second primary risk and influence surgical decision-making. The CARRIERS study adds useful granularity: BRCA1/2 and CHEK2 carriers had significantly elevated contralateral breast cancer risk, PALB2 carriers had elevated risk primarily in ER-negative disease, and ATM carriers did not show a significant increase. Include the TP53-specific concern about radiation-associated second malignancies, and it becomes obvious that genetic positivity is not a single surgical signal. The whole value of beyond-BRCA assessment is that it makes the treatment discussion more individualized, not merely more complicated.
Common errors in beyond-BRCA assessment
One common mistake is treating every positive non-BRCA result as if it were BRCA1/2. That collapses high- and moderate-penetrance genes into a single category and invites overtreatment. TP53, PALB2, ATM, and CHEK2 do not mean the same thing. The NCI’s penetrance framework, the contralateral-risk data from CARRIERS, and the current FDA labels all point in the same direction: Inherited findings must be interpreted gene by gene, not panel by panel.
The opposite mistake is stopping too early. If the only hereditary question asked in a breast cancer workup is whether the patient carries a BRCA mutation, clinically relevant findings in PALB2, TP53, CHEK2, ATM, PTEN, CDH1, or STK11 may never be identified. Likewise, if clinicians treat a negative BRCA result as the end of hereditary assessment, or a VUS as a quasi-positive result, both under-management and over-management become more likely. The best protection against those errors is a structured process that combines phenotype, pedigree, thoughtful panel selection, and disciplined result interpretation.
Cascade testing is where the benefit multiplies
The benefit of hereditary assessment does not stop with the proband. The NCI notes that cascade testing offers biological relatives the chance to learn whether they carry the familial pathogenic variant before cancer develops, which is where prevention and early detection become possible, but uptake remains limited. In hereditary breast and ovarian cancer families, a systematic review found that probands informed relatives about the familial pathogenic variant only 21% to 44% of the time, and overall follow-up cascade testing rates ranged from 15% to 57%. Those numbers help explain why even excellent testing programs can underperform at the population level.
That gap is a workflow problem as much as a patient problem. The NCI notes that disclosure barriers include anxiety, strained family dynamics, limited contact information, and concern that relatives will misunderstand the result. In practice, the clinics that do this best provide written family letters, clear next-step instructions, and some way to revisit cascade testing after the initial shock of diagnosis and treatment planning has passed. A strong hereditary program is not just one that identifies pathogenic variants, it is one that helps those results travel through the family.
A practical workflow for breast cancer clinics
At diagnosis, apply the current ASCO-SSO criteria for BRCA1/2 testing, then ask whether the phenotype or pedigree suggests a panel that needs to go beyond BRCA.
Record a focused but real three-generation history, including young ages at diagnosis, bilateral disease, male breast cancer, diffuse gastric cancer, pancreatic cancer, and syndromic clues (such as macrocephaly or mucocutaneous findings).
Choose a phenotype-driven multigene panel rather than the broadest default menu. The relevant question is which genes have value for this patient’s personal and family history.
Pair the order with pretest counseling that prepares the patient for pathogenic findings, negative results, and VUS outcomes, along with the family implications of each.
When results return, interpret them in a gene-specific context. A PALB2 result is not the same as TP53, and ATM is not CHEK2. Map each finding to therapy, local treatment, surveillance, and contralateral risk counseling.
Build cascade testing into the care pathway and revisit indeterminate results if reclassification occurs or if the treatment context changes later in survivorship.
Summary
Hereditary risk assessment beyond BRCA i is part of contemporary oncologic decision-making. The BRCA gene question still matters, but it now is only one part of a larger hereditary framework that includes PALB2, TP53, PTEN, CDH1, STK11, CHEK2, ATM, and the structured use of multigene panels. Done well, this approach improves treatment selection, sharpens surgical counseling, refines contralateral risk estimates, and extends the value of a breast cancer diagnosis into meaningful prevention for relatives. Done poorly, it creates noise, overtreatment, and false reassurance. The difference is not whether clinicians test, it is whether they test with enough precision to make the result clinically useful.