Hereditary cancer testing in a diverse sample across three breast imaging centers

PURPOSE

Up to 10% of all breast cancers (BC) are attributed to inherited pathogenic variants (PV) in BC susceptibility genes; however, most carriers of PVs remain unidentified. Here, we sought to determine the yield of hereditary cancer gene PVs among diverse women attending breast imaging centers, who could benefit from enhanced surveillance and/or risk reduction interventions.

METHODS

This cross-sectional retrospective cohort study included consecutive women, unselected for personal or family cancer history, who were offered genetic testing for hereditary cancer genes at the time of breast imaging at three centers (November 2020-March 2022).

RESULTS

Among 1943 patients (median age: 66 years), self-reported race/ethnicity was White (34.5%), Hispanic (27.7%), African American (17.9%), Asian (4.5%), Ashkenazi Jewish (0.6%), Other (3.5%), and missing (13.0%). Thirty-nine patients (2%) were identified as carriers of a PV in an autosomal dominant clinically actionable hereditary breast and ovarian cancer (HBOC)-related or Lynch syndrome gene, most frequently, BRCA2 (6/39; 15.4%), PALB2 (8/39; 20.5%), CHEK2 (10/39; 25.6%), and PMS2 (5/39; 12.8%). Of the 34 PVs with known race/ethnicity, 47% were detected among non-White patients. Overall, 354/1,943 (18.2%) of patients met NCCN guidelines for HBOC gene testing and only 15/39 (38.5%) patients with an autosomal dominant clinically actionable PV met guidelines.

CONCLUSION

This population health approach extended the reach of genetic cancer risk assessment in a diverse population and highlighted the limits of a guideline-based approach. This may help address inequity in access to risk-appropriate screening and cancer prevention.

Abstract P6-02-06: Implementation and outcomes of population-based hereditary cancer testing across a diverse multi-location breast imaging center

Introduction: Up to 10% of all breast cancers (BC) are attributed to inherited pathogenic variants (PV) in BC susceptibility genes, and genetic testing at the time of breast imaging may identify more patients who could benefit from enhanced surveillance and/or risk reduction interventions. Data are limited on the yield of PVs in the setting of a breast imaging center. Hypothesis: Hereditary cancer gene screening at the time of breast imaging may identify patients and families who could benefit from cancer risk management. Methods: This retrospective cohort study included de-identified clinical data and commercial multi-cancer panel (40 genes) test results from sequential patients undergoing breast imaging at 3 centers in Texas over a 17 month period. Patients of providers who elected not to participate were excluded from this cohort. PV prevalence was quantified and stratified based on level of risk for BC and other cancers: high-risk (relative risk >4) for BC, moderate-risk (relative risk 2-4) for BC, high-risk for other cancers, moderate-risk or undefined risk for other cancers. Results: A total of 1,943 patients undergoing breast imaging chose to have genetic testing during the study period. Median age was 66 yrs (range 18-89 yrs). Self-reported race/ethnicity: White (34.5%), Hispanic (27.7%), African American (17.9%), Asian (4.5%), Ashkenazi Jewish (0.6%), Other (3.5%) and unreported (13.0%). A personal history of breast or ovarian-related cancers was reported in 4% (n=78) and a family history of these cancers was reported in 38.9% (n=835) of patients. Among those tested, 44/1,943 (2.3%) had one or more PV in an autosomal dominant clinically actionable gene, further categorized as: high-risk BC gene (36.3%) moderate-risk BC gene (34.1%), high-risk gene for other cancers (13.6%), moderate-risk gene for other cancers (6.8%), or uncertain level of increased risk for other cancers (9.1%). A heterozygous PV in an autosomal recessive gene was present in 31/1943 (1.6%) patients. Overall, 354/1943 (18.2%) patients met current NCCN guidelines for hereditary breast and ovarian cancer (HBOC) gene testing. Only 15/44 (34.1%) patients with an autosomal dominant clinically actionable PV met current NCCN guidelines for HBOC testing. Genetic education was provided to 20/44 (45.5%) patients by lab-based genetic counselors and/or the patient’s healthcare provider. Conclusions: Offering genetic testing in a diverse breast imaging center population was associated with a significant yield (4%) of both dominant and recessive clinically actionable PVs. Of note, almost 2/3 of PVs in hereditary cancer genes were among women who did not meet NCCN testing guidelines. Identification of a PV enables risk stratification, cascade testing of family members and an opportunity to access enhanced surveillance and risk reduction interventions.

Citation Format: Darlene Miltenburg, Laura Westbrook, Vivienne Souter, Melissa K. Maisenbacher, Katherine L. Howard, Youbao Sha, Maygol Yavari, Nicholas Kypraios, Sofia Hurtado, Mayra Rodas, Jeffrey N. Weitzel. Implementation and outcomes of population-based hereditary cancer testing across a diverse multi-location breast imaging center [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-02-06.

Advances in genetic testing for Alzheimer's disease

As the prevalence of Alzheimer's disease (AD), the most common dementia in the elderly, continues to increase, neurologists will encounter a growing number of questions about genetic testing for dementia patients, their relatives, and people concerned about memory or cognitive function who have no apparent risk except advancing age. Until recently, clinical gene testing only included apolipoprotein E genotyping and testing for presenilin 1 mutations. In 2008, testing expanded to include the presenilin 2 and amyloid precursor protein genes. Despite these advances, genetic testing is currently not appropriate for most individuals diagnosed with AD and has limited utility for predictive purposes. Further research, however, is likely to expand the usefulness of this testing for both dementia patients and their relatives. If genetic testing is undertaken, thorough counseling, whether by the physician or a qualified genetic counselor, is an integral component of the testing process for both affected individuals and their families.

Adult-onset Alexander disease with progressive ataxia and palatal tremor

A novel glial fibrillary acidic protein (GFAP) mutation, Y257C, is reported in a patient with adult-onset Alexander disease. This is the oldest reported case with confirmation of a GFAP mutation. Onset was late in the sixth decade. Genetic analysis of the GFAP gene is recommended in cases of progressive ataxia and palatal tremor.

The Genetics of Very Early Onset Alzheimer Disease

OBJECTIVE

This study was undertaken to clarify the genetics of very early onset Alzheimer disease (VEOAD), defined as AD beginning before age 35.

BACKGROUND

Early onset AD (EOAD) is defined by onset of symptoms before age 65, and affected individuals may harbor a mutation in presenilin 1 (PSEN1), presenilin 2 (PSEN2), or amyloid precursor protein. VEOAD is exceedingly rare, and PSEN1 mutations have been implicated. We encountered a man with phenotypic frontotemporal dementia beginning at age 32 and a strong family history of an autosomal dominant dementia who was found at autopsy to have AD.

METHODS

Histologic and genetic analyses of the patient's brain were undertaken, and a review of all published VEOAD cases was performed.

RESULTS

Histologic findings were diagnostic of advanced stage AD. Genetic evaluation of brain tissue identified an intronic PSEN1 polymorphism; no known pathogenic mutation was found. Literature review (1934 to 2007) disclosed 101 cases of VEOAD; the youngest age of dementia onset was 24 years. In all cases in which definitive genetic analysis was available, either a PSEN1 mutation or linkage to chromosome 14 was found.

CONCLUSIONS

VEOAD can present with atypical clinical features, including findings suggestive of frontotemporal dementia. All reported cases of VEOAD with conclusive genetic analysis seem to be associated with PSEN1 mutations. Genetic testing in adults younger than 35 with dementia can identify the genetic defect and assist in diagnosis and family counseling.

Delayed apoptotic responses associated with radiation-induced neoplastic transformation of human hybrid cells

HeLa X human skin fibroblast hybrid cells have been developed into a model for radiation-induced neoplastic transformation of human cells. Previous studies indicate that the appearance of neoplastically transformed foci in this system is delayed for several population doublings after irradiation and appears to involve the loss of putative tumor suppressor loci on fibroblast chromosomes 11 and 14. We now show that after treatment with 7 Gy of X-rays, transformed foci initiation correlates with delayed apoptosis initiated in the progeny of the irradiated cells after 10-12 cell divisions and with reduced plating efficiency (delayed death). The cells develop classic apoptotic morphology, positive terminal deoxynucleotidyl transferase-mediated nick end labeling and phosphatidylserine (annexin V) staining, and cleavage of poly(ADP-ribose) polymerase. In addition, a delayed induction of the p53 protein and the proapoptotic Bax protein is evident over a week after radiation exposure. We propose that a delayed build-up of mitosis-dependent genomic DNA damage or a loss of genetic material over time (10-12 cell divisions postirradiation) has two relevant outcomes: (a) cell death due to the delayed induction of a p53-dependent apoptosis; and (b) neoplastic transformation of a minor subset of survivors that has lost fibroblast chromosomes 11 and 14 (tumor suppressor loci for this system) and has either evaded apoptosis or not acquired enough genetic damage to induce apoptosis. It is postulated that both phenomena result from X-ray-induced, translesion-mediated genomic instability.

Relationship between platinum-DNA adducts in leukocytes of patients with advanced germ cell cancer and survival

Platinum-DNA adducts can be measured in peripheral blood leukocytes during platinum-based chemotherapy, and high adduct levels have been correlated with favorable clinical response in patients with germ cell cancer. Twenty-five patients with advanced germ cell cancer were treated with platinum-based chemotherapy regimens using the same dose and schedule of cisplatin. Platinum-DNA adducts were measured by atomic absorption spectrometry on the first and fifth days of the first cycle of cisplatin-based therapy. The patients were followed prospectively for 6-35 months (median, 26 months). Twenty-two patients had adduct levels measured 24 h after the first dose of cisplatin. There was no difference in the mean adduct levels of those who were alive and without progression of disease compared to those who were dead or progressing (P = 0.65). Twenty-three patients had day 5 adduct levels measured. The mean day 5 adduct level in the 15 patients who were alive and without progression was 62.133 fmol/microgram compared to 153.50 fmol/microgram in the patients who were dead or progressing (two-sided P = 0.02). Contrary to previous reports, these data indicate that high platinum-DNA adduct levels do not correlate with favorable outcome in patients with advanced germ cell cancer.

Exogenous ochronosis in a Mexican-American woman

Exogenous ochronosis resulting from the topical application of hydroquinone-containing bleaching creams has been reported to occur almost exclusively in black subjects, and only after use of high concentrations of hydroquinone (greater than 3 percent) for many years. A Mexican-American patient is described who experienced exogenous ochronosis after using 2 percent hydroquinone cream for less than six months.