Rates of Variants of Uncertain Significance Among Patients With Breast Cancer Undergoing Genetic Testing: Regional Perspectives

Purpose

Contrary to BRCA pathogenic variants, recommendations for management of variants of uncertain significance (VUS) are not clear and focus more on the patient’s family and personal history of cancer. Local and regional data on VUS are scarce. In this paper, we study patterns and frequency of VUS among breast cancer patients undergoing genetic testing.

Patients and Methods

Patients with breast cancer at high risk for pathogenic variants, as per the National Comprehensive Cancer Network (NCCN) guidelines, were tested at reference laboratories. Related surgical interventions were reviewed.

Results

Among a group of 1,197 patients with breast cancer who underwent genetic testing and counseling, 110 (9.2%) had VUS; most (n = 79, 71.8%) were in BRCA2. Median age (range) was 39 (25–66) years with 65 (59.1%) patients who were 40 years or younger at diagnosis. Among 103 patients with non-metastatic disease, 48 (46.6%) had breast-conserving surgery (BCS) while only 5 (4.9%) had bilateral mastectomies; all were due to bilateral disease and not prophylactic. VUS diagnosis was known prior to initial surgery in 34 (33.0%) patients; 11 (32.4%) of them had BCS only. Over the study period, only one VUS variant was upgraded to “likely positive.” The recent introduction of multiple-gene panel testing had resulted in a surge in VUS rate (22.2%) in genes other than BRCA1 or BRCA2, like PALB2, CHEK2, and ATM.

Conclusions

Rates of VUS are relatively high and increasing, mostly in non-BRCA1 or BRCA2, and this had no impact on the therapeutic or prophylactic surgical decisions. Adherence to guidelines is extremely important to avoid unnecessary procedures.

Prevalence and predictors of germline BRCA1 and BRCA2 mutations among young patients with breast cancer in Jordan

BRCA1 and BRCA2 mutations are not uncommon in breast cancer patients. Western studies show that such mutations are more prevalent among younger patients. This study evaluates the prevalence of germline mutations in BRCA1 and BRCA2 among breast cancer patients diagnosed at age 40 or younger in Jordan. Blood samples of patients with breast cancer diagnosed at age 40 years or younger were obtained for DNA extraction and BRCA sequencing. Mutations were classified as benign/likely benign (non-carrier), pathogenic/likely pathogenic variant (carrier) and variant of uncertain significance (VUS). Genetic testing and counseling were completed on 616 eligible patients. Among the whole group, 75 (12.2%) had pathogenic or likely pathogenic variants; two of the BRCA2 mutations were novel. In multivariate analysis, triple-negative disease (Odd Ratio [OR]: 5.37; 95% CI 2.88-10.02, P < 0.0001), breast cancer in ≥ 2 family members (OR: 4.44; 95% CI 2.52-7.84, P < 0.0001), and a personal history ≥ 2 primary breast cancers (OR: 3.43; 95% CI 1.62-7.24, P = 0.001) were associated with higher mutation rates. In conclusion, among young Jordanian patients with breast cancer, mutation rates are significantly higher in patients with triple-negative disease, personal history of breast cancer and those with two or more close relatives with breast cancer.

Patterns and Prevalence of BRCA1 and BRCA2 Germline Mutations Among Patients with Triple-Negative Breast Cancer: Regional Perspectives

Background

Among all subtypes, patients with triple-negative (TN) breast cancer is known for their poor outcome and their higher risk of harboring BRCA1 or BRCA2 pathogenic mutations. Identification of such mutations has clinical impact on breast and ovarian cancer prevention and treatment decisions. We here report on patterns and prevalence of BRCA1 and BRCA2 mutations among Arab patients diagnosed with TN subtype.

Patients and Methods

Patients with TN-breast cancer (n=197) were enrolled regardless of their age or family history. Following a detailed genetic counseling, BRCA1/2 testing was performed at reference labs. BRCA1 and BRCA2 variants were classified as negative, pathogenic/likely pathogenic (positive) and variants of uncertain significance (VUS).

Results

Median age of enrolled patients was 42 (range, 19–74) years and 27 (13.7%) were non-Jordanian Arabs. Among the study group, 50 (25.4%) were tested positive for BRCA1 (n=36, 18.3%) or BRCA2 (n=14, 7.1%), while 14 (7.1%) others had VUS. Compared to older ones, mutation rates were higher among patients <40 years (32.9%, P= 0.034), those with close relatives with breast, ovarian, pancreatic or prostate cancer (37.8%, P=0.002) and those with two or more breast cancers (41.4%, P=0.032). Among eligible patients, 23 (63.9%) patients underwent prophylactic mastectomy, while 19 (52.8%) patients had risk-reducing salpingo-oophorectomy. None of the patients with VUS underwent any prophylactic surgery.

Conclusion

Arab patients with TN-breast cancer have relatively high BRCA1 or BRCA2 mutation rates. Young age at diagnosis and personal and family history of breast cancer further increase this risk.

Effect of level of hormone-receptor expression on treatment outcomes of "triple-positive" early-stage breast cancer

PURPOSE

Breast cancer that overexpresses the human epidermal growth factor receptor-2 (HER2) and both estrogen (ER) and progesterone (PR) receptors is recently recognized as a subtype (triple-positive) with distinctive behavior and response to treatment. In this study, we investigate the treatment outcomes and the beneficial effect of anti-HER2 treatment in relation to level of hormone-receptor (HR) expression.

METHODS

Consecutive breast cancer patients with triple-positive disease, diagnosed, treated and followed at our institution between 2006 and 2016 were enrolled. Disease-free survival (DFS) was studied in relation to the level of HR-positivity.

RESULTS

During the study period, a total of 312 were enrolled; median age (range) was 47 (20-83) years. Fifty (16.0%) of the enrolled patients received adjuvant chemotherapy without trastuzumab (cohort A). All remaining patients were treated with both chemotherapy and trastuzumab and were divided into two groups: Cohort B with both ER and PR scores ≥ 50% (n = 130, 41.7%) and Cohort C with ER and/or PR < 50% (n = 132, 42.3%). After a median follow-up of 47 months, 14 (28.0%), 30 (23.1%) and 20 (15.2%) patients in cohorts A, B, and C had an event in a form of local/system relapse or death while disease-free. The estimated 5-year DFS was 56.2%, 75.4%, and 80.8%, respectively, and at 7 year was 56.2%, 67.1%, and 78.0%, respectively (p < 0.001).

CONCLUSIONS

HER2-positive tumors are not homogeneous; stronger ER/PR co-expression may weaken the beneficial effect of anti-HER2 therapy. Such findings may have potential implication on modifying anti-HER2 treatment based on the strength of HR expression.