The BRCA1 c. 5096G>A p.Arg1699Gln (R1699Q) intermediate risk variant: breast and ovarian cancer risk estimation and recommendations for clinical management from the ENIGMA consortium

BACKGROUND

We previously showed that the BRCA1 variant c.5096G>A p.Arg1699Gln (R1699Q) was associated with an intermediate risk of breast cancer (BC) and ovarian cancer (OC). This study aimed to assess these cancer risks for R1699Q carriers in a larger cohort, including follow-up of previously studied families, to further define cancer risks and to propose adjusted clinical management of female BRCA1*R1699Q carriers.

METHODS

Data were collected from 129 BRCA1*R1699Q families ascertained internationally by ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles) consortium members. A modified segregation analysis was used to calculate BC and OC risks. Relative risks were calculated under both monogenic model and major gene plus polygenic model assumptions.

RESULTS

In this cohort the cumulative risk of BC and OC by age 70 years was 20% and 6%, respectively. The relative risk for developing cancer was higher when using a model that included the effects of both the R1699Q variant and a residual polygenic component compared with monogenic model (for BC 3.67 vs 2.83, and for OC 6.41 vs 5.83).

CONCLUSION

Our results confirm that BRCA1*R1699Q confers an intermediate risk for BC and OC. Breast surveillance for female carriers based on mammogram annually from age 40 is advised. Bilateral salpingo-oophorectomy should be considered based on family history.

Abstract 810: The CARRIERS consortium: Establishing refined breast cancer risk estimates in known predisposition genes

Breast cancer is the most common type of cancer, and has a strong heritable component, with approximately 15 percent of new cases having family history of breast cancer. Genetic panel testing for patients with a family history of breast cancer has become a popular clinical resource. However, the risk of breast cancer associated with inactivating mutations in the predisposition genes is largely undefined, creating critical limitations in the interpretations of the results from panel testing and subsequent medical management. The Cancer Risk Estimates Related to Susceptibility Genes (CARRIERS) consortium was established to determine the risk of cancers associated with truncating mutations in the known predisposition genes and to extend these studies to the clinical classification of variants of uncertain significance (VUS) in the relevant genes.

CARRIERS involves screening of approximately 30,000 population-based breast cancer cases and 30,000 study matched controls for mutations in 28 established or proposed breast cancer predisposition genes. Population-based risks for breast cancer associated with mutations in each gene will be estimated. In parallel, 10,000 breast cancer cases from moderate and high-risk breast cancer families will be similarly screened for mutations and the penetrance of the mutations in high-risk families will be estimated. Furthermore, VUS identified by mutation screening will be characterized by functional and family-based studies and models for classification of the clinical relevance of VUS in each gene will be developed. These data are expected to lead to improvements in cancer risk assessment and improved management of patients found to carry mutations or VUS in breast cancer predisposition.

Citation Format: Jenna Lilyquist, Peter Kraft, Steven N. Hart, Emily J. Hallberg, Chunling Hu, Raymond Moore, Rohan Gnanaolivu, Susan M. Domchek, Jeffrey N. Weitzel, Katherine L. Nathanson, David E. Goldgar, Fergus J. Couch. The CARRIERS consortium: Establishing refined breast cancer risk estimates in known predisposition genes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 810.

Impact that Timing of Genetic Mutation Diagnosis has on Surgical Decision Making and Outcome for BRCA1/BRCA2 Mutation Carriers with Breast Cancer

BACKGROUND

Deleterious BRCA mutation carriers with breast cancer are at increased risk for additional breast cancer events. This study evaluated the impact that timing of identification of BRCA+ status has on surgical decision and outcome.

METHODS

The authors reviewed all BRCA carriers at their institution whose breast cancer was diagnosed between January 1996 and June 2015. Patient surveys, medical records, and institutional databases were used to collect data. Differences in surgical choice were analyzed using the chi-square test, and rates of subsequent breast cancer events were estimated using the Kaplan-Meier method.

RESULTS

The study investigated 173 BRCA carriers with breast cancer (100 BRCA1, 73 BRCA2). Of the women with known BRCA mutation before surgery and unilateral stages 0 to 3 breast cancer (n = 63), 12.7 % underwent lumpectomy, 4.8 % underwent unilateral mastectomy (UM), and 82.5 % underwent bilateral mastectomy (BM). These surgical choices differed significantly (p < 0.0001) from those of patients unaware of their mutation at the time of surgery (n = 93) (51.6 % had lumpectomy, 19.4 % had UM, 29 % had BM). Of the patients with BRCA mutation identified after surgery who underwent lumpectomy or UM, 36 (59 %) of 66 underwent delayed BM. The patients with BRCA+ known before diagnosis presented with significantly lower-stage disease (p = 0.02) at diagnosis (69 % stage 0 or 1) than those whose BRCA mutation was identified after cancer diagnosis (40 % stage 0 or 1).

CONCLUSIONS

The study findings showed that BRCA mutation status influences surgical decision. The rates of BM were higher for the patients with BRCA mutation known before surgery. Identification of BRCA mutation after surgery frequently leads to subsequent breast surgery. Genetic testing before surgery is important for patients at elevated risk for BRCA mutation.

Abstract 274: Occupational exposure to agricultural pesticides and CLL risk

Background

Previous literature regarding the association between occupational exposure to agricultural pesticides and non-Hodgkin lymphoma (NHL) risk has been inconsistent, particularly when looking at specific lymphoma subtypes. Most recently, a large European case-control study showed an elevated risk of chronic lymphocytic leukemia (CLL) among those ever exposed to inorganic and organic pesticides with the strongest association among those exposed to organophosphates. However, when restricting the analysis to subjects with high confidence of exposure, these associations were attenuated (Cocco P., 2013). We used case-control data from the Mayo Clinic to evaluate whether there is an increased risk of CLL among individuals with known occupational exposure to agricultural pesticides.

Methods

We evaluated pesticide exposure and CLL risk in a clinic-based study of newly diagnosed CLL cases and frequency-matched controls enrolled at the Mayo Clinic from 2002-2012. 200 CLL cases and 474 controls returned a detailed farming and pesticide exposure questionnaire that was modeled after the Agricultural Health Study, where exposure was based on pesticide-specific application. Unconditional logistic regression, adjusted for age and sex, was used to estimate odds ratios (ORs) and 95% confidence intervals (CI). We evaluated the effect of each pesticide individually, by chemical class of pesticides, and by an aggregate of multiple pesticide exposure on CLL risk.

Results

Among those participants with detailed farming data, the mean age of CLL diagnosis was 66 years and 76% were male; for controls, the mean age at enrollment was 65 years and 66% were male. Risk of CLL was mildly elevated, but not significant, amongst those with application of any pesticide (OR 1.39; 95% C.I. 0.92-2.10). When broken down by chemical class, risk of CLL was also mildly elevated, but not significant, for application of organophosphates and carbamates (OR 1.21; 95% CI 0.84-1.73; OR 1.21; 95% 0.85-1.73, respectively). Organochlorines, phenoxy compounds, pyrethriods and triazines showed no evidence of an elevated risk, nor did we see evidence of a trend that CLL risk increases with number of pesticides applied.

Discussion

Our preliminary results provide inconclusive support for the role of pesticide exposure as a possible risk factor for CLL. However our sample size was small. Additional data will be incorporated, including confidence of exposure measures, as well as other modifying factors, to further evaluate these results.

Citation Format: Emily J. Hallberg, Sara J. Achenbach, Kari G. Rabe, Timothy G. Call, Cristine Allmer, Tait D. Shanafelt, Mark Liebow, Neil E. Kay, James R. Cerhan, Susan L. Slager. Occupational exposure to agricultural pesticides and CLL risk. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 274. doi:10.1158/1538-7445.AM2014-274

Incidence of chronic lymphocytic leukemia and high-count monoclonal B-cell lymphocytosis using the 2008 guidelines

BACKGROUND

The 1996 National Cancer Institute Working Group (NCI-WG 96) guidelines classified disease in individuals who had a B-cell clone with chronic lymphocytic leukemia (CLL) immunophenotype as CLL if their absolute lymphocyte count was ≥5 × 10(9)/L. The 2008 International Workshop on CLL guidelines (IWCLL 2008) classified disease as CLL if the absolute B-cell count was ≥5 × 10(9)/L or as monoclonal B-cell lymphocytosis (MBL) if the absolute B-cell count was <5 × 10(9)/L. The objective of the current study of Olmsted County, Minnesota, was to assess the effects of these changes on incidence rates and presentation from 2000 to 2010.

METHODS

Using diagnostic indices available through the Rochester Epidemiology Project and the Mayo CLL database, the authors identified all patients with newly diagnosed CLL and high-count MBL from 2000 to 2010. Age-specific and sex-specific incidence rates were determined.

RESULTS

According to NCI-WG 96 criteria, there were 115 patients with CLL and 8 patients with MBL during the period studied. Using the IWCLL 2008 classification, there were 79 patients with CLL and 40 patients with MBL. Rai stage distribution (low risk, intermediate risk, and high risk) using NCI-WG 96 criteria was 60.9%, 33.9%, and 5.2%, respectively, compared with 43%, 49.4%, and 7.6%, respectively, using IWCLL 2008 criteria. The age-adjusted and sex-adjusted incidence rates (per 100,000) for CLL and MBL were 10.0 and 0.66, respectively, using NCI-WG 96 criteria versus 6.8 and 3.5, respectively, using IWCLL 2008 criteria. The median time to treatment according to NCI-WG 96 criteria was 9.2 years versus 6.5 years with IWCLL 2008 criteria.

CONCLUSIONS

Use of the IWCLL 2008 guidelines reduced the incidence of CLL, altered the distribution of initial Rai stage at diagnosis, and shortened the median time to treatment.

Abstract 2287: Incidence of chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis in Olmsted county, 2000-2010: impact of the 2008 International Workshop on CLL Guidelines

Background:

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) is the most common adult leukemia in the United States. Prior studies in Olmsted County, Minnesota, showed a CLL age and sex adjusted incidence rate of 6.6 per 100,000 during 1985-89. Subsequently, the definition of CLL is now based on the 2008 International Workshop on CLL (IWCLL) Guidelines. Individuals having a CLL immunophenotype by flow cytometry are classified as CLL if the absolute B-cell count (ABC) is &gt;5 x 109/L or classified as monoclonal B-cell lymphocytosis (MBL) if ABC is &lt;5 x 109/L. To assess the impact of these changes on the incidence of CLL and clinically discovered MBL, we conducted an incidence study in Olmsted County for the years 2000-2010.

Methods

Using diagnostic indexes available through the Rochester Epidemiology Project and the Mayo CLL database, we identified all CLL and clinically identified MBL cases from 2000-2010. Incidence rates and demographics were compared between the older National Cancer Institute-Working Groups 1996 guidelines (NCI-WG 96) defined as absolute lymphocyte count (ALC)&gt; 5 x 109/L and the IWCLL 2008 guidelines defined as ABC &gt; 5 x 109/L. Incidence rates were age and sex adjusted using the 2010 US white population. Time to treatment (TTT) survival analyses was from time of diagnosis to date of first treatment or last follow-up and Cox regression analysis was used.

Results

Using the NCI-WG 96 classification, there were 8 MBL cases and 115 CLLs in whom 61% were Rai stage 0, 34% were Rai stage 1-2, and 5% were Rai stage 3-4. Using the IWCLL 2008 classification, there were 44 MBL cases and 79 CLLs in whom 43% Rai stage 0, 49% were Rai stage 1-2 and 8% Rai stage 3-4. Median ALC at diagnosis was 8.1 x 109/L for CLL and 5.9 x 109/L for MBL. Median ABC count at diagnosis was 7.1 x 109/L for CLL and 2.8 x 109/L for MBL. The age and sex adjusted incidence rate (per 100,000) for CLL for 2000-2010 was 10.0 using NCI-WG 96 and 6.8 using IWCLL 2008. Rates for MBL were 0.66 using NCI-WG 96 and 3.5 using IWCLL 2008. The median TTT for CLL was 9.2 years using NCI-WG 96 and 6.5 years by IWCLL 2008.

Discussion

This study demonstrates that reclassification of CLL using the IWCLL 2008 guidelines decreases CLL incidence relative to the NCI-WG 96 criteria. For the first time, this population based study also establishes an incidence rate for clinically identified MBL. Approximately 50% of previously labeled Rai 0 CLL are now reclassified as MBL. Re-classification increases the percent of Rai stage 1-2 and decreases the percent of Rai 0 cases at diagnosis. Reclassification also substantially shortens the median TTT for newly diagnosed CLL cases classified by the 2008 criteria relative to the NCI-WG 96 criteria. In summary, the IWCLL 2008 reclassification has significant implications for incidence studies, staging, and prognosis of CLL and MBL.

Citation Format: Aaron D. Norman, Timothy G. Call, Curtis A. Hanson, Neil E. Kay, Clive S. Zent, Wei Ding, James R. Cerhan, Sara J. Achenbach, Kari G. Rabe, Celine M. Vachon, Emily J. Hallberg, Tait D. Shanafelt, Susan L. Slager. Incidence of chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis in Olmsted county, 2000-2010: impact of the 2008 International Workshop on CLL Guidelines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2287. doi:10.1158/1538-7445.AM2013-2287