Oberg, Ann L.

Abstract Background: Pancreatic cancer (PC) ranks among the top causes of cancer mortality. Risk stratification is an important step toward prevention and early detection. Prior work has shown that ABO blood type (non-O) and first-degree family history of PC are associated with increased PC risk. Individuals with first-degree family history of PC have a 2- to 3-fold increased risk, but it is unclear if ABO blood type plays a role in the familial aggregation of PC. We investigated PC risk among first-degree relatives (FDRs) of PC probands based on the probands' serologic blood type (O vs non-O). Methods: A total of 702 probands sequentially enrolled in the Mayo Clinic Pancreas Research Registry from 2000-2016 with serologic ABO blood type provided information on family history of cancer for 5,178 FDRs. FDRs were grouped based on their related probands' blood type as type O (n=242; 1,768 FDRs) vs non-O (n=460; 3,410 FDRs). Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated by comparing the number of PC cases observed among FDRs to those expected using data from the Surveillance, Epidemiology and End Results (SEER) Program as the reference population. SIRs for PC risk were calculated separately for FDRs of probands with type O vs FDRs of probands with non-O blood, and stratified by sex of FDRs and relationship to proband (parent, sibling, or offspring). Results: Compared to the SEER reference, PC risk was nearly 2-fold higher among FDRs of PC probands (SIR=1.76; 95%CI: 1.35-2.26). When stratified by probands' ABO type, risk for PC was higher among FDRs of probands with non-O blood (SIR=1.94; 95%CI: 1.41-2.60), compared to FDRs of probands with O blood (SIR=1.42; 95%CI: 0.83-2.28). Parents of probands with non-O blood had increased PC risk (SIR=3.28; 95%CI: 2.18-4.74, n=920), but not parents of probands with O blood (SIR=1.75; 95%CI: 0.75-3.45, n=484), p-value for between-group difference=0.10. Among FDRs of probands with O blood, female FDRs had increased PC risk (SIR=2.12; 95%CI: 1.06-3.79), but male FDRs did not (SIR=0.86; 95%CI: 0.31-1.88). Higher PC risk was observed among female FDRs of probands with non-O blood (SIR=2.28; 95%CI: 1.44-3.41) than male FDRs of probands with non-O blood (SIR=1.62; 95%CI: 1.00-2.48). Mothers of probands with O blood had increased PC risk (SIR=2.89; 95%CI: 1.05-6.28) compared to fathers (SIR=0.79; 95%CI: 0.09-2.84). Both mothers (SIR=3.60; 95%CI: 1.96-6.03) and fathers (SIR=2.95; 95%CI: 1.61-4.95) of probands with non-O blood had increased PC risk. No major findings were observed among probands' siblings or offspring. Conclusions: PC risk is greater among FDRs of PC probands with non-O blood than among FDRs of probands with type O. PC risk is higher among parents of probands with non-O blood, and female FDRs and mothers of probands with non-O blood. Possible clustering of non-O blood type in families may contribute to increased PC risk. Citation Format: Aarti Kolluri, Samuel O. Antwi, Sarah E. Fagan, Kari G. Chaffee, Brendan T. Broderick, William R. Bamlet, Ann L. Oberg, Robert R. McWilliams, Gloria M. Petersen. Risk of pancreatic cancer is increased among first-degree relatives of pancreatic cancer probands who have non-O ABO blood type [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1239.

THBS2 and CA19-9 markers in human blood improve detection of pancreatic ductal adenocarcinoma.

Abstract Background: There have been varying reports on risk of different cancers, other than pancreatic cancer (PC), among first-degree relatives (FDRs) of PC patients. Because the pattern and scope of aggregation of PC with other malignancies in families of PC patients are not entirely clear, we investigated risk of 15 common malignancies among FDRs of unselected PC probands. Methods: The study included 17,181 FDRs with more than 336,000 person-years at risk. The FDRs were identified through sequentially enrolled PC probands (n=2,305) in the Mayo Clinic prospective pancreatic cancer patient registry from 2000-2016. Data on family history of cancer were provided by the probands at the time of enrollment in structured risk factor questionnaires. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated by comparing cases of each cancer type observed among the FDRs with those expected using data from the Surveillance Epidemiology and End Results Program (SEER). Stratified analyses were performed among siblings of the probands based on whether the related proband tested positive for a mutation in ATM, BARD1, BRCA1, BRCA2, CDKN2A, CHEK2, MUTYH, NBN, PALB2, or PMS2; or tested negative for mutation in a total of 25 sequenced cancer susceptibility genes. Results: Compared to the SEER reference population, risk of PC was two-fold higher than expected among the FDRs (SIR=2.04, 95% CI: 1.78-2.31) and 12-fold higher than expected among FDRs with history of PC in at least two blood relatives (SIR=11.99, 95% CI: 10.48-13.64). Siblings of mutation-positive probands had higher risk of PC (SIR=13.57, 95% CI: 6.19-25.76) than siblings of mutation-negative probands (SIR=8.91, 95% CI=6.73-11.57). For other cancer types, primary liver cancer was elevated among female FDRs (SIR=2.10, 95% CI: 1.34-3.12), whereas breast (SIR=3.16, 95% CI: 1.63-5.52) and ovarian (SIR =6.61, 95% CI: 1.33-19.31) cancers were elevated only among siblings of the mutation-positive probands. There also were suggestions of lower than expected risk of other malignancies, such as bladder, colorectal and prostate cancers, among the FDRs as compared with the SEER population. Conclusions: These findings confirm familial aggregation of PC with breast and ovarian cancers, and further suggest a potential aggregation of PC and primary liver cancer among female FDRs of PC probands. The elevated risks of breast cancer and ovarian cancer among siblings of the mutation-positive probands suggests a strong influence of genetic susceptibility shared with the related proband, possibly due to an inherited mutation in BRCA1, BRCA2, or PALB2. These findings lend support to genetic counseling and targeted screening of certain cancers in high-risk families. Citation Format: Samuel O. Antwi, Sarah E. Fagan, Kari G. Chaffee, William R. Bamlet, McWilliams R. Robert, Ann L. Oberg, Gloria M. Petersen. Risk of different cancers among first-degree relatives of pancreatic cancer patients and impact of probands’ germline mutation on sibling cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4269. doi:10.1158/1538-7445.AM2017-4269