Lynch syndrome (LS) is an autosomal dominant disorder caused by DNA mismatch repair (MMR) system deficiencies. Women affected by LS present a 40 to 60% lifetime risk of endometrial cancer (EC). Objective This case-case study aims to determine the frequency of the hMLH1, hMSH2, and hMSH6 MMR proteins and the factors (age, family history of cancer [FHC] related to LS, and body mass index [BMI]) associated to their absence in EC patients attending the University District Hospital of San Juan, Puerto Rico. Method/Materials Twenty cases were preliminary evaluated for the MMR protein expression by immunohistochemistry testing and classified as positive-cases (presence of protein) or negative-cases (absence of protein). The statistical analysis was based on the logistic regression model using the Maximum Likelihood estimation (MLE). The Bayesian approach was used to determine the posterior probability {posterior Pr[OR>1]}. Results Results showed absence for at least one MMR protein in 25% of the cases; 15% for hMLH1 and 10% for hMSH2. None of the cases showed an absence for hMSH6. The MLE demonstrated that women diagnosed with EC before the age of 50 (OR: 12.4; 95%CI = 0.5–322.7), having FHC related to LS (OR: 17.7; 95%CI = 0.6–534.6), and having lower BMI (OR: 2.38; 95%CI = 0.39–14.28) present higher odds than their counterparts of lacking an MMR protein, once adjusting for potential predictors (p > .05). The posterior probability that an excess risk of lacking an MMR protein occurs was ≥ 95% for each predictor. Conclusion Our study in this Hispanic population supports previous studies in that younger age, FHC, and lower BMI are associated with increased odds of having an absence of MMR protein expression. Further studies with larger sample sizes should be performed.

BACKGROUND: In Puerto Rico (PR), colorectal cancer (CRC) represents the second most common cause of cancer in men and women. Incidence and mortality of CRC are increasing in Puerto Rican Hispanics, especially among young individuals. Screening rates for CRC are lower in Hispanic-American individuals compared to non-Hispanic patients. However, there is limited data on genetic epidemiological CRC disparities in Hispanic patients. OBJECTIVES: (1) To prospectively identify and recruit 30 probands with a family history of CRC and 15 family-history negative (2) To prospectively identify and recruit selected relatives from the 45 probands. METHODS: Eligible cases are Hispanic patients with incident diagnosis of CRC, ≥ 21 years old. We identified the probands and their selected family members using the Puerto Rico Central Cancer Registry from July 1, 2007 to the present. PRELIMINARY DATA AND RECRUITMENT: Seven hundred and fifty-one communications were sent to the physicians, three hundred and seventy-four communications were responded (374/751=49.8%).Three hundred and forty-one communications were sent to the patients, one hundred and forty-seven letters were responded (147/341=43.1%) and 16 refused. One hundred and fifty-nine participants (probands and relatives) were enrolled. One hundred and two probands (mean age 56.9 ±13.3 yrs., 54.9% male); 30 with and 72 without family history of CRC. At present, we collected 153 (96.2%) risk factors questionnaires, 135 (84.9%) blood samples and 60 (52.6%) blocks of tissue. CONCLUSIONS: Successful implementation of logistics for identification of incident CRC through the PR Central Cancer Registry during a three-year period. We established the first Familial CRC island-wide registry in Puerto Rico through the implementation of a network of community physicians, laboratories and professional societies. We are developing a tissue and blood bank with epidemiological, nutritional, and demographic data that will assist us to understand the genetic epidemiology of CRC in Puerto Ricans. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3767. doi:10.1158/1538-7445.AM2011-3767