Familial adenomatous polyposis: data from the Hereditary Colorectal Cancer Registry (HCCR)

ABSTRACT

Family adenomatous polyposis (FAP) is a dominant autossomic disease responsible for nearly 1% of colorectal cancer (CRC) cases caused by mutations in gene APC and nearly complete penetrance. The identification of germinative mutations can be useful in the definition of the therapeutic conduct by means of the correlation genotype-phenotype. Objective: To describe clinical and molecular characteristics of families with FAP or attenuated FAP. Method: The study included families registered in the Hereditary Colorectal Cancer Registry of A.C.Camargo Hospital. Cancer records were registered and heredograms were created. Data were collected and stored in a database. Results: From 1992 to 2007 22 families were registered that had FAP, 16 with classic FAP, nine with Gardner Syndrome, and 6 with attenuated FAP. From 604 individuals, 120 had polyposis, 62 CRC, 10 desmoid tumors, three breast tumors, two tumors of the stomach, two thyroid tumors and one with prostate tumor. From 22 families, three were submitted to molecular analysis and mutations were identified in gene APC. Discussion: Half of the individuals presented CRC concomitant to polyposis, which can indicate a late diagnostic of the disease; three identified mutations presented correlations genotype-phenotype as predicted by the literature. Follow-up of patients with FAP, although they account for less than 1% of CRC cases, is vital for early cancer diagnosis.