Identification of familial clustering for cancer through the family health strategy program in the municipality of Angra dos Reis, Rio de Janeiro, Brazil.

Abstract

Identification of families with history of cancer in the municipality of Angra dos Reis, Rio de Janeiro (Brazil), through the Brazilian Unified Primary Health Care System was explored based in the Community Health Agents (CHA) program. This study was divided into two phases: a descriptive one with a cross-sectional epidemiological data of families with history of cancer based on CHA-collected data from home visits in four primary health care units. The second phase consisted in identifying familial clustering of three or more individuals with cancer through construction of a three-generation pedigree and revisited by an itinerant group of medical geneticists. Genetic counseling was carried out with the intent of selecting potential families at risk for hereditary familial cancers. In the first phase of the study, 1,581 families were interviewed by the CHA at their homes. A positive history for cancer was present in 42.3% of families, comprising 22.3% with only one case per family, 11.2% with two cases, and 8.6% with three or more cases in the family. The informant reported that 15% of the cases were from the father lineage, 12% from the mother lineage, and 12.1% within siblings. In the remaining 60.9% families, cancer was present in both sides of the family. The types of cancer reported were uterus 8.7% (n = 137), stomach 7.7% (n = 122), breast 6.9% (n = 109), throat 6.8% (n = 99), prostate 5.4% (n = 85), lung 5.6% (n = 88), bowel 3.7% (n = 59), and unspecified sites in 6.8% (n = 108) of families. No statistical differences were noted between the data collected on each primary care unit. In the second phase of the study, 136 families (2.9%) from the total of families interviewed in phase 1 were selected due to the presence of three or more individuals with cancer in the family. Among those, only 73 families attended genetic counseling. Comparison between the data obtained by the CHA and the medical geneticists shows complete agreement in 36 cases (49.3%), partial agreement in 25 cases (34.2%) with more detailed information in the CHA sheets, discordance in 4 cases (5.5%), and not possible to correlate in 8 cases due to identification inconsistency. Risk assessment for cancer was calculated based on the criteria adopted by Scheuner et al. (Genet Med 12(11):726-735, 2010) and revealed that 50.0% of the families were classified as having a weak risk, 36.1% a moderate risk, and 13.8% were considered of high risk. Concerning known hereditary cancer syndromes, we found one family that met the criteria for breast and ovary hereditary cancer (1.4%) and one family with non-polyposis hereditary colon cancer as revised by Bethesda protocol. Such preliminary results indicated that the Brazilian Primary Health Care system based on the CHA framework can be an effective entrance into the Unified Brazilian Health Care System (SUS-Brazil) for individuals with genetically determined diseases, such as familial cancer. Families with a history of three or more cases of cancer and considered of high risk for familial cancer could be referred to a tertiary health center for proper oncogenetic counseling.