A Family-Based Study of Genes and Environment in Young-Onset Breast Cancer

To study environmental and genetic causes of young onset breast cancer, we recruited women who had been young when recently diagnosed (under age 50 and within 4 years of enrollment), and had been identified as potentially eligible by a sister who was already participating in the ongoing Sister Study. The unaffected sister had already provided consent, questionnaire-based information and DNA (blood-based) when she enrolled in the Sister Study. Her case sister then provided comparable questionnaire-based information and DNA via a mail-back saliva collection kit. To enable family-based analyses, parents were also asked to (only) provide consent and a saliva sample. Because the cases were young-onset, most parents were alive, but unavailability of the parents was not a basis for exclusion. The study was funded in part by Susan G. Komen for the Cure.]]>
Controls were women whose sister had been diagnosed with breast cancer. They had to be between 35 and 75 years old, be living in the US or Puerto Rico, and be fluent in either English or Spanish. They agreed to be followed over time, to participate in two lengthy interviews by phone and submit to a blood draw, urine and house dust collection, and measurement of blood pressure and weight. They provided informed consent. Their information included their sister's age at diagnosis and how recently it had occurred. The sister did not have to be living. Cases were women whose full sister was fully enrolled in the Sister Study. They had to be able to answer questions in English and they had to have been diagnosed before age 50 and within 4 years of enrollment. They agreed to be followed over time, to participate in three interviews by phone and provide saliva for DNA extraction via a mail-back kit (Oragene) and they provided informed consent. They were asked to send a letter from us to their parents, inviting them to provide saliva samples. Parents provided informed consent for genotyping. The consent forms all made clear that genotype results would not be returned to participants. When both parents were available, the control sister was not genotyped, as non-transmitted parental alleles can fill that role.]]>
Enrollment was carried out between September, 2008 and December, 2010, and 1422 case sisters were enrolled. When new young-onset (under age 50) cases were reported to study staff during follow-up in the Sister Study, we also asked them to invite their parents to provide a saliva sample. So the study has been augmented by including family members as available for young-onset Sister Study participants. A few of those also had an unaffected sister participating in Sister, but most did not. The study will also be following the case cohort made up of Two Sister cases together with the incident cases from the Sister Study in order to identify genetic and environmental factors that promote healthy and recurrence-free survival.]]>