Informed consent and research with stored biological samples.

Objective: To report practical experience in obtaining consent for a retrospective study conducted at the Brazilian National Cancer Institute (INCA). The study involved review of medical records and analysis of paraffin blocks of patients surgically treated for colon cancer between 2000 and 2004. Attempts to obtain informed consent were made in compliance with the resolution 196/96 of the Brazilian National Health Council and determination of INCA Research Ethics Committee.
Methods: At scheduled appointments, we could approach only four patients for consent during three months. After attempting contact by phone, an information sheet summarizing the content of informed consent, two copies of the consent form and a prepaid return envelope were then mailed to the patients.
Results: Of the 155 consent forms mailed, 115 were returned (74%). Of these, 111 patients gave consent to participate in the study, one refused consent, and we were informed that three patients had died. The time course of return of these forms ranged from 2 to 89 days (median: 10 days). Attempts to contact patients by phone were successful in 60 out of 160 cases (37.5%). The Research Ethics Committee waived the requirement of consent for those who had died or not responded. Overall mailing cost was R$ 1,004.40.
Conclusion: Obtaining consent from patients by phone and mail for a retrospective clinical study is feasible. Most patients responded to contact and gave consent to participate. However, the process entails costs and risks that cannot be overlooked.