How well informed is the informed consent for cancer clinical trials?

The purpose of this study was to analyze the content of informed consent forms for clinical trials in medical oncology to assess readability, determine their completeness, and identify any shortcomings.

Informed consent forms for Phase I-III studies that were conducted at two tertiary care cancer centers over a 3-year period were reviewed. Information pertaining to length of the informed consent form, research regimen/methods, treatment agent, potential risks, and benefits was extracted. The reading level was assessed by Flesch-Kincaid and Gunning-Fog index readability tests.

All of the 112 informed consent forms clearly stated the voluntary nature of participation. Nearly one half of the forms (51.8%) were of Phase I studies. The median length of informed consent form was 20 pages (range: 8-28). A detailed estimation of the frequency or intensity of risks (range: 3-8 pages) was provided. The average reading level of the informed consent forms was high (Flesch-Kincaid Grade Level of 9.8), which corresponds roughly to 10th-grade reading level. Less than 15% of all consent forms were written at the recommended eighth-grade reading level. A substantial number of forms did not report a potential risk to pregnant/lactating women (16.9%), mechanism of action of the investigational agent (34.8%), study schema (77.6%), a possibility of receiving sub-therapeutic dose (37%), or death (12.5%). Nearly one half of the forms (49.1%) stated clearly that individual participants may not benefit.

Overall, these informed consent forms provided a detailed description of the trials in accordance to international guidelines. However, there remains room for improvement, particularly in areas of readability and document length.