Manipulating perceptions of colorectal cancer threat: implications for screening intentions and behaviors

Affecting peoples' perceptions of the health threat of colorectal cancer (CRC), that is, the probability of the cancer's occurrence multiplied by the severity of the outcomes, has not been experimentally manipulated as a means to increase CRC screening intentions and behaviors. As an exploratory pilot study to inform a larger randomized trial on CRC screening, we used a four-group pre-post longitudinal design to test whether providing information about: 1) colorectal cancer risks (no/yes) and, 2) the severity of treatment and illness consequences (no/yes) affected CRC screening intentions (i.e., fecal occult blood test/sigmoidoscopy) and behaviors at a six-month follow-up. The sample consisted of 119 men and women aged 50 and older who were off schedule for having a fecal occult blood test (FOBT). Although perceptions of CRC risks were not affected by the experimental manipulations, perceived severity increased screening intentions for FOBT and lowered felt ambivalence towards FOBT. At the six-month follow-up, 31% participants had a FOBT. Participants who received severity information were significantly more likely to report having had a FOBT. These results suggest that: 1) more attention needs to be given to developing strategies to affect perception of CRC risk, and 2) increasing the perceived severity of CRC is an important construct to increase FOBT screening.