Purpose: Cancer survivors face risks of cancer recurrence in addition to elevated risks of new cancers. But, do people think about these risks in the same ways? Concern that the prior cancer might still be "inside me" could give it special status, making the risk of its recurrence seem more likely or more worrisome than equally likely risks of a new cancer.

Methods: 911 people recruited from a demographically balanced sample completed an Internet survey on medical decision making. One scenario asked respondents to imagine that they previously had either skin cancer or thyroid cancer (randomized), which was successfully treated into remission. Respondents were then informed of two future risks (in random order): the risk of recurrence of their prior cancer and the risk of developing the alternate cancer. The first risk seen was numerically defined (1%), while the second was said to have a "very similar" likelihood. This yields a 2x2 factorial design: original cancer type X order of presentation. Respondents indicated which risk they felt was more likely: skin, thyroid, or both equal, and rated how much they would worry about each cancer risk. We tested for differences in the proportion of subjects rating recurrence risks as more likely and for differences in mean ratings of worry.

Results: Of respondents imagining being a skin cancer survivor, 43% felt that skin cancer recurrence was more likely than a new thyroid cancer, 5% perceived thyroid cancer as more likely, and 52% said both risks were equally likely (with no significant order effects). Yet, for respondents imagining being a thyroid cancer survivor, these percentages were: Skin: 10%, Thyroid: 44%, Equal: 46% (Χ²(2)=225.93, p<0.0001). Thus, almost half of respondents saw recurrence risks as more likely, regardless of cancer type. Similarly, worry about recurrence risks was significantly higher than worry about new cancer risks in all conditions (M=5.64 vs. 3.57 on a 0-10 scale, p<0.0001).

Conclusions: Many people see cancer recurrence as more likely and more worrisome than an equally likely new cancer, even when cancer type is randomly varied. The extra consideration given to the possibility of cancer recurrence may influence how patients assess the risk-benefit tradeoff of adjuvant therapies (likely encouraging more invasive approaches), which may in turn decrease the quality of life of cancer survivors.