Our overall findings from this study suggest that both colon cancer cases and relatives of cancer patients would like to know if they or a member of their immediate family is a carrier of a genetic mutation for cancer. Further, the sample population would most likely inform their spouse, parents, siblings, and children. Over 90% of both cases and relatives anticipated that their practice and promotion of cancer prevention behaviors (i.e., diet, exercise, and screening) would change if a genetic test showed that they themselves or their family members were at increased risk for cancer.
Overall, these data are consistent with the findings of Petersen and colleagues (1999)
, who reported that over 90% of relatives agreed that they would be interested in receiving information about their genetic susceptibility to cancer. Although Peterson and colleagues did report a positive association between the strength of family history for colon cancer (i.e., number of family members diagnosed with colon cancer) and perception of risk, similar to our study, family history was not related to willingness to undergo testing. Although retrospective studies have reported some barriers to communication during disclosure among colon cancer cases (Kohut et al., 2007
), they have also revealed a strong willingness and a sense of obligation to disclose both positive and negative genetic test results to relatives (Peterson et al., 2003
; Kohut et al., 2007
). The willingness to disclose information in these studies was largely equivalent to the levels identified in the current investigation. Recognizing that relatives have similar concerns and interests as do colon cancer cases to learn about genetic status and disclosure provides preliminary evidence that the topic of genetic testing is an acceptable option for many with a family history of colon cancer.
However, multiple studies have shown that disclosure and dissemination of genetic information needs to be considered on a case-by-case basis (Esplen et al., 2001
; Koehly et al., 2003
; Pentz et al., 2005
; Gilbar, 2007
). While identifying genetic susceptibility to cancer provides an opportunity for preventive behavior, including improvement in diet, exercise, and screening practices, negative consequences are also possible. For example, a recent paper by Lynch et al. (2007)
noted the potential emotional distress that may occur following identification of a genetic susceptibility to cancer, as well as the distress that those who have negative or ambiguous results can experience. These findings highlight the importance of evaluating participant willingness a priori
to receive such information and discussing implications of results. Several authors (Bookman et al., 2006
; Burke and Press, 2006
) have drafted guidelines regarding the selection of individuals for genetic testing and a program of individualized assessments to discuss testing and dissemination. Our study, which assessed the opinions of a subset of individuals from the Seattle C-CFR, was conducted as an initial step in this process of disclosure for participants enrolled in the cancer registry.
This study had many strengths, including the population-based nature of the sample. The wide age and gender distribution enhance the generalizability of study results to the larger Seattle C-CFR population. This encourages further work into the interest and disclosure of genetic status among individuals enrolled in the C-CFR and their relatives, as well as colorectal cancer families in the population.
Some limitations should be considered, however. First, the sample size was limited, and the relative group was not an independent series. Caution should be taken in generalizing these findings to other populations. Second, participants enrolled in the C-CFR may be more willing than the general population to discuss factors that may contribute to increased risk of cancer. Third, our participants were predominantly Caucasian, of higher education, and of higher income compared to national averages (Buckner, 2004
, May 10; U.S. Census Bureau, 2006
). This feature is generally similar to individuals enrolled in the larger Seattle C-CFR, the population from which our participants arose, and Seattle in general. Previous research studies have found mixed results with regard to education and income effects on interest and intent to undergo genetic screening for cancer susceptibility (Lerman et al., 1996
; Petersen et al., 1999
; Satia et al., 2006
). For example, in contrast to the current study, studies with similar educational distributions to ours showed no relationship between education and willingness to undergo genetic screening (Glanz et al., 1999
; Petersen et al., 1999
; Kinney et al., 2001
). While age, education, and income were significant predictors of participant response in this study, the inclusion of these variables in the multiple regression analysis did not significantly affect differences (or lack of differences) between cases and relatives.
Future studies can address the potential limitations of C-CFR participation, education, and income by including a true unaffected population-based control group. Factors, such as age, that may have influenced the difference between cases and relatives in personal cancer screening behaviors should also be investigated to determine if the difference is because of increased awareness or a reduced sense of urgency among our younger relatives. Finally, although the assessment tool did elicit responses regarding a wide range of issues in genetic testing, it should be expanded to include more comprehensive questioning about the issue of genetic testing for colorectal cancer specifically, and for LS status in particular.
In summary, much of the discussion around genetic testing has involved concern about the effect of disclosure on colorectal cancer cases and their relatives. This study was an initial attempt at evaluating the interest and willingness of colorectal cancer cases and relatives enrolled in the population-based registry to receive genetic testing. These findings suggest that relatives of registered cases are as interested in receiving genetic information about cancer risk for them and their family as individuals already diagnosed with colon cancer. Study results suggest that a high percentage of both colorectal cancer cases and relatives are interested in learning the results of genetic tests, disclosing information about their status, and encouraging behavioral changes that may reduce cancer risk.