We examined whether screening behavior of siblings, friends, coworkers, and spouses influenced analogous screening behaviors of individuals. We found that mammography screening increases with an increasing proportion of sisters who have had a mammogram (although women with more sisters were less likely to get mammograms, a finding of borderline statistical significance). PSA testing did not vary by the proportion of brothers, friends, or coworkers who had the test. Colorectal cancer screening was strongly associated with screening among one’s spouse, but not with the proportion of friends who were screened.
Several studies suggest that support of others increases an individual’s likelihood of participating in cancer screening. For example, women with higher scores on the social network index6, 7
or who report social support from physicians, family, and friends8
are more likely to undergo mammography and Pap smears. In addition, a study of employed women found that women who perceived that screening is normative among their peers were more likely to undergo regular mammography, although the extent of social support and the size of one’s social network was not associated with screening behavior.9
On the other hand, two studies have observed that women reporting explicit encouragement to undergo mammography by social network members were less likely to be screened,9, 32
suggesting that the women who avoid mammography may be more likely to be offered encouragement from others. Perceived risk of cancer is also associated with mammography screening, and this perceived risk is often due to a family history of cancer.33
In a previous study using data from the Framingham study, reporting a family history of breast cancer was strongly associated with reporting a mammogram in the last 2 years.34
In the current study, we were able to broaden the scope of social contacts examined (to include friends and coworkers), broaden the nature of cancers considered, and, most important, trace out direct ties between people and directly query alters about screening behavior rather than merely surveying egos about alters.
Past research suggests that friends can influence mammography behavior with direct efforts. One study randomized individuals to call or not call friends to encourage them to get a mammogram. Friends who received a call had a 15% increase in mammography compared with those who did not receive a call. This effect remained after controlling for demographic characteristics, was effective for black and white women of all ages, and was most pronounced among women with lower household incomes.35
In addition, women reporting close friends with whom they could discuss their health were more likely to have ever had a Pap smear.11
Programs have thus been developed that successfully use social support to improve screening for cervical cancer and breast cancer.36
Fewer data are available about the impact of interventions on social contacts on prostate cancer screening or colorectal cancer screening. The value of PSA testing for prostate cancer remains controversial,37
yet research suggests that patients deciding about PSA testing value anecdotes about the decisions of friends, family, or media celebrities.38
Thus, we had expected that the prostate screening behaviors of alters would influence those of the egos in our study. Consistent with other research,39
we found that married men were more likely than unmarried men to undergo PSA screening. Men may be encouraged by their wives to get more routine and preventive care, or may be persuaded to get PSA testing specifically.
Colorectal cancer screening can be inconvenient and invasive, and, for colonoscopy, requires time off from work and someone to accompany the individual to the procedure. These factors may lead to negative attitudes about screening.40
Nevertheless, support from friends and family has been associated with screening, as have positive attitudes about the screening and beliefs that it is safe.41
We found a strong association of colorectal cancer screening among spouses of individuals who have been screened, but no associations based on the proportion of siblings, friends, or coworkers who were screened.
Overall, this work again reinforces the distinction between social support and social network effects.42
The existence of social ties, and the willingness of others to help with health care can affect screening, as suggested by prior work. However, this is a different effect than that of the specific influence whereby an alter’s actual behavior influences a similar behavior in an ego. By analogy, it is the difference between the impact on a person’s happiness of having many friends versus the impact on a person’s happiness of having friends who are themselves happy.43
We found that the screening behaviors of one’s contacts, at least among those contacts included in the study, had little relevance to screening behaviors. Screening behaviors may be less “contagious” because they are not easily observed (unlike smoking, alcohol, obesity, and happiness)18–20, 43
and may not be comfortable topics to discuss. New evidence suggests that ties among friends are influenced by observable characteristics such as obesity and smoking, but not by less easily observed traits, such as blood pressure and depression score.44
Our findings should be interpreted in light of some limitations. First, information on screening was only collected in two waves of the Framingham Study, both during the late 1990s. Thus, we cannot be certain that the findings are relevant to current screening behaviors; screening rates for colorectal cancer have increased since this time,45
although our study period corresponded with the peaking of mammography rates, which declined in the early 2000s.46
Second, our study focused on a single community that was lacking in racial and ethnic diversity, so the generalizability of our findings to other populations requires further study. Rates of prostate cancer screening in our cohort were lower than those of colorectal cancer screening, which has not been observed nationally.47
Third, we could only assess screening behaviors among alters who were included in the Framingham cohorts and of ages that would make them eligible for screening themselves, and our cohort of egos had relatively few alters in the study, limiting our power to observe effects. Moreover, if an individual had many friends but few were in the Framingham cohorts, then our study would likely underestimate the effects of the other friends’ behaviors. Fourth, the survey question about stool blood testing did not distinguish in-office or at-home testing. Finally, self-report of screening may overestimate use.48
In conclusion, mammography receipt among sisters and colorectal screening among spouses slightly influenced personal screening behaviors, but otherwise screening behaviors of siblings, friends, and coworkers were not associated with increased rates of cancer-specific screening. These observations suggest that while many health behaviors may spread across social ties, not all health behaviors necessarily do. Some behaviors may be intrinsically more “contagious”, just like some fashions are easier to adopt and some germs are more contagious than others.