Our study was designed to evaluate associations with use of CAM among breast cancer survivors, particularly since information about CAM in long-term (>10 year) survivors had been lacking. CAM is important to study among breast cancer survivors especially because some of the remedies may interact with conventional treatment or may affect prognosis.
We restricted our CAM variable to “herbal or alternative” remedies in an attempt to create a more cohesive assessment of well-recognized alternative treatments. We found that CAM usage was strongly associated with non-cancer-related medical conditions that were present at follow-up. Cancer-related conditions, type of surgery or type of treatment for breast cancer, on the other hand were not associated with CAM usage. CAM was inversely associated with mental health functioning, but was not associated with physical functioning.
The differences in the observed prevalence of CAM across studies may be related to study design, length of time since diagnosis, CAM definition, age, ethnicity, or population-structure. CAM usage in our study (59%) exceeded usage by healthy adults (36%) [1
], and unaffected family members at risk for breast cancer (42%) [3
], but was similar to that observed in studies of CAM in breast (62–69%) [4
], and other cancer survivors (55%) [7
]. CAM use in our study population was lower compared to a population survey of CAM usage among California cancer survivors (87%) [28
], and California residents (73%) [29
], and higher than that found in a longitudinal study of women with early stage breast cancer (12%) [8
], and, in registry-identified multi-ethnic breast cancer cases in Northern California (48%) [9
Motivation to alleviate cancer-related symptoms may drive breast cancer patients to seek CAM as an alternative. However, women in our study, who developed second breast cancers, recurrences and other cancer-related-conditions, did not use CAM more frequently than women without these health outcomes. Moreover, women who received chemotherapy, radiation or hormonal therapies were not more likely to use CAM either. Some studies suggest that relief of cancer-related symptoms and treatment of cancer are what induces breast cancer patients to turn to CAM [10
]. In the California-based population survey of CAM in cancer survivors, it was found that only a small proportion of CAM use was taken specifically to “treat” cancer [28
] suggesting that the majority of use was for other reasons. We found that CAM usage was associated with non-cancer related medical conditions present after diagnosis and that the likelihood of use increased as a function of the number of medical conditions reported (0, 1, or 2 or more). Quite possibly women in our study population are not seeking CAM to treat their breast cancers but are using it to treat other medical conditions. It is important to note that our study participants have survived breast cancer over 10 years, and the impact of their original diagnosis may have, in general, declined.
Use of alternative therapies may be related to QOL. That is, women may turn to alternative medicine in response to psychological symptoms or distress. We observed significantly lower mental health functioning measured by the SF-36 among CAM users than among non-users. Low SF-36 mental health scores among CAM users was also reported in the Nurses Health Study [6
], the longitudinal study of early stage breast cancer survivors [8
], and the Ganz et al. study of longer-term survivors [11
]. Ganz et al. studied young breast cancer survivors with late treatment effects in a more recent study and found low mental health scores overall, with even lower scores among younger women under age 35 [22
]. We attempted to evaluate CAM usage according to original interview age, however, the proportion of women diagnosed with breast cancer under age 35 in our study population was small, and we could not draw a similar comparison. We further adjusted our association analysis for age and found the association between CAM use and MCS score remained unchanged. The association between CAM use and mental health functioning appears to be independent of age in our study.
We evaluated fear of recurrence in relationship to CAM and found no differences between users and non-users, suggesting that the psychological distress we observed may have reflected other aspects of life rather than breast cancer. Burstein et al. found fear of recurrence, in addition to low mental health functioning, was stronger among CAM users [8
]. Their longitudinal cohort was composed of newly diagnosed breast cancer patients recruited within three months of their diagnosis, while our study population consisted of long-term survivors exclusively. Fear of recurrence may be more likely to occur shortly after diagnosis, as compared to longer periods of time, which may explain why we did not observe an association with CAM usage.
Our study has several limitations which may affect the results we observed. We measured CAM usage in a cross-sectional design so it was unclear whether CAM occurred before or after factors we found were associated with CAM. For instance, CAM may have led to adverse medical conditions, or adverse medical conditions may have prompted CAM usage. Burstein et al. found number of symptoms (side effects of surgery, chemotherapy, radiation as well as other health and cancer-related problems) to be related to new CAM usage in their longitudinal design [8
], but whether the same trend occurred in our study is unclear.
We relied on self reported information about medical and cancer-related co-morbidities and therefore some misclassification may have occurred. Our questions were carefully worded, and we mailed scales and questionnaire items to our participants in advance of the interview to enhance comprehension and consistency of reporting. Length of time since diagnosis may have influenced accurate recall of events immediately post-diagnosis. Any recall bias that may be in operation, however, is unlikely to be differential [30
], since all subjects in the study had breast cancer. Moreover, CAM questions asked about usage within the past six months.
Length of follow-up period is also a strength of our study. We contacted our subjects on the average of 13.2 years since diagnosis. Most studies of CAM in breast cancer survivors have much shorter follow-up periods [3
]. We observed a high prevalence of medical conditions post-diagnosis (83%) in our study sample with 52% having multiple medical conditions. Having one or more than one medical condition was strongly associated with CAM usage. Our results suggest that CAM users have poorer mental health functioning confirming observations from previous studies. Women in our study may be more likely to use CAM for medical conditions, but do not necessarily turn to CAM for cancer-related symptoms.