NCCN guidelines recommend consideration of adjuvant HT for women undergoing BCS for DCIS. However, wide practice variation in recommendations for use and uptake of these therapies for DCIS suggests that communication with physicians can exert a strong influence on whether or not patients use these medications.1,13,18,19
This study identified several patient, tumor, treatment, and physician-patient communication-related factors associated with the discussion, use, and discontinuation of adjuvant HT in a demographically and ethnically diverse sample of women.
In multivariable analysis, Latina Spanish-speaking women were less likely than white women to discuss adjuvant HT with their physicians, in contrast to research by Nakhlis et al.,18
which found no differences according to race/ethnicity in the proportion of women who were offered tamoxifen for treatment of in situ or early stage breast cancer by their physicians. Prior research indicates that Latina women in particular perceive the physician-patient relationship as important and may rely heavily on physicians to make treatment decisions.28,29
As a result, the lower likelihood of discussing adjuvant HT with a physician observed for Latina Spanish speakers may have important implications for treatment initiation and adherence within this group. Although there were no significant differences in the use of adjuvant HT according to ethnicity/language in our sample, Latina Spanish speakers in our sample who did report use of adjuvant HT were more likely than white women to discontinue use.
The lack of a significant ethnic difference we found in use of adjuvant HT is in contrast to research by Bickell et al.,21
which found that among women with invasive breast cancer, racial/ethnic minority women (Hispanic and African American women combined) were less likely than white women to use adjuvant therapy (hormonal or chemotherapy) for breast cancer treatment. However, the combined analysis of use of adjuvant HT or chemotherapy, rather than looking at outcomes of HT and chemotherapy separately, may account for this difference, and primary language was not accounted for. Additionally, factors associated with use for DCIS may differ from factors associated with use for invasive disease.
The higher likelihood of discontinuing adjuvant HT among Latina Spanish speakers may reflect poorer understanding upfront of the potential side effects or complications associated with treatment or the optimal length of time for which the therapy should be taken. Prior research suggests that breast cancer physicians simplify their discussion of treatment risks and benefits when communicating with patients of limited English proficiency.30
Thus, unanticipated side effects may be one reason for discontinuation of HT. Latina English speakers were equally likely to discuss, use, and discontinue adjuvant HT as white women, supporting the notion that there is heterogeneity among Latina women and that differences by primary language in this ethnic group should be considered.
Other patient demographic characteristics, including education level, were not associated with either discussing or using adjuvant therapy. However, women with less than a high school education were less likely than women with a college education or beyond to discontinue use of adjuvant HT. This finding is inconsistent with prior research among women with invasive disease indicating that women of low SES are more likely to discontinue treatment.26
In addition, women in our sample with a family history of breast cancer were more likely to discontinue use of adjuvant HT, also inconsistent with prior literature demonstrating that higher perceived risk among breast cancer patients is positively associated with adherence for women with invasive disease.26
Further research is needed to explore these relationships and adherence to adjuvant HT for DCIS.
Women treated with BCS, including radiation, were more likely to discuss adjuvant HT with their physician. This finding is consistent with the fact that tamoxifen has been demonstrated to benefit women whose primary treatment included BCS and radiation.12
In contrast, women in our sample who were treated with BCS alone were more likely to discontinue use of adjuvant HT, a finding that may identify a subset of women who opt for a less conservative treatment course overall (e.g., no radiation and discontinuation of adjuvant HT).
Seeing an oncologist for follow-up care was also strongly associated with both discussion of and use of adjuvant HT, consistent with prior research among women with invasive disease that found that referral to an oncologist was positively associated with adjuvant therapy use.21
This underscores the important role that physician specialty plays in use of adjuvant HT. Although we do not know from our data whether women took adjuvant HT as a result of seeing an oncologist or saw an oncologist as a result of taking adjuvant HT, the former scenario is more likely. We could not determine why some patients were referred to see a medical oncologist, although overall, 77% reported an oncology visit for DCIS.
Finally, the importance of physician recommendation in the use of adjuvant HT for DCIS is illustrated in our findings. The high proportion of women in our study who reported discussing adjuvant HT with their physician (>80%) suggests that despite the lack of agreement among physicians on its usefulness, adjuvant HT is being discussed with this group of women. The smaller percentage of women, roughly half of the sample, who reported actually using this type of treatment, suggests that other factors, such as the strength of the recommendation, may play a role in the decision to use adjuvant HT. Women in our sample who indicated that adjuvant HT was not recommended by their physician (i.e., was unnecessary) or was not discussed were far less likely to use adjuvant HT than those who were told it was optional. Similarly, women who were told that the treatment was necessary were far more likely to use and far less likely to discontinue use compared to women who were told that the treatment was optional. Results can be compared to findings from one study demonstrating a high correlation between physician recommendation and the decision to use tamoxifen, although the analysis was conducted among women at high risk for breast cancer, not among those who had already developed disease.31
Results are also consistent with findings from women with invasive breast cancer, indicating that physician recommendation is positively associated with adherence to adjuvant HT.26,27
Physician recommendation may be one of the most influential factors driving use of adjuvant HT. As we noted earlier, in light of the demonstrated benefit of tamoxifen among women whose primary treatment included BCS and radiation,12
we might expect women who were initially treated with BCS followed by radiation to be more likely to both discuss and use adjuvant HT than women treated with mastectomy or BCS without radiation. Although this group of women was more likely to discuss adjuvant HT than were women treated with mastectomy, these women were not more likely to use adjuvant HT in our multivariable adjusted analysis. This finding underscores the importance of physician recommendation in that despite the presence of prior treatment characteristics to guide the use of adjuvant HT, physician recommendation appeared to have the strongest influence on use of treatment.
Our study has several limitations. The sample included women with ER−/PR− tumors who may not be expected to benefit from adjuvant HT, as well as women with tumors of unknown hormone receptor status, although we controlled for hormone receptor status in the analysis. Of note, data from the NASBP B24 trial demonstrated a reduction in risk of ipsilateral and contralateral breast cancer events among hormone receptor-negative DCIS tumors, albeit a smaller reduction in risk than was demonstrated for hormone receptor-positive tumors.1,32,33
It is plausible that in our sample, some physicians of women with ER-/PR- disease may have recommended adjuvant HT for their patients in order to prevent future breast cancer-related events. Additionally, although ER/PR status was not reported for all patients in CCR/SEER records, the treating physicians for some of these women may have known the tumor status and treated their patients accordingly.
Although our study relied on self-reported use of adjuvant HT, which was collected retrospectively, several validation studies have documented that self-reported use of adjuvant HT obtained from breast cancer survivors can be considered a valid proxy for treatment information contained in medical records.34–36
Further, although women in the sample were diagnosed over a range of years and those women diagnosed in earlier years had a greater opportunity to have discontinued use by the time they were interviewed, our analysis was adjusted for time between diagnosis and interview to control for this source of bias.