We performed a population-based study of the correlates of surgical treatment and adjuvant radiation therapy for women diagnosed with DCIS in 2002 in the metropolitan areas of Los Angeles and Detroit. We found that the receipt of different surgical treatment options was highly associated with recurrence risk when tumor size and histologic grade were used as measures of the risk of recurrence. Nearly nine out of 10 patients in the lowest risk group received BCS, whereas less than half of the patients in the highest risk group received BCS. Surgeon discussion and recommendation seemed to be powerful factors contributing to this practice pattern. Two thirds of patients received a recommendation from their surgeons. Compared with patients in the highest recurrence risk group, patients in the lowest recurrence risk group were more likely to have discussed only BCS with their surgeons and were much more likely to have received a recommendation for BCS. A substantial proportion of women who received a recommendation for mastectomy recalled a clinical contraindication to BCS based on conservative coding criteria. Most women received the surgical treatment recommended by their surgeon(s).
However, patients’ attitudes also were powerful contributing factors to receipt of surgical treatment. Many patients reported that their decision about surgery was greatly influenced by concerns about recurrence of disease and, to a lesser extent, concerns about the side effects of radiation. These patients were much more likely to have received mastectomy compared with patients who reported being less influenced by these concerns. These patient attitudes seemed to explain the large difference between the proportion of women who underwent mastectomy and the proportion of women who reported that their surgeon recommended a mastectomy. For example, more than half of patients in the highest risk group underwent mastectomy, but only approximately one quarter of patients in this group reported that their surgeon recommended a mastectomy. Taken together, surgeon clinical recommendations and patient preferences strongly drove the decision to perform mastectomy; eight of 10 women who had high-risk tumors and were greatly concerned about disease recurrence received mastectomy, whereas only one of 25 women at low risk whose decision was not influenced or was only slightly influenced by recurrence concerns received mastectomy.
Use of radiation therapy after BCS also varied markedly by recurrence risk group. Women with the lowest risk of recurrence were less likely to have received radiation after BCS than women at highest risk. But this was much more the case in Los Angeles than in Detroit. These regional differences seemed to be explained by regional differences in surgeons’ recommendations for radiation after BCS. Patient attitudes also played a role in the receipt of radiation after BCS. Patients who reported being greatly concerned about the side effects of radiation were less likely to have received radiation after BCS. Together, patient attitudes and surgeon attitudes strongly limited the use of radiation after BCS in low-risk women. For example, in Los Angeles, nine of 10 women at highest risk and who were not concerned or only slightly concerned about radiation side effects received radiation after BCS, whereas two of 10 women at lowest risk whose decision was moderately or greatly influenced by concerns about radiation side effects received radiation. These patient and surgeon perspectives seem to reflect legitimate individual variation in attitudes towards risks and benefits of treatment and cannot be deemed inappropriate.
Several aspects of the study merit comment. Although our study was population-based, we had to exclude Asian women with DCIS in Los Angeles because of their involvement in other studies. Thus, our findings cannot be generalized to this group. The recurrence risk measure we derived was based on tumor size and histologic grade. Other factors, such as patient age and margin status,11–13,18
are predictors of outcomes and may be important factors in surgical treatment decisions. Our risk analyses for both receipt of mastectomy and radiotherapy were adjusted for age. However, pathology data describing margin status was not available. The majority of DCIS presents as mammographic abnormalities, and core needle biopsy is the most common method of diagnosis.29,30
Thus, at the time of initial surgical decision making, margin status is often unknown or may be of limited importance in initial treatment choice. However, after attempts at definitive surgical treatment, margin status assumes much greater importance in decision making because patients with persistent positive margins are at high risk for local recurrence and should undergo mastectomy.15
Although the risk measure we used provides a reasonable approximation of risk status based on what is generally known at an initial surgical consultation, the addition of information about margin status might improve the accuracy of the risk measure. Because persistent positive margins are correlated with tumor size and subsequent receipt of mastectomy, incorporating margin status into the recurrence risk measure would likely strengthen the association between measure and surgeon recommendation for mastectomy that we found in our study. We could have underestimated clinical contraindications to BCS because our coding criteria were conservative and patient reports based on one open-ended question may have been imprecise. The study was necessarily retrospective in design. Patients’ recall of their encounters with clinicians may vary because of the passage of time or be influenced by their posttreatment experiences.
Our results have important implications for patients, providers, and policy. Some investigators and policy groups have argued that persistently high rates of mastectomy for women with noninvasive breast cancer suggest overtreatment,2,6,8,15,17,19,20,31
whereas the failure of women to receive radiation after BCS is considered by some to be undertreatment.2,25,32
However, our findings should temper these concerns because they suggest that surgeon recommendation for mastectomy is infrequent, highly associated with patient report of clinical contraindications to BCS, and highly associated with known clinical indicators of local recurrence risk. Differences between surgeon perspectives in Los Angeles and Detroit regarding radiation after BCS seem to be the result of legitimate differences in the perspectives of regional opinion leaders regarding this issue, especially for patients at low attributable risk of recurrence.17,21
The powerful role patient attitudes and preferences play in treatment decision making underscores the need for clinicians to communicate clearly about risks and benefits of treatment. Prognosis for patients with DCIS is excellent across several treatment options. Yet, a substantial proportion of patients with DCIS do not accurately recall basic information about risks and benefits of treatment (Fagerlin et al, submitted for publication).33
Thus, it is particularly important to discuss survival and local recurrence risk issues with patients. Improving the precision of clinical recurrence risk assessment for women with DCIS may help facilitate these discussions and ultimately improve the match between patient preferences and appropriate receipt of local therapy.