The contralateral prophylactic mastectomy (CPM) rate has increased dramatically over the past decade. The reasons for this trend are multiple but include patient misperceptions about the risk of contralateral breast cancer (CBC) and how a CPM affects recurrence and survival.1,2 Little is known, however, about surgeons’ knowledge of CPM and CBC and how this informs medical decision making. The literature on these topics is continually evolving, but definitive outcomes data and recommendations for CPM are lacking. Because surgeons are most patients’ preferred source of medical information regarding breast cancer,1 we thought it prudent to examine surgeons’ knowledge of CPM. We hypothesized that surgeons’ knowledge of CPM is variable and represents an opportunity for improved education on the topic.
Methods |
Between December 2013 and February 2014, we emailed a survey to 2436 active members of the American Society of Breast Surgeons, obtaining 592 responses (24.3%). The survey assessed demographics, training, practice characteristics, and knowledge. For knowledge, we presented 2 clinical cases and 3 factual questions developed by breast surgeons and medical oncologists (Table 1). We dichotomized responses into “low” (0–3 correct) and “high” (4–5 correct) knowledge categories and tabulated frequencies. Logistic regression was used to examine which demographic factors predicted a “high level” of knowledge. Institutional review board approval was waived by the authority of NorthShore University HealthSystem in Evanston, Illinois. The surgeons completing the survey did not provide informed consent because the data were deidentified. P < .05 was considered statistically significant.
Table 1.
Knowledge Questions About Contralateral Prophylactic Mastectomy (CPM)
| Question | Answer Options | Correct Answer(s) | Surgeons Who Answered Correctly, No./Total No. (%) |
|---|---|---|---|
| What is the 10-year risk of developing breast cancer in a 40-year-old BRCA carrier newly diagnosed with breast cancer? | <5%, 5%−10%, 10%−20%, 20%−30%, 30%−40%, and/or >40% |
20%−30% or 30%−40%3 |
220/551 (39.9) |
| Does CPM provide a breast cancer-specific survival benefit for patients with early-stage breast cancer? | Yes or no | No4 | 508/557 (91.2) |
| What is the contralateral breast cancer risk at 10 years for a 40-year-old woman with no additional risk factors? | <5%, 5%−10%, 10%−20%, 20%−30%, 30%−40%, and/or >40% |
<5% or 5%−10%5 |
493/548 (90.0) |
| What is the 5-year risk of developing a contralateral breast cancer for an invasive ductal carcinoma patient with no additional risk factors? | <2%, 2%−5%, 5%−10%, 10%−15%, 15%−20%, and/or >20% |
<2% or 2%−5%5 | 482/552 (87.3) |
| In a patient with invasive lobular carcinoma, what risk do you quote of developing a contralateral breast cancer over a 5-year period? | <2%, 2%−5%, 5%−10%, 10%−15%, 15%−20%, and/or >20% |
<2% or 2%−5%5 |
387/548 (70.6) |
Results |
Of the 592 surgeons who completed the survey, 224 (37.8%) had completed fellowship training, 350 (59.1%) were in private practice, 352 (59.5%) were male, and 343 (57.9%) devoted at least 80% of their practice to breast disease. Table 1 lists knowledge questions and answer options that were used in the survey and the ratio of correct answers to each question. In aggregate, 232 (39.2%) of respondents had a “low level” of knowledge, and 360 (60.8%) had a “high level” of knowledge. Surgeons scored 85% or better on questions about the survival benefit of CPM and the 5- and 10-year risk of CBC in patients with no additional risk factors.Working at university/ teaching hospitals, a higher proportion of practice devoted to breast disease, and completion of fellowship training were significantly associated with a high level of knowledge in univariate analyses (Table 2). However, duration of practice and completion of fellowship training remained significant predictors of a high level of knowledge in multivariate analysis.
Table 2.
Univariate Analysis of the Association Between Demographic Factors and Knowledge Score
| Surgeons, No. (%) | ||||
|---|---|---|---|---|
| Characteristics | Total | High Level of Knowledge of CPM (4–5 Correct) | Odds Ratio (95% CI) | P Value |
| Age, y (n = 576) | ||||
| 30–40 | 85 (14.8) | 54 (63.5) | 1 [Reference] | |
| 41–50 | 176 (30.6) | 108 (61.4) | 0.91 (0.53–1.56) | .74 |
| 51–60 | 192 (33.3) | 119 (62.0) | 0.94 (0.55–1.59) | .81 |
| >60 | 123 (21.3) | 72 (58.5) | 0.81 (0.46–1.43) | .47 |
| Years in practice (n = 589) | ||||
| <5 | 47 (8.0) | 23 (48.9) | 1 [Reference] | |
| 5–19 | 251 (42.6) | 159 (63.4) | 1.80 (0.96–3.38) | .07 |
| ≥20 | 291 (49.4) | 178 (61.2) | 1.64 (0.89–3.05) | .12 |
| Work setting (n = 578) | ||||
| Private practice | 350 (60.6) | 202 (57.7) | 1 [Reference] | |
| University/teaching hospital | 163 (28.2) | 114 (69.9) | 1.70 (1.15–2.53) | .01 |
| Other, please specify | 65 (11.2) | 38 (58.5) | 1.03 (0.60–1.76) | .91 |
| Location (n = 585) | ||||
| New England | 132 (22.6) | 77 (58.3) | 1 [Reference] | |
| Midwest | 144 (24.6) | 83 (57.6) | 0.97 (0.60–1.57) | .91 |
| South | 195 (33.3) | 124 (63.6) | 1.25 (0.79–1.96) | .34 |
| West | 114 (19.5) | 73 (64.0) | 1.27 (0.76–2.13) | .36 |
| Proportion of practice devoted to breast disease (n = 580) | ||||
| <20 | 32(5.5) | 16 (50.0) | 1 [Reference] | |
| 20–50 | 114 (19.7) | 59 (51.7) | 1.07 (0.49–2.35) | .86 |
| 50–80 | 87 (15.0) | 50 (57.5) | 1.35 (0.60–3.05) | .47 |
| >80 | 347 (59.8) | 233 (67.1) | 2.04 (1.01–4.24) | .03 |
| Level of postgraduate training (n = 576) | ||||
| General and other surgery residency | 393 (68.2) | 230 (58.5) | 1 [Reference] | |
| Breast surgery/surgical oncology fellowship | 183 (31.8) | 130 (71.0) | 1.74 (1.19–2.54) | .004 |
| Sex (n = 574) | ||||
| Male | 352 (61.3) | 228 (64.8) | 1 [Reference] | |
| Female | 222 (38.7) | 130 (58.6) | 0.77 (0.54–1.09) | .13 |
| No. of CPMs per mo (n = 573) | ||||
| 0 | 80 (13.9) | 48 (60.0) | 1 [Reference] | |
| 1 | 182 (31.8) | 116 (63.7) | 1.17 (0.68–2.01) | .57 |
| 2–4 | 233 (40.7) | 149 (63.9) | 1.18 (0.70–1.99) | .53 |
| 4–6 | 51 (8.9) | 30 (58.8) | 0.95 (0.47–1.95) | .89 |
| >6 | 27 (4.7) | 17 (63.0) | 1.13 (0.46–2.79) | .79 |
Abbreviation: CPM, contralateral prophylactic mastectomy.
Discussion |
Four in 10 respondents to our survey had a low level of knowledge about CPM. Surgeons scored well on questions addressing the survival benefit of CPM and the overall 5- and 10-year risk of CBC, but they did not score as high on CBC risk for specific subgroups of patients such as BRCA carriers and those with lobular carcinoma. Our study was limited in that the knowledge questions only addressed CBC risk and CPM’s effect on survival; we did not address other aspects of CPM such as operative complications, reconstruction risks, or CBC risk for patients with other risk factors. Therefore, our findings may not reflect overall knowledge about CPM. Our low response rate is also a limitation because the nonresponders could have systematically higher or lower levels knowledge than those who responded.
Despite these limitations and to the best of our knowledge, the present study represents the largest and only study in the United States to examine surgeons’ knowledge about CPM. A study of 81 surgeons in Australia asked about CPM but did not question surgeons about CBC risk or survival after CPM.6 What is not clear is how surgeons’ knowledge translates into treatment patterns. Are patients undergoing CPM more frequently because surgeons are not adequately informing them? Could this be because the surgeons themselves are not well informed? Decision aids or teaching materials that address CPM and its utility for a patient with newly diagnosed breast cancer are needed. Part of this intervention will have to involve not only educating patients on CPM’s risks and benefits, but also teaching surgeons how to effectively counsel patients on CPM to ensure informed decision making.
Footnotes
Conflict of Interest Disclosures: None reported.
Author Contributions: Dr Yao had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Yao, Belkora, Sisco, Bedrosian.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Yao, Belkora, Liederbach, Wang.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Yao, Liederbach, Wang.
Administrative, technical, or material support: Yao, Liederbach.
Contributor Information
Katharine Yao, Department of Surgery, NorthShore University HealthSystem, Evanston Hospital, Evanston, Illinois.
Jeff Belkora, University of California, San Francisco, School of Medicine, San Francisco.
Mark Sisco, Department of Surgery, NorthShore University HealthSystem, Evanston Hospital, Evanston, Illinois.
Shoshana Rosenberg, Dana Farber Cancer Institute, Boston, Massachusetts.
Isabelle Bedrosian, Department of Surgery, MD Anderson Cancer Center, Houston, Texas.
Erik Liederbach, Department of Surgery, NorthShore University HealthSystem, Evanston Hospital, Evanston, Illinois.
Chihsiung Wang, Center for Biomedical Research Informatics, NorthShore University HealthSystem, Evanston, Illinois..
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