Annals of Surgical Oncology

, Volume 17, Issue 10, pp 2554–2562

Trends in Contralateral Prophylactic Mastectomy for Unilateral Cancer: A Report From the National Cancer Data Base, 1998–2007

Authors

    • Department of SurgeryUniversity of Chicago, Pritzker School of Medicine, NorthShore University Health System, Evanston Hospital
  • Andrew K. Stewart
    • National Cancer Data Base, Commission on CancerAmerican College of Surgeons
  • David J. Winchester
    • Department of SurgeryUniversity of Chicago, Pritzker School of Medicine, NorthShore University Health System, Evanston Hospital
  • David P. Winchester
    • Department of SurgeryUniversity of Chicago, Pritzker School of Medicine, NorthShore University Health System, Evanston Hospital
Healthcare Policy and Outcomes

DOI: 10.1245/s10434-010-1091-3

Cite this article as:
Yao, K., Stewart, A.K., Winchester, D.J. et al. Ann Surg Oncol (2010) 17: 2554. doi:10.1245/s10434-010-1091-3

Abstract

Background

Several studies have reported an increased rate of contralateral prophylactic mastectomy (CPM) in patients with unilateral breast cancer. This study reports on CPM trends from the American College of Surgeon’s National Cancer Data Base (NCDB) diagnosed over a 10-year period.

Methods

Data about women diagnosed with unilateral breast cancer between 1998 and 2007 undergoing CPM were extracted from the NCDB. Temporal trends were analyzed across patient demographic, tumor, and provider characteristics. Logistic regression models identified characteristics independently associated with use of CPM.

Results

A total of 1,166,456 patients, of whom 23,218 patients underwent CPM, were reviewed; use increased from 0.4% in 1998 to 4.7% in 2007 of surgically treated patients. The greatest comparative increases in CPM was among white patients <40 years of age residing in high socioeconomic status areas with private or managed care insurance plans and treated at high-volume medical centers in the Midwest region of the country. A greater proportion of patients with in-situ disease undergo CPM compared to invasive disease. Independent factors associated with CPM include patient demographic and socioeconomic factors, tumor stage and histopathology, and provider characteristics.

Conclusions

Although an increase in the proportion of surgically treated women undergoing CPM was universally observed across a broad range of patient, biological, and provider factors, the increase was more noticeably associated with patient-related factors rather than tumor or biological characteristics. Further studies are needed to determine why patients seem to choose CPM and whether a survival benefit can be associated with this choice of surgical management.

The reported frequency of contralateral prophylactic mastectomy (CPM) for unilateral breast cancer has been increasing over the past 10 years and has been documented in several recent reports.15 These trends are observed despite any evidence suggesting an increase in the incidence of contralateral cancers, evidence suggesting the lack of survival benefit associated with CPM, and evidence suggesting that some adjuvant therapies decrease the incidence of subsequent primary breast cancers. The reasons for these increased trends are likely multifactorial and complex.

In this study, we report CPM trends among women with unilateral breast cancer whose data were reported to the American College of Surgeon’s National Cancer Data Base (NCDB), a prospectively collected database containing over three million breast cancer patients. Patient demographics, hospital factors, and tumor characteristics were examined to determine which factors are most likely associated with the use of CPM. This study reports on cases over a 10-year period and to our knowledge represents the largest cohort of patients to date in a study examining the use of CPM among surgically treated breast cancer patients.

Materials and Methods

Data Source

The NCDB, a joint project of the American Cancer Society and the Commission on Cancer (CoC) of the American College of Surgeons, is a nationwide, facility-based oncology data set that currently captures 70% of all newly diagnosed malignant cancers in the United States annually reported from approximately 1450 hospitals with CoC-accredited cancer programs. Data reported from these hospital-based cancer registries include patient demographics, American Joint Committee on Cancer (AJCC) staging and tumor histopathology characteristics, first-course treatment, and vital status follow-up information. Area-based indicators of socioeconomic status and facility level characteristics are also available through the NCDB. Data are coded and reported according to nationally established protocols coordinated under the auspices of the North American Association of Central Cancer Registries. The NCDB currently contains information on approximately 25 million cancer cases, diagnosed between 1985 and 2007. Aspects of the NCDB data have been described elsewhere.6,7

This study was in compliance with the privacy requirements of the Health Insurance Portability and Accountability Act of 1996 as reported in the Standards for Privacy of Individually Identifiable Health Information (Final Rule, 45 CFR, Parts 160 and 164). No patient, provider, or hospital identifiers were examined in this study, no protected health information was reviewed, and the analysis was retrospective. Institutional review board approval was not required for this study.

Study Population

Data from 1,890,972 women diagnosed with breast cancer between January 1, 1998, and December 31, 2007, were queried from the NCDB. The study cohort was further limited to adults (>19 years of age at diagnosis) diagnosed with unilateral AJCC stage 0, I, II, or III solid tumors originating in the breast that were surgically treated and who received all or part of their first treatment at nonfederal hospitals that are currently CoC accredited. Patients with tumor histologies of infiltrating duct carcinoma, infiltrating lobular carcinoma, ductal carcinoma-in-situ, and 12 other specified types were retained for analysis. Women with multiple primary breast cancers diagnosed within a year of one another were excluded. A total of 1,166,456 cases met the eligibility criteria for this study.

Data

Patient age was stratified into deciles. Patient race was categorized as non-Hispanic white, black, Hispanic, Asian/Pacific Islanders, and other. Patient insurance status at the time of diagnosis was grouped into the following categories: uninsured, self-pay, insured not otherwise specified (NOS), managed care, Medicaid, and Medicare. Area-based indicators of income and educational attainment were derived at the zip code level from 2000 U.S. Census data and included as quartiles of the observed distribution in the general U.S. population. Geographic region was based on the reported state of residence at diagnosis and categorized as Northeast, Southeast, Atlantic, Great Lakes, South, Midwest, West, Mountain, and Pacific, as classified in the United States Census Report.8

Tumor size (T) and regional lymph node involvement (N) were categorized according to the definition of the AJCC 5th and 6th editions.9,10 Tumor histology was limited to ICD-O classification codes for ductal carcinoma-in-situ, infiltrating duct carcinoma, lobular carcinoma, and other specified types.11 Tumor grade was classified as I/II (low–intermediate grade) and III (high). Patient comorbid disease status is represented by Dayo’s adoption of Charlson’s comorbidity index.12

Facility-level characteristics included the type of cancer program (community, comprehensive community, and teaching center) and the annual volume of surgically treated breast cancer patients. Community hospitals treat at least 300 cancer patients of all types per year and have a full range of services for cancer care, but patients may be referred for portions of their treatment. Comprehensive community cancer centers are facilities that offer the same range of services as the community hospitals but treat at least 750 annual cancer patients and conduct weekly cancer conferences. Teaching or research facilities have residency programs and ongoing cancer research. Volume categories were created by computing a weighted average of the number of surgically treated breast cancer patients at each reporting cancer program for the years 2005 to 2007 and dividing the distribution into equal-sized quartiles of facilities: <45, 45–84, 85–144, and ≥145.

Patients were dichotomized into two groups: those undergoing bilateral total mastectomy for unilateral cancer with or without reconstructive surgery, and those undergoing lumpectomy or breast conservation surgery, total mastectomy (with or without reconstructive surgery), modified radical mastectomy (unilateral or bilateral, with or without reconstruction), or surgery NOS.

Statistical Analysis

All analyses were performed by the SPSS statistical software (SPSS for Windows, version 13; SPSS, Chicago, IL). All statistical tests were two-sided, and a P value of ≤0.05 was considered statistically significant. Forward stepwise binary logistic regression modeling was used to evaluate the effect of patient, biologic, and structural factors on determination of type of surgical treatment (CPM compared to other surgeries). The Wald statistic was used to test significance. Exponentiated estimates of the beta coefficients were interpreted as the estimates for the adjusted effect (odds ratio, OR) of a particular variable.

Results

Patient Demographics and Tumor Characteristics

Data from 1,166,456 women with unilateral breast cancer were examined; 23,218 of these patients underwent CPM. Over the 10-year period reviewed, the proportion of women undergoing CPM increased from 0.4% (n = 395) in 1998 to 4.7% (n = 5835) in 2007 (Table 1). The average age of patients was 61.2 years, but age declined slightly from 61.6 years in 1998 to 60.8 years in 2007 (P < 0.0001). Between the earlier and later years of the study cohort, the slight proportional increase of 40- to 69-year-olds from 62.3 to 66.8% and concomitant decrease in the proportion of 70- to 79-year-olds from 21.5 to 17.7% underpins this decline. An increasing proportional representation of nonwhite patients (black, Hispanic, and women of Asian/Pacific Island origin) was also observed among reported breast cancer cases, increasing from 13.2% to 16.9%. Other patient demographic characteristics remained relatively unchanged.
Table 1

Proportion of surgically treated female breast cancer patients with unilateral disease undergoing bilateral mastectomy

Year of diagnosis

No. of surgically treated cases

Bilateral mastectomy

n

%

1998

105,864

395

0.4

1999

111,850

635

0.6

2000

120,653

933

0.8

2001

120,583

1,290

1.1

2002

121,534

1,657

1.4

2003

111,676

2,257

2.0

2004

114,327

2,657

2.3

2005

115,844

3,266

2.8

2006

120,574

4,293

3.6

2007

123,551

5,835

4.7

Total

1,166,456

23,218

Patient Factors

The frequency with which women aged <40 years receiving CPM increased; more than 10.5% of women aged <40 underwent CPM, and women aged 40 to 49 were 39% less likely to undergo CPM compared to those in their 20s (OR = 0.61 95% confidence interval [95% CI], 0.51–0.73), and women ≥80 years were 95% less likely (OR = 0.05 95% CI, 0.04–0.06) (Fig. 1a; Table 2). By 2006–2007, white women were statistically significantly more frequently treated with CPM than black, Hispanic, or women of Asian/Pacific Island heritage, increasing from 0.5 to 4.5% (Table 2). Women with private insurance were more than twice as likely to undergo CPM compared to uninsured or patients covered by Medicare as their primary insurer (Fig. 1b; Table 2). At the end of this study period, women from socioeconomically advantaged areas were twice as likely to undergo CPM than women in the least advantaged areas: OR = 2.1, 95% CI 1.94–2.28 for patients living in the highest income areas, and OR = 2.11, 95% CI 1.96–2.27 where areas have the lowest proportion of the population without a high school diploma (Table 2). Patients living in the Midwest region of the country were the most likely to undergo CPM (OR = 1.97, 95% CI 1.78–2.18), followed by patients in the South and Mountain regions, respectively (Table 2).
https://static-content.springer.com/image/art%3A10.1245%2Fs10434-010-1091-3/MediaObjects/10434_2010_1091_Fig1_HTML.gif
Fig. 1

a Percentage by age, b percentage by insurance status, c percentage by household income

Table 2

Demographics and tumor characteristics of surgically treated breast cancer patients diagnosed in 1998–1999 and 2006–2007

 

1998–1999

2006–2007

OR

95% CI

All surgeries

Bilateral mastectomy

All surgeries

Bilateral mastectomy

n

%

n

%

Age (y)

 20–29

886

15

1.7

1,076

133

12.4

1 (ref)

 

 30–39

10,811

109

1.0

10,623

1,245

11.7

0.941

0.778–1.139

 40–49

37,480

329

0.9

43,888

3,467

7.9

0.608

0.506–0.732

 50–59

51,078

290

0.6

60,916

2,868

4.7

0.350

0.291–0.422

 60–69

46,966

158

0.3

58,190

1,659

2.9

0.208

0.172–0.251

 70–79

46,828

80

0.2

43,369

588

1.4

0.097

0.080–0.119

 80+

23,665

49

0.2

26,063

168

0.6

0.046

0.036–0.058

Race

 White

186,052

925

0.5

198,281

8,884

4.5

1 (ref)

 

 Black

17,866

50

0.3

24,019

528

2.2

0.479

0.438–0.524

 Hispanic

6,463

21

0.3

10,206

301

2.9

0.648

0.577–0.728

 Asian/Pacific Islands

4,219

14

0.3

6,530

193

3.0

0.649

0.562–0.750

 Other/unknown

3,114

20

0.6

5,089

222

4.4

  

Insurance status

 Not insured

1,888

5

0.3

1,651

45

2.7

1 (ref)

 

 Self-pay

3,230

10

0.3

2,670

75

2.8

1.031

0.709–1.500

 Insured, NOS

51,232

323

0.6

28,834

1,547

5.4

2.023

1.498–2.733

 Managed care

67,418

471

0.7

102,399

6,345

6.2

2.357

1.751–3.174

 Medicaid

6,064

15

0.2

14,450

487

3.4

1.245

0.913–1.697

 Medicare

78,639

160

0.2

87,749

1,430

1.6

0.591

0.438–0.799

 Other/unknown

9,243

46

0.5

6,372

199

3.1

  

Income

 <$30,000

25,166

68

0.3

26,360

658

2.5

1 (ref)

 

 $30,000–$35,999

35,199

137

0.4

38,031

1,261

3.3

1.340

1.217–1.474

 $36,000–$45,999

57,495

225

0.4

64,573

2,413

3.7

1.516

1.389–1.655

 $46,000+

90,705

554

0.6

104,077

5,314

5.1

2.102

1.936–2.282

 Unknown

9,149

46

0.5

11,084

482

4.3

  

Education

 29%+

30,426

76

0.2

33,205

839

2.5

1 (ref)

 

 20–28.9%

44,878

161

0.4

49,366

1,685

3.4

1.363

1.253–1.483

 14–19.9%

48,825

198

0.4

55,184

2,189

4.0

1.593

1.470–1.728

 <14%

84,426

549

0.7

95,277

4,931

5.2

2.105

1.955–2.268

 Unknown

9,159

46

0.5

11,093

484

4.4

  

Census region

 Northeast

15,992

50

0.3

16,986

569

3.3

1 (ref)

 

 Southeast

33,689

157

0.5

36,539

1420

3.9

1.167

1.057–1.288

 Atlantic

43,676

222

0.5

52,348

2065

3.9

1.185

1.078–1.302

 Great Lakes

39,952

141

0.4

43,380

1431

3.3

0.984

0.892–1.086

 South

13,547

64

0.5

14,907

832

5.6

1.706

1.529–1.902

 Midwest

13,759

84

0.6

18,732

1198

6.4

1.971

1.780–2.183

 West

16,397

82

0.5

18,291

736

4.0

1.210

1.082–1.352

 Mountain

9,310

57

0.6

10,535

505

4.8

1.453

1.285–1.642

 Pacific

31,392

173

0.6

32,300

1372

4.2

1.280

1.159–1.414

AJCC stage

 0

8,188

169

2.1

13,874

779

5.6

1 (ref)

 

 I

110,703

465

0.4

121,975

4,894

4.0

0.703

0.650–0.759

 II

83,617

336

0.4

80,175

3,586

4.5

0.787

0.727–0.852

 III

15,206

60

0.4

28,101

869

3.1

0.536

0.486–0.592

Tumor size

 Tis

5,650

129

2.3

11,719

705

6.0

1 (ref)

 

 T1 (<2 cm)

123,799

532

0.4

140,298

5,623

4.0

0.652

0.602–0.707

 T2 (≥2 cm, <5 cm)

68,690

259

0.4

73,129

3,044

4.2

0.679

0.624–0.738

 T3 (≥5 cm)

12,186

59

0.5

13,781

594

4.3

0.704

0.629–0.787

 T4

4,507

16

0.4

3,434

83

2.4

0.387

0.307–0.487

 Unknown

2,882

35

1.2

1,764

79

4.5

  

Regional lymph node status

 N0 (no positive nodes)

133,482

639

0.5

160,314

7,077

4.4

1 (ref)

 

 N1 (1–3+ nodes)

40,693

168

0.4

47,854

2,004

4.2

0.946

0.900–0.996

 N2 (4–9+ nodes)

14,546

48

0.3

15,117

466

3.1

0.689

0.626–0.758

 N3 (≥10+ nodes)

8,115

32

0.4

7,812

214

2.7

0.610

0.531–0.700

 Unknown

20,878

143

0.7

13,028

367

2.8

  

Histology

 DCIS

8,188

169

2.1

13,874

779

5.6

1 (ref)

 

 Infiltrating duct carcinoma

161,733

565

0.3

182,164

7,042

3.9

0.679

0.629–0.733

 Lobular carcinoma

19,733

146

0.7

20,958

1,173

5.6

1.001

0.912–1.099

 Other specified invasive types

27,986

151

0.5

27,145

1,138

4.2

0.739

0.673–0.811

Grade

 I/II

115,005

469

0.4

148,070

5,749

3.9

1 (ref)

 

 III

71,048

314

0.4

80,017

3,607

4.5

1.169

1.120–1.219

 Unknown

31,661

247

0.8

16,038

772

4.8

  

Comorbidity index

 0

NA

NA

NA

207,843

8,996

4.3

1 (ref)

 

 1

NA

NA

NA

28,945

959

3.3

0.757

0.708–0.811

 2+

NA

NA

NA

7,337

173

2.4

0.534

0.458–0.622

Hospital type

 Community

32,059

105

0.3

38,419

867

2.3

1 (ref)

 

 Comprehensive

117,814

496

0.4

132,622

5,428

4.1

1.848

1.719–1.988

 Teaching/research

67,841

429

0.6

73,084

3,833

5.2

2.397

2.225–2.583

Annual surgical case volume

 ≥145

112,947

641

0.6

132,582

7,057

5.3

1 (ref)

 

 85–144

54,246

215

0.4

58,548

1,816

3.1

1.323

1.156–1.514

 45–84

36,136

113

0.3

38,664

979

2.5

1.630

1.434–1.853

 <45

14,385

61

0.4

14,331

276

1.9

2.863

2.535–3.233

 Total

217,714

1,030

0.5

244,125

10,128

4.1

  

OR odds ratio, 95% CI 95% confidence interval, AJCC American Joint Committee on Cancer, DCIS ductal carcinoma-in situ, NA not available, NOS not otherwise specified

Tumor Factors

In 1998–1999, women with in-situ cancers more frequently underwent CPM (2.1%) than women with stage I, II, or III disease (0.4%) (P < 0.0001; Fig. 2a). The odds of women undergoing CPM declined with increasing stage of disease. Stage III cases were 46% less likely to undergo CPM compared to women with stage 0 disease (Fig. 2b; Table 2). Among patients diagnosed in 2006–2007, the likelihood of undergoing CPM decreased with increasing tumor size. Women with T1–T3 tumors were approximately 30% less likely to undergo CPM when compared to women with Tis tumors, and women with T4 cancers were 60% less likely (OR = 0.39, 95% CI 0.31–0.49) (Table 2). Use of CPM increased for all histologic types of breast cancers; patients with lobular carcinoma were more frequently treated by CPM when compared to either infiltrating duct or other specified histologic types of disease and more likely to undergo CPM (OR = 1.00, 95% CI 0.91–1.1) (Fig. 2b).
https://static-content.springer.com/image/art%3A10.1245%2Fs10434-010-1091-3/MediaObjects/10434_2010_1091_Fig2_HTML.gif
Fig. 2

a Percentage by American Joint Committee on Cancer stage, b percentage by tumor histology

Hospital Factors

Use of CPM has increased across all provider settings, and there is evidence of greater differentiation in CPM use across providers, with women treated at comprehensive community cancer programs 85% more likely to undergo CPM and women treated at teaching/research facilities almost 2.5 times likely to undergo CPM (OR = 2.4, 95% CI 2.23–2.58) when compared to small community hospitals (Table 2). By 2006–2007, statistically significant differentiation in the frequency of CPM was noted at high-volume centers providing CPM to 5.3% of patients and proportionally fewer cases undergoing CPM as hospital volume decreased (Fig. 3a). The likelihood of undergoing CPM increased with increasing hospital surgical volume. The highest-volume centers were almost three times as likely to treat women with CPM compared to the smallest-volume centers (Table 2).
https://static-content.springer.com/image/art%3A10.1245%2Fs10434-010-1091-3/MediaObjects/10434_2010_1091_Fig3_HTML.gif
Fig. 3

Percentage by breast surgical volume

Multivariate Logistic Regression

Independent predictors of CPM were explored by multivariate logistic regression modeling. A broad set of covariates was assessed by forward stepwise tests for significance to arrive at the list of patient-, tumor-, and facility-level covariates provided in Table 3. Young (<40 years of age) white women with private insurance coverage living in the Midwest and Southern parts of the United States with early-stage disease treated at high-volume or teaching research centers were more likely to under undergo CPM in 2006–2007 than other women with nonmetastatic breast cancer. The receiver operator curve by the C statistic for this model was 0.752, suggesting a high degree of specificity and sensitivity for the model.
Table 3

Independent factors associated with contralateral prophylactic mastectomy, 2006 and 2007

Factor

No. of cases

P

OR

95% CI

Age (y)

 20–29

915

 

1 (ref)

 

 30–39

9,252

0.413

0.914

0.737–1.133

 40–49

39,431

0.000

0.530

0.430–0.653

 50–59

55,157

0.000

0.294

0.238–0.362

 60–69

53,093

0.000

0.182

0.147–0.226

 70–79

40,267

0.000

0.091

0.072–0.115

 80+

24,297

0.000

0.042

0.032–0.055

Race

 White

185,383

 

1 (ref)

 

 Black

21,956

0.000

0.452

0.410–0.498

 Hispanic

9,197

0.000

0.636

0.560–0.722

 Asian/Pacific Islands

5,876

0.000

0.488

0.417–0.571

Insurance status

 Not insured

1,540

 

1 (ref)

 

 Self-pay

2,393

0.630

0.908

0.613–1.346

 Insured, NOS

27,108

0.003

1.602

1.175–2.183

 Managed care

95,082

0.000

1.819

1.339–2.470

 Medicaid

13,365

0.226

1.218

0.886–1.674

 Medicare

82,924

0.028

1.423

1.039–1.948

Population without high school degree

 29%+

31,357

 

1 (ref)

 

 20–28.9%

47,201

0.000

1.229

1.125–1.342

 14–19.9%

52,819

0.000

1.442

1.322–1.573

Census region

 South

14,064

0.000

2.331

2.072–2.623

 Midwest

17,816

0.000

2.043

1.832–2.277

 West

15,995

0.000

1.650

1.463–1.861

 Mountain

9,281

0.000

1.662

1.457–1.897

 Pacific

29,152

0.000

1.455

1.306–1.620

Tumor stage and histology

 Stage 0

  DCIS

12,583

 

1 (ref)

 

 Stage I

  Ductal carcinoma

89,053

0.000

0.768

0.705–0.837

  Lobular carcinoma

8,424

0.000

1.314

1.161–1.487

  Other invasive types

14,001

0.018

0.870

0.774–0.976

 Stage II

  Ductal carcinoma

57,615

0.000

0.721

0.660–0.788

  Lobular carcinoma

7,185

0.000

1.461

1.290–1.655

  Other invasive types

8,000

0.053

0.877

0.768–1.002

 Stage III

  Ductal carcinoma

19,174

0.000

0.435

0.386–0.490

  Lobular carcinoma

3,607

0.097

0.859

0.717–1.028

  Other invasive types

2,770

0.004

0.742

0.604–0.911

Hospital type

 Community

35,335

 

1 (ref)

 

 Comprehensive

121,426

0.053

1.101

0.999–1.214

 Teaching/research

65,651

0.000

1.400

1.263–1.552

Annual surgical case volume

 <45

12,871

 

1 (ref)

 

 45–84

34,637

0.040

1.168

1.007–1.354

 85–144

53,809

0.004

1.250

1.072–1.456

 ≥145

121,095

0.000

1.834

1.575–2.137

OR odds ratio, 95% CI 95% confidence interval, DCIS ductal carcinoma-in situ, NOS not otherwise specified

Discussion

In this study, we were able to show that the proportion of surgically treated patients undergoing CPM increased statistically significantly between 1998 and 2007, from 0.4 to 4.7% (Table 1). To our knowledge, this is the largest cohort of patients and the most current study to date that demonstrates these trends. In addition, this increase in CPM is associated with certain patient and hospital factors that have not been reported elsewhere. The increase in CPM can be largely attributed to young, white, insured, educated patients with high household incomes, living in the Midwest region of the country. Although increases in CPM were seen across all stages of disease, tumor histology, and tumor size, logistic regression showed that patient factors were more powerful predictors of CPM than tumor factors.

These findings have been corroborated by others. Tuttle et al. examined the Surveillance, Epidemiology, and End Results Program database and found a 162% increase (4.3 to 11%) in the contralateral prophylactic mastectomies from 1998 to 2003 for invasive disease and a 188% increase (6.4 to 18.4%) for noninvasive disease.1,2 This increase was statistically significantly associated with young patient age, non-Hispanic white race, and lobular-type histology.2 As in the Tuttle study, we found an increase in CPM in lobular cancer, across all stages, among younger patients and in whites, but our study also examined additional patient demographics and provider factors that were not present in either Tuttle study.1,2 Jones et al. showed that CPM rates increased from 6.5% in 1999 to 16.1% in 2007. Patient age, higher education, and family history of cancer were associated with higher rates of contralateral mastectomy.4 Arrington et al. reviewed 165 patients undergoing CPM and reported tumor size, family history, lobular histology, multicentric disease, and surgeon sex were all independent predictors of increased CPM rates.13 By means of linked cancer registry and state discharge data sets, McLaughlin et al. estimated the proportion of women in the state of New York undergoing CPM increased from 1.9% in 1995–1996 to 4.2% in 2004–2005.5

Why patients choose contralateral mastectomy likely involves a multitude of factors: surveillance of the breasts, plastic reconstructive concerns, suspicious family history, patient anxiety about tumor recurrence, failed attempts at breast conservation, and the use of preoperative magnetic resonance imaging (MRI) are commonly cited reasons why patients choose prophylactic mastectomy. Anxiety about local recurrence despite 10-year local recurrence rates from 3.5 to 6.5% for node-negative patients and 4 to 10% for node-positive patients and persistent tumor-positive margins at lumpectomy may spur patients to pursue more aggressive surgery and choose CPM.14 Indeed, reexcision rates for lumpectomy can range from 16 to 49%.15,16

Genetics no doubt plays a role in the decision for CPM. Studies have demonstrated that women who develop breast cancer when they are aged <40 are at a statistically significantly increased risk for a second primary breast cancer, suggesting an underlying genetic predisposition for their index tumor.1721 In a study of more than 9000 women diagnosed between 1946 and 1976, average annual incidence rates for a contralateral primary tumor were 5.0, 4.1, and 3.0 per 1000 women for patients aged <45, 45 to 54, and >55 years, respectively, at diagnosis of their first primary breast cancer.19 In the Myriad database (http://www.myriadtests.com/provider/brca-mutation-prevalence-observations.htm), the prevalence of a BRCA1 or BRCA2 mutation more than doubles if the patient’s age is <50 years compared to a patient whose age is ≥50, regardless of Ashkenazi Jewish descent. Young age at presentation may be an appropriate indication for CPM, given the prevalence of BRCA mutations in young breast cancer patients. Cancer registries do not contain family history or BRCA status, so it is impossible to determine what proportion of the young patients are at high hereditary risk. Last, patients who test negative for a BRCA1 or BRCA2 mutation with suspicious family histories may still opt for a CPM because BRCA testing may miss up to 10% of mutations, and there is always a worry about undiscovered gene mutations that may contribute to increased risk of future new primary breast cancers.22

CPM does not offer a definitive survival benefit, although two studies have questioned this dogma.23,24 Likewise, CPM offers no survival benefit to BRCA carriers.25,26 For most patients, survival is dictated by their primary cancer, not the presentation of a second new primary in the contralateral breast. Studies report rates of contralateral cancer presentation to be between 0.5 to 0.75% per year; these rates have remained constant over 15 to 20 years.17,19,2729 In unselected populations such as those enrolled onto the National Surgical Adjuvant Breast and Bowel Project B-06 trial, the rate of contralateral cancer was 8.5, 8.8, and 9.4% in the total mastectomy, lumpectomy alone, and lumpectomy plus irradiation arms, respectively, at 20-year follow-up.30 One in 25 breast cancer survivors will develop a second primary breast cancer, either in the index breast or the contralateral breast, but contralateral cancers account for only 2.5% of breast cancer deaths.27,31 Moreover, adjuvant therapies such as chemotherapy and hormone therapy have been shown to decrease the risk of developing cancer in the contralateral breast.28,30,32

The use of breast MRI has been related to increased use of mastectomy. In a single institutional series, Katipamula et al. showed that patients undergoing preoperative MRI were more likely to undergo mastectomy than those who did not, but these were not necessarily contralateral prophylactic mastectomies.3 In a subsequent study by Sorbero et al., women who underwent a MRI were nearly twice as likely to have a CPM, and this increase was seen in stage I and II disease.33 Cancer registries do not collect information on preoperative imaging studies, and so no correlation is possible.

There are several limitations to our study. First, determining the cause of these mastectomy trends is difficult using cancer registry data because registry-based cancer surveillance systems in the United States do not capture many of the patient factors discussed that possibly contribute to decisions favoring use of CPM. Second, only breast cancers reported from CoC-accredited cancer programs were reviewed, which could introduce some selection bias in our reported results. The NCDB collects data on more than two-thirds of diagnosed breast malignancies annually, and the fact that trends reported here are consistent with other reports should support the generalizability of our findings. Finally, because the NCDB does not collect direct patient identifiers, studies that use this resource must rely on area-based measures of socioeconomic status estimated at the zip code level.

Nonetheless, this report—the largest and most current to date—adds to a growing body of literature demonstrating that an increase in CPM is strongly associated with age and other patient-related factors. Further studies are needed to explain rising CPM rates and how patients make surgical treatment decisions. Currently, National Comprehensive Cancer Network guidelines discourage CPM in women other than those at high risk because of its small benefit-to-risk ratio (http://www.nccn.org). Finally, outcomes studies involving CPM are needed to demonstrate to patients and clinicians alike whether CPM influences disease-free and overall survival after diagnosis of noninvasive and invasive breast cancers.

Copyright information

© Society of Surgical Oncology 2010