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Journal of Women's Health logoLink to Journal of Women's Health
. 2017 Jul 1;26(7):735–744. doi: 10.1089/jwh.2015.5639

Disparities in the Initial Local Treatment of Older Women with Early-Stage Breast Cancer: A Population-Based Study

Traci J LeMasters 1,✉, Suresh S Madhavan 1, Usha Sambamoorthi 1, Ami M Vyas 1
PMCID: PMC5770130  PMID: 28170302

Abstract

Background

Although breast cancer is most prevalent among older women, the majority are diagnosed at an early stage. When diagnosed at an early stage, women have the option of breast-conserving surgery (BCS) plus radiation therapy (RT) or mastectomy for the treatment of early-stage breast cancer (ESBC). Omission of RT when receiving BCS increases the risk for recurrence and poor survival. Yet, a small subset of older women may omit RT after BCS. This study examines the current patterns of local treatment for ESBC among older women.

Methods

This study conducted a retrospective observational analysis using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked dataset of women age ≥66 diagnosed with stage I-II breast cancer in 2003–2009. SEER-Medicare data was additionally linked with data from the Area Resource File (ARF) to examine the association between area-level healthcare resources and treatment. Two logistic regression models were used to estimate how study factors were associated with receiving (1) BCS versus BCS+RT and (2) Mastectomy versus BCS+RT. A stratified analysis was also conducted among women aged <70 years.

Results

Among 45,924 patients, 55% received BCS+RT, 23% received mastectomy, and 22% received BCS only. Women of increasing age, comorbidity, primary care provider visits, stage II disease, and nonwhite race were more likely to have mastectomy or BCS only, than BCS+RT. Women diagnosed in 2004–2006, treated by an oncology surgeon, residing in metro areas, areas of greater education and income, were less likely to receive mastectomy or BCS only, than BCS+RT. While women aged <70 years were more likely to receive BCS+RT, socioeconomic and physician specialties were associated with receiving BCS only.

Conclusions

Over half of older women with ESBC initially receive BCS+RT. The likelihood for mastectomy and BCS only increases with age, comorbidity, and vulnerable socio-demographic characteristics. Findings demonstrate continued treatment disparities among certain vulnerable populations.

Keywords: : breast cancer, early-stage, treatment, elderly

Introduction

Breast conserving surgery (BCS) followed by radiation therapy (RT) is an equally effective local treatment for long-term survival of invasive early-stage breast cancer (ESBC), as is mastectomy,1–3 and is the preferred choice of local treatment, with ∼60% or more women receiving BCS plus RT (BCS+RT).4,5 Treatment guidelines allow older women, age ≥70 years, stage I, estrogen receptor (ER) positive, and taking tamoxifen, to omit RT following BCS, and recommend RT for all other women undergoing BCS.6 RT omission is associated with short-term treatment failure, and consequently, mastectomy, in addition to an increased risk of recurrence and breast cancer mortality.7–13 Unfortunately, a substantial number of clinically eligible older women do not receive RT following BCS, and a greater number may initially be treated with mastectomy, than younger women.7,11,14,15

Following publication of the CALGB trial study results,16 rates of BCS+RT have declined among all older women with ESBC, irrespective of clinical indications.12,17,18 The decline in rates may be due to individual patient characteristics. Retrospective studies have shown age and comorbidity to be the strongest predictors for type of local treatment received. As age and comorbidity increase, so do rates of mastectomy or BCS only.9,14,15,18,19 Omission of RT or use of mastectomy, is intended to preserve quality of life and avoid adverse effects in patients with limited life expectancy, frail health, or low functional status. However, RT omission when receiving BCS increases the risk of recurrence, while mastectomy results in loss of breast preservation and greater physical limitations.20

Therefore, the purpose of this study is to determine patterns of local treatment (BCS+RT, mastectomy, or BCS only) among women aged ≥66 years, with stage I and II breast cancer using the U.S. population-based linked SEER-Medicare dataset. Furthermore, this study aims to determine how age, comorbidity, frequency of primary care provider (PCP) visits, clinical prognostic factors, oncology care resources, and socio-demographic characteristics are associated with choice of local treatment.

Materials and Methods

Data source and cohort definition

The SEER-Medicare linked database was created in a collaborative effort by the National Cancer Institute (NCI) and Centers for Medicare and Medicaid Services (CMS). SEER data collected from 17 tumor registries, representing 26% of the United States (US) population, is successfully matched to Medicare enrollment records for 94% of patients aged ≥65 years.21 SEER-Medicare data contains information about date of diagnosis, cancer site, stage, tumor characteristics, treatment, healthcare use, patient enrollment and eligibility, selected demographic characteristics, and vital status information. County and state of diagnosis were used to identify the area-level density of mammography screening and oncology centers from the U.S. Department of Health and Human Resource's 2009 Area Resource File (ARF).22 This study was approved for exemption by the West Virginia University Institutional Review Board.

We identified 69,376 females aged ≥66 years with a first ever and primary diagnosis of stage I or II incident case of breast cancer between January 1, 2003 and December 31, 2009 who were continuously enrolled in Medicare Part A and B fee-for-service programs 1 year before and after diagnosis. Other exclusion criteria were as follows: enrollment in managed care programs at any time during the year before or after diagnosis (n = 20,872), died within the first year of diagnosis (n = 710), if tumor size was missing (n = 64), if surgeon specialty was missing (n = 852), or did not have any definitive surgery (n = 954). After these exclusions, the final analytic sample consisted of 45,924 patients.

Local treatment variable

The local treatment received (BCS+RT, mastectomy, or BCS only) was identified using surgical and Medicare radiation claims where the claim date was within 366 days of the diagnosis. BCS (i.e., lumpectomy, partial mastectomy, segmental mastectomy), mastectomy, and RT were identified using International Classification of Diseases, 9th Revision (ICD-9) diagnosis and procedure codes and Current Procedural Terminology/Healthcare Common Procedure Coding System (CPT/HCPCS) (Appendix 1).

Explanatory variables

Explanatory variables used in this study include individual-level and area-level measures. Individual-level patient characteristics included diagnosis year, age, race, comorbidity, frequency of PCP visits, clinical prognostic factors, and surgeon specialty. Area-level measures include census tract level of education, census tract level of income, metro status, local density of mammography screening facilities, and local density of oncology treatment centers. Comorbidity scores were calculated using the Klabunde adaptation of the Charlson index (score = 0, 1, ≥ 2).23,24 Frequency of PCP visits was determined by counting the number of unique PCP claim dates the year before diagnosis and dividing by lower and upper 50th percent median cutoff. Clinical prognostic factors included stage at diagnosis, ER status, progesterone receptor (PR) status, and tumor grade. Oncology care resources were captured by the area-level density of mammography screening and oncology treatment centers, and specialty of the treating surgeon. Area-level densities were determined by dividing proportions found in the ARF by lower and upper 50th percent median cutoffs. Surgeon specialty (general only, oncology only, or both) was ascertained using provider specialty claims codes. Demographic characteristics were race, metro status, census-tract level, education, and income

Statistical analysis

Patient characteristics were summarized using descriptive statistics. Mantel–Haenszel chi-square tests of location shift, using either modified ridit scores or table scores, and Mantel–Haenszel chi-square tests of general association, depending on whether the independent measure was dichotomous, nominal, or ordinal, were used to compare significant group differences between patients receiving BCS+RT, mastectomy, or BCS only. Two multivariable logistic regression models were used to estimate likelihood for type of local treatment received (mastectomy vs. BCS+RT and BCS only vs. BCS+RT), adjusting for year of diagnosis, age and health characteristics, clinical prognostic factors, oncology care resources, and socio-demographic characteristics. Parameter estimates calculated in the regression models are presented as adjusted odds ratios (AOR) with their corresponding 95% confidence intervals (CI). p values <0.05 were considered statistically significant. Analysis was conducted using SAS version 9.4 software (SAS Institute, Inc., Cary, NC).

Results

Patient characteristics

Of 45,924 female fee-for-service Medicare beneficiaries diagnosed in 2003–2009 and in our analytic sample 54.5% received BCS+RT, 23.4% had mastectomy, and 22.1% had BCS only; 25.5% were aged 70–74 years at diagnosis, and 56.7% had comorbidity score = 0. Most were treated by both general and oncology surgeons (75.7%) (Table 1).

Table 1.

Descriptive Characteristics of Older Women with Early-Stage Breast Cancer SEER -Medicare, 2003–2009

  N %
All 45924 100.0
Treatment
 BCS+RT 25038 54.5
 Mastectomy 10755 23.4
 BCS only 10131 22.1
Year of diagnosis
 2003 6620 14.4
 2004 6523 14.2
 2005 6416 14.0
 2006 6493 14.1
 2007 6563 14.3
 2008 6628 14.4
 2009 6681 14.6
Age & health
 Age at diagnosis
  66–69 10319 22.5
  70–74 11728 25.5
  75–79 10718 23.3
  80–84 7974 17.4
  85–89 3900 8.5
  ≥ 90 1285 2.8
 Comorbidity score
  0 26024 56.7
  1 12422 27.1
  ≥ 2 7478 16.3
 PCP visits
  Low 24805 54.0
  High 21119 46.0
Clinical prognostic factors
 Stage at diagnosis
  I 28884 62.9
  II 17040 37.1
 ER status
  Positive 36321 79.1
  Negative 6298 13.7
  Borderline/unknown 3305 7.2
 PR status
  Positive 30470 66.4
  Negative 11754 25.6
  Borderline/unknown 3700 8.1
 Tumor size
  0–1 cm 14837 32.3
  <2 cm 18001 39.2
  2–5 cm 12371 26.9
  >5 cm 715 1.6
 Tumor grade
  Well differentiated 12096 26.3
  Moderately differentiated 20024 43.6
  Poorly differentiated 10826 23.6
  Undifferentiated/unknown 2978 6.5
Oncology care resources
 Mammography screening centers
  Low 23761 51.7
  High 22163 48.3
 Oncology treatment centers
  Low 25733 56.0
  High 20191 44.0
 Type of surgeon seen
  General only 8536 18.6
  Oncology only 2640 5.8
  Both 34748 75.7
Socio-demographic characteristics
 Race
  White 41034 89.4
  Other 4890 10.7
 Education
  <15% college degree 13543 29.5
  ≥15% college degree 32381 70.5
 Annual income
  ≤$35,000 10839 23.6
  >$35,000 35085 76.4
 Metro status
  Nonmetro 7673 16.7
  Metro 38251 83.3
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BCS, breast-conserving surgery; RT, radiation therapy; PCP, primary care physician; ER, estrogen receptor; PR, progesterone receptor; SEER, Surveillance, Epidemiology, and End Results.

Univariate analysis

All p-values are significant at the p < 0.001 level. The proportion of patients receiving BCS+RT decreased with increasing age: 65.0% of women 66–69 years to 14.2% of women ≥90 years (Table 2). In contrast, rates of mastectomy and BCS only were highest among those aged ≥90 years versus 66–69 years (30.9% and 54.9% vs. 20.0% and 15.0%). Women with a comorbidity score = 2 versus 0 had the lowest rates of BCS+RT (47.8% vs. 57.5%), while rates of mastectomy (25.6% vs. 22.6%) and BCS only (26.6% vs. 19.9%) were the highest among women with a score = 2 versus 0. Patients with stage I disease, hormone receptor-positive, and well-differentiated tumors had higher rates of BCS+RT, while those with poor prognostic factors had higher rates of mastectomy and BCS only. Women treated by an oncology surgeon only or both an oncology and general surgeon had the highest rates of BCS+RT, compared to those treated by a general surgeon only, while rates of BCS only were the highest among those treated by a general surgeon only.

Table 2.

Univariate Analysis of Local Treatment Among Older Women with Early-Stage Breast Cancer SEER-Medicare, 2003–2009

  BCS+RT Mastectomy BCS Only  
  N % N % N %  
All 25067 54.5 10768 23.4 10146 22.1 p-value
Year of diagnosis             <0.001***
 2003 3498 52.8 1646 24.9 1476 22.3  
 2004 3502 53.7 1436 22.0 1585 24.3  
 2005 3388 52.8 1462 22.8 1566 24.4  
 2006 3572 55.0 1418 21.8 1503 23.2  
 2007 3636 55.4 1560 23.8 1367 20.8  
 2008 3675 55.5 1610 24.3 1343 20.3  
 2009 3767 56.4 1623 24.3 1291 19.3  
Age & health
 Age at diagnosis             <0.001***
  66–69 6708 65.0 2064 20.0 1547 15.0  
  70–74 7259 61.9 2521 21.5 1948 16.6  
  75–79 6025 56.2 2523 23.5 2170 20.3  
  80–84 3713 46.6 2085 26.2 2176 27.3  
  85–89 1151 29.5 1165 29.9 1584 40.6  
  ≥90 182 14.2 397 30.9 706 54.9  
 Comorbidity score             <0.001***
  0 14969 57.5 5882 22.6 5173 19.9  
  1 6495 52.3 2956 23.8 2971 23.9  
  ≥2 3574 47.8 1917 25.6 1987 26.6  
 PCP visits             <0.001***
  Low 14142 57.0 5679 22.9 4984 20.1  
  High 10896 51.6 5076 24.0 5147 24.4  
Clinical prognostic factors
 Stage at diagnosis             <0.001***
  I 17734 61.4 4508 15.6 6642 23.0  
  II 7304 42.9 6247 36.7 3489 20.5  
 ER status             <0.001***
  Positive 20577 56.7 7855 21.6 7889 21.7  
  Negative 3157 50.1 1911 30.3 1230 19.5  
  Borderline/Unknown 1304 39.5 989 29.9 1012 30.6  
 PR status             <0.001***
  Positive 17386 57.1 6453 21.2 6631 21.8  
  Negative 6144 52.3 3217 27.4 2393 20.4  
  Borderline/unknown 1508 40.8 1085 29.3 1107 29.9  
 Tumor size             <0.001***
  0–1 cm 9495 64.0 1859 12.5 3483 23.5  
  <2 cm 10509 58.4 3622 20.1 3870 21.5  
  2–5 cm 4824 39.0 4913 39.7 2634 21.3  
  >5 cm 210 29.8 361 50.5 144 20.1  
 Tumor gradea             <0.001***
  Well differentiated 7115 58.8 2194 18.1 2787 23.1  
  Moderately differentiated 11119 55.5 4600 23.0 4305 21.5  
  Poorly differentiated 5410 50.0 3266 30.2 2150 19.9  
  Undifferentiated/unknown 1394 46.8 695 23.4 889 29.9  
Oncology care resources
 Mammography screening centersa             <0.001***
  Low 12263 51.6 6014 25.3 5484 23.1  
  High 12775 57.6 4741 21.4 4647 21.0  
 Oncology treatment centersa             <0.001***
  Low 13378 52.0 6488 25.2 5867 22.8  
  High 11660 57.8 4267 21.1 4264 21.1  
 Type of surgeon seena             <0.001***
  General only 3627 42.5 2027 23.8 2882 33.8  
  Oncology only 1535 58.1 605 22.9 500 18.9  
  Both 19876 57.2 8123 23.4 6749 19.4  
Socio-demographic characteristics
 Racea             <0.001***
  White 22667 55.2 9377 22.9 8990 21.9  
  Other 2371 48.5 1378 28.2 1141 23.3  
 Educationa             <0.001***
  <15% college degree 6311 46.6 3869 28.6 3363 24.8  
  ≥15% college degree 18727 57.8 6886 21.3 6768 20.9  
 Annual incomea             <0.001***
  ≤$35,000 4872 45.0 3137 28.9 2830 26.1  
  >$35,000 20166 57.5 7618 21.7 7301 20.8  
 Metro statusa             <0.001***
  Nonmetro 3360 43.8 2287 29.8 2026 26.4  
  Metro 21678 56.7 8468 22.1 8105 21.2  
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*

p < 0.05.

**

p < 0.01.

***

p < 0.001.

Multivariate analysis

The two models of factors associated with treatment (Mastectomy vs. BCS+RT and BCS only vs. BCT+RT) of ESBC among elderly women is given in Table 3. Compared to women aged 66–69 years, women of increasing age were more likely to be treated with mastectomy and BCS only versus BCS+RT, with women aged ≥90 years being the most likely to have mastectomy (AOR 6.16, 95% CI, 5.10–7.44) and BCS only (AOR 14.13, 95% CI, 11.80–16.80). Greater comorbidity (score = 2) was associated with an increased likelihood of have mastectomy (AOR 1.14, 95% CI, 1.07–1.22) and BCS only (AOR 1.38, 95% CI, 1.29–1.48). Women diagnosed with stage II breast cancer were more likely to receive mastectomy (AOR 3.15, 95% CI, 3.00–3.31) and BCS only (AOR 1.26, 95% CI, 1.19–1.32) versus BCS+RT. Those with negative and borderline/unknown ER and PR tumors, and moderately, poorly, and undifferentiated/unknown tumors were more likely to have mastectomy or BCS only.

Table 3.

Odds Ratios from the Fully Adjusted Model of Local Treatment Among Older Women with Early-Stage Breast Cancer SEER-Medicare, 2003–2009

  Treatment
  Mastectomy vs. BCS+RT BCS Only vs. BCS+RT
  AOR 95% CI Sig. AOR 95% CI Sig.
Year of diagnosis
 2003 1.00 —   1.00 —  
 2004 0.95 0.87–1.04   1.15 1.05–1.26 **
 2005 1.01 0.92–1.10   1.22 1.11–1.33 ***
 2006 0.95 0.87–1.04   1.13 1.03–1.23 *
 2007 1.03 0.95–1.13   0.99 0.91–1.09  
 2008 1.08 0.99–1.18   1.00 0.91–1.09  
 2009 1.08 0.98–1.17   0.94 0.85–1.03  
Age & health
 Age at diagnosis
  66–69 1.00 —   1.00 —  
  70–74 1.12 1.05–1.20 ** 1.12 1.04–1.21 **
  75–79 1.40 1.30–1.50 *** 1.49 1.38–1.61 ***
  80–84 1.87 1.73–2.02 *** 2.39 2.21–2.59 ***
  85–89 3.21 2.90–3.55 *** 5.39 4.89–5.94 ***
  ≥90 6.16 5.10–7.44 *** 14.13 11.80–16.80 ***
 Comorbidity score
  0 1.00 —   1.00 —  
  1 1.08 1.02–1.14 * 1.22 1.16–1.30 ***
  ≥2 1.14 1.07–1.22 *** 1.38 1.29–1.48 ***
 PCP visits
  Low 1.00 —   1.00 —  
  High 1.05 1.00–1.10 * 1.10 1.05–1.16 ***
Clinical prognostic factors
 Stage at diagnosis
  I 1.00 —   1.00 —  
  II 3.15 3.00–3.31 *** 1.26 1.19–1.32 ***
 ER status
  Positive 1.00 —   1.00 —  
  Negative 1.19 1.09–1.30 *** 1.03 0.93–1.13  
  Borderline/unknown 1.56 1.24–1.96 *** 1.47 1.16–1.84 ***
 PR status
  Positive 1.00 —   1.00 —  
  Negative 1.12 1.05–1.20 *** 0.99 0.92–1.07  
  Borderline/unknown 1.18 0.95–1.47   1.17 0.94–1.46  
 Tumor size
  0–1 cm 1.00 —   1.00 —  
  <2 cm 1.58 1.48–1.69 *** 0.96 0.91–1.02  
  2–5 cm 2.92 2.65–3.22 *** 1.30 1.17–1.44 ***
  >5 cm 4.73 3.88–5.75 *** 1.47 1.15–1.87 **
 Tumor grade
  Well differentiated 1.00 —   1.00 —  
  Moderately differentiated 1.06 0.99–1.12   0.95 0.89–1.01  
  Poorly differentiated 1.12 1.04–1.21 ** 0.93 0.86–1.00 *
  Undifferentiated/unknown 1.15 1.03–1.28 * 1.40 1.27–1.55 ***
Oncology care resources
 Mammography screening centers
  Low 1.00 —   1.00 —  
  High 0.99 0.90–1.09   0.89 0.80–0.98 *
 Oncology treatment centers
  Low 1.00 —   1.00 —  
  High 0.85 0.77–0.93 *** 1.04 0.94–1.14  
 Type of surgeon seen
  General only 1.00 —   1.00 —  
  Oncology only 0.78 0.70–0.88 *** 0.56 0.50–0.63 ***
  Both 0.79 0.74–0.84 *** 0.57 0.53–0.60 ***
Socio-demographic characteristics
 Race
  White 1.00 —   1.00 —  
  Other 1.29 1.20–1.40 *** 1.25 1.15–1.36 ***
 Education
  <15% college degree 1.00 —   1.00 —  
  ≥15% college degree 0.75 0.70–0.79 *** 0.81 0.76–0.86 ***
 Annual income
  ≤$35,000 1.00 —   1.00 —  
  >$35,000 0.88 0.82–0.94 *** 0.84 0.78–0.90 ***
 Metro status
  Nonmetro 1.00 —   1.00 —  
  Metro 0.70 0.65–0.76 *** 0.73 0.67–0.78 ***
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*

p < 0.05.

**

p < 0.01.

***

p < 0.001.

AOR, adjusted odds ratios; CI, confidence interval.

Women, residing in areas with a high-density of mammography screening centers were less likely to be treated with BCS only versus BCS+RT (AOR 0.89, 95% CI, 0.80–0.98). Similarly, women residing in areas with a high-density of oncology treatment centers (AOR 0.85, 95% CI, 0.77–0.93) were less likely to have mastectomy. Compared to women treated by a general surgeon only, those treated by an oncology surgeon only or treated by both types of surgeons were less likely (AOR 0.78, 95% CI, 0.70–0.88 and AOR 0.79, 95% CI, 0.74–0.84) to receive mastectomy, or BCS only (AOR 0.56, 95% CI, 0.50–0.63 and AOR 0.57, 95% CI, 0.53–0.60). Women of other races were more likely to have mastectomy or BCS only. Women living in areas of greater education, income, or metro status were less likely to receive mastectomy or BCS only.

Stratified analysis

Taking into account the guideline recommendation that BCS only may be an appropriate option for some women aged ≥70 years, we performed a stratified analysis on women aged 66–69 with comorbidity = 0 who would have been recommended to receive BCS+RT, thus eliminating patients who were eligible for BCS only as a treatment option (Table 4). Therefore, a secondary analysis was conducted to explore associations with treatment among these (age 66–69 years at diagnosis and a Charlson comorbidity score = 0) (Table 4). Among this subgroup of women (n = 6,369), 66.7% were treated with BCS+RT, 19.5% mastectomy, and 13.9% BCS only. Women diagnosed at stage II were more likely (AOR 1.91, 95% CI 1.55–2.35) to be treated with mastectomy, than those diagnosed at stage I. Women with ER negative tumors were more likely to be treated with mastectomy, than those with ER positive tumors. Women with undifferentiated/unknown and poorly differentiated tumors were also more likely to be treated with mastectomy or BCS only versus BCS+RT. Compared to those treated by a general surgeon only, women treated by an oncology surgeon (AOR 0.44, 95% CI, 0.29–0.66) or both an oncology and general surgeon (AOR 0.65, 95% CI. 0.53–0.80) were less likely to be treated with BCS only versus BCS+RT.

Table 4.

Characteristics and Adjusted Odds Ratios of Women Aged 66–69 Years and with a Charlson Comorbidity Score = 0 Diagnosed with Early-Stage Breast Cancer in SEER Regions SEER -Medicare, 2003–2009

  Treatment
  N % Mastectomy vs. BCS + RT BCS Only vs. BCS + RT
All 6369 100.0 AOR 95% CI Sig. AOR 95% CI Sig.
Treatment
 BCS+Radiation 4246 66.7            
 Mastectomy 1239 19.5            
 BCS only 884 13.9            
Year of diagnosis
 2003 875 13.7 1.00 —   1.00 —  
 2004 908 14.3 0.90 0.70–1.17   1.11 0.85–1.45  
 2005 896 14.1 0.90 0.70–1.16   1.07 0.82–1.41  
 2006 888 13.9 0.83 0.64–1.08   1.06 0.81–1.40  
 2007 932 14.6 0.89 0.70–1.15   0.89 0.67–1.17  
 2008 961 15.1 1.27 1.00–1.62   1.02 0.77–1.35  
 2009 909 14.3 1.12 0.87–1.44   0.80 0.60–1.08  
Age & health
 PCP visits
  Low 4622 72.6 1.00 —   1.00 —  
  High 1747 27.4 0.95 0.81–1.10   1.05 0.89–1.24  
Clinical prognostic factors
 Stage at diagnosis
  I 4142 65.0 1.00 —   1.00 —  
  II 2227 35.0 1.91 1.55–2.35 *** 1.17 0.91–1.50  
 ER status
  Positive 5055 79.4 1.00 —   1.00 —  
  Negative 933 14.7 1.25 0.98–1.60   1.07 0.80–1.42  
  Borderline/unknown 381 6.0 1.90 0.91–3.96   1.07 0.56–2.07  
 PR status
  Positive 4261 66.9 1.00 —   1.00 —  
  Negative 1682 26.4 1.19 0.98–1.45   0.97 0.77–1.22  
  Borderline/unknown 426 6.7 0.91 0.44–1.86   1.73 0.93–3.24  
 Tumor size
  0–1 cm 2220 34.9 1.00 —   1.00 —  
  >2 cm 2570 40.4 1.62 1.36–1.94 *** 0.93 0.78–1.12  
  2–5 cm 1498 23.5 2.86 2.21–3.70 *** 1.56 1.15–2.10 **
  >5 cm 81 1.3 4.31 2.52–7.35 *** 1.60 0.78–3.29  
 Tumor grade
  Well differentiated 1694 26.6 1.00 —   1.00 —  
  Moderately differentiated 2788 43.8 1.09 0.91–1.30   1.00 0.83–1.21  
  Poorly differentiated 1494 23.5 1.10 0.89–1.36   1.27 1.01–1.60 *
  Undifferentiated/unknown 393 6.2 1.37 1.01–1.85 * 1.61 1.18–2.18 **
Oncology care resources
 Mammography screening centers
  Low 3386 53.2 1.00 —   1.00 —  
  High 2983 46.8 1.20 0.93–1.55   0.86 0.63–1.17  
 Oncology treatment centers
  Low 3656 57.4 1.00 —   1.00 —  
  High 2713 42.6 0.81 0.63–1.05   1.13 0.84–1.54  
 Type of surgeon seen
  General only 761 12.0 1.00 —   1.00 —  
  Oncology only 393 6.2 0.96 0.69–1.35   0.44 0.29–0.66 ***
  Both 5215 81.9 0.92 0.74–1.14   0.65 0.53–0.80 ***
Socio-demographic characteristics
 Race
  White 5786 90.9 1.00 —   1.00 —  
  Other 583 9.2 1.22 0.98–1.53   1.30 1.02–1.67 *
 Education
  <15% college degree 1699 26.7 1.00 —   1.00 —  
  ≥15% college degree 4670 73.3 0.85 0.71–1.01   0.90 0.74–1.09  
 Annual income
  ≤$35,000 1295 20.3 1.00 —   1.00 —  
  >$35,000 5074 79.7 0.78 0.65–0.95 * 0.65 0.53–0.80 ***
 Metro status
  Nonmetro 1115 17.5 1.00 —   1.00 —  
  Metro 5254 82.5 0.79 0.64–0.96 * 0.79 0.63–0.98 *
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*

p < 0.05.

**

p < 0.01.

***

p < 0.001.

Discussion

This is the most recent population-based study to examine patterns of local treatment of ESBC among older women. Previous retrospective studies show that older women are more likely to be treated with mastectomy or BCS only, than BCS+RT. We demonstrated that from 2003 to 2009, 22% had BCS without RT, similar to published studies.25 However, the rates of BCS with RT are lower and mastectomy are higher as compared to published literature. Although these differences may in part be due to differences in study inclusion/exclusion criteria, recent studies examining trends in treatment for ESBC have found that women are increasingly opting for more aggressive treatment, such as mastectomy.26,27

Consistent with previous studies,10,28 age was strongly associated with BCS only or mastectomy. Increasing age is commonly cited as the main reason for omission of RT among older women due to greater comorbidity, intolerance to RT toxicity, adverse effects, and shorter life expectancy.14,29,30 In fact, RT is not always recommended for all women over the age of 70 years, as it has not been shown to improve survival among those with shortened life expectancies.31 Similarly, older women may be more likely to receive mastectomy to avoid any adverse effects associated with RT following BCS. However, not all experts agree that RT is more toxic or less tolerable among older women, than younger women. In fact, several studies have found RT to be well-tolerated among older women, and determined that it did not increase the risk of myocardial infarction or cardiovascular disease.32,33 Declining health is a common occurrence among older individuals, and presents additional challenges to undergoing cancer treatments, particularly RT. Although patients with a comorbidity score = 2 were more likely to have mastectomy or BCS only, 43% of women with a score = 0 were treated with mastectomy or BCS only, suggesting that increased comorbidity may not always drive the type of treatment.

Women diagnosed at stage II versus I, were over three times more likely to undergo mastectomy. While the likelihood of mastectomy intuitively increases with increasing stage, it may be that the increasing use of mastectomy among older women can also be partially explained by age. Mastectomy may be increasingly utilized to avoid any adverse effects of RT and the burden of multiple treatments. However, women who had an oncology surgeon involved in their treatment were less likely to be treated with mastectomy or BCS only. Evidence suggest that surgeon specialty is associated with more advanced methods of breast cancer treatment,34 and having both an oncology and general surgeon involved may be an indication of caseload sharing within high volume treatment centers, a factor associated with better treatment practices.35 Moreover, those treated by an oncology surgeon may have shorter travel distances to access specialty care or are more likely to undergo treatments that require repeated visits, such as BCS+RT.36 This may explain why patients who resided in areas with a high density of mammography screening and oncology treatment centers were less likely to have BCS only or mastectomy.

Findings from the stratified analysis of women who were the youngest and healthiest at diagnosis, and thus the most ideal candidates for BCS+RT, barring other unknown factors, showed that considerably more of these women were treated with BCS+RT, than the entire study sample (66.6% vs. 54.5%). It is understandable from a clinical perspective that those diagnosed at stage II versus I and with unfavorable tumor characteristics were more likely to be treated with mastectomy. However, it is troubling that some groups of women in this stratified analysis were also more likely to be treated with BCS only. Not only do women in this subgroup not meet the NCCN guideline requirements for omission of RT because of age, but patients with these cancer characteristics often require more aggressive treatments that include RT when BCS is the surgical treatment choice. It is possible that this finding is explained by the socio-demographic disparities in treatment observed in this subgroup analysis. Women of other race were more likely to be treated with BCS only, while those residing in areas of higher income, and metro areas were less likely to be treated with BCS only. Similarly, women residing in areas of higher education, higher income, and metro areas were less likely to be treated with mastectomy. Therefore, women with vulnerable socio-demographic characteristics with difficulty accessing equitable treatment may also have not been receiving routine mammography screening before diagnosis, leading to a later stage at diagnosis. In the multivariate analyses of the whole study sample, women who had were treated by an oncology surgeon only or both an oncology and general surgeon were less likely to receive mastectomy or BCS only. In the subgroup analysis only a difference in the likelihood for treatment with BCS only was observed. Younger, healthier patients who had an oncology surgeon as part of their care were 35%–56% less likely to have BCS only. This finding reiterates the importance of having an oncology specialist as member of the patient's oncology care team to ensure that all patients have access to specialized oncology care.

Several limitations should be noted when interpreting the results of this study. While this study examined the relationships between type of treatment and a range of covariates, patient preference was not measured. Completion of RT was not assessed, only the initiation of therapy. Another limitation is the lack of information available regarding patients' HER2/neu tumor status and its association with type of treatment. Given that women diagnosed at stage I and II have 99% and 93% 5-year overall survival rates,37 respectively, it is likely that those who die within the first year of diagnosis, die from noncancer related causes. Because this study excluded women who died in the first year following diagnosis, the findings may underrepresent the proportion of women who received less aggressive treatment due to poor health or old age. Finally, the SEER individuals within the SEER database have been found to be of higher income, and higher concentrations of racial and ethnic minorities, compared to the U.S. population.38

Conclusions

A little more than half of older women receive BCS+RT for treatment of ESBC. Women of increasing age, comorbidity, and stage were the most likely to have mastectomy or BCS only. While it may not be appropriate for all elderly women with ESBC to receive RT, some groups of women still do not receive RT with BCS when they are clinically indicated to do so. In particular, this study identified a subgroup of women younger than 70 years, whose omission of RT was associated with access to an oncology specialist and socioeconomic disparities. Current research focusing on individualized and targeted therapies, and immunotherapy may provide more tolerable treatment options for the elderly population. Furthermore, continued efforts are needed to ensure all patients have equitable access to oncology specialty resources and treatment options.

Appendix 1.

Claims Codes Used for Identifying Types of Treatment

Type of Treatment ICD-9 Diagnostic ICD-9 Procedure HCPCS/CPT Revenue Center
Breast-Conserving
Surgery		   85.20–85.29 19120, 19125–19126, 19160, 19162, 19301–19302  
Mastectomy   85.33–85.36, 85.40–85.48 19140, 19180, 19182, 19300, 19303–19307, 19200, 19220, 19240, 19260, 19271–19272  
Radiation Therapy V58.0, V66.1, V67.1 92.20–92.39 77261–77799, G0256, G0261, G0173–G0174, G0243, G0251, G0338–G03340 0330, 0333
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Acknowledgments

This study was funded by the Agency for Healthcare Research and Quality (AHRQ) grant (1 P20 HS15930-02) and partial support from the West Virginia Clinical and Translational Science Institute (WVCTSI), National Institute of General Medical Sciences grant (U54GM104942).

Author Disclosure Statement

No competing financial interests exist.

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