The age of breast cancer diagnosis has decreased over time (P=0.02). During the late 1990s, 24% of breast cancer diagnoses occurred among women aged 70–79 years, contrasted with only 7% in the 2010s. The increasing number of diagnoses over time seems to be occurring mostly among women in their 50s and 60s (Table 1, Fig. 2). There has been a significant shift from rural to urban in the population of women with breast cancer at the VA. More cases were drawn from rural regions of the United States in the 1990s (21%) than in the 2010s (18%, P=0.04; Table 1).
The reported tumor characteristics of breast cancer among women diagnosed at the VA have changed over time. In recent years, the VACCR classified breast cancer as invasive ductal carcinoma more often, whereas the proportion described as other or unspecified types of carcinomas declined (P<0.001; Table 2). The change in distribution of size of the primary breast tumor over time did not reach significance (P=0.10), however, tumors were less likely to involve lymph nodes in recent years; after excluding tumors with missing node status, 65% were node negative in 2010–2012 increasing from 58% in 1995–1999 (P<0.001). Lymph node status within the VACCR was coded as unknown for 22% of cancers diagnosed in the 1990s but unknown for only 2% of cancers diagnosed in 2010–2012.
Corresponding to the decreasing lymph node involvement over time, breast cancers in recent years are more likely to be diagnosed at a lower American Joint Committee on Cancer stage than those diagnosed in the 1990s and early 2000s. In particular, the number of stage 1 diagnoses has increased from 35% in 1995–1999 to 45% in 2010–2012 (P<0.001). The grading of breast tumors by pathologists has not changed significantly over time, although the VACCR data for this category is more completely documented in recent years. The number of ER-positive breast tumors has increased over time, from 47% in 1995–1999 to 65% in 2010–2012 (P=0.05; Table 2).
Rates of adjuvant hormone therapy administration did not change significantly over time (P=0.31); however, reported chemotherapy administration in the adjuvant setting increased substantially from 10% in 1995–1999 to 46% in 2010–2012 (Table 2; P<0.001).
Women living in urban areas of the United States diagnosed with breast cancer were more likely to have been diagnosed at a younger age (57 compared with 60 for rural women, P=0.04), and urban women were significantly more likely to be an ethnic minority (31% urban nonwhite vs. 13% rural nonwhite, P<0.001). Breast cancer characteristics of women (lymph node status, stage of breast cancer, and ER status) did not differ significantly between rural and urban women (P=0.98, 0.12, 0.9, respectively) (Table 3).
The number of women diagnosed with breast cancer and receiving oncologic care at the VA has increased steadily over time, which is likely a result of multiple factors. Increasing numbers of women serving in the armed forces in recent years has contributed to the change in the face of breast cancer at the VA. Although representing only an estimated 0.1% of the 226,870 breast cancer diagnoses in the United States in 2012, the number of women diagnosed with breast cancer at the VA has more than tripled from 1995 to 2012 and from 2000 to 2009 increased by about 60%, which is similar to the 83% increase in all women enrolled at the VA from 2000 to 2009.2,19 The caseload at the VA would also be affected by women’s decisions about where to receive their medical care as not all women elect to receive care at the VA shown by a 2003 national survey of women veterans, when only about one third of all women veterans were enrolled at the VA and receiving medical care there.20
The number of black women diagnosed with breast cancer within the VA has markedly increased in recent years from this analysis of VACCR data, from 16% to 25% from 1995 to 2012, and this is likely a result of increasing numbers of black women serving in the US Armed Forces in recent years. The percentage of women veterans who were black in 2000 was 17%, and 1 decade later, in 2010, that figure nearly doubled to 31% of women in active-duty military being black. The commensurate general population of black women in the United States aged 18–44 years in 2010 was only 15%.21,22
In addition, the age of diagnosis of breast cancer within the VA population has decreased over time. The largest portion of women veterans alive, at 27.7%, served during Operation Enduring Freedom/Operation Iraqi Freedom underscoring the young age of many women veterans.4 In comparison, Surveillance Epidemiology and End Results data reports that for the years 2010–2011 the proportion of incident breast cancers diagnosed in women in their 70s and 80s was 18% and 12%, respectively, data described here from the VACCR for 2010–2012, reported, 7% for women in their 70s and only 4% for women in their 80s.23 The real and proportional increase among women veterans aged 45–64 (30% to 44%) and the proportional decrease in veterans over age 65 (19% to 14%) documented from 2000 to 2009 likely accounts for much of this difference.2 In addition, the VA has documented very high mammography rates, at 87% of eligible women in 2011, which could be another reason for the younger age at diagnosis within the VA.24
We observed a stage shift of breast cancer at the VA over time, with fewer women diagnosed with lymph node involvement, a corresponding lower stage at diagnosis, and a larger proportion of tumors that were ER positive. This change is similar to what has been observed for breast cancer among the general population, with increased obesity in postmenopausal women being associated with more indolent ER-positive tumors, and increasing mammography rates diagnosing breast cancers at an earlier stage.25
The percent of women reported as receiving adjuvant chemotherapy for breast cancer at the VA has increased greatly over time. In general, younger women are more likely to receive adjuvant chemotherapy than older women and, as documented above, women treated within the VA system are currently younger than previously, thus there could be a real increase in the use of chemotherapy in VA breast cancer patients. Capture of chemotherapy and hormonal treatment in cancer registry records is recognized to be incomplete.26–28 For example, the cancer registry chemotherapy variable is estimated to be 68% sensitive relative to Medicare claims.29 Therefore, it should be considered that some or all of the trend with time could be a result of a change in reporting.
Women with breast cancer at the VA became more urban by zip code-classification over time, which mirrors the overall changes of the US population.30 Further, black women are much more likely to live in urban areas, and the increase in black women with breast cancer at the VA occurred primarily within urban areas. Our comparison of rural and urban status among women diagnosed with breast cancer at the VA revealed that urban women are more likely to be younger and of an ethnic minority, consistent with known differences between rural and urban women in the general population, however, the presenting characteristics of breast cancer were not different between these 2 populations.31 The outcomes of breast cancer among rural women should be further evaluated, considering both the region where the patient lives and the distance from the closest hospital providing subspecialty care.
This description of breast cancer at the VA is limited by several factors. First, it relies nearly exclusively on 1 source of data, the VACCR, which does not include all information of interest to describe cancer patients, treatment, and outcomes. However, cancer registry data, in general, are considered highly complete with respect to case ascertainment and valid for cancer diagnosis and patient demographics.32,33
Second, women receiving care at the VA may receive portions of their care at various non-VA facilities, adding a layer of difficulty when interpreting VA datasets. There are 3 main arms of breast cancer treatment—radiation, surgery, and medical oncology. Nearly all radiation oncology for cancer treatment of VA patients is provided at outside facilities by non-VA care, however, the majority of surgical and medical treatment for breast cancer is provided by VA physicians. Luther et al34 estimated that for women within the VACCR from 2000 to 2006, only about 10% received breast cancer surgery at an outside facility. And although exact numbers of women treated by medical oncology for breast cancer outside the VA are unknown, most women are likely treated adjuvantly with chemotherapy or hormone therapy by VA medical oncologist as there are 134 VA facilities with cancer treating capabilities, which includes by necessity a medical oncologist.17 As there are so few women diagnosed with breast cancer at the VA per year (365 in 2012) and there are nearly 150 treating VA facilities, the number of breast cancer patients seen by a particular physician could be quite low, and this fact calls for an evaluation of the quality of care and outcomes of the women being treated for breast cancer at the VA.
Breast cancer treatments and outcomes need to be further explored with attention to patient comorbidities and breast cancer volume of the treating facility. To properly compare those outcomes, it will be necessary to utilize multiple VA datasets to ensure data completeness and accuracy and to appropriately control for the many confounding factors within the population of women receiving care at the VA. Methods have been developed to obtain and validate information through VA electronic medical records, including use of text fields and pharmacy data.35,36 Further research on cancer treatment within the VA should include validating methods to obtain information on adjuvant treatment, comorbidities, and functional status to better evaluate treatment trends and receipt of guideline-concordant therapies.
Given the rapidly increasing number of women at the VA, it is key that both the clinical care and the research goals include specialization in breast cancer care and validation of methods to evaluate breast cancer outcomes. This description of women with breast cancer at the VA from 1995 to 2012 is an initial step necessary to define parameters by which breast cancer at the VA can be judged to improve both the quality of medical care and outcomes for women with breast cancer.
The authors acknowledge biostatistics core resources support from NIH 1ULTR001067 and Huntsman Cancer Institute P30CA042014. The authors acknowledge the VACCR for allowing access to the dataset for breast cancer at the VHA hospitals and for aiding them in procurement and definition of the data. This material is the result of work supported with resources from the VA Informatics and Computing Infrastructure (VINCI) and the use of facilities at the George E. Whalen VA Medical Center.
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Keywords:Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
breast cancer; women veterans; VA