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© 2002 American Society for Clinical Oncology Costs of Treatment for Elderly Women With Early-Stage Breast Cancer in Fee-for-Service SettingsByFrom the National Cancer Institute, Bethesda; Information Management Services, Silver Spring; and the Center for Medicare and Medicaid Services, Baltimore, MD. Address reprint requests to Joan L. Warren, PhD, Applied Research Program, National Cancer Institute, Executive Plaza North, Rm 4005, 6130 Executive Blvd, Bethesda, MD 20892-7344; email: joan_warren @nih.gov.
PURPOSE: This study provides population-based estimates of the treatment costs for elderly women with early-stage breast cancer, with emphasis on costs of modified radical mastectomy (MRM) compared with breast-conserving surgery (BCS) and radiation therapy (RT). PATIENTS AND METHODS: Women with breast cancer from the Surveillance, Epidemiology, and End Results cancer registries were linked with their Medicare claims, 1990 through 1998. Each claim was assigned to an initial, continuing, or terminal care phase after a cancer diagnosis. Mean monthly phase-specific costs were determined for all health care and for treatment related only to cancer. Cumulative long-term costs of care that accrue during a women’s remaining lifetime were calculated by treatment group. RESULTS: Initial care costs for the 6 months after diagnosis for women who underwent BCS with RT were approximately $450 per month higher than for women with MRM. During the continuing-care phase, costs for women undergoing BCS with RT were significantly less expensive than for MRM cases. The two groups had similar costs in the terminal-care phase. Assuming the same survival distributions, long-term costs for women undergoing BCS with RT were not statistically different than for women undergoing MRM. CONCLUSION: Although mastectomy was less costly in the initial phase, the lifetime costs of BCS with RT and mastectomy were equivalent. Thus, women’s preferences, resources to cover out-of-pocket costs, and life situations should be the major factors addressed in shared decision making about treatment options.
AMONG AMERICAN women, breast cancer is the most frequently diagnosed cancer and the second leading cause of cancer-related deaths.1 An estimated 182,000 women were diagnosed with incident breast cancer in 2000, the majority of whom were older women with early-stage disease.1,2 Because of its high incidence, prevalence, and mortality, the costs for breast cancer treatment are significant, with estimated national expenditures of $6 billion in 1996.3,4 Increasing numbers of women with early-stage breast cancer are undergoing breast-conserving surgery (BCS) with radiation therapy (RT) as an alternative to mastectomy.5-8 Several studies of the economic impact of changes in breast cancer surgical treatment have suggested that BCS with RT may be more costly than mastectomy without reconstruction, although the results are not conclusive.9-11 Other studies that have assessed the costs of breast cancer treatment have focused on costs of all medical care received by individuals with a breast cancer diagnosis12 or have included care provided in a single location.13-15 This study provides estimates of the cost of treatment derived from a cross-section of a large population-based cohort of elderly women diagnosed with early-stage breast cancer. These findings may resolve the ambiguity in regard to the costs of specific cancer treatments and update earlier findings. We also build on a method developed by Brown et al16 to estimate costs for women diagnosed with breast cancer in two ways, the total costs of all health care as well as the costs that are related to the cancer treatment. Cost estimates are presented by differing phases after a cancer diagnosis and include costs for patients who received varying treatment modalities, with special emphasis on comparing the costs of mastectomy versus BCS with RT. In addition, we estimate the cumulative long-term costs of care that accrue during a woman’s remaining lifetime and present costs by treatment group and stage. Information about the phase and treatment-specific expenditures can be used to inform decision making in regard to the costs and benefits of selected treatments. Long-term costs of care are needed as part of cost-effectiveness analyses, such as studies related to screening and treatment. These estimates can also inform public policy decisions regarding resource allocation for breast cancer, a disease that is a major source of morbidity and mortality among American women.
Data Sources Data for this analysis were obtained from two sources, the cancer registry data from the Surveillance, Epidemiology, and End Results (SEER) program maintained by the National Cancer Institute (NCI) and from Medicare claims. The SEER data are reported by population-based registries that collect clinical information about incident cancer cases and follow up vital status. The SEER areas in this analysis included cancer registries that covered five states (Connecticut, Hawaii, Iowa, New Mexico, and Utah) and six metropolitan areas (Atlanta, Detroit, Los Angeles, San Francisco/Oakland, San Jose/Monterey, and Seattle) that represented approximately 14% of the U.S. population.2 For each patient, the SEER data contained a unique case number; demographics such as age, race, and sex; each occurrence of a primary incident cancer; month and year of diagnosis; type of surgery performed; and stage of disease at diagnosis, using tumor-node-metastasis classification from the American Joint Committee on Cancer (AJCC).2,17 Follow-up information collected by SEER registries included the date and cause of death, using International Classification of Diseases (ICD)-9-CM coding.18 The Medicare data, collected by the Center for Medicare and Medicaid Services, included a master enrollment file for all Medicare beneficiaries. For beneficiaries with fee-for-service coverage, Medicare data also included claims submitted for all inpatient hospitalizations, skilled nursing facility, outpatient hospital services, physician and supplier services, and hospice and home health care. All files included specific dates of service and codes for specific diagnoses and procedures using either ICD-9-CM codes or modified Common Procedure Terminology codes.19 Persons reported to SEER were matched against the Medicare master enrollment file, and for Medicare-eligible persons, their claims data were extracted, as described elsewhere.20 For persons reported to SEER who were age 65 or older, 94% were linked to the Medicare enrollment file. The current linkage of the SEER-Medicare data includes persons diagnosed with cancer from 1973 to 1996 and their Medicare claims through 1998. Using the linked SEER-Medicare data allowed us to estimate the total direct costs of cancer treatment across years and across the continuum of Medicare-covered health care services. The term costs as used in this article refers to the amount reimbursed by Medicare. We used the amount paid by Medicare rather than charges on the claim as a proxy for the direct medical care costs. Medicare charges are not necessarily related to the cost of providing services,21 although Medicare costs are actual payments derived from reimbursement formulas that are intended to reflect the average resource utilization for that health service. A study by Burkhardt and Sunshine22 concluded that actual payments "may be preferred" because they most closely correspond to the economic concept of opportunity cost, "a measure of the dollars that become unavailable for purchasing other things in the economy."
Sample Selection We included women with breast cancer, excluding cases where any other cancer was reported to the SEER program. Cases that were diagnosed through death certificate or autopsy were also excluded. The focus of this analysis was on the treatment costs of early-stage breast cancer, so we retained only women with AJCC stage I or II cancer. Women were categorized by AJCC stage, age group (65 to 69, 70 to 74, 75 to 79, 80 to 84, and 85 and older), and race (white, black, other, and unknown). Women had to be enrolled in Medicare Part A and Part B and have fee-for-service coverage for some time during 1990 to 1998. We were only able to use claims from the time that a woman had fee-for-service coverage because Medicare does not receive claims from health maintenance organizations (HMOs). Between 1990 to 1998, the portion of Medicare beneficiaries enrolled in HMOs increased from approximately 10% to 20%. To calculate costs related to cancer care, we estimated and subtracted the costs for care that would have been routinely provided in the absence of a breast cancer diagnosis. To estimate these costs, we identified a control group of women who had not been diagnosed with any cancer, drawn from a 5% random sample of Medicare beneficiaries residing in the same SEER areas. Controls were matched to cases by age, race, and geographic area. Controls had to meet the same conditions as the cases in regard to Medicare eligibility and coverage. We used Medicare claims for the controls from 1990 to 1998.
Definition of Cancer Phases
Defining Treatment In addition to surgical treatment, we reviewed both data sources for a report of RT administered within 4 months of diagnosis. Medicare claims were used to identify whether chemotherapy was administered. Chemotherapy administered during the initial phase was considered adjuvant therapy. During the continuing-care and terminal phases, chemotherapy was considered treatment for a recurrence. Codes used to classify the treatments and procedures are presented in Table 1.
Estimating Total and Cancer-Related Costs Total costs for each phase were calculated by estimating the mean monthly costs per phase on the basis of the date of service on the claim. We adjusted payments to 1998 constant dollars using the Center for Medicare and Medicaid Services time series and geographical adjustment factors for Part A and Part B.24-26 Costs related to cancer treatment were obtained by calculating the routine costs of health care not related to cancer treatment and subtracting these from the total health care costs. The routine costs of care were derived from the health care costs of controls that had been matched with cases by age, race, and region using a method described more fully elsewhere.16 We presented total costs as both unadjusted and adjusted figures. The adjusted data were estimated using an ordinary least squares regression that controlled for age, race, region, type of surgical treatment, stage, and year of diagnosis. For the initial phase only, we also adjusted for the use of adjuvant chemotherapy and any differences between patients in prediagnosis comorbidity. A measure of comorbidity was included because a woman’s preoperative health status might influence choices regarding initial treatment. This adjustment was made using the Deyo adaptation of ICD-9 codes to the Charlson comorbidity index27,28 and included a review of all diagnostic codes reported during any hospitalization in the 12 months before breast cancer diagnosis. We did not include a measure of comorbidity during the continuing-care and terminal phases because the continuing-care phase may span years, long after the measurement of initial comorbidity had occurred. In the intervening period, a woman’s health status could have changed, particularly among women in the elderly population.
Estimating Cumulative Long-Term Costs of Cancer Treatment Unadjusted estimates of long-term costs for each stage or treatment strata were a weighted average of all survival experiences within that strata, assuming that all individuals in that strata experienced identical phase-specific costs but may have different survival experiences. To estimate survival curves, we used SEER cases diagnosed from 1983 to 1996, excluding Los Angeles and San Jose, with follow-up through December 31, 1996. Death or censoring times were recorded to the nearest month and assumed to occur in the middle of those months. Survival was estimated using a Weibull model, with an additional term equal to year of diagnosis for any diagnosis year before 1990. This was done to account for increasing survival during the 1980s associated with the advent of screening.29 When we estimated long-term costs by treatment modality, we applied the respective phase-specific costs for BCS with RT and MRM to the survival experience of the combined group of women undergoing either procedure, recognizing that in our cohort the observed survival for women undergoing BCS with RT was greater than for women undergoing MRM, probably caused by selection bias. Despite the observed difference in survival between these two groups, we opted to combine the two groups because we thought that the relevant policy question was the cost difference that would emerge if a women who received one treatment modality had instead received the other. We calculated confidence intervals for the long-term costs using percentile bootstrap confidence intervals.30 This method estimates the variability of a statistic by repeatedly calculating that statistic on many bootstrap samples; we used 1,000. For a simple statistic, a bootstrap sample is a simulated sample of the same size as the original formed by repeatedly and randomly selecting one observation from the complete original data. This simulated sampling is called resampling. The 95% bootstrap percentile interval includes the middle 95% of the statistics calculated from the bootstrap samples. Because our data came from more than one source, the formation of each bootstrap sample is not straightforward and requires several resampling steps. We first resampled women from the SEER data used to estimate survival. For women in that sample who were also in the SEER-Medicare data (including repeat samples) we resampled these cases used to estimate costs. Because we used matching controls in our calculations, we needed matching controls for each bootstrap sample. The controls were resampled from the SEER-Medicare data with matches in proportion to the resampled SEER-Medicare cases.
Table 2 shows the mean monthly total costs for each phase and by subgroup as well as the number and percent of cases in each strata. Table 3 shows the same type of data for cancer-related costs. The mean monthly cancer-related costs during the initial phase were $1,462, totaling $8,338 for the entire phase. During the continuing-care phase, mean monthly care-related costs declined to $112, and for women with cancer as a cause of death, monthly costs increased to $2,561 during the last 6 months of life or $15,257 for the entire phase.
Women who underwent BCS with RT accounted for 31% of all women in the initial phase. During the initial phase, the total and cancer-related care unadjusted mean monthly costs for women treated with BCS and RT were approximately $450 higher than the costs of care for women with MRM, who accounted for 53% of all women in the initial phase. The adjusted mean total monthly cost during the initial phase was $625 higher for women who underwent BCS with RT than costs for women treated with MRM (Table 4). In the continuing-care phase, the total costs for cases treated with BCS with RT were $20 (unadjusted) and $16 lower (adjusted) than those for women treated with MRM. Both the adjusted and unadjusted differences were statistically significant. Unadjusted and adjusted monthly terminal-care costs for cancer-related deaths were not significantly different between the two groups.
The mean monthly costs for cancer-related care for women who received chemotherapy were higher than for women who did not receive chemotherapy, although the differences varied markedly by phase. During the initial phase, the difference in the mean monthly total costs between women who received chemotherapy in contrast with those who did not was $673 for unadjusted and $566 for adjusted. With chemotherapy administered for recurrences or during the terminal phase, the unadjusted difference in total costs was $1,050. During the initial and continuing-care phases, the unadjusted and adjusted mean monthly costs were higher for women with stage II disease than for women with stage I cancer. The adjusted initial phase costs included a covariate for the use of adjuvant chemotherapy, so the higher costs for patients with stage II disease reflect expenses in addition to adjuvant treatment. For all phases, women in the oldest age group had total and cancer-related costs of care that were significantly lower than for women in the age group of 65 to 69 years, even after controlling for differences in surgical treatment. The greatest differences in costs by age group were noted during the terminal phase, with the adjusted mean monthly costs for women age 85 and older $1,365 dollars less than women in the 65-to-69 age group. In all phases, the total and cancer-related costs for treating black women were significantly higher when compared with the costs of treating white women. These differences persisted even after controlling for variation in stage and treatment in all phases as well as pre-existing comorbidities and the use of adjuvant chemotherapy during the initial phase. The adjusted mean monthly cost for black women was $320 higher than for that for white women during the initial phase and $537 higher during the terminal phase. The average long-term cost of health care during 25 years for women with early-stage breast cancer was $72,594, of which $27,697 was expended for cancer-related treatment (Tables 5 and 6). For women who underwent BCS with RT, their long-term unadjusted cancer-related costs were almost $2,800 more than for women who received MRM, and their total costs were approximately $1,200 higher. Bootstrap confidence intervals of the differences in costs between the two treatment groups were not significant at the .05 level. By stage, long-term cancer-related costs were highest for women with stage IIB disease, although their lifetime total health care costs were the lowest because they had fewer months of survival.
Tables 4 and 5 also reflects the percentage of long-term costs by phase. For women undergoing BCS with RT, more of their long-term cancer-related costs occurred in the initial phase compared with women undergoing MRM: 35% and 28%, respectively. Women who died of stage IIB cancer had a higher percentage of their long-term costs related to terminal care compared with women who died of stage I cancer (29% v 11%).
The current study is the first to provide national population-based estimates of the phase-specific and long-term costs of breast cancer care by type of treatment for fee-for-service Medicare beneficiaries. We concluded that the long-term costs for women treated with BCS with RT were comparable to MRM, although there were significant differences in costs for the two treatment modalities during the initial phase of care. Two earlier studies have compared the total health care costs of BCS with RT versus MRM and found that BCS with RT was more expensive. However, the magnitude of the differences varied between the two analyses. An analysis by Munoz et al11 included hospital charges (not costs), surgeons’ fees, and a standard 6-week course of RT for women who received BCS with RT. They reported that total charges for women who underwent BCS with RT were approximately $3,800 higher than for women who underwent mastectomy. Assuming the follow-up period for women in their study was 3 months, their estimates of the difference between the two procedures is considerably larger than that which we observed during the initial phase, $1,350 for the same period ($450 a month for 3 months). A second study by Desch et al9 followed women younger than 65 for up to 3 years after their breast cancer surgery. They found during this period that BCS with RT was $5,400 more expensive than MRM. Unlike the earlier studies, we estimated costs for up to 25 years and observed that long-term total health care costs were only $1,200 greater for women undergoing BCS with RT than for MRM. The difference in the treatment cost of women who received BCS with RT as compared with MRM was not statistically significant and is modest when viewed for the remainder of a woman’s life. A recent study performed at a single, large HMO observed a similar difference in the long-term costs by treatment. In that study, patients treated with BCS with RT experienced costs that were a few thousand dollars higher than MRM patients during the first 6 months after diagnosis, but costs between the two groups were equivalent for subsequent periods up to 5 years after diagnosis.31 It should be noted that the estimates of the cost differential between BCS with RT and MRM does not include any costs for reconstructive surgery. MRM followed by reconstruction is the most expensive of all treatment modalities.9,11 The differences we have documented in treatment costs between BCS with RT and MRM may seem meaningful or not, depending on the time horizon of the decision maker. From a long-term view, the cost of BCS with RT over time is comparable to MRM. However, a recent study has suggested that many health plans may shape their coverage policy by considering short-term costs only.32 With the real difference in costs for breast cancer treatment occurring in the initial phase, health plan administrators may not consider the costs of the two treatments to be equivalent unless they recognize that most of the woman diagnosed with breast cancer will remain in the plan for the long-term.33 Several earlier studies have provided estimates of the total and phase-specific costs of breast cancer treatment by stage. Using SEER-Medicare data, Riley et al12 found that costs for women age 65 and older diagnosed with breast cancer reported total mean monthly costs during the initial and continuing-care phase that were lower than the current study, even when inflating the costs from earlier years to match 1998 dollars. Their costs were $200 lower in the initial phases and $120 lower during the continuing-care phase. The higher costs in the present analysis may be caused in part by the increased use of chemotherapy among elderly women since 1990. Studies that used data from two large staff-model HMOs,13,15 Kaiser Permanente in northern California and Group Health Cooperative in Seattle found that initial-phase costs were higher than those reported in our study, $800 higher for Kaiser-Permanente and $200 higher for GHC. These differences may be explained by the fact that their study included costs of deductibles and copayments and that their sample included women of all ages, at least one half of whom were under the age of 60. Younger women are more likely to receive more aggressive treatment for their breast cancer, including more adjuvant chemotherapy, breast reconstruction after a mastectomy, and autologous bone marrow transplantation for metastatic disease. The use of chemotherapy was an important determinant of cost across all phases. Costs differed by phase, which may reflect variation in the intensity of chemotherapy administered by phase and the reason for administering the treatment. During the initial phase, use of adjuvant chemotherapy resulted in an adjusted mean monthly increase in total costs of $566. Twenty-five percent of women in our study with stage IIB cancer received adjuvant chemotherapy during the initial phase, less than the 40% reported in an earlier study of women age 60 and older with node-positive early-stage breast cancer.34 It should be noted that approximately 75% of women in our study were age 70 or older, and there are limited data to define the optimal use of adjuvant chemotherapy for women more than 70 years of age.35 However, a report from the Institute of Medicine states that underuse of adjuvant therapy for women with early-stage breast cancer may be a quality-of-care problem.36 Earlier studies have not assessed the use of chemotherapy at the end of life. For women who died of cancer, there was common use of chemotherapy during the terminal phase, with 32% of women receiving such care. Given how our cohorts were structured, we were unable to use these data to estimate the long-term costs between women who did and did not receive adjuvant chemotherapy. The cost of cancer-related care during the initial stage declined significantly with age, even after controlling for differences in treatment and stage and pre-existing comorbidity. These findings suggest that age alone is a determinant of the intensity of treatment a women receives. Earlier studies have found that care for women with breast cancer decreased with age.15,37-39 A study by Ballard-Barbash et al40 concluded that, even after adjusting for prior comorbidity, chronologic age was an important independent factor associated with intensity of care. There were significant differences between white and black women in terms of total and cancer-related costs. These differences might be attributed to black women presenting with more advanced-stage disease or receiving different treatment. However, as noted earlier, our multivariate analysis included these variables that might explain higher costs for black women. Despite inclusion of these covariates, race continued to be a significant independent factor associated with cost. The higher costs among black women may reflect unmeasured pre-existing health problems. It may also capture differences in care after a cancer diagnosis. Although black Medicare beneficiaries have been shown to receive less preventive and diagnostic services,41 Gornick et al42 found that black Medicare beneficiaries were more likely to be hospitalized, and hospitalization is the most expensive component of health care. This study has several limitations that should be noted. Our data reflect the costs to Medicare for women age 65 and older with fee-for-service coverage. The study does not include all costs to these patients, including copayments and deductibles. Estimates are that the costs of copayments and deductibles would increase the hospital (Part A) expenses by 7% and Part B expenses by 38%.3 The costs cited in this article do not include noncovered Medicare services, such as oral prescription drugs. Tamoxifen, which is recommended for all postmenopausal women with early-stage breast cancer except those with lesions smaller than 1 cm,35 currently costs $100 per month.43 Women who use tamoxifen for the recommended 5 years44 have $6,000 more in lifetime costs, assuming a monthly cost of $100. An additional $6,000 would increase the cancer-related costs by more than 26% for those women who use tamoxifen. We are also unable to generalize these findings to women under age 65, who may be more likely to receive more aggressive treatment. This study does not reflect the costs for Medicare women in HMOs who may receive different care.45,46 This study does not report on the cost experience of women with advanced breast cancer, although women with early-stage disease account for almost three quarters of incident breast cancer cases. Earlier studies12,13 have shown that women with early-stage disease have lower phase-specific costs than women with more advanced disease but have higher long-term costs because of their better survival rates. An additional limitation relates to issues of comparability. We compared the costs of cases and controls during the 7-to-18-month period before diagnosis. Comparisons were made according to age, race, stage, treatment modality, and the use of chemotherapy. We found that prediagnosis costs were similar between cases and controls, with the exception of some groups. For women who underwent simple mastectomy, monthly costs averaged $363 for cases and $282 for controls, although for BCS only, cases averaged $341 and controls averaged $287. Monthly prediagnosis costs were approximately $198 for women who underwent BCS with RT, compared with $220 for their controls. Stage IIB cases had monthly costs of $213 as compared with $241 for their controls. In the circumstance in which prediagnosis costs are higher for cases than for controls, there may be a modest overestimate of cancer-related costs. In the converse situation, an underestimate of cancer-related costs may result. It should be noted that the differences between women who undergo selected treatment modalities may be reflected in total costs as well. This study used observational data; women in this study were not randomly assigned to treatment groups. Therefore, women in one group may have had pre-existing health problems that influenced the type of cancer treatment they received as well as other types of health care. Therefore, although the data presented on total costs represents the actual average cost of treatment, some of the differences in postdiagnosis costs may capture prediagnostic differences. In the multivariate analysis of initial-phase costs, we have included a measure of prediagnosis comorbidity to adjust for prediagnosis differences between who women underwent different treatments. However, our assessment of comorbidity was derived from hospital claims only, which underestimate the true burden of concomitant disease. Any differences in prediagnosis status not captured by the comorbidity measure during the initial phase as well as differences in health status during the continuing-care and terminal phase may influence the total costs. As more women have breast cancer and survive for longer periods of time, the long-term costs of care will increase because of longer continuing-care phases. Changes in treatment may also impact the total and cancer-related costs. For example, changes in chemotherapy regimens or the introduction of new agents could increase the cost of care. Other nonclinical factors, such as changes in Medicare’s reimbursement policy, could also influence the cost of treatment. Increases in costs, however, are not likely to have an impact on the relative costs of care by surgical treatment unless the changes target one treatment and not the other. We anticipate that the long-term costs of treatment for women who undergo BCS with RT as related to the costs of MRM will be relatively similar over time. Therefore, we conclude that, for the long-term, there is no evidence from this analysis to suggest that the cost of care should play a significant role in medical decision making in regard to treatment options for elderly women with early-stage breast cancer, although there are some differences in treatment costs during the initial months of care.
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Copyright © 2002 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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ABSTRACT
INTRODUCTION
