Analysis of Utility Assessment Scores to Objectify the Health Burden Caused by Breast Conservation Therapy

Abstract

Background:

Lumpectomy followed by radiation, known as breast conservation therapy (BCT), is a viable surgical treatment option for early-stage breast cancer. However, the current literature suggests that patients prefer mastectomy over BCT, likely due to the wide variety of postmastectomy reconstructive options. Our aim is to investigate the objective health burden of living with BCT to help surgeons gain a better understanding of patient treatment preferences.

Methods:

Three validated health state utility tools were used to objectify the burden of living with post-BCT results: visual analogue scale (VAS), time trade-off (TTO), and standard gamble (SG). A prospective sample of the general population and medical students were recruited, and their responses analyzed to attain these scores.

Results:

Utility scores for living with BCT are VAS 0.81 ± 0.19, TTO 0.93 ± 0.10, and SG 0.92 ± 0.14. The TTO and SG suggest a willingness to trade 2.5 years of life years and an 8% chance of death undergoing reconstructive procedures to correct a BCT defect, respectively. Age, gender, race, education, and income were not statistically significant independent predictors for higher or lower utility scores.

Conclusion:

The impact of the health burden of BCT was ascertained using validated objective numeric utility scores. These indices demonstrate a willingness to trade less life years to undergo correction of a BCT defect than reconstruction following unilateral mastectomy. They can provide surgeons with the best objective understanding of patient preferences for shared decision-making in the management of breast cancer.

Introduction

Approximately 2 50 000 new breast cancer cases are being diagnosed each year, rendering it one of the most common malignant neoplastic diseases in the United States.¹ In 2014, approximately 60% of women who were diagnosed with early-stage breast cancer opted for a partial mastectomy followed by postoperative radiotherapy, also known as breast conservation therapy (BCT).² Over the last century, surgical treatment of breast cancer has been subject to immense changes. Although radical mastectomy had been the undisputed standard of care for decades, critical appraisal of the unsatisfactory results and the emotional impact of full removal of the breast had resulted in the development of less invasive surgical techniques.^3,4

Breast conservation therapy as a treatment modality has increased steadily due to survival rates comparable to mastectomy and superior outcomes in operative time, intraoperative blood loss, and length of stay.^5,6 Additionally, 20 years of randomized controlled clinical trial follow-up data confirmed BCT as the recommended surgical therapy for women diagnosed with early stage breast cancer.^7,8 Moreover, it maintains the breast mound and nipple areola complex contributing to improved aesthetic appearance and sensation.

Despite these perceived advantages, patient satisfaction scores have not varied when compared with mastectomy followed by reconstruction.⁹ This notion is echoed by Katz et al who reported that more patient involvement in decision-making was still associated with a higher rate of mastectomy.¹⁰ This contradiction reflects the difference between subjective patient preferences and objective measured outcomes in the current literature. The reason for this shift toward mastectomy remains unclear, but one of the suggested explanations is the increasing array of options available for postmastectomy reconstruction.¹¹ Indeed, BCT is not without its aesthetic limitations. This is best exemplified by the appearance of the breast following radiation therapy where surgical scars can be accentuated due to contracture resulting in distortion of breast shape and breast asymmetry compared to the contralateral side. With the advancement in current techniques for breast reconstruction following mastectomy and the ensuing satisfactory aesthetic outcome, patients may favor the latter over BCT regardless of the opportunity to keep a majority of their own breast. However, this discrepancy may simply be based on a lack of objective analysis of patient satisfaction in previous studies.^12,13

In the current health care environment, treatment is not only focused on disease cure but also patient satisfaction. This is highlighted by the fact that shared decision-making and patient-reported outcomes have become an essential component in choosing the desired treatment modality.^13,14 In order to properly employ shared decision-making in cancer treatment, it is necessary to understand patient preferences and concerns. However, to date, quantifying the burden associated with a post-BCT health state has not been reported. To bridge the gap between patients and physicians’ perceptions of what would lead to a satisfactory result, we attempted to objectify this burden using utility outcome measures. These utility indices serve as a measure of a patients’ quality of life and their preference for a particular health state. Quality-adjusted life years (QALYs) can also be calculated from these utility scores. Utility indices, including time trade-off (TTO), standard gamble (SG), and visual analogue scales (VASs), are validated methods used to measure and objectify the impact of certain health conditions.¹⁵ These utility scores have been previously used to assess the health burden for a broad range of medical conditions.^16-18 The aim of this study is to objectify BCT utility scores which may help surgeons to better understand patient preferences for shared decision-making in the management of breast cancer.

Methods

Recruitment Procedure

Members of the general population were prospectively recruited using online ads platforms (www.kijiji.ca and www.craiglist.org), directing them to our online utility assessment website. Additionally, medical students at McGill University (Montreal, Quebec) were recruited through email, directing them to the same utility website. This gave us the opportunity to increase sample size and compare groups with and without a medical background. Demographic information of the recruited population was collected (age, gender, race, educational level, and income). Participation was completely voluntary and anonymous. There was a 6-month period for participant enrollment. Electronical consent was obtained from every participant.

Case Rating

A representative case presentation of a BCT patient was shown to all participants (Figure 1). The patient whose photograph is used in this study had consented to its use for research, presentation, and publication. Objectifying the health burden of BCT was performed using 3 validated utility instruments: VAS, TTO, and SG.¹⁵ With these psychometric instruments, the health state preference of BCT was determined. The results of 3 tools, VAS, TTO, and SG, were combined to minimize possible shortcomings of any single measure.¹⁹

Figure 1.

Representative picture of a patient who underwent breast-conserving therapy.

Rating Instruments

The VAS is a validated tool measuring either health quality of life of a given health state or a patient’s own health state. It is a sliding scale representing 0 to 100 points, 0 being “death” and 100 being a “perfect health state.” In our study, participants are rating the given health state. The scores were recalculated between 0 and 1 point using the formula:

$$\text{Utility score VAS }=\text{Score}/100.$$

The TTO instrument is a widely used instrument designed to identify QALYs. It calculates the ratio difference between the number of life years spent in the best attainable health state compared to the number of life years spent in the deteriorated health state.²⁰ The scale ranges from 0 (death) to 1 (perfect health). The utility score is calculated using the following formula:

$$\text{Utility score TTO}=\left(\text{Number of years specified in the described health state}-\text{number of years traded off at the indifference point}\right)/\left(\text{Number of years specified in the described health state}\right)\text{.}$$

The SG utility value represents the respective probability of success. In SG, participants are asked to choose between either remaining in a given health state or taking a chance (gamble) with some probability of success (perfect health) and some probability of failure (death). Percentages of success and failure are systematically alternated until the patient is indifferent between taking the gamble and remaining in the described health state. The utility score is derived from this point of indifference using the following formula:

$$\text{Utility score SG}\text{=}\left(1.00-\text{Risk of death at the point of indifference}\right)/100\text{.}$$

In SG, the study volunteers were asked to decide whether it was worth the risk of undergoing treatment (ie, to undergo further reconstruction/correction of the BCT defect) resulting in either an improved health state or immediate painless death (staying in the deteriorated health state, ie, remaining with the BCT outcome).

A control measure assuring correct utility outcomes was employed using monocular and binocular blindness to test participants understanding of the study. Volunteers ranking binocular blindness with higher utility scores compared to monocular blindness were excluded, since ranking binocular blindness closer to perfect health than monocular blindness would indicate a misunderstanding of the utility scores. This ensured standardization of the scores assigned to the given health state.

Statistical Analysis

Data were analyzed using IBM SPSS statistical software, version 18.0. Means of utility scores of BCT, monocular, and binocular blindness were compared using the paired sample t test. Linear regression was performed to identify independent predictors for higher or lower outcome scores. A P value of <.05 was defined as being statistically significant.

Results

A total of 117 participants volunteered for inclusion in this study. Fourteen were excluded due to incorrect ranking of the binocular blindness, most likely due to a misunderstanding of how the study was conducted. Mean age was 24.4 ± 8.1 years, predominantly female (71.8%), Caucasian (49.5%), with some college education (41.7%), and an annual income greater than $10 000 (55.3%; Table 1).

Table 1.

Participant Demographics.

Characteristics	No. (%)
Age	24.4 ± 8.1
Gender
Male	29 (28.2%)
Female	74 (71.8%)
Race
Caucasians	51 (49.5%)
Non-Caucasians	52 (50.5%)
Asians	21 (20.4%)
Native Americans	1 (1.0%)
African American	1 (1.0%)
Hispanic	2 (1.9%)
Prefer not to answer	16 (15.5%)
Others	11 (10.7%)
Education
Medical education	2 (1.9%)
Nonmedical education	101 (98.1%)
High school	1 (1.0%)
Some college	43 (41.7%)
College graduate	32 (31.1%)
Professional degree	9 (8.7%)
Prefer not to answer	16 (15.5%)
Income
<$10 000	46 (44.7%)
>$10 000	57 (55.3%)
$10 000-$25 000	7 (6.8%)
$25 000-$50 000	3 (2.9%)
$50 000-$100 000	2 (1.9%)
Prefer not to answer	44 (42.7%)

Utility Scores

Utility scores (VAS, TTO, SG) for BCT with the potential to undergo oncoplastic reconstruction were 0.81 ± 0.19, 0.93 ± 0.10, and 0.92 ± 0.14, respectively. These indices were statistically different compared to the corresponding scores for monocular (0.63 ± 0.19, 0.86 ± 0.14, and 0.86 ± 0.19, respectively) and binocular blindness (0.32 ± 0.18, 0.61 ± 0.25, and 0.62 ± 0.25, respectively; VAS P < .0001, TTO P < .0001, SG P < .0001, respectively; Table 2).

Table 2.

Comparison of the Utility Scores for Breast Conservation Therapy to Monocular and Binocular Blindness.

Utility score	Monocular	Binocular	BCT	P valuea
VAS (mean ± SD)	0.63 ± 0.19	0.32 ± 0.18	0.81 ± 0.19	<.0001
TTO (mean ± SD)	0.86 ± 0.14	0.61 ± 0.25	0.93 ± 0.10	<.0001
SG (mean ± SD)	0.86 ± 0.186	0.62 ± 0.25	0.92 ± 0.14	<.0001

Abbreviations: BCT, breast conservation therapy; SD, standard deviation; SG, standard gamble; TTO, time trade-off; VAS, visual analog scale.

^a t test.

Independent Risk Factors

Linear regression revealed that education, race, gender, and income were not statistically significant determinants of health state preference for BCT.

Discussion

In this study, we quantified the health burden of living with a defect resulting from BCT. Our results demonstrated that participants perceived this health state as being closer to perfect health (1) than to death (0). Time-trade off scores translated to a willingness to trade 2.5 years of their remaining life years to undergo a reconstructive procedure to correct the defect caused by BCT. Standard gamble scores showed a willingness to gamble an 8% chance of death to undergo a rejuvenating reconstructive procedure. To our knowledge, this is the first study to quantify utility outcomes for BCT.

In addition to serving as a means to exclude participants who did not comprehend the study, the utility scores for monocular and binocular blindness also provide context for the severity of the health burden caused by BCT. Utility scores for BCT were significantly higher than monocular and binocular blindness. This suggests that living with a post-BCT defect is not considered as unfavorable as living with full or partial blindness. Similarly, the utility scores for unilateral mastectomy from a previous study were significantly different from monocular blindness.²¹ The VAS score (0.75 ± 0.17) and the TTO score (0.87 ± 0.14) for unilateral mastectomy are lower than the corresponding scores for BCT. If faced with living with a unilateral mastectomy, this population would be willing to trade 4.2 life years and gamble with a 14% chance of death. Specifically, participants would give up more to undergo a reconstructive procedure to correct a unilateral mastectomy defect than they would to address the outcome of BCT.²¹ This suggests that from an aesthetic standpoint, a mastectomy defect is less favorable. Utility scores for bilateral mastectomy (0.70 ± 0.18, 0.85 ± 0.16, and 0.86 ± 0.17, respectively) were not significantly different from the corresponding scores for monocular blindness.²² In other words, living with the health burden caused by bilateral mastectomy was quantified to be as severe as living with monocular blindness and worse than living with a defect caused by BCT. Utility scores for BCT, unilateral mastectomy, and bilateral mastectomy are displayed in Table 3.

Table 3.

Comparison of the Utility Scores for Breast Conservation Therapy to Unilateral Mastectomy and Bilateral Mastectomy.

Utility score	BCT	Unilateral mastectomy (33)	Bilateral mastectomy (21)
VAS (mean ± SD)	0.81 ± 0.19	0.75 ± 0.17	0.70 ± 0.18
TTO (mean ± SD)	0.93 ± 0.10	0.87 ± 0.14	0.85 ± 0.16
SG (mean ± SD)	0.92 ± 0.14	0.86 ± 0.18	0.86 ± 0.17

Abbreviations: BCT, breast conservation therapy; SD, standard deviation; SG, standard gamble; TTO, time trade-off.

Postmastectomy reconstructive options have increased over the last decades and are known to influence patient preferences regarding breast cancer management.²¹ Alderman et al concluded that during the decision-making process, patients were more willing to undergo a mastectomy, with subsequent reconstruction than the less invasive BCT.²³ This could be attributed to the wealth of reconstructive options available following mastectomy despite the preservation of autologous breast tissue in BCT which in itself may deter patients fearful of cancer recurrence. Perhaps, there is a need to further patient education regarding the long-term results of various modalities of breast cancer management. Mallinger et al reinforced this notion reporting that breast cancer survivors were less satisfied with long-term outcomes despite receiving what they deemed to be adequate information related to treatment.²⁴

Oncoplastic surgery, in which cancer resection is combined with plastic surgery techniques for reconstruction to optimize aesthetic result, is an alternative option aimed at improving the quality of life for patients with breast cancer.²⁵ It has been shown to have similar or even superior oncologic safety profiles and favorable aesthetic outcomes when compared with BCT alone.^26,27 Furthermore, when compared with mastectomy, the impact on body image and psychosocial aspects of oncoplastic surgery is less severe.²⁸ However, several factors should be considered when choosing to proceed with oncoplastic surgery including size of the affected breast, size of the tumor, and location of the tumor. In addition, it requires a multidisciplinary team approach involving a surgical oncologist, plastic surgeon, radiologist, medical oncologist, and pathologist. Moreover, the type of reconstruction chosen may necessitate a symmetry surgery of the other breast reinforcing the need for patient participation in the decision-making process.²⁹

The advantages of utility scores include the ability to provide scientific evidence related to the impact of treatment on a disease in relation to their final outcome. It addresses shortcomings in clinical practice by providing rationale for the development of gold standards of care.^30,31 Additionally, health care practitioners can inform patients of evidence-based rationales for treatments. Health care and insurance agencies can also identify improved cost–benefit options for the purposes of disease prevention.³⁰ These scores can be used to offer patients a quantitative comparison to other related procedures which enhances the shared decision-making process while improving patients’ understanding of the expected quality of life of living with the health states they strive for.

This study comes with several limitations. Sampling bias is implicated as our population might not be representative of society as a whole. Unfortunately, information on prior negative experiences with BCT was not ascertained in this study which may have skewed the utility scores toward a more favorable outcome. Furthermore, our study targeted the general population instead of actual BCT patients. A recent study, assessing patient preferences for hypothetical breast cancer treatment outcome scenarios (3 surgical: mastectomy, mastectomy with immediate implant-based reconstruction, and BCT; and 3 noninvasive: radiofrequency ablation, magnetic resonance-guided high-intensity focused ultrasound ablation, and single-dose ablative radiotherapy) demonstrated that BCT had the highest utility outcomes scores. Interestingly, VAS and TTO scores were almost identical to those reported in our study (VAS: 0.81 vs 0.80; and TTO: 0.93 vs 0.90, respectively) and higher than those for mastectomy. The authors attributed this to previous experiences with specific treatment options when compared with healthy women.³² Moreover, societal perspectives are, in general, favorable in terms of cost-effectiveness and directly advising decision makers. Institutions (eg, national health insurance, health systems agencies, and health-maintenance organizations) place greater emphasis on the societal perspectives, continuously increasing the importance, and value of cost-effectiveness measures.³³ However, this may have resulted in an underestimation of the true burden of BCT. Not questioning patients might cause a discrepancy in the true impact of this disease state. We did not elaborate on symptomatology regarding pain following radiation therapy, clothing, undergarment fit, and local recurrences. However, simplifying comprehension was needed to standardize the outcomes of this study allowing for a fair comparison to previously published utility outcome scores.^22,34 Despite these limitations, this is the first utility study to objectively analyze living with BCT using validated numeric measures. Providing this objective assessment can aid surgeons in the shared decision-making process.

Future studies should incorporate patient-reported outcome measures (PROMs) to identify the ailments associated with BCT and provide the best reflection of patients’ BCT burden. Patient-reported outcome measures are validated measures for patient experiences in terms of outcomes⁹ and can be used to assess the numerous options for breast cancer treatment.^2,8,14,35

Conclusion

For the first time, the impact of the health burden of BCT was ascertained using validated objective numeric utility scores and translated to a willingness to gamble with an 8% chance of death and to trade 2.5 years of existing life years to undergo correction of a BCT defect. When combined with PROMs, these scores can provide surgeons with the best objective understanding of patient preferences when making future shared decisions between mastectomy and BCT.