Trends in the use of postprostatectomy therapies for patients with prostate cancer: A Surveillance, Epidemiology, and End Results Medicare analysis


  • Nathan C. Sheets MD,

    1. Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    Search for more papers by this author
  • Laura H. Hendrix MS,

    1. Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    Search for more papers by this author
  • Ian M. Allen MD,

    1. Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    2. School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    Search for more papers by this author
  • Ronald C. Chen MD, MPH

    Corresponding author
    1. Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    2. Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    3. Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
    • Corresponding author: Ronald C. Chen, MD, MPH, Department of Radiation Oncology, University of North Carolina Hospitals, CB #7512, Chapel Hill, NC 27599; Fax: (919) 966-7681;

    Search for more papers by this author

  • Presented at the Annual Meeting of the American Society for Radiation Oncology; October 28-31, 2012; Boston, MA.



For patients with adverse pathologic factors (positive surgical margins, extracapsular extension, or seminal vesicle invasion) on prostatectomy pathology, the use and timing of postsurgical treatments are controversial. The goal of the current study was to examine patterns of care in patients with a pathologic indication for postprostatectomy radiotherapy (RT) using the Surveillance, Epidemiology, and End Results (SEER)-Medicare–linked database.


A total of 3460 men treated with radical prostatectomy for localized prostate cancer between 2000 and 2006 with at least 1 adverse pathologic factor and at least 3 years of claims data after surgery were included. Medicare claims through December 31, 2009 were examined. Rates of postprostatectomy hormonal therapy, RT, or both were examined. Logistic regression analysis examined potential factors associated with the receipt and timing of RT.


Within 3 years after surgery, 1076 patients (31%) received some form of further therapy, including 850 (25%) who received RT. Receipt of RT was < 35% in all subgroups including every year of study. Fewer than one-half of patients who received RT (43%) did so within 6 months of surgery. On multivariate analysis, pathologic T classification and tumor grade were associated with receipt of RT within 6 months or 3 years of surgery, as were younger age, geographic region, and population density.


Rates of postprostatectomy RT remain low and the timing of RT has not appreciably changed since the publication of the randomized trials supporting the use of adjuvant RT. The use of hormone therapy is almost as common as RT, despite a relative lack of evidence supporting its use in this setting. Cancer 2013;119:3295–301. © 2013 American Cancer Society.


More than 240,000 men are diagnosed with prostate cancer each year.[1] Radical prostatectomy is a standard treatment for patients with localized prostate cancer. Although prostatectomy alone is curative in many patients, up to 30% will develop biochemical disease recurrence after surgery.[2, 3] Multiple randomized trials have demonstrated an improvement in biochemical control[4-6] and overall survival[8] with the use of early adjuvant radiotherapy (RT) (usually defined as treatment within 6 months of surgery) for patients with adverse pathologic features, such as positive surgical margins, extracapsular extension, and/or seminal vesicle invasion. In this “high-risk” group, up to two-thirds of patients will develop biochemical disease recurrence without postoperative RT.[4-6] However, substantial controversy remains regarding the timing of RT after surgery, and some data suggest salvage RT at the time of disease recurrence may be equally as effective as adjuvant therapy.[3]

For patients with prostate cancer not cured by prostatectomy alone, RT, either in the adjuvant or salvage setting, offers a potential for cure and is recommended by the National Comprehensive Cancer Network guidelines.[9] Conversely, the role of hormonal therapy either alone or in combination with RT in the postprostatectomy setting is currently unclear.[10]

A prior study using the Surveillance, Epidemiology, and End Results (SEER) database reported that only 11.5% of patients with adverse pathologic features received adjuvant RT, and the practice patterns demonstrated little change after the publication of randomized trials.[11] However, SEER lacks information regarding treatments beyond the “first course” and therefore this study may have underestimated the use of postsurgical RT, especially treatment administered > 6 months after surgery (ie, salvage RT). Furthermore, because SEER does not capture information concerning hormonal therapy, the frequency of its use in the postsurgical setting is unknown. The purpose of the current study was to examine patterns of care in patients with adverse prostatectomy pathologic features within the 3 years after surgery, specifically examining issues of current uncertainty or controversy: the use of hormonal therapy as well as the use and timing of RT.


Data Source

The SEER database is composed of 16 population-based cancer registries that together represent approximately 26% of the US population. SEER-Medicare links the registry data with Medicare administrative and health care claims data, which provide benefits to 97% of US residents aged ≥ 65 years. Approval from the University of North Carolina Institutional Review Board was waived.

Study Cohorts

We defined our study cohort as patients diagnosed with nonmetastatic (no lymph node or distant disease) prostate cancer as their first and only cancer between 2000 and 2006. Using Current Procedural Terminology (CPT)/Healthcare Common Procedure Coding System (HCPCS) procedure codes (Table 1), we identified men between the ages of 65 years and 80 years who underwent radical prostatectomy. We included patients found to have adverse features on surgical pathology, defined as positive surgical margins and/or pT3 to pT4 disease to be consistent with the published randomized trials.[4-6] Patients with pathologic lymph node involvement were excluded from the analysis. All pathologic information was extracted from the SEER database. To ensure complete capture of health services received, we excluded men who were enrolled in a health maintenance organization or who were not enrolled in both Medicare Part A and Part B from 1 year before prostatectomy through the duration of the study.

Table 1. Procedure Codes for Radiotherapy and Hormonal Therapy
Cancer Therapy CPT and ICD-9 Codes
  1. Abbreviations: CPT, Current Procedural Terminology; CRT, conformal radiotherapy; HCPCS, Healthcare Common Procedure Coding System; ICD-9, International Classification of Diseases-Ninth Revision; IMRT, intensity-modulated radiotherapy; MIRP, minimally invasive radical prostatectomy; ORP, open radical prostatectomy.

External beam radiation 77305, 77310, 77315, 77321, 77371, 77372, 77373, 77402, 77403, 77404, 77406, 77407, 77408, 77409, 77411, 77412, 77413, 77414, 77416, 77422, 77423, 92.24, 92.26, 77301, 77418, 0073T, 77380, 77381, 77520, 77522, 77523, and 77525
Androgen deprivationOrchiectomyG9132, 54520, 54522, 54530, 54535, 54690, 62.3, 62.41, and 62.42
  therapyHormone therapy54520, 54522, 54530, 54535, 54690, J1050, J1051, J1950, J3315, J9202, J9217, J9218, J9219, J9165, S0175, C9216, C9430, G0356, J0128, S0165, S9560, 62.4, 62.41, and 62.42
Radical Prostatectomy 55866, 55810, 55812, 55815, 55840, 55842, 55845, and 60.5


Receipt of postoperative therapy was determined using CPT/International Classification of Diseases-Ninth Revision (ICD-9) codes for RT and hormonal therapy (Table 1). Treatments received and dates of treatments were obtained from Medicare data. In this study, we report receipt of treatments within 3 years after prostatectomy. This timeframe was selected clinically to minimize the inclusion of palliative treatments, and the ability to examine treatments beyond 6 months after surgery in claims data allowed for a more complete assessment of postsurgical treatments received compared with using SEER data alone. Herein, we describe the timing of RT calculated from the date of prostatectomy to examine the use of “adjuvant” (within 6 months) versus salvage treatment.

Control Variables

The SEER registry provided patient-level demographic variables, including race, age at diagnosis, and marital status; census tract measures of income and education; SEER region; and population density (urban vs rural). Patient comorbidity was assessed using a validated claims-based algorithm.[7]

Statistical Analysis

We reported unadjusted rates of postprostatectomy therapies and compared among subgroups of patients using the chi-square test. Multivariable logistic models examined the potential association between covariates and receipt of RT. A 2-sided result of P < .05 was considered to be statistically significant. All analyses were performed using SAS statistical software (version 9.2; SAS Institute Inc, Cary, NC).


Of the 3460 patients included in this analysis, 850 (25%) received RT within 3 years of prostatectomy; 363 (43%) of those who received RT also received androgen deprivation therapy (ADT). A total of 587 patients (17% of the overall cohort) received ADT, with or without RT. Characteristics of those patients who received no postprostatectomy treatment, ADT alone, RT alone, or RT and ADT are described in Table 2. Higher pathologic stage and surgical grade were found to be significantly associated with a higher rate of postprostatectomy treatment; however, these treatments were not commonly used in any subgroup. In patients with pathologic T3 or T4 disease, or high-grade disease on surgical pathology, < 35% in each subgroup received RT. Older patients were less likely to receive postoperative treatment. There was no significant trend over time noted with regard to the use of postoperative therapies.

Table 2. Patient Characteristics by Postprostatectomy Treatment Type
CharacteristicCategoryTotalNo Postoperative Treatment, No. (%)ADT Alone, No. (%)RT Alone, No. (%)RT and ADT, No. (%)Pa
  1. SEER sites were grouped into four geographic regions for analysis.*Ranges are given to prevent calculation of cell sizes <11 per SEER rules.

  2. Abbreviations: ADT, androgen deprivation therapy; NCI, National Cancer Institute; RT, radiotherapy; SEER, Surveillance, Epidemiology and End Results.

  3. a

    Determined using the chi-square test.

Year of surgery      .11
 2000450303 (67)34 (8)75 (17)38 (8) 
 2001509359 (70)30 (6)75 (15)45 (9) 
 2002526386 (73)26 (5)58 (11)56 (11) 
 2003536383 (72)39 (7)65 (12)49 (9) 
 2004535361 (68)32 (6)81 (15)61 (11) 
 2005511341 (67)36 (7)73 (14)61 (12) 
 2006393251 (64)27 (7)62 (16)53 (13) 
Age, y      .01
 66–6918861276 (68)105 (5)298 (16)207 (11) 
 70–741313924 (70)100 (8)154 (12)135 (10) 
 75–79261184 (71)19 (7)37 (14)21 (8) 
Race      .50
 White30822122 (69)194 (6)437 (14)329 (11) 
 Nonwhite378262 (69)30 (8)52 (14)34 (9) 
NCI comorbidity index      .08
 025441745 (69)157 (6)381 (15)261 (10) 
 >0916639 (70)67 (7)108 (12)102 (11) 
Marital status      .52
 Married28771984 (69)178 (6)409 (14)306 (11) 
 Unmarried481332 (69)36–45 (7–9)*62 (13)47–56 (10–12)* 
 Unknown10268 (67)<11 (<10)18 (17)<11(<10) 
Education (census tract)      .76
 Quartile 1 (0–25)870592 (68)57 (7)123 (14)98 (11) 
 Quartile 2 (25–50)866594 (69)61 (7)126 (14)85 (10) 
 Quartile 3 (50–75)861582 (68)54 (6)133 (15)92 (11) 
 Quartile 4 (75–100)863616 (72)52 (6)107 (12)88 (10) 
Income (census tract)      .70
 Quartile 1 (0–25)868613 (71)51 (6)121 (14)83 (9) 
 Quartile 2 (25–50)866591 (68)55 (7)131 (15)89 (10) 
 Quartile 3 (50–75)873610 (70)53 (6)119 (14)91 (10) 
 Quartile 4 (75–100)853570 (67)65 (7)118 (14)100 (12) 
SEER region      .02
 West18011263 (70)103 (6)248 (14)187 (10) 
 Central521359 (69)47 (9)66 (13)49 (9) 
 South-Southwest822566 (69)50 (6)127 (15)79 (10) 
 Northeast316196 (62)24 (8)48 (15)48 (15) 
Population density      .33
 Rural532361 (68)42 (8)68 (13)61 (11) 
 Urban29282023 (69)182 (6)421 (15)302 (10) 
Pathologic T classification      <.001
 pT2 with positive margin12931016 (79)41–53 (3–4)*167 (13)57–69 (4–5)* 
 pT320391295 (64)171 (8)297 (15)276 (13)* 
 pT412873 (57)<11 (<9)25 (20)18–30 (14–23)* 
Surgical grade      <.001
 1–215431211 (79)59 (4)189 (12)84 (5) 
 3–419101169 (61)164 (9)299 (16)278 (15) 

Timing of RT is shown in Figure 1. Overall, 43% of patients who received postprostatectomy RT received it within 6 months of undergoing surgery. Characteristics of the patients who received no RT, adjuvant RT, and salvage RT are described in Table 3. Similar to the findings above, more advanced pathologic stage, surgical grade, and younger patient age were associated with a higher rate of postprostatectomy RT. In all subgroups, < 15% of patients received adjuvant (administered within 6 months of surgery) RT.

Figure 1.

The cumulative incidence of receipt of radiotherapy is shown for all patients treated with radiotherapy within 3 years of undergoing surgery (N = 850).

Table 3. Patient Characteristics by Timing of Postprostatectomy RT
CharacteristicCategoryTotalNo RT No. (%)RT Within 6 Months of Surgery No. (%)RT 6 to 36 Months After Surgery No. (%)Pa
  1. Abbreviations: NCI, National Cancer Institute; RT, radiotherapy; SEER, Surveillance, Epidemiology and End Results.

  2. a

    Determined using the chi-square test.

Year of surgery     .007
 2000450337 (75)61 (14)52 (11) 
 2001509389 (76)54 (11)66 (13) 
 2002526412 (78)50 (10)64 (12) 
 2003536422 (79)37 (7)77 (14) 
 2004535393 (73)64 (12)78 (15) 
 2005511377 (74)46 (9)88 (17) 
 2006393278 (71)51 (13)64 (16) 
Age, y     .02
 66–6918861381 (73)212 (11)293 (16) 
 70–7413131024 (78)122 (9)167 (13) 
 75–79261203 (78)29 (11)29 (11) 
Race     .42
 White30822316 (75)322 (11)444 (14) 
 Nonwhite378292 (77)41 (11)45 (12) 
NCI comorbidity index     .35
 025441902 (75)276 (11)366 (14) 
 >0916706 (77)87 (10)123 (13) 
Marital status     .92
 Married28772162 (75)302 (11)413 (14) 
 Unmarried481369 (77)49 (10)63 (13) 
 Unknown10277 (75)12 (12)13 (13) 
Education (census tract)     .08
 Quartile 1 (0%-25%)870649 (75)85 (10)136 (15) 
 Quartile 2 (25%-50%)866855 (76)107 (12)104 (12) 
 Quartile 3 (50%-75%)861636 (74)94 (11)131 (15) 
 Quartile 4 (75%-100%)863668 (77)77 (9)118 (14) 
Income (census tract)     .74
 Quartile 1 (0%-25%)868664 (76)85 (10)119 (14) 
 Quartile 2 (25%-50%)866646 (75)87 (10)133 (15) 
 Quartile 3 (50%-75%)873663 (76)97 (11)113 (13) 
 Quartile 4 (75%-100%)853635 (74)97 (11)124 (15) 
SEER region     .09
 West18011366 (76)178 (10)257 (14) 
 Central521406 (78)45 (9)70 (13) 
 South-Southwest822616 (75)94 (11)112 (14) 
 Northeast316220 (70)46 (14)50 (16) 
Population density     .11
 Rural532403 (76)44 (8)85 (16) 
 Urban29282205 (75)319 (11)404 (14) 
Pathologic T classification     <.001
 pT2 with positive margin12931059 (82)88 (7)146 (11) 
 pT320391466 (72)256 (12)317 (16) 
 pT412883 (65)19 (15)26 (20) 
Surgical grade     <.001
 1–215431270 (82)104 (7)169 (11) 
 3–419101333 (70)257 (13)320 (17) 

On multivariate analysis (Table 4), pathologic characteristics were found to be strongly associated with adjuvant RT (administered within 6 months of surgery) as well as any RT administered within 3 years of surgery. Compared with patients with grade 1 to grade 2 (well to moderately differentiated) prostate cancer, those with grade 3 to grade 4 (poorly differentiated or undifferentiated) disease had higher odds of receiving adjuvant RT (odds ratio [OR], 2.29; P < .001) and any RT within 3 years (OR, 1.97; P < .001). Findings were similar for patients with pT4 versus pT2 disease. Older patients were less likely to receive RT within 3 years of surgery compared with those aged 65 to 69 years (age 70-74 years: OR, 0.77 [P < .01]; age 75-80 years: OR, 0.73 [P = .05]). There was regional variation noted in the use of postprostatectomy RT. Furthermore, the use of adjuvant RT decreased in more recent years compared with the year 2000 (year 2006: OR, 0.62 [P = .03]). Other variables including marital status, race, and comorbidity were not found to be associated with postprostatectomy use of RT.

Table 4. Multivariate Logistic Regression Models for Receipt of Adjuvant or Any RT After Prostatectomy
  RT Within 6 Months of SurgeryRT Within 3 Years of Surgery
Covariate (Referent)CategoryMultivariate OR (95% CI)Multivariate PMultivariate OR (95% CI)Multivariate P
  1. Abbreviations: 95% CI, 95% confidence interval; OR, odds radio; RT, radiotherapy; SEER, Surveillance, Epidemiology and End Results.

Year of surgery (2000)20010.73 (0.49–1.08).110.91 (0.68–1.24).54
 20020.65 (0.44–0.98).040.83 (0.61–1.12).21
 20030.41 (0.27–0.63)<.0010.73 (0.54–1.00).04
 20040.63 (0.42–0.93).020.82 (0.61–1.10).18
 20050.42 (0.28–0.65)<.0010.76 (0.56–1.04).08
 20060.62 (0.41–0.95).030.87 (0.63–1.20).37
Age, y (66–69 y)70–740.81 (0.63–1.03).070.77 (0.65–0.91)<.01
 75–800.90 (0.59–1.37).610.73 (0.53–1.00).05
Education quartile (0%-25%)25%-50%1.43 (1.01–2.03).050.96 (0.75–1.24).74
 50%-75%1.24 (0.82–1.88).311.03 (0.77–1.37).89
 75%-100%1.07 (0.67–1.73).790.90 (0.65–1.26).52
Income quartile (0%-25%)25%-50%1.00 (0.71–1.42).991.04 (0.81–1.32).81
 50%-75%0.96 (0.64–1.42).810.95 (0.72–1.26).71
 75%-100%1.08 (0.68–1.73).760.95 (0.68–1.33).76
SEER region (Northeast)Central0.63 (0.40–0.99).040.72 (0.52–1.00).04
 South-Southwest0.84 (0.57–1.25).380.83 (0.62–1.12).21
 West0.73 (0.51–1.04).080.84 (0.64–1.10).18
Marital status (married)Not married0.98 (0.71–1.37).900.94 (0.74–1.19).57
 Unknown1.09 (0.58–2.06).800.98 (0.61–1.56).90
Race (white)Nonwhite1.02 (0.71–1.46).930.86 (0.66–1.13).27
Comorbidity (0)>00.91 (0.70–1.18).450.91 (0.75–1.09).27
Population density (metropolitan area)Rural0.69 (0.48–1.00).040.93 (0.73–1.19).54
Pathology (pT2 with positive margins)pT31.64 (1.26–2.13)<.0011.55 (1.30–1.84)<.001
 pT42.16 (1.25–3.72)<.012.33 (1.56–3.47)<.001
Surgical grade (1–2)3–42.29 (1.75–2.99)<.0011.97 (1.64–2.37)<.001


Three randomized trials have demonstrated improved disease control and possibly overall survival with the use of adjuvant RT for patients found to have adverse risk factors on prostatectomy pathology.[4, 5, 8] Postprostatectomy RT offers a potential curative treatment for those patients not cured by surgery;[6, 12] however, there is substantial disagreement regarding the timing of RT.[3, 13] Because a percentage of patients who receive adjuvant RT may receive unneeded treatment, an alternative strategy is early salvage treatment at the time of biochemical disease recurrence.[12, 14] Another area of current uncertainty is the use of hormonal therapy in these patients, either alone or in combination with RT. Given these areas of uncertainty, we sought to examine current practice patterns using the population-based SEER-Medicare database. Our study significantly extends prior SEER studies[11, 15] by: 1) examining RT use up to 3 years after surgery, thus capturing both adjuvant and salvage RT; and 2) examining the use of hormonal therapy, which is not available in SEER. In addition, there has been recent recognition that SEER may underestimate the true rates of RT,[16] whereas SEER-Medicare is considered the gold standard for examining treatment use.[17, 18]

Based on randomized trial data, we expected 40% of patients with adverse pathologic factors to develop disease recurrence and thus require RT within 3 years of undergoing prostatectomy.[4-6] However, we found that only 25% of these patients received RT. Of those patients who did receive radiation, the minority (43%) did so within 6 months after surgery. Higher pathologic T classification and grade were found to be associated with higher rates of RT use, but even in subgroups of patients with T4 or grade 3 to grade 4 disease, overall postprostatectomy RT use was < 35%. These rates changed little over time, with only a minimal shift toward earlier treatment noted despite the publication of randomized trial data.

There are several possible explanations for this finding. Historically, physicians are often conservative when integrating new clinical evidence into routine practice, and change may be particularly difficult if it requires coordination across multiple specialties.[19] Reasons for this slow pace of adoption are numerous but often include disagreement over the strength of the available evidence, a situation that is not unique to health care in the United States.[20] In the case of postprostatectomy RT, we believe this is undoubtedly true. Substantial controversy exists in the urologic community regarding the merits of adjuvant versus salvage RT. Because a large percentage of patients with positive surgical margins or extracapsular extension are cured by prostatectomy alone, many practitioners may view early salvage RT as a preferable alternative to adjuvant therapy.[21]

These considerations must be balanced against another important finding of our study: a substantial percentage of these same high-risk patients receive postoperative ADT, either alone or with RT. In contrast to the evidence for postprostatectomy RT, there are relatively few data to support the use of ADT in the postprostatectomy setting. Randomized trials of adjuvant RT have not included concurrent ADT, and there is little evidence for the use of ADT alone after prostatectomy in patients without lymph node or distant metastasis.[22] Recently presented but not yet published results from the Radiation Therapy Oncology Group (RTOG) 96-01 trial suggest there may be a role for ADT with salvage RT in selected high-risk patients,[23] and a currently ongoing randomized trial (RTOG 0534) is assessing the role of ADT with salvage RT in modern patients. More concerning is the finding that approximately 5% to 8% of patients received ADT alone after prostatectomy, which was not because of pathologic lymph node positivity, because those patients were excluded from this analysis. Although ADT alone could have been given for patients who developed metastatic disease, our finding suggests that practitioners may be using ADT for biochemical disease recurrence in lieu of salvage RT.

Another finding of the current study is that older men were less likely to receive postprostatectomy RT. That this difference is evident after controlling for pathologic factors and comorbidity suggests that physicians may have an inherent bias toward minimizing postoperative therapy for older patients with prostate cancer.[24] It may be that physicians of older patients or the patients themselves have concerns about the toxicity of RT, and observation of prostate cancer may be an appropriate strategy for patients with a limited life expectancy, especially if the patient's health status has significantly changed since undergoing prostatectomy. The 3 trials of adjuvant RT did demonstrate increases in morbidity such as bowel and bladder symptoms with the use of postprostatectomy RT[6]; however, such symptoms largely resolve with longer follow-up, thereby resulting in a net improvement in quality of life favoring adjuvant RT.[25]

There are several limitations to the current study. SEER-Medicare data lack detailed clinical information such as prostate-specific antigen values after prostatectomy, thereby making it impossible to determine whether early RT is given as salvage or true adjuvant therapy. Therefore, the finding of 15% of patients receiving RT within 6 months of surgery may have been an overestimation of the true use of adjuvant RT as some of these patients may already have had detectable PSA. In addition, we were unable to determine whether patients received RT as salvage curative therapy or for metastatic disease. However, based on randomized trial data, we expect the development of metastatic disease to be rare within 3 years of prostatectomy.[4, 5, 8] Our expectation that 40% of patients would develop disease recurrence within 3 years was based on randomized evidence, but may be an overestimate due to stage migration since trial enrollment. However, this does not explain the rate of postoperative ADT use in the same population.

The strengths of the current study include a well-established methodology using SEER-Medicare data to examine patterns of care, and an ability to more comprehensively examine treatments received compared with the SEER database alone. Overall, the current study (for patients aged > 65 years) and those previously published consistently demonstrate a potential underuse of postprostatectomy RT in those patients most likely to benefit.

The rates of adjuvant RT use appear to have increased little since the publication of the randomized trials whereas a substantial percentage of patients receive postprostatectomy ADT, which has relatively less supporting evidence. Rates of adjuvant and salvage RT use were found to be low across all patient subgroups. Further studies are needed to examine the potential reasons for the underuse of this potentially curative and tolerable treatment modality.


No specific funding was disclosed.


Dr. Chen has received a grant from Accuray Inc.