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A hospital-based study of initial observation for low-risk prostate cancer and its predictors in the United States.


The overdiagnosis and overtreatment of prostate cancer has become a national public health concern. (1) Early prostate cancer detection through widespread prostate-specific antigen (PSA) screening reduces cancer-specific mortality and the incidence of metastatic disease in a small proportion of men at the expense of exposing many more men to its associated risks. (2,3) Early detection with PSA screening over-diagnoses 23% to 42% of prostate cancer, leading to over-treatment and its related harms. (4-6) Citing this unfavourable risk-benefit ratio, the United States Preventative Services Task Force (USPSTF) recommended against screening in all men. (1) While a ban on screening would eliminate overdiagnosis entirely, it also would permit 3000 to 4000 avoidable prostate cancer deaths annually. (7) An alternative solution to overtreatment is to restrict screening to age-appropriate men and to limit treatment based on patient life expectancy and disease characteristics.

Watchful waiting (WW) and active surveillance (AS) minimize overtreatment by avoiding or delaying curative treatment in well-selected men, respectively. Both strategies involve a period of initial observation (IO) followed either by continued observation in elderly or sickly men who are unlikely to benefit from active treatment (WW) or by active monitoring with selective delayed intervention in men at higher risk for disease progression (AS). It is now clear that neither strategy sacrifices short-term cancer-specific survival in men with low-risk disease. (8-11) Seemingly, the primary barrier limiting the effectiveness of IO to combat overtreatment in this country has been its acceptance by urologists. (12)

Historically IO has been used at very low rates in the United States, largely relegated to use in older men. (13,14) With the introduction of AS in 2002, IO became a feasible option for all men with low-risk prostate cancer. (15) While recent IO usage appears to be robust in Scandinavia, little is known about its contemporary uptake in the United States or the factors that influence its utilization. (11,16) We sought to examine IO utilization and its predictors in a national sample of men using the National Cancer Database (NCDB).


The NCDB, a joint project of the American Cancer Society and the Commission on Cancer (CoC) of the American College of Surgeons, is a comprehensive clinical oncology dataset that captures 70% of all incident malignancies in the United States. It has been validated previously against the SEER (Surveillance, Epidemiology and End Results) database. (17) The dataset contains only de-identified data, obviating the need for institutional review board approval.

We identified 1 666 913 patients with histologically confirmed prostate cancer based on ICD-O-3 primary site (C619) and histology (8140) codes. The study period was limited to diagnosis years 2004 to 2011 because PSA data were not available prior to 2004 (n = 973 558). Only patients with prostate cancer as their sole or first cancer diagnosis were included to avoid confounding from prior cancer treatments (n = 900 580). We limited our cohort to men with low-risk prostate cancer by the D'Amico criteria, defined as Gleason score <6 (no Gleason pattern 4 or 5), TNM clinical T stage T1-T2a, and PSA <10 (n = 220 187). After excluding nodal and metastatic disease, 219 971 patients were available for analysis.

The NCDB only includes data on "first course of treatment," defined as all methods of treatment recorded in the treatment plan and administered to the patient before disease progression or recurrence. IO was defined as no first course treatment. Active treatment included prostatectomy, radiation therapy, androgen deprivation, and other unspecified treatments (which accounted for <3% of cases). To identify factors associated with IO utilization for low-risk prostate cancer, we compared men who underwent IO to those who received active treatment.

Univariate analysis was performed using the Pearson chi-square test. For multivariate logistic regression, adjusted odds ratios were calculated with IO as the response variable and diagnosis year, race, residence, education, income, insurance, age, comorbidity, hospital type, and hospital location as covariates. Statistical tests were performed using SAS version 9.3 (SAS Institute Inc., Cary, NC). P values <0.01 were considered statistically significant.


Overall, from 2004-2011, 9.7% (21 231/219 971) of men with low-risk prostate cancer were managed with IO, while 198,740 were actively treated. The low-risk prostate cancer population was composed of predominantly more educated, wealthier, insured Caucasian men living in metropolitan areas who sought care at major academic and comprehensive cancer centers throughout the United States (Table 1). Patients were primarily healthy and younger than age 70. Most men had clinical T1c prostate cancer and PSA >4.

Diagnosis year was one of the strongest determinants of receiving IO. From 2004 to 2007, IO utilization remained relatively stable (range: 7.2-7.5%). Beginning in 2008, IO usage rose steadily, peaking at 14.3% by 2011 (Fig. 1). Compared to 2004, patients diagnosed in 2011 had 2.5 times the odds of receiving IO (odds ratio [OR] 2.5, confidence interval [CI] 2.3-2.6, p < 0.01).

Aside from diagnosis year, clinical factors were also significant predictors of IO usage (Table 2). In particular, age was the single greatest predictor of IO utilization. Compared to patients <50 years, patients >70 years had 2.5 times the odds of receiving IO (OR 2.5, CI 2.3-2.7, p < 0.01) and those >80 years had 7.2 times greater odds (OR 7.2, CI 6.4-8.0, p < 0.01). Charlson comorbidity index (CCI) had a small, but significant, impact on IO utilization as well. Patients with more than one comorbidity had 10% increased odds of receiving IO than those without comorbidities (p < 0.01). Men with PSA >4 or clinical T2 disease were significantly less likely (10% and 30% decreased odds, respectively) of undergoing IO than those with T1 disease or PSA <4 (p < 0.01).

Albeit to a lesser extent, demographic factors were also important predictors of IO usage. African American and other, non-Hispanic minority men had 20% and 30% increased odds of receiving IO compared to Caucasian men (OR 1.2, CI 1.2-1.3; OR 1.3, CI 1.2-1.4; p < 0.01, respectively). Less educated men and wealthier men were both significantly less likely to receive IO (OR 0.8, CI 0.8-0.9; OR 0.8, CI 0.8-0.9; p < 0.01, respectively).

Non-clinical factors that significantly predicted IO use included: insurance provider, hospital type, and, to a lesser degree, hospital region. IO usage was highest in the uninsured and in patients with social insurance. Compared to patients with private insurance, patients with social insurance had 1.2 times the odds of receiving IO (OR 1.2, CI 1.2-1.3, p < 0.01), while uninsured patients had 2.5 times the odds (OR 2.5, CI 2.3-2.8, p < 0.01). IO was most frequently utilized at academic centres. Men treated at academic centres had 2.1, 1.2, and 1.9 times the odds of receiving IO compared to patients treated at comprehensive centres, community cancer programs, and other hospitals, respectively (p < 0.01). IO was most common in western United States, followed by the northeast, south, and midwest regions (p < 0.01) (See Appendix). Within a particular region, IO selection did not significantly depend on the patient's place of residence (rural, urban, or metropolitan, using the typology published by the United States Department of Agriculture Economic Research Service). (18)


From 2007 onward, IO usage increased gradually at a rate of 1.7% per year, peaking at 14.3%. This rise may be related to greater acceptance of AS, which was first included in clinical practice guidelines as an alternative to active treatment in 2007. (19) In general, however, IO use was higher in men with limited life expectancies (age >70 and CCI [greater than or equal to] 2), suggesting WW-predominant practice patterns. (20) This is a change from pre-2008 trends, in which aggressive treatment was administered regardless of patient life expectancy. (21) We found that academic centres in the United States led the way in IO adoption. Interestingly, men receiving IO were more likely to be poor or belong to a minority group and were less likely to have private health insurance than their counterparts.

While our study is one of the first to demonstrate the more recent rise in IO utilization in the United States, our baseline IO rate (7.4%) from 2004 to 2007 is consistent with prior research. Cooperberg and colleagues reported an 8.5% utilization rate of observation for low-risk prostate cancer from 2004 to 2007, using the CaPSURE database. (22) On the contrary, Ritch and colleagues recently reported a much higher and rising rate of observation (from 18% in 2004 to 29% in 2009) in men with low-risk disease; however, since their data only included men age 65 and older, these results may have been influenced by selection bias. (23) Loeb and colleagues also noted increasing AS utilization in Sweden over the same interval (2007-201 1). (16) However, AS rates for low- and very low-risk disease in Sweden were much higher (41%-59%) than our IO rates, possibly reflecting both cultural and financial disparities in practice patterns between the United States and Scandinavia. (16)

It is estimated that 38% to 60% of patients diagnosed with early prostate cancer are considered low risk by D'Amico criteria and thus are candidates for management with IO. (11,24) Based on these estimates, our findings suggest that IO is still being underutilized in the United States despite its recent gains. The reasons behind underutilization are likely multifactorial.

The lack of clear recommendations favouring AS may have contributed to IO underutilization. For most of the diagnosis period (2004-2007), AS was not an accepted strategy for low-risk prostate cancer. (18) Also, preliminary results from the largest prospective AS cohort (Prostate Cancer Research International: Active Surveillance, PRIAS), were not available until 2009.25 Moreover, the limited benefit of active treatment for low-risk, screen-detected prostate cancer was not yet known. (8) Consequently, community urologists may have considered AS experimental, explaining why academic centres were primarily responsible for the rise in IO use.

Racial/ethnic and socioeconomic disparities in treatment selection for prostate cancer are well-recognized. It has been shown that African-American men are more likely to be managed expectantly than white men. (26) Similarly, poor men and men with public health insurance are more likely to be treated conservatively. (27,28) In keeping with these disparities, we found that minority men, especially African-Americans, men from lower socioeconomic groups, and uninsured or socially insured men preferentially received IO. While increased IO utilization as a whole should be considered an achievement, its preferential use in certain racial and socioeconomic groups is not evidence-based and may be detrimental. In particular, African-American men, who have a higher disease progression rate on AS, may not be the best candidates for this approach. (29) Furthermore, poor men may experience inferior outcomes when managed conservatively. (28)

It is unclear why poor and uninsured or underinsured men were more inclined to receive IO. This disparity does not appear to be caused by local differences in resource availability, since area of residence did not affect IO selection. Given that IO is associated with lower upfront costs than active treatments, it is possible that financial considerations influenced treatment decisions. (30) This also may explain why non-academic/non-research hospitals, which rely on fee-for-service reimbursement, preferentially utilized higher-cost treatments. In contrast, at government-sponsored Veterans Affairs hospitals, which are less influenced by reimbursement concerns, IO utilization is higher. (31)

There are significant barriers to widespread AS adoption in the United States. While patient anxieties may limit utilization, physician influence is the single most important factor influencing the decision to undergo AS. (12,32) Interestingly, we found that education level was associated with treatment selection, with educated men more likely to choose IO. Men with poor prostate cancer knowledge have more decisional conflict and decision-making impairment than educated men, potentially explaining their reluctance to pursue AS. (33) Urologists must promote AS, educating and reassuring low-risk patients on the benefits of IO relative to active treatment.

A clear strength of our study is the NCDB's comprehensiveness, capturing over 70% of incident cancers in the United States regardless of age. Since hospitals included in the NCDB exhibit higher levels of cancer specialization than other hospitals, our findings may demonstrate the best-case scenario in terms of contemporary IO utilization.

The main limitation of this study is its retrospective nature. Since the NCDB does not code IO as a unique treatment, we used lack of treatment to define IO. This definition is somewhat flawed because treatment delay may be erroneously construed as IO, leading to misclassification and overestimation of the IO rate. Fortunately, the NCBD makes every effort to assign treatments appropriately to minimize this error. Similarly, the NCDB does not differentiate AS from WW, nor does it include data on number of positive cores, re-biopsies or second-course treatments, limiting our ability to selectively identify AS patients.


IO has been utilized increasingly for low-risk prostate cancer in the United States, especially in patients least likely to benefit from active treatment. Despite this progress, IO is still underutilized, possibly due to the influence of non-clinical factors. The future of AS and, for that matter, of prostate cancer diagnosis depends on the continued adoption of IO by urologists.

Acknowledgements: An abstract of the work was presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium in San Francisco, CA on January 30, 201 4 and at the American Urological Association annual meeting in Orlando, FL on May 20, 201 4. The American College of Surgeons and the Commission on Cancer have not verified and are not responsible for the analytic or statistical methodology employed, or the conclusions drawn from these data by the investigator.

Competing interests: The authors declare no competing financial or personal interests.

This paper has been peer-reviewed.


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Correspondence: Dr. Robert Abouassaly, University Hospitals Case Medical Center, Cleveland, OH;

Appendix 1. Regions and their corresponding states

Region        State/District

Northeast     Connecticut
              New Hampshire
              New Jersey
              New York
              Rhode Island

Midwest       Illinois
              North Dakota
              South Dakota

South         Alabama
              North Carolina
              South Carolina
              Washington, D.C.
              West Virginia

West          Alaska
              New Mexico

Matthew J. Maurice, MD;* Hui Zhu, MD([dagger]) Robert Abouassaly, MD*

University Hospitals Case Medical Center, Cleveland, OH; ([dagger]) Louis Stokes Cleveland VA Medical Center and Cleveland Clinic South Pointe Hospital, Cleveland, OH

Published online April 13 2015.

Caption: Fig. 1. Initial observation utilization for low-risk prostate cancer.

Table 1. Characteristics of men with low-risk prostate cancer managed
with initial observation vs. active treatment

                         IO        %        T         %

  Non-Hispanic white   16 262    76.6    160 041    80.5
  Hispanic               789      3.7      6429      3.2
  African-American      2885     13.6     23 378    11.8
  Other minority        1295      6.1      8892      4.5
Patient residence
  Metropolitan         16 896    82.9    154 550    81.7
  Rural                  417      2.0      4427      2.3
  Urban                 3073     15.1     30 224    16.0
Education level
  Lowest                2943     14.5     25 902    13.7
  Lower middle          4015     19.8     39 967    21.2
  Upper middle          4575     22.6     45 428    23.9
  Highest               8752     43.1     78 454    41.3
Income level
  Lowest                2500     12.3     21 440    11.3
  Lower middle          3392     16.7     31 048    16.4
  Upper middle          5341     26.3     51 491    27.1
  Highest               9054     44.6     85 786    45.2
  Private               9244     81.4    110 638    56.5
  Uninsured              489      2.4      2201      1.1
  Federal/social       10 867    52.8     82 844    42.3
Age, years
  <50                    656      3.1      9249      4.7
  50-59                 4487     21.1     57 948    29.2
  60-69                 8680     40.9     86 371    43.5
  70-79                 6168     29.1     41 894    21.1
  >80                   1240      5.8      3278      1.6
Charlson score
  0                    18 978    89.4    173 227    87.2
  1                     1828      8.6     22 429    11.3
  >1                     425      2.0      3084      1.6
Clinical T stage
  T1a                    985      4.6      3698      1.9
  T1b                    251      1.2      1305      0.7
  T1c                  17 972    84.6    169 171    85.1
  T2a                   2023      9.5     24 566    12.4
  <4                    5072     23.9     46 818    23.6
  4-10                 16 159    76.1    151 922    76.4
Hospital type
  Academic             10 652    50.2     71 332    35.9
  Community             2100      9.9     16 122     8.1
  Comprehensive         8349     39.3    109 727    55.2
  Other                  130      0.6      1559      0.8
Hospital location
  Midwest               5017     23.6     50 323    25.3
  Northwest             5481     25.8     45 897    23.1
  South                 6958     32.8     70 341    35.4
  West                  3775     17.8     32 179    16.2

                        Total       %     p value *

Race                                        <0.01
  Non-Hispanic white   176 303    80.1
  Hispanic               7218      3.3
  African-American      26 263    11.9
  Other minority        10 187     4.6
Patient residence                           <0.01
  Metropolitan         171 446    81.8
  Rural                  4844      2.3
  Urban                 33 297    15.9
Education level                             <0.01
  Lowest                28 845    13.7
  Lower middle          43 982    20.9
  Upper middle          50 003    23.8
  Highest               87 206    41.5
Income level                                <0.01
  Lowest                23 940    11.4
  Lower middle          34 440    16.4
  Upper middle          56 832    27.1
  Highest               94 840    45.2
Insurance                                   <0.01
  Private              119 882    55.4
  Uninsured              2690      1.2
  Federal/social        93 711    43.3
Age, years                                  <0.01
  <50                    9905      4.5
  50-59                 62 435    28.4
  60-69                 95 051    43.2
  70-79                 48 062    21.8
  >80                    4518      2.1
Charlson score                              <0.01
  0                    192 205    87.4
  1                     24 257    11.0
  >1                     3509      1.6
Clinical T stage                            <0.01
  T1a                    4683      2.1
  T1b                    1556      0.7
  T1c                  187 143    85.1
  T2a                   26 589    12.1
PSA                                          0.11
  <4                    51 890    23.6
  4-10                 168 081    76.4
Hospital type                               <0.01
  Academic              81 984    37.3
  Community             18 222     8.3
  Comprehensive        118 076    53.7
  Other                  1689      0.8
Hospital location                           <0.01
  Midwest               55 340    25.2
  Northwest             51 378    23.4
  South                 77 299    35.1
  West                  35 954    16.3

* p values <0.01 considered significant. IO: initial observation;
T: active treatment; PSA: prostate-specific antigen.

Table 2. Multivariate logistic regression analysis of predictors of
initial observation utilization

Variable               Adjusted OR     95% CI     p value *

Diagnosis year                                      <0.01
  2004                     1.0       (referent)
  2005                     1.0        1.0-1.1
  2006                     1.1        1.0-1.1
  2007                     1.1        1.0-1.2
  2008                     1.4        1.3-1.5
  2009                     1.9        1.8-2.0
  2010                     2.0        1.9-2.1
  2011                     2.5        2.3-2.6
Race                                                <0.01
  Non-Hispanic white       1.0       (referent)
  Hispanic                 1.1        1.0-1.2
  African-American         1.2        1.2-1.3
  Other                    1.3        1.2-1.4
Patient residence                                   0.10
  Metropolitan             1.0       (referent)
  Rural                    0.9        0.8-1.0
  Urban                    1.0        0.9-1.0
Education level                                     <0.01
  Highest                  1.0       (referent)
  Upper middle             0.9        0.8-0.9
  Lower middle             0.8        0.8-0.8
  Lowest                   0.8        0.8-0.9
Income level                                        <0.01
  Lowest                   1.0       (referent)
  Lower middle             1.0        0.9-1.1
  Upper middle             0.9        0.9-1.0
  Highest                  0.8        0.8-0.9
Insurance                                           <0.01
  Private                  1.0       (referent)
  Federal/social           1.2        1.2-1.3
  Uninsured                2.5        2.3-2.8
Age, years                                          <0.01
  <50                      1.0       (referent)
  50-59                    1.2        1.1-1.3
  60-69                    1.6        1.4-1.7
  70-79                    2.5        2.3-2.7
  >80                      7.2        6.4-8.0
Charlson score                                      <0.01
  0                        1.0       (referent)
  1                        0.7        0.7-0.7
  >1                       1.1        1.0-1.3
Clinical T stage                                    <0.01
  T1                       1.0       (referent)
  T2                       0.7        0.7-0.8
  PSA                                               <0.01
  <4                       1.0       (referent)
  >4                       0.9        0.9-0.9
Hospital type                                       <0.01
  Academic                 1.0       (referent)
  Community                0.8        0.8-0.9
  Comprehensive            0.5        0.5-0.5
  Other                    0.5        0.4-0.6
Hospital location                                   <0.01
  Midwest                  1.0       (referent)
  Northwest                1.1        1.1-1.2
  South                    1.1        1.0-1.1
  West                     1.3        1.3-1.4

* p values <0.01 considered significant. PSA: prostate-specific
antigen; OR: odds ratio; CI: confidence interval.


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Author:Maurice, Matthew J.; Zhu, Hui; Abouassaly, Robert
Publication:Canadian Urological Association Journal (CUAJ)
Article Type:Report
Date:Apr 1, 2015
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