|
Advertisement |
|
|
||
 |
|
|||||
|
|||||
|
 |
||||||
|
||||||
|
||||||
|
Journal of Clinical Oncology, Vol 26, No 1 (January 1), 2008: pp. 112-120 © 2008 American Society of Clinical Oncology. DOI: 10.1200/JCO.2006.10.4505 Health-Related Quality of Life Results in Pathologic Stage C Prostate Cancer From a Southwest Oncology Group Trial Comparing Radical Prostatectomy Alone With Radical Prostatectomy Plus Radiation Therapy
From the Southwest Oncology Group Statistical Center, Fred Hutchinson Cancer Research Center, Seattle, WA Corresponding author: Carol M. Moinpour, PhD, Southwest Oncology Group Statistical Center, Fred Hutchinson Cancer Research Center, M3-C102, 1100 Fairview Ave North, Box 19024, Seattle, WA 98109-1024; e-mail: cmoinpou{at}fhcrc.org
Purpose To compare short- and long-term effects of adjuvant treatment versus observation after surgery on health-related quality of life (HRQL) of prostate cancer patients. Patients and Methods The Southwest Oncology Group (SWOG) intergroup trial compared radical prostatectomy (RP) plus observation versus RP plus adjuvant radiation therapy (RT). Two-hundred seventeen of 425 therapeutic trial patients were eligible and registered to the HRQL study. Patients completed the SWOG Quality of Life Questionnaire (emotional, physical, social, and role function; general symptom status; treatment/disease-specific symptoms; and global HRQL [GHRQL]) at baseline, 6 weeks, 6 months, and annually for 5 years. Prespecified outcomes were three genitourinary symptoms (bowel function tenderness, frequent urination, and erectile dysfunction [ED]) and measures of physical and emotional function. Adjustments were made for the baseline score. Results Patients receiving adjuvant RT reported worse bowel function (through approximately 2 years) and worse urinary function. There were no statistically significant differences for ED. GHRQL was initially worse for the RP+RT arm but improved over time and was better at the end of the period than the GHRQL reported for RP alone (treatment arm x time interaction, P = .0004). Symptom distress was significantly worse for the RP+RT arm compared with the RP alone arm, but the treatment arms did not differ with respect to other general measures of HRQL. Conclusion The addition of RT to surgery resulted in more frequent urination, as well as early report of more bowel dysfunction, although bowel function differences disappeared over the 5-year period. The addition of RT did not negatively impact ED.
The relative health-related quality of life (HRQL) for patients with completely resected, pathologically advanced (T3N0M0) carcinoma of the prostate treated with adjuvant radiotherapy (RT) versus no adjuvant therapy was unknown at the time this protocol was designed.1,2 Few studies have examined the impact of RT on HRQL. A retrospective study found no difference in recovery of potency and continence for patients receiving RT after radical prostatectomy (RP) versus no RT.3 Interim results of a European Organisation for Research and Treatment of Cancer (EORTC) randomized trial of postoperative RT after RP indicated no significant effect of RT on urinary incontinence (24 months of follow-up).4 Final trial results reported grade 1 and 2 levels of diarrhea, urinary frequency, dysuria, and skin toxicities during treatment; RT patients reported significantly more late effects of all grades and of grades 2 and 3.5 HRQL and sexual function were not assessed, and comprehensive assessments of incontinence were not obtained after 24 months. Systematic assessment of symptoms and adverse effects associated with treatment for prostate cancer, particularly sexual function, is important.6-8 A Southwest Oncology Group (SWOG) trial compared adjuvant RT versus observation after RP and collected patient-reported treatment-related adverse effects and general domains of HRQL for 5 years. Therapeutic results were reported previously.9 Time to prostate-specific antigen relapse and disease recurrence were significantly longer for the adjuvant RT arm; overall survival and metastasis-free survival did not differ significantly by treatment arm. Adverse events were significantly more likely to occur in the RP+RT arm compared with the RP arm (23.8% v 11.9%, respectively), including urethral strictures (17.8% v 9.5%, respectively), total urinary incontinence (6.5% v 2.8%, respectively), and rectal complications (3.3% v 0%, respectively).9
Patient Selection and Study Design S8794 randomly assigned patients to RP plus observation versus RP plus RT. RT patients received 60 to 64 Gy in 30 to 32 fractions to the prostatic bed. Eligibility criteria included RP within 16 weeks before random assignment, negative bone scan, and extraprostatic disease criteria (institutional pathology confirmation of at least one of the following: seminal vesicle invasion, positive surgical margins, or extracapsular tumor extension).9 The trial was activated in August 1988, with HRQL assessments added in February 1990.10 The trial closed on January 1, 1997. Patients registered after February 1990 were required to provide baseline HRQL data before random assignment unless they required a non-English translation. A validated Spanish translation of the questionnaire was available in 1995.11,12 In accordance with institutional and federal guidelines, all patients were informed of the study's investigational nature and signed written informed consents; trial procedures were approved by each site's institutional review board.
HRQL Assessment Procedures
Binary Outcomes
Continuous Outcome Physical function and emotional well-being primary outcomes were measured with the Rand Medical Outcomes Study Short Form-20 and -36 scales (Table 1).20,21 In addition, the questionnaire included social and role function scales20,21 and a measure of general symptom status (Symptom Distress Scale).22-27
Statistical Methods Missing data. Potential cohort biases were evaluated by comparing baseline characteristics of patients who did participate in the HRQL study versus patients who did not. In addition, baseline characteristics were compared between participating patients who subsequently did and did not drop out of the study at 6 months and at 5 years. We also examined plots of HRQL means for groups of patients based on the number of follow-up assessments.16,36 Longitudinal analysis: binary outcomes. Generalized estimating equations were used for the analysis of binary outcomes.37 Generalized estimating equations produce unbiased results if missing data are missing completely at random. Analyses were performed using the SAS9 procedure PROC GENMOD with a specified logit link and the compound symmetric correlation structure (SAS v 9; SAS Institute, Cary, NC). Longitudinal analysis: continuous outcomes. For continuous HRQL outcomes, we used linear mixed model analysis. Analyses were performed using the SAS9 procedure PROC MIXED (SAS v 9; SAS Institute),37A with specified random effects for the intercept and slope, a compound symmetric correlation structure, and restricted maximum likelihood estimation method.37A
For each outcome, models included treatment and assessment time as independent variables, the baseline score as a model covariate, and a treatment x time (linear) interaction. Additionally, a treatment x time (squared) interaction was evaluated. Because models were nested, the log-likelihood values were compared using a Interpretation of model results. In the analysis of each domain, RP+RT treatment was coded as a 1, and RP alone was coded as a 0; time was coded as a continuous variable in years. In cases where the simple linear model (no interaction) represents the best model fit, the fitted models will have parallel trajectories for the treatment arms, representing a treatment effect that is constant over time, with a positive coefficient indicating RP+RT higher than RP alone and a negative coefficient indicating RP alone higher than RP+RT. In addition, a positive coefficient for time indicates an upward trajectory for both arms as time increases, and a negative coefficient for time indicates a downward trajectory as time increases. Models with an interaction indicate a differential treatment effect over time, so the trajectories will be nonparallel. In the case of a square interaction with time, the differential treatment effect over time is quadratic (ie, nonlinear or curved). With significant interactions, the coefficients for treatment and time cannot be interpreted independently but must be considered in combination with the coefficients for the interaction terms.
Therapeutic Results Four hundred thirty-one patients were randomly assigned to the two study arms, with 425 eligible patients. See Thompson et al9 for therapeutic results.
Patient Characteristics: HRQL Sample
Questionnaire Submission Rates From study entry to year 5, HRQL submission rates ranged from 96% to 67% as a percentage of the total sample (including deaths; see rates by arm in Fig 1) and from 96% to 75% as a percentage of forms due (compliance). Missing data were primarily attributed to institutional error (eg, forgetting to administer the HRQL form) and inability to contact the patient.
Analysis of Missing Data
Binary Outcomes
Tenderness/urgency, bowel movements. For this item, a model with a quadratic interaction between assessment time and outcome represented the best fit of the data (Table 3). This reflects the more noticeable bowel complication rate for the RP+RT arm at 6 weeks after the completion of RT. In particular, the regression model estimate of the proportion of patients with compromise at 6 weeks (the fitted value) was 47% on the adjuvant RT arm compared with 5% on the RP arm (Fig 2); this difference was much larger than the predicted difference of  15%. Throughout the entire period, patients on the RP+RT arm experienced more bowel compromise than patients receiving RP alone. However, the increased compromise for patients on the RP+RT arm waned dramatically over time as illustrated in Figure 2, with little difference between the two arms evident after year 2. Frequent urination. There was no evidence of an interaction between treatment arm and time (P = .66). However, the proportion of men reporting frequent urination was different between the treatment arms, with patients on the RP+RT arm reporting significantly more frequent urination over the course of the period (P = .0002; Table 3). The regression model showed a consistent difference of 15% in the proportion of patients reporting the frequent urination adverse effect on the adjuvant RT arm (Fig 2). ED. There was no evidence of an interaction between treatment arm and time (P = .06). Baseline levels of ED were high for both RP-only patients (94%) and for RP+RT patients (93%). As shown in Table 3, ED levels did not vary significantly by treatment (P = .16). However, the proportion of patients with ED did decrease significantly over time for both treatments (P = .02). GHRQL. There was evidence of a significant interaction between assessment time and outcome. Fewer patients on the RP+RT arm reported normal GHRQL early in the period; for example, at 6 weeks, 40% of RP+RT patients reported normal GHRQL compared with 56% of patients on the RP-only arm. However, more patients on the RP+RT arm had normal GHRQL by year 5 (51%) compared with patients on the RP-only arm (69%; Fig 2). The presence of an interaction is likely partly explained by the high proportion of patients experiencing bowel compromise early in the study for the RP+RT regimen.
Continuous Outcomes
A comprehensive assessment of HRQL was conducted to evaluate disease- and treatment-related morbidity in a prostate cancer clinical trial. The validity of the model-based estimates derived in this analysis depends in part on the amount of missing data and the extent to which missing data are nonrandom. Substantial evidence of nonrandom dropout could bias model results, particularly if dropout patterns differ for treatment arms. Follow-up for this study was high, even up to 5 years, and further analysis found no instances of a differential impact by treatment arm in patterns of missing data for known baseline characteristics and, therefore, no evidence that model estimates were biased as a result of missing data. A consistent pattern of outcomes emerges from the symptom data, with early compromise in bowel function for the RP+RT arm for the first 2 years and more frequent urination over the 5-year period. As expected because both arms had surgery, the two arms did not differ significantly with respect to ED (94% of patients at baseline reported such problems). A treatment x assessment time interaction was evident for GHRQL, with more patients in the RP+RT arm experiencing diminished GHRQL early in the study compared with patients receiving surgery alone. However, later in the study, the trend reversed, showing better GHRQL for the RP+RT arm. This shift is perhaps consistent with the symptom burden described earlier. There were no consistent differences in general domains of HRQL for the two treatment arms. Other published data for treatments examined in this trial have indicated minimal impact on general HRQL domains over time, although RT in these trials was not administered as adjuvant therapy.38,39 The EORTC trial addressed late effects of adjuvant RT after surgery up to 5 years after treatment, using the WHO acute effects scale during treatment and the Late Radiation Morbidity Scoring Scheme of the Radiation Therapy Oncology Group/EORTC; the latter system did not include a measure of incontinence.5 Statistically significantly more late effects specific to RT (with the exception of urinary frequency) were reported in the RT arm compared with the surveillance arm; acute effects of RT were most commonly mild to moderate, with 45% of patients experiencing grade 1 and 17% experiencing grade 2 urinary frequency. The EORTC trial did not include any HRQL or patient-reported outcomes. Therefore, data from the SWOG trial provide the most comprehensive picture of patient-reported urinary function over a prolonged follow-up period and suggest that frequent urination remains a problem for men receiving adjuvant RT after surgery. Clearly, data for urinary function after adjuvant RT present a varied picture. The statistically significantly compromised urinary function throughout the 5-year follow-up period for RP+RT patients (patient-reported HRQL) and the more frequent urethral stricture (P = .02) and total urinary incontinence (P = .11) reported for the RP+RT patients in the main trial results9 are not consistent with findings reported in the literature for either RT as primary therapy or in the adjuvant context. However, the report of complications for the therapeutic trial reflects the highest grade of toxicity reported and cannot distinguish time of occurrence. The importance of the issue for survivors requires additional research targeting the persistence of this adverse effect beyond the acute, treatment administration phase, using both physician-rated toxicities and comprehensive, patient-reported assessments. The symptom burden associated with adjuvant RT is further shown by the significant treatment arm and time effects in Table 4, indicating that report of overall symptom burden is mirroring the treatment arm differences observed for urinary and bowel function that were associated with adjuvant RT. The fact that GHRQL at 5 years was statistically significantly better for patients receiving adjuvant RT suggests that urinary and bowel adverse effects and compromised general symptom status did not outweigh the overall positive benefit of RP+RT on self-reported GHRQL. It was notable that each respective baseline measure was a significant predictor of each outcome's rate of change. Efficace et al40 reviewed randomized trials evaluating treatments for patients with prostate cancer that included HRQL assessments; the authors noted various methodologic shortcomings in these studies. We believe that the data presented in this study were generated by a well-designed trial and good assessment methodology for HRQL outcomes. In addition, HRQL data were collected for 5 years after random assignment to monitor for later effects, allowing comment on the HRQL status of prostate cancer survivors. Limitations of the study include the nonavailability of a more comprehensive measure of sexual dysfunction such as the International Index of Erectile Function.41 However, the GU symptom items used in the trial, including the sexual function items, were evaluated by clinicians and patients before their use in the trial. In addition, the bowel and urinary function items were sensitive to change and treatment assignment in previously published studies.15,28 Another potential limitation was the fact that the trial was activated in 1988 before the inclusion of the HRQL assessments as a result of the need to complete ongoing efforts to define quality control procedures for inclusion of HRQL outcomes in SWOG trials.10 However, differences in patient-reported GU symptom problems were still detected by treatment arm and over time. Finally, there is the question of how representative the study population is, particularly with respect to racial/ethnic categories and socioeconomic factors. African American race is of particular interest for prostate cancer, given the higher incidence and generally worse survival in this group.42 The SWOG trial accrued 26% African American men in the RP-only arm and 23% in the RP+RT arm, an accrual as large as that reported by Litwin et al43 and larger than in many similar studies examining prostate cancer treatment effects.38,44,45 In addition to race, education level and socioeconomic status have been shown to affect HRQL for patients with prostate cancer.46-49 Analyses of such factors were not prespecified, and the study was not powered for subset analyses; as in the previous studies cited, outcomes by socioeconomic status/race factors were not reported. We believe that these data inform the clinician/patient consultation process regarding treatment selection for this patient population. Adding RT to RP produces significantly worse bowel symptoms initially (through 2 years) and significantly worse urinary symptoms. However, additional short-term morbidity does not translate into compromised HRQL. Clinicians can inform patients that, although some adverse effects will be bothersome during the first 2 years (particularly near the end of RT), these problems largely disappear by 3 to 5 years, with the exception of urinary dysfunction. Because this patient group has less advanced disease, the 5-year benchmark for recovery from treatment adverse effects is not trivial and is meaningful for the longer term perspective held by these patients. Clinicians can also tell patients that patients on the combined regimen reported better overall HRQL at 5 years than patients receiving surgery alone.
The author(s) indicated no potential conflicts of interest.
Conception and design: Carol M. Moinpour, Katherine A. Hayden, Ian M. Thompson Jr, E. David Crawford Administrative support: Katherine A. Hayden Provision of study materials or patients: Katherine A. Hayden, Edith D. Canby-Hagino, Jerry W. Sullivan, Dianne Lemmon, Sheila Breslin Collection and assembly of data: Katherine A. Hayden, Joseph M. Unger, Betsy A. Higgins Data analysis and interpretation: Carol M. Moinpour, Joseph M. Unger, Mary W. Redman Manuscript writing: Carol M. Moinpour, Katherine A. Hayden, Joseph M. Unger, Ian M. Thompson Jr, Mary W. Redman, Edith D. Canby-Hagino, Jerry W. Sullivan, E. David Crawford Final approval of manuscript: Carol M. Moinpour, Katherine A. Hayden, Joseph M. Unger, Ian M. Thompson Jr, Mary W. Redman, Edith D. Canby-Hagino, Betsy A. Higgins, Jerry W. Sullivan, Dianne Lemmon, Sheila Breslin, E. David Crawford
We thank the patients who submitted health-related quality-of-life data for this trial and the nurses and clinical research associates who collected and monitored the submission of patient-completed forms. We also acknowledge the data management assistance provided by Anne Ryan and Jean Barce.
Supported in part by the following Public Health Service Cooperative Agreement Grants awarded by the National Cancer Institute, Department of Health and Human Services: CA38926, CA32102, CA14028, CA58416, CA58658, CA42777, CA27057, CA46136, CA35431, CA58882, CA12644, CA58861, CA35090, CA37981, CA76429, CA04919, CA76132, CA35119, CA35178, CA35176, CA46282, CA67575, CA45377, CA46113, CA74647, CA35261, CA04920, CA20319, CA76447, CA58723, CA12213, CA22433, and CA46441. Authors’ disclosures of potential conflicts of interest and author contributions are found at the end of this article.
1. National Institutes of Health Consensus Development Panel: National Institutes of Health Consensus Development Conference Statement on Clinically Localized Prostate Cancer (June 15-17, 1988). Bethesda, MD, National Institutes of Health Government Printing Office, 1988 2. Halperin E, Fraser R, Hughes J: The management of clinically localized prostate cancer: A summary of the Consensus Statement of the National Institutes of Health. N C Med J 49:75-79, 1988[Medline] 3. Formenti SC, Lieskovsky G, Simoneau AR, et al: Impact of moderate dose of postoperative radiation on urinary continence and potency in patients with prostate cancer treated with nerve sparing prostatectomy. J Urol 155:616-619, 1996[CrossRef][Medline] 4. Van Cangh P, Richard F, Lorge F, et al: Adjuvant radiation therapy does not cause urinary incontinence after radical prostatectomy: Results of a prospective randomized study. J Urol 159:164-166, 1998[CrossRef][Medline] 5. Bolla M, van Poppel H, Collette L, et al: Postoperative radiotherapy after radical prostatectomy: A randomised controlled trial (EORTC trial 22911). Lancet 366:572-578, 2005[CrossRef][Medline] 6. Fitzpatrick JM, Kirby JS, Krane RJ, et al: Sexual dysfunction associated with the management of prostate cancer. Eur Urol 33:513-522, 1998[CrossRef][Medline] 7. Davidson BJ, Keyes M, Elliott S, et al: Preferences for sexual information resources in patients treated for early-stage prostate cancer with either radical prostatectomy or brachytherapy. BJU Int 93:965-969, 2004[CrossRef][Medline] 8. Haas GP: Strategies to manage prostate cancer. J Urol 155:628-629, 1996[CrossRef][Medline] 9. Thompson IM Jr, Tangen CM, Paradelo J, et al: Adjuvant radiotherapy for pathologically advanced prostate cancer: A randomized clinical trial. JAMA 296:2329-2335, 2006 10. Moinpour CM, Feigl P, Metch B, et al: Quality of life end points in cancer clinical trials: Review and recommendations. J Natl Cancer Inst 81:485-495, 1989 11. Moinpour C, Donaldson G, Padilla G, et al: English and Spanish versions of the Southwest Oncology Group (SWOG) Quality of Life (QOL) Questionnaire: Validation of a total score. Qual Life Res 7:638-639, 1998 12. Moinpour CM, Donaldson G, Padilla G, et al: Health-Related quality of life (HRQL) correlates of perceived overall health in Spanish and English breast cancer populations. Qual Life Res 9:250, 2000 (abstr 1759) 13. Moinpour CM, Hayden KA, Thompson IM, et al: Quality of life assessment in Southwest Oncology Group trials, in Tchekmedyian NS, Cella DF (eds): Quality of Life in Oncology Practice and Research. Williston Park, NY, Dominus Publishing Co, 1991, pp 43-49 14. Moinpour CM, Savage M, Hayden KA, et al: Quality of life assessment in cancer clinical trials, in Dimsdale JE, Baum A (eds): Quality of Life in Behavioral Medicine Research. Hillsdale, NJ, Lawrence Erlbaum Associates, 1995, pp 79-95 15. Moinpour CM, Savage MJ, Troxel A, et al: Quality of life in advanced prostate cancer: Results of a randomized therapeutic trial. J Natl Cancer Inst 90:1537-1544, 1998 16. Moinpour CM, Sawyers TJ, McKnight B, et al: Challenges posed by non-random missing quality of life data in an advanced-stage colorectal cancer clinical trial. Psychooncology 9:340-354, 2000[CrossRef][Medline] 17. Hayden K, Moinpour C, Metch B, et al: Pitfalls in quality-of-life assessment: Lessons from a Southwest Oncology Group breast cancer clinical trial. Oncol Nurs Forum 20:1415-1419, 1993[Medline] 18. Loll L, Moinpour C, Feigl P: Southwest Oncology Group (SWOG). J Natl Cancer Inst Monogr 20:83-85, 1996 19. Moinpour CM, Lovato LC: Ensuring the quality of quality of life data: The Southwest Oncology Group experience. Stat Med 17:641-651, 1998[CrossRef][Medline] 20. Stewart AL, Hays RD, Ware JE Jr: The MOS Short-form General Health Survey: Reliability and validity in a patient population. Med Care 26:724-735, 1988[Medline] 21. Ware JE Jr, Sherbourne CD: The MOS 36-item Short-Form Health Survey (SF-36): I. Conceptual framework and item selection. Med Care 30:473-483, 1992[Medline] 22. McCorkle R, Young K: Development of a symptom distress scale. Cancer Nurs 1:373-378, 1978[Medline] 23. Young KJ, Longman AJ: Quality of life and persons with melanoma: A pilot study. Cancer Nurs 6:219-225, 1983[Medline] 24. McCorkle R, Benoliel JQ: Symptom distress, current concerns, and mood disturbance after diagnosis of life threatening disease. Soc Sci Med 17:431-438, 1983[CrossRef][Medline] 25. McCorkle R: The measurement of symptom distress. Semin Oncol Nurs 3:248-256, 1987[Medline] 26. McCorkle R, Benoliel J, Donaldson G, et al: A randomized clinical trial of home nursing care for lung cancer patients. Cancer 64:1375-1382, 1989[CrossRef][Medline] 27. McCorkle R, Cooley ME, Shea JA: A User's Manual for the Symptom Distress Scale. Philadelphia, PA, University of Pennsylvania School of Nursing, 1998 28. Kucuk O, Fisher E, Moinpour CM, et al: Phase II trial of bicalutamide in patients with advanced prostate cancer in whom conventional hormonal therapy failed: A Southwest Oncology Group study (SWOG 9235). Urology 58:53-58, 2001[CrossRef][Medline] 29. Rodriquez FR, Thompson IM, Corrie D, et al: Radical retropubic prostatectomy: A quality of life survey. 36th Annual James C. Kimbrough Urological Seminar, Norfolk, Virginia, October 31-November 4, 1988 (abstr) 30. Selby P, Chapman J-A, Etazadi-Amoli J, et al: The development of a method for assessing the quality of life of cancer patients. Br J Cancer 50:13-22, 1984[Medline] 31. Selby P, Campbell J, Chapman J, et al: Measurement of the quality of life in patients with breast cancer. Rev Endocr Rel Cancer Suppl 14:245-247, 1984 32. Stewart AL, Greenfield S, Hays RD, et al: Functional status and well-being of patients with chronic conditions: Results from the Medical Outcomes Study. JAMA 262:907-913, 1989 33. McHorney CA, Ware JE Jr, Lu RJF, et al: The MOS 36-item Short-Form Health Survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care 32:40-46, 1994[Medline] 34. Sloan JA, Loprinzi CL, Kuross SA, et al: Randomized comparison of four tools measuring overall quality of life in patients with advanced cancer. J Clin Oncol 16:3662-3673, 1998[Abstract] 35. Ware JE Jr: Monitoring and evaluating health services. Med Care 23:705-709, 1985[CrossRef][Medline] 36. Hopwood P, Stephens R, Machin D: Approaches to the analysis of quality of life data: Experiences gained from a Medical Research Council Lung Cancer Working Party palliative chemotherapy trial. Qual Life Res 3:339-352, 1994[CrossRef][Medline] 37. Liang KY, Zeger SL: Longitudinal data analysis using generalized linear models. Biometrika 73:13-22, 1986 37. Laird NM, Ware JH: Random-effects models for lungitudinal data. Biometrics 38:963-974, 1982[CrossRef][Medline] 38. Hamilton AS, Stanford JL, Gilliland FD, et al: Health outcomes after external-beam radiation therapy for clinically localized prostate cancer: Results from the Prostate Cancer Outcomes Study. J Clin Oncol 19:2517-2526, 2001 39. Penson D, Feng Z, Kuniyuki A, et al: General quality of life 2 years following treatment for prostate cancer: What influences outcomes? Results from the Prostate Cancer Outcomes study. J Clin Oncol 21:1147-1154, 2003 40. Efficace F, Bottomley A, van Andel G: Health related quality of life in prostate carcinoma: A systematic review of randomized controlled trials. Cancer 97:377-388, 2003[CrossRef][Medline] 41. Rosen RC, Riley A, Wagner G, et al: The International Index of Erectile Function (IIEF): A multidimensional scale for assessment of erectile dysfunction. Urology 49:822-830, 1997[CrossRef][Medline] 42. Ries LAG, Melbert D, Krapcho M, et al: SEER Cancer Statistics Review, 1975-2004. Bethesda, MD, National Cancer Institute, 2007 43. Litwin MS, Hays RD, Fink A, et al: Quality of life outcomes in men treated for localized prostate cancer. JAMA 273:129-135, 1995 44. Lubeck D, Litwin M, Henning J, et al: Changes in health-related quality of life in the first year after treatment for prostate cancer: Results from CaPSURE. Urology 53:180-186, 1999[CrossRef][Medline] 45. Potosky A, Legler J, Albertsen P, et al: Health outcomes after prostatectomy or radiotherapy for prostate cancer: Results from the prostate cancer outcomes study. J Natl Cancer Inst 92:1582-1592, 2000 46. Knight S, Siston A, Slimack N, et al: Racial differences in quality of life among veterans with localized prostate cancer. Proc Am Soc Clin Oncol 19:442a, 2000 (abstr 1735) 47. Knight SJ, Latini DM, Hart SL, et al: Education predicts quality of life among men with prostate cancer cared for in the Department of Veterans Affairs: A longitudinal quality of life analysis from CaPSURE. Cancer 109:1769-1776, 2007[Medline] 48. Eton DT, Lepore SJ, Helgesen VS: Early quality of life in patients with localized prostate carcinoma: An examination of treatment-related, demographic, and psychosocial factors. Cancer 92:1451-1459, 2001[CrossRef][Medline] 49. Penson D: The effect of erectile dysfunction on quality of life following treatment for localized prostate cancer. Rev Urol 3:113-119, 2001[Medline] Submitted December 27, 2006; accepted September 27, 2007.
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||
|
|||||||||||
|
|
Copyright © 2008 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
|
TOP
ABSTRACT
INTRODUCTION
2 test with appropriate df to assess which model provided a best fit of the data. The model-based analysis represents a powerful approach for analyzing and interpreting the data and represents the definitive analysis. However, observed values are provided in the figures for illustration and comparison. 
