Table 1. Characteristics of the Study Cohorta.
| Characteristics | Primary Radiation Therapy (n = 40,508) | Conservative Management (n= 17,241) |
|---|---|---|
| Age, median (IQR), y | 74 (70-77) | 76 (72-80) |
| Black race | 3,932 (9.7) | 2,052 (11.9) |
| Married at diagnosis | 29,892 (73.8) | 10,428 (60.5) |
| Urban residence | 35,138 (86.7) | 14,640 (84.9) |
| Income, median (IQR), US $ | 49,421 (38897-63682) | 46,328 (35853-60646) |
| SEER Regions | ||
| Northeast | 6,537 (16.1) | 2,121 (12.3) |
| North central | 13,486 (33.3) | 4,774 (27.7) |
| West | 17,547 (43.3) | 9,542 (55.3) |
| South | 2,938 (7.3) | 804 (4.7) |
| Cancer grade | ||
| Low/ Intermediate | 28,565 (70.5) | 14,670 (85.1) |
| High | 1,1943 (29.5) | 2,571 (14.9) |
| Clinical stage at diagnosis | ||
| T1 | 15,327 (37.8) | 8,454 (49.0) |
| T2 | 25,181 (62.2) | 8,787 (51.0) |
| PSA, median (IQR)* | 6.8 (5.0-10.2) | 6.6 (4.7-10.2) |
| Gleason Score* | ||
| <=6 | 5,129 (45.0) | 2,807 (71.2) |
| 7 | 4,506 (39.6) | 889 (22.5) |
| 8-10 | 1,759 (15.4) | 248 (6.3) |
| Comorbidity status | ||
| Charlson comorbidity score 0 | 31,465 (77.7) | 12,901 (74.8) |
| Charlson comorbidity score 1 | 6,586 (16.3) | 2,791 (16.2) |
| Charlson comorbidity score ≥2 | 2,457 (6.1) | 1,549 (8.9) |
| Year of diagnosis | ||
| 1992-1999 | 16,854 (41.6) | 9,214 (53.4) |
| 2000-2003 | 12,260 (30.3) | 4,083 (23.7) |
| 2004+ | 11,394 (28.1) | 3,944 (22.9) |
| Type of radiation therapy | ||
| External beam radiation b | 27,214 (67.2) | N/A |
| 3D Conformal Radiotherapy | 17,575 | N/A |
| Intensity-modulated radiation therapy | 6,176 | N/A |
| Protons | 240 | N/A |
| Unknown | 3,223 | N/A |
| Brachytherapy | 8,106 (20.0) | N/A |
| External beam plus brachytherapy | 5,188 (12.8) | N/A |
| ADT use in 1st year | 16,601 (41.0) | N/A |
Abbreviations: IQR, interquartile range; SD, standard deviation: PSA, prostate-specific antigen; ADT, androgen deprivation therapy; SEER, Surveillance, Epidemiology, and End Results; N/A, not applicable.
PSA and Gleason score distributions were based on cases diagnosed in 2004 or thereafter
Data are presented as No.(%) unless otherwise specified. Race was self-determined by the patients. Clinical extension information provided by SEER was used to determine cancer stage (T1, T2). PSA and Gleason score were limited to those diagnosed in 2004 or thereafter. Charlson comorbidity score was derived from Medicare claims during the year before prostate cancer diagnosis by using a validated algorithm.14 Low/intermediate grade cancer consisted of Gleason score 2-7 before 2003 and Gleason score 2-6 thereafter.
Intensity-modulated radiation therapy (IMRT) was defined as IMRT only or the combination of 3D Conformal Radiotherapy (3D CRT) and IMRT. Proton beam therapy was defined as protons only or protons combined with 3D CRT or IMRT. 3D CRT defined as 3D CRT only. Unknown included unknown type of external beam radiation therapy.