Schymura et al. BMC Cancer 2010, 10:152 http://www.biomedcentral.com/1471-2407/10/152 Table 1: Distribution of initial treatment by sociodemographic and economic characteristics of the patient. (Continued) Page 6 of 15 <0.0001 Registry California Colorado Illinois Louisiana New York Rhode Island South Carolina 507 509 522 530 445 464 351 (15) (15) (16) (16) (13) (14) (11) 503 507 521 529 435 459 346 (15) (15) (16) (16) (13) (14) (10) 43.74 44.18 36.28 42.53 34.94 36.17 38.73 25.25 28.60 31.48 26.47 40.69 35.29 35.26 12.52 10.45 10.36 11.53 9.43 8.71 7.80 18.49 16.77 21.88 19.47 14.94 19.83 18.21 1: Sample size for analysis of conservative versus definite therapy. 2: Sample size for dividing conservative treatment into hormone therapy and watchful waiting (excludes 28 observations missing dates for hormone therapy). Used for calculating proportions in this table. 3: Probability from a two-sided X2 test comparing the distribution of treatments across levels of the variable. 4: Information missing for 17 individuals. Among men who received definitive treatment, unmar- ried patients were more likely to receive radiation therapy than married patients. With the exception of Louisiana, patients residing in the remaining five states were signifi- cantly more likely to receive radiation therapy than patients residing in California. Prostate cancer patients with PSA values above 10 were more likely to receive radiation therapy. Men with poorly differentiated tumors (Gleason score 8-10) were more likely to receive radiation therapy than men with well differentiated tumors (Glea- son score 2-4). The survival analysis was limited to 3,297 patients. Three patients for whom information on year of last con- tact was missing were excluded from the 3,300 patients with known treatment modality (n = 3,300; see Table 1). All sociodemographic, economic, and clinical character- istics shown in Tables 1 and 2 were found to be signifi- cantly associated with survival, as was treatment modality. Five-year survival rates and crude and adjusted hazard ratios for factors retained in the final model are shown in Table 6. The proportional hazards assumption for comorbidity was found to hold for the following inter- vals: ≤ 1 year post-diagnosis; >1 to 3 years post-diagnosis; and >3 years post-diagnosis. Risk of death from any cause increased substantially with age. Hispanic men had a significantly lower risk of death than non-Hispanic white men; this difference remained borderline significant after adjusting for other factors (p = 0.0511). Married men had a lower risk of death than unmarried men; this difference also remained borderline significant after adjustment (p = 0.0551). Five- year survival rates varied by state of residence, from 78.8% for Louisiana to 90.0% for Colorado. After adjust- ing for other factors, the hazard ratio remained signifi- cantly higher (significantly lower survival) for Louisiana and South Carolina. Risk of death increased with increas- ing PSA levels. However, the increase in risk attenuated after adjustment for other factors; only men with unknown PSA levels remained at significantly increased risk. Men with undifferentiated tumors, Gleason score 8- 10, or with tumors of unknown grade were at significantly higher risk of death even after adjusting for other factors. Five-year survival varied significantly with treatment modality; survival was highest for patients who received radical prostatectomy (93.7%) and lowest for patients who received hormone therapy (65.2%). For patients who received radiation therapy and for patients who under- went watchful waiting, the five-year survival rates were 86.0% and 74.5%, respectively. Even after adjusting for factors that were predictive of treatment, patients who did not receive a radical prostatectomy were significantly more likely to die. The risk of death associated with comorbid conditions attenuated with time since diagno- sis; the attenuation was greater after adjusting for other factors. Within the first year following diagnosis, the haz- ard ratio was 2.16 for patients with a comorbidity score of 1 and 6.39 for patients with a score of 2 or more. One to three years post diagnosis, patients with a comorbidity score of 1 were no longer at increased risk of dying com- pared to patients with no comorbidity, whereas patients with a comorbidity score of 2 or more were still at signifi- cantly increased risk but the hazard ratio was reduced to 2.67. Three years after diagnosis, comorbidity at diagno- sis was no longer associated with survival. After adjust- ment for other factors, no statistically significant differences in survival were observed for insurance, edu- cation, poverty, working class status, urban-rural resi- dence, whether the tumor was screen detected, or digital rectal exam (DRE) results. We found further survival differences within the group receiving radiation therapy. Compared to radical pros- tatectomy, the adjusted hazard ratio and 95% confidence intervals for brachytherapy, external beam radiation, and combined radiotherapy were 0.58 (0.29, 1.16), 1.90 (1.41, 2.55), and 1.70 (0.93, 3.08), respectively. Thus the appar- ent survival advantage of radical prostatectomy com-