Demographic characteristics of prostate cancer patients
From January 1, 2014 to December 31, 2018, 662 men at the time, they were diagnosed with prostate cancer at Cancer Disease Hospital in Lusaka. Patients in this study were 69.6 years old when they were diagnosed.
Early onset diagnosis was aged less than 55 years, which comprised 40 (6.0%) and 622 (94.0%) were 55 years or more. Patients with Gleason score (GS) less than or equal to 8 were more than 428 (64.7%) compared to those with GS greater than 8, which constituted 234 (35.3%) of the patients. Table 1 shows that most of the participants were HIV negative, with 463 (69.9%) and 199 (30.1%) HIV positive. Among the HIV positives were those on antiretroviral medications 411 cells/mm3 was the median CD4 count. The majority of the participants were married (501, or 7.4%), and 155 (23.6%) were unmarried. Of the 248 (38.3%) of the participants who had either smoked or were currently smoking, 341 (52.5%) either took alcohol or used to take it, and 132 (22.3%) were diabetic. 92 (13.9%) indicated having prostate cancer patients in the family. For most patients, the cancer stage was at stage three and four, 638 (96.4%). About 290 (43.8%) of the patients died at the time of the study; 56.2% (372) were either alive or lost to follow-up and were censored. Those who were on chemotherapy treatment were about 135 (20.4%), radiotherapy 296 (44.7%), hormonal therapy 388 (58.6%) and prostatectomy were 44 (6.7%).
Table 1: Demographic and Clinical Characteristics of Prostate Cancer Patients.
Variable
|
|
Proportion
(total sample=662)
|
Dead
|
|
|
Yes
|
|
43.8% (290)
|
No
|
|
56.2 % (372)
|
Tumour stage
|
|
|
One
|
|
1.7% (11)
|
Two
|
|
2.0% (13)
|
Three
|
|
11.0% (73)
|
Four
|
|
85.3% (24)
|
Marital status
|
|
|
Not Married
|
|
23.6% (155)
|
Married
|
|
76.4% (501)
|
Smoke
|
|
|
No
|
|
61.7% (400)
|
Yes
|
|
38.3% (248)
|
PCs in the family
|
|
|
No
|
|
86.1% (570)
|
Yes
|
|
13.9% (92)
|
Alcohol
|
|
|
No
|
|
47.5% (309)
|
Yes
|
|
52.5% (341)
|
Prostatectomy
|
|
|
No
|
|
93.4% (618)
|
Yes
|
|
6.6% (44)
|
Diabetes
|
|
|
No
|
|
77.7% (459)
|
Yes
|
|
22.3% (132)
|
Hormonal therapy
|
|
|
No
|
|
41.4% (274)
|
Yes
|
|
58.6% (388)
|
Gleason score
|
|
|
1=<8 77.8% (514)
|
2>8
|
|
22.2% (147)
|
Patient on Antiretroviral therapy
(ART)
|
No
|
|
84.3% (558)
|
Yes
|
|
15.7% (104)
|
Chemotherapy
|
|
|
No
|
|
79.6% (527)
|
Yes
|
|
20.4% (135)
|
Radiation therapy
|
No
|
|
55.3%(366)
|
Yes
|
|
44.7% (296)
|
Human Immunodeficiency Virus
|
No
|
|
69.9% (463)
|
Yes
|
|
30.1% (199)
|
Overall survival was 16 months in this study, 33 months in HIV patients, and 14 months in HIV negative patients. The total amount of time at risk was 7548 months. Assuming the incident rate to be constant, the incident rate was estimated as 0.04 per month or 40 per 1000 persons per month, which would correspond to 0.43 per year or 430 per 1000 persons per year. During the follow-up period, 291 (44.0%) deaths occurred as stated by prostate cancer, and the one-year overall survival rate was 0.65 (65%). The overall survival time for the 5-year survival rate was 0.03 (3%). The overall survival in the HIV uninfected was 0.61 (61%), while it was 0.75 (75%) in the HIV infected.
Factors associated with Prostate Cancer Patients' Mortality
There was evidence (p-value=0.0001) of a difference in the proportions of those that reported dying and those that did not die. The results are presented in Table 2. There was a difference in being a year older (p-values=0.0001) and the Gleason score level (P=0.0001). Furthermore, there is no discernible difference in mortality between married and unmarried patients (p-value = 0.672), a unit increase in body mass (p-value=0.643), prostate specific antigen (p-value=0.477), whether they smoked or did not smoke (p-value=0.075), whether they had prostate cancer in their family or not (p-value=0.060), whether they took alcohol or not (p-value=0.180), whether they had prostectomy done or not (There was also no evidence of a difference in mortality between individuals who got and those who did not receive radiation therapy (p-value=0.248), between those who received antiretroviral therapy and those who did not (p-value=0.065), and between those who received chemotherapy and those who did not (p-value = 0.825).
TABLE 2: Bivariate analysis of background and clinical characteristics prostate cancer patients from Zambia Cancer Disease routinely collected data, 2014–2018
|
Prostate cancer patients Mortality
(total sample=662)
|
p-value
|
Factors
|
Yes
N= 290 (43.8%)
|
No
N= 372 (56.2%)
|
0.0001
|
Age, years, mean (SD)
|
72.7years (7.9)
|
67.4years (9.2)
|
0.0001T
|
Body mass index, mean (SD)
|
25.6kg/m2 (4.7)
|
25.4 kg/m2 (4.5)
|
0.643T
|
Prostate specific antigen,
Median (IQR)
|
69.3ng/ml(30.0,115.0)
|
68.7ng/ml(31.1115)
|
0.477W
|
Tumour stage
One and Two
Three and Four
|
9 (4.5%)
190(95.5%)
|
15 (3.2%)
448 (96.8%)
|
0.418C
|
Marital status
Not married
Married
|
66(22.8%)
223 (77.2%)
|
89 (24.3%)
278 (75.8%)
|
0.672C
|
Smoke
No
Yes
|
185 (65.6%)
97(34.4%)
|
215 (58.7%)
151 (41.3%)
|
0.075C
|
History of Prostate Cancer in family
No
Yes
|
258 (89.0%)
32 (11.0%)
|
312 (83.9%)
60 (16.1%)
|
0.060C
|
Alcohol
No
Yes
|
143 (50.5%)
140 (49.5%)
|
166 (45.2%)
201 (54.8%)
|
0.180C
|
Diabetes
No
Yes
|
213 (81.3%)
49 (18.7%)
|
246 (74.8%)
83 (25.2%)
|
0.058C
|
Prostatectomy
No
Yes
|
274 (94.5%)
16 (5.5%)
|
344 (92.5%)
28 (7.5%)
|
0.303C
|
Hormonal therapy
No
Yes
|
124 (42.8%)
166(57.2%)
|
150 (40.3%)
222 (59.7%)
|
0.528C
|
Gleason Score
1=<8
2 >8
|
203 (70.0%)
87 (30.0%)
|
312 (83.9%)
60 (16.1%)
|
0.0001C
|
Radiotherapy
No
Yes
|
153 (52.8%)
137 (47.2%)
|
213 (57.3%)
159 (42.7%)
|
0.248C
|
Chemotherapy
No
Yes
|
232 (80.0%)
58 (20.0%)
|
295 (79.3%)
77 (20.7%)
|
0.825C
|
Human Immunodeficiency Virus
No
Yes
|
227 (78.3%)
63 (21.7%)
|
236 (63.4%)
136 (36.6%)
|
0.0001C
|
Antiretroviral therapy
No
Yes
|
253 (87.2%)
37 (12.8%)
|
305 (82.0%)
67 (18.0%)
|
0.065C
|
P=Z-test of two proportions, C=Chi squared test, T=student’s t test, E=Fisher’s exact test, W=Wilcoxon rank sum test.
Key Predictors for Prostate Cancer mortality
A Wilcoxon (Breslow) test for equality of survival functions showed evidence of statistical significance with (chi2 = 8.83) and (P-value = 0.003) for the difference in HIV survival rates between negative and positive prostate cancer patients Shown in figure 1 with the confidence interval.
Similarly, the Kaplan-Meier (K-M) estimate using the Wilcoxon (Breslow) test for equality of survival functions, there was enough evidence of a statistical difference (chi2 = 25.38) and (P-value = 0.003) for the difference in Gleason scores with narrow confidence interval in figure 2.
Further figure 3, the Kaplan-Meier (K-M) estimate functions Survival functions showed evidence of a statistical difference using the Wilcoxon test for equality (chi2 = 4.46) and (P-value = 0.035).
Factors Associated with Prostate Cancer Patients' Mortality
In table 3, the following variables had a statistically significant effect on the hazard of death in the unadjusted Weibull model : one year increase in age, increased the hazard of death by about 3%, HR: 1.03 (95% CI: 1.02, 1.04, p= 0.0001); patients who were HIV positive had reduced hazard of death by about 43%, HR: 0.57 (95% CI: 0.43, 0.75, p= 0.0001); patients with Gleason score less or equal to eight had reduced hazard of death by about 60%, HR: 0.40 (95% CI: 0.30, 0.52, p= 0.0001); those on hormonal therapy had reduced hazard of death by about 26%, HR: 0.74 (95% CI: 0.59, 0.93, p= 0.011); and a unity increase in the radio therapy dose reduced the hazard of death by about 2%, HR: 0.98 (95% CI: 0.96, 1.00, p= 0.039). The predictors such as body mass index, HR: 1.00 (95% CI: 1.98, 1.03, p= 0.527), prostate specific antigen HR: 1.00 (95% CI: 0.99, 1.00, p= 0.645), tumour stage HR: 1.70 (95% CI: 0.84, 3.43, p= 0.138), marital status HR: 0.90 (95% CI: 0.0.67, 1.17, p= 0.395), smoking HR: 0.96 (95% CI: 0.75, 1.23, p= 0.769), alcohols HR: 1.00 (95% CI: 0.79, 1.26, p= 0.808), and history of prostate cancer in the family HR: 1.14 (95% CI: 0.79, 1.65, p= 0.473), prostatectomy HR: 0.75 (95% CI: 0.45, 1.25, p= 0.268), diabetes HR: 1.00 (95% CI: 0.73, 1.36, p= 0.979), and radiotherapy HR: 0.84 (95% CI: 0.67, 1.06, p= 0.141) did not have significant effect on mortality.
In the adjusted Weibull model, the following variables had a statistically significant effect on the hazard of death: A one-year increase in age increased the risk of death by approximately 3%.AHR: 1.03 (95% CI: 1.02, 1.05, p= 0.0001); patients who were HIV positive had reduced hazard of death by about 42%, AHR: 0.58 (95% CI: 0.43, 0.78, p= 0.0001); patients with Gleason score less or equal to eight had reduced hazard of death by about 55%, AHR: 0.45 (95% CI: 0.33, 0.61, p= 0.0001); those on hormonal therapy had reduced hazard of death by about 28%, AHR: 0.71 (95% CI: 0.54, 0.94, p= 0.015); and patients presented with tumour stage three and four were 2.1 times likely to experience the hazard of death compared to those with cancer stage one and two AHR: 2.13 (95% CI: 1.02, 4.48, p= 0.044). The predictors such as body mass index AHR: 1.02 (95% CI: 1.00, 1.04, p= 0.116), prostate specific antigen, AHR: 0.99 (95% CI: 0.99, 1.00, p= 0.645), radiotherapy dose, AHR: 0.99 (95% CI: 0.97, 1.02, p= 0.639), marital status, AHR: 1.03 (95% CI: 0.76, 1.41, p= 0.820), smoking, AHR: 1.08 (95% CI: 0.81, 0.1.43, p= 0.613), alcohols, AHR: 1.03 (95% CI: 0.78, 1.36, p= 0.808), and history of prostate cancer in the family, AHR: 1.33 (95% CI: 0.88, 2.02, p= 0.176), prostatectomy, AHR: 0.77 (95% CI: 0.45, 1.31, p= 0.331), diabetes, AHR: 1.02 (95% CI: 0.75, 1.40, p= 0.880), and radiotherapy, AHR: 1.04 (95% CI: 0.73, 1.47, p= 0.845), there was no evidence of any significant effect on mortality.
Table 3: Crude and Adjusted Weibull model of factors associated with Mortality of Prostate Cancer Patients.
Factors
|
Crude
HR (95% CI)
|
p-value
|
Adjusted
HR (95% CI)
|
p-value
|
Age, years
|
1.03 (1.02, 1.04)
|
0.0001
|
1.03(1.02, 1.04)
|
0.0001
|
Marital Status
Not married
Married
|
Ref
0.90 (0.67, 1.17)
|
n/a
0.395
|
Ref
1.03(0.76, 1.41)
|
n/a
0.820
|
Human Immunodeficiency Virus
No
Yes
|
Ref
0.57 (0.43, 0.75)
|
n/a
0.0001
|
Ref
0.58(0.43, 0.78)
|
n/a
0.0001
|
Antiretroviral therapy
No
Yes
|
Ref
0.80 (0.57, 1.13)
|
n/a
0.204
|
Ref
0.81 (0.56,1.18)
|
n/a
0.273
|
Body Mass Index (BMI)
|
1.00 (0.98, 1.03)
|
0.527
|
1.02(1.00, 1.04)
|
0.116
|
Tumour Stage,
One /Two
Three/Four
|
Ref
1.70 (0.84, 3.43)
|
n/a
0.138
|
Ref
2.13(1.02, 4.48)
|
n/a
0.044
|
Smoke
No
Yes
|
Ref
0.96 (0.75, 1.23)
|
n/a
0.769
|
Ref
1.08(0.81, 1.43)
|
n/a
0.613
|
Alcohol
No
Yes
|
Ref
1.00 (0.79, 1.26)
|
0.980
|
Ref
1.03(0.78, 1.36)
|
n/a
0.808
|
Diabetes
No
Yes
|
Ref
1.00 (0.73, 1.36)
|
0.979
|
Ref
1.02(0.75, 1.40)
|
n/a
0.880
|
Prostate Specific Antigen
|
1.00 (0.99, 1.00)
|
0.456
|
0.99(0.99, 1.00)
|
0.645
|
Gleason Score
> 8
=<8
|
0.40 (0.30, 0.52)
|
0.0001
|
0.45(0.33, 0.61)
|
0.0001
|
Prostatectomy
No
Yes
|
Ref
0.75 (0.45, 1.25)
|
n/a
0.268
|
Ref
0.77(0.45, 1.31)
|
n/a
0.331
|
Hormonal therapy
No
Yes
|
Ref
0.74 (0.59, 0.93)
|
n/a
0.011
|
Ref
0.71(0.54, 0.94)
|
n/a
0.015
|
Radiation therapy
No
Yes
|
Ref
0.84 (0.67, 1.06)
|
n/a
0.141
|
Ref
1.04(0.73, 1.47)
|
n/a
0.845
|
Chemotherapy
No
Yes
|
Ref
1.11 (0.83, 1.48)
|
n/a
0.476
|
Ref
1.29(0.74, 2.23)
|
0.370
|
History of Prostate Cancer in family
No
Yes
|
Ref
1.14(0.79,1.65)
|
0.473
|
Ref
1.33(0.88,2.02)
|
0.176
|
Radiation therapy dose
|
0.98 (0.96, 1.00)
|
0.039
|
0.99(0.97,1.02)
|
0.639
|