Cortisol is known as the stress hormone.
Wiki: "It is released in response to stress and low blood-glucose concentration. It functions to increase blood sugar through gluconeogenesis, to suppress the immune system ... It also decreases bone formation." 
"Diurnal cycles of cortisol levels are found in humans. In humans, the amount of cortisol present in the blood undergoes diurnal variation; the level peaks in the early morning (around 8 am) and reaches its lowest level at about midnight-4 am, or three to five hours after the onset of sleep." 
For me, the PCa diagnosis caused stress that was most pronounced at about 3 in the morning - leading up to when cortisol would already be high. I came across the supplement Relora, with two ingredients that have anti-PCa activity. Oddly, it was being promoted for weight control. (There is a form of overeating that is due to stress.) Relora before bed lowers cortisol production. 
Sources: , , etc.
 (2011 - Belgium - Life Events [LE] - Cortisol - PSA)
"... controlling for age, body mass index and the ratio of triglycerides to HDL cholesterol, we found evidence for a synergistic interaction between LE and cortisol.
"... Among men with low cortisol, number of LE were inversely and significantly correlated with PSA
"... while in men with high cortisol, number of LE were positively and significantly correlated with PSA"
I remember a founder of UsToo blaming his PCa on stress.
I might claim the same except that stress was par for the course late in my career (1990s). Downsizing, outplacement, rightsizing & all those other made up names for ageism. Older men earn more than younger men, cost more for insurance & pension plan contributions. I worked with many men who were hanging in & hoping to make it to retirement but didn't. Brutal times. No company loyalty.
 (2016 - Argentina)
"We evaluated the relationship between cortisol, leptin and estrogens in 141 men, 71 with PCa and the remaining 70 constituting a low risk group (LRG). They were recruited for this study from a total of 2906 middleaged men (ages 4570 years) who completed an evaluation for prostatic diseases at the Urology Division, Hospital de Clinicas "Jose de San Martin", University of Buenos Aires, in May 2009."
"We observed increased cortisol levels in PCa patients as compared to LRG cases ... Leptin and estradiol levels were also higher in PCa patients ..."
 (2016 - Taiwan)
"The circadian-related hormones, melatonin and cortisol, have oncostatic and immunosuppressive properties. This study examined the relationship between these two biomarkers and the presence of prostate cancer. We measured their major metabolites in urine collected from 120 newly diagnosed prostate cancer patients and 240 age-matched controls from January 2011 to April 2014. Compared with patients with lower urinary melatonin-sulfate or melatonin-sulfate/cortisol (MT/C) ratio levels, those with above-median levels were significantly less likely to have prostate cancer (adjusted OR (aOR) = 0.59 ...; aOR = 0.46 ...) or advanced stage prostate cancer (aOR = 0.49, ... aOR = 0.33 ...). The combined effect of both low MT/C ratios and PSA levels exceeding 10 ng/ml was an 8.82-fold greater likelihood of prostate cancer and a 32.06-fold greater likelihood of advanced stage prostate cancer, compared to those with both high MT/C ratios and PSA levels less than 10 ng/ml. In conclusion, patients with high melatonin-sulfate levels or a high MT/C ratio were less likely to have prostate cancer or advanced stage prostate. Besides, a finding of a low MT/C ratio combined with a PSA level exceeding 10 ng/ml showed the greatest potential in detecting prostate cancer and advanced stage prostate cancer."
No need to beat this to death. Would anyone believe that elevated cortisol is harmless. Coping mechanisms might help. A good whiskey before bed. Relora.