Final answer:
The most common cause of a bladder infection is bacterial contamination of the bladder, predominantly affecting females. Prostate cancer, although not directly related to urinary infections, is the most common cancer in men and varies in treatment necessity.
Step-by-step explanation:
The most common cause of a bladder infection, a type of urinary tract infection, is bacteria entering the bladder from the GI tract, with females being at higher risk due to their anatomy. A much less common urinary infection is pyelonephritis, where the kidney becomes infected. Unrelated to bladder infection but important to mention, prostate cancer is the most common type of cancer in men and can be detected through medical history, a blood test, and a rectal exam. Despite its frequency, not all forms of prostate cancer require treatment; it depends on the growth rate of the tumor.