Prostate cancer originates in the prostate, a small gland located just below the bladder in men. This gland produces fluid that forms part of semen. It is one of the most frequently diagnosed cancers in men globally, with about one in eight men receiving a diagnosis in their lifetime. When cancer cells break away from the original tumor, the disease is considered metastatic, meaning it has spread to other areas of the body. Understanding the pathways and common destinations of this spread is important for patients.
The Metastasis Pathway
The process by which prostate cancer cells leave the primary tumor and travel to distant sites is known as metastasis. This journey begins when cancer cells detach from the main mass and invade surrounding tissue. They then enter one of the body’s transportation networks, which serve as pathways to remote organs.
The lymphatic system is one route for this spread, as cancer cells enter lymph vessels to travel to nearby and distant lymph nodes. The other major pathway is the hematogenous route, where cancer cells penetrate blood vessel walls, a process called intravasation. Once in the bloodstream, these circulating tumor cells can travel almost anywhere. The specific destination depends on the anatomical connections of the prostate’s blood supply and the unique environment of the target organ.
Primary Sites of Prostate Cancer Spread
Prostate cancer has a distinct pattern of spread, favoring specific locations once it becomes metastatic. The most common site for prostate cancer to spread is the bone, occurring in approximately 84 to 90 percent of patients with advanced disease. This preference distinguishes prostate cancer from many other types of cancer. The cells often settle in the axial skeleton, particularly the spine, hips, and pelvis.
Beyond the bone, the next most frequent destinations are the distant lymph nodes, involved in about 10 percent of metastatic cases. These nodes are often located in the pelvic and abdominal regions. Less common sites of distant spread include soft organs such as the lungs and the liver. Their involvement indicates a more advanced stage of the disease.
Kidney Involvement and Indirect Effects
Direct metastasis of prostate cancer to the kidney tissue itself, known as the renal parenchyma, is exceedingly rare. This type of spread is considered an atypical event in the progression of the disease. Fewer than 50 cases of direct spread to the kidney have been documented in scientific literature worldwide. Therefore, concerns about prostate cancer cells directly colonizing the kidney are generally unfounded for most patients.
However, prostate cancer can significantly compromise kidney function through an indirect mechanism. As the primary tumor in the prostate grows, or if metastatic lymph nodes in the pelvis enlarge, they can press on the ureters. The ureters are the tubes that carry urine from the kidneys down to the bladder.
Compression or invasion of these tubes obstructs the normal flow of urine, causing it to back up. This backup leads to a condition called hydronephrosis, which is the swelling of the kidney due to the accumulation of urine. The pressure from the retained fluid can damage the kidney tissue over time, potentially leading to a loss of kidney function if the obstruction is not relieved. This indirect effect is the most common way prostate cancer impacts the kidneys and is a serious complication that requires careful management.