Prostate Cancer – Causes, Symptoms, Treatments

What is Prostate Cancer?

Prostate cancer is a type of cancer that develops in the prostate gland, a small walnut-shaped gland in men that sits below the bladder and surrounds the urethra (the tube that carries urine out of the body). The prostate gland produces a fluid that nourishes and transports sperm.

Prostate cancer occurs when some cells in the prostate gland grow abnormally and out of control. These abnormal cells can form a tumor. In some cases, the cancer may stay confined to the prostate and not cause any problems. However, in other cases, the cancer cells may spread (metastasize) to other parts of the body, such as the bones and lymph nodes.

According to the data gathered by the World Cancer Research Fund International, prostate cancer was the second most commonly occurring cancer in men globally in 2020, with over 1.4 million new cases.

According to the American Cancer Society, the 5-year relative survival rate for localized prostate cancer is 100%. This means that men diagnosed with localized prostate cancer are, on average, about as likely as men without prostate cancer to live for at least 5 years after being diagnosed.

The risk of developing prostate cancer increases significantly with age. Here’s a breakdown: 

• Rare in Younger Men: Prostate cancer is rare in men younger than 40.
• Sharp Rise After 45: Age-specific incidence rates start climbing steeply around 45-49 years old.
• Majority Diagnosed Over 65: Around 60% of all prostate cancers are diagnosed in men 65 years old or older. The average age of diagnosis is about 67.
• Peak Around 75: Incidence rates reach a peak in the 75-79 age group.
• Possible Decline After 80: Rates may stabilize or even slightly decrease in men over 80.

This trend reflects the accumulation of cell DNA damage over time. As we age, our cells are exposed to more and more risk factors that can damage DNA, potentially leading to cancer development.

Important to Consider:

• Race: African American men and Caribbean men of African descent have a higher risk of prostate cancer compared to other races, and they may develop it at a younger age.
• Family History: Men with a close relative (father, brother, son) diagnosed with prostate cancer have an increased risk.

Stages of Prostate Cancer

The TNM staging system is the standard method for classifying prostate cancer, providing detailed information about the extent of the cancer’s spread. Here’s a breakdown of each category and its subcategories:

T (Tumor): This category assesses the size and location of the primary tumor within the prostate gland.

• T1: The cancer is very small and cannot be felt during a digital rectal exam (DRE) or seen with imaging tests.
  • T1a: The tumor is very small and involves only a tiny focus of tissue within the prostate.
  • T1b: The cancer is slightly larger than T1a, but still confined to the prostate.
• T2: The tumor is larger than T1 and is confined entirely within the prostate, although it may be detectable during a DRE or with imaging.
  • T2a: The tumor involves half or less of one side of the prostate.
  • T2b: The tumor involves more than half of one side of the prostate, but not both sides.
  • T2c: The cancer involves both sides of the prostate.
• T3: The cancer has grown outside the prostate capsule, the tissue surrounding the prostate.
  • T3a: The tumor has spread to tissues next to the prostate, but not the seminal vesicles (glands that produce seminal fluid).
  • T3b: The cancer has grown into the seminal vesicles.
• T4: The most advanced stage of the primary tumor. The cancer has spread to nearby structures, such as the bladder, rectum, pelvic wall, or lymph nodes closest to the prostate.

N (Node): This category indicates whether the cancer has spread to lymph nodes, especially those in the pelvic region near the prostate.

• N0: The cancer has not spread to any lymph nodes.
• N1: The cancer has spread to one or more lymph nodes.

M (Metastasis): This category signifies if the cancer has spread beyond the prostate and regional lymph nodes to distant parts of the body, such as bones or other organs.

• M0: There is no sign of distant spread.
• M1: The cancer has metastasized to distant lymph nodes or other organs.

Combining TNM Categories:

Once healthcare professionals determine the category for each (T, N, and M), they combine this information to assign an overall stage of prostate cancer. The stage ranges from I (one), indicating the earliest stage with minimal spread, to IV (four), representing the most advanced stage with distant metastasis.

Additional Grading System:

In conjunction with the TNM staging system, doctors often use the Gleason score to assess prostate cancer aggressiveness. A pathologist examines prostate tissue samples under a microscope and assigns a grade based on the appearance and organization of the cancer cells. Higher Gleason scores indicate a more aggressive cancer likely to grow and spread faster.

Symptoms of Prostate Cancer

Prostate cancer often goes unnoticed in its early stages. Many men with early-stage prostate cancer don’t experience any symptoms because the cancer is confined to the prostate gland. This emphasizes the importance of early detection, as successful treatment is most likely when the cancer is localized.

As prostate cancer progresses, however, some signs and symptoms may develop. These symptoms are often linked to the prostate’s location near the urethra (urine tube) and seminal vesicles (semen-producing glands). In the localized stage of prostate cancer, some possible indicators include difficulty starting urination, frequent urination at night, a weak urine flow, or a burning sensation during urination.

If the cancer advances beyond the prostate gland, symptoms can become more noticeable and involve other parts of the body. Blood in the urine or semen, although less common, can be a sign of advanced prostate cancer. Pain in the lower back, hips, or upper thighs may occur if the cancer spreads to bones. Erectile dysfunction and difficulty controlling urination or bowel movements can also develop in later stages. In some severe cases, men with advanced prostate cancer may experience unexplained weight loss and fatigue.

Metastasis of Prostate Cancer

Prostate cancer metastasis, the spread of cancer cells beyond the prostate gland, is a complex multi-step process that scientists are still actively researching. It all starts within the prostate gland itself. Cancer cells develop and begin to invade nearby tissues. This initial local invasion allows cancer cells to move outside the prostate’s boundaries.

Once cancer cells have breached the prostate’s outer layer, they need to enter the bloodstream or lymphatic system to travel to distant sites. This process of cancer cells entering the bloodstream is called intravasation. Scientists believe enzymes produced by the tumor cells can break down proteins in the surrounding tissue, creating a pathway for them to enter blood vessels or lymph vessels.

After entering the bloodstream or lymphatic vessels, cancer cells circulate throughout the body. However, most of these circulating cancer cells don’t survive. The body’s immune system and other natural defense mechanisms eliminate many of them.

If some cancer cells manage to evade the immune system, they may reach distant organs like bones. They need to extravasate, exit the bloodstream or lymphatic system, and invade the tissue of the new location. At this stage, they often form small clusters of cancer cells called micrometastases. These micrometastases may lay dormant for some time before they acquire the ability to grow and form clinically detectable metastases.

An interesting concept in metastasis is the “seed and soil” theory. It proposes that cancer cells (seeds) need a favorable environment (soil) to grow in a new location. The bones, rich in blood supply and specific growth factors, provide a suitable environment for prostate cancer cells to thrive.

Genetic mutations within the cancer cells themselves play a crucial role in their metastatic potential. These mutations can enhance their ability to invade surrounding tissues, intravasate, survive in circulation, and extravasate to form new tumors. The tumor microenvironment, the surrounding tissue and signaling molecules near the tumor, can also influence metastasis.

Prostate cancer most commonly spreads to bones when it metastasizes, beyond the confines of the prostate gland itself. Bones are the most frequent site for prostate cancer metastasis, affecting around 85-90% of cases. The cancer cells often spread to the spine, pelvis, ribs, and upper leg bones. Bone metastases can cause significant pain, weakness, and fractures.

Lymph nodes are small, bean-shaped organs that act as filters in the lymphatic system, a network of vessels that drain fluid and waste products from tissues throughout the body. Prostate cancer can spread to nearby lymph nodes in the pelvic region first. In advanced stages, it can involve lymph nodes in other areas as well.

In some cases, prostate cancer can metastasize to other organs, though this is less frequent than bone or lymph node involvement. These less common sites include the lungs, the liver and in very rare cases the brain. 

Risk Factors for Prostate Cancer

Having a close relative (father, brother, son) diagnosed with prostate cancer increases a man’s risk two to three times compared to the general population. The risk goes up even further if multiple family members are affected or if the relative was diagnosed at a young age. Inherited gene mutations, like BRCA1 and BRCA2 (more commonly linked to breast and ovarian cancer), can also raise prostate cancer risk.

African American men and Caribbean men of African descent have a higher risk of prostate cancer compared to men of other races. The reasons for this racial disparity are not entirely clear, but factors like genetics and socioeconomic background might play a role.

While the exact link is still being studied, some research suggests a diet high in saturated fats, processed meats, and dairy products might be associated with a slightly increased risk of prostate cancer. Conversely, diets rich in fruits, vegetables, whole grains, and lean proteins may offer some protective benefits.

The link between obesity and prostate cancer risk is complex. While obesity itself may not directly increase the overall risk, it can influence how prostate cancer is diagnosed and treated. Obese men may be more likely to have a slower-growing, less aggressive form of the cancer.

Chronic inflammation in the body has been linked to an increased risk of various cancers, including prostate cancer. Conditions like prostatitis (inflammation of the prostate) might be a contributing factor, although more research is needed.

Androgen deprivation therapy (ADT), a treatment that reduces testosterone levels for prostate cancer, might ironically increase the risk of developing a more aggressive form of prostate cancer in some men later on.

Long Term Complications of Prostate Cancer

Even though prostate cancer, especially in its early stages, has high cure rates with good treatment outcomes, there can be some long-term complications to consider. These complications can arise from the cancer itself, the treatments used to eradicate it, or a combination of both. 

Urinary Issues:

• Urinary incontinence: Treatments like surgery or radiation therapy can damage nerves and muscles responsible for bladder control. This can lead to leakage of urine, ranging from occasional dribbling to complete loss of bladder control.
• Urinary urgency and frequency: These symptoms can occur due to irritation in the bladder or urethra from treatment or the cancer itself.

Sexual Dysfunction:

• Erectile dysfunction (ED): This is a common long-term complication, especially after surgery or radiation therapy to the prostate gland. The nerves responsible for erection can be affected, making it difficult to achieve or maintain an erection.
• Low libido: Loss of desire for sexual activity can occur due to hormonal changes associated with treatment or psychological factors related to the diagnosis and potential impact on sexual function.

Bowel Problems:

• Bowel incontinence: Though less common than urinary incontinence, damage to nerves or muscles near the rectum during surgery or radiation can lead to difficulty controlling bowel movements.
• Strictures: Narrowing of the urethra or rectum can occur due to scar tissue formation after treatment, causing difficulty passing urine or stool.

Lymphedema:

• This is a buildup of lymph fluid that can cause swelling in the legs or genitals if lymph nodes are removed during treatment.

Mental and Emotional Health:

• Prostate cancer diagnosis and treatment can take a toll on mental and emotional well-being. Men may experience anxiety, depression, or difficulty adjusting to changes in their bodies and sexual function.

How is Prostate Cancer Diagnosed?

Detecting prostate cancer often involves a combination of tests. 

The Digital Rectal Exam (DRE) is a routine screening procedure for men of a certain age or with risk factors. During a DRE, a doctor inserts a gloved, lubricated finger into the rectum to feel the prostate gland for any abnormalities in size, shape, or texture. While not definitive, a lumpy or enlarged prostate can raise suspicion of cancer.

The Prostate-Specific Antigen (PSA) Blood Test measures the level of prostate-specific antigen (PSA) in the bloodstream. PSA is a protein produced by the prostate gland. Elevated PSA levels can indicate prostate cancer, but other factors like infection or inflammation can also cause a rise. A high PSA doesn’t necessarily mean cancer, but it warrants further investigation.

If a DRE or PSA test raises concerns, a biopsy is often the next step to confirm or rule out prostate cancer. During a biopsy, a small tissue sample is extracted from the prostate gland, usually with a thin needle guided by ultrasound or MRI imaging. The tissue sample is then examined by a pathologist under a microscope to determine if cancer cells are present.

Depending on the situation, additional tests might be recommended. MRI scans are imaging tests that can provide detailed pictures of the prostate gland and surrounding tissues, aiding in biopsy guidance or assessing cancer spread in advanced stages. If there’s a high suspicion of cancer spread to bones, a bone scan can help detect abnormalities.

How is Prostate Cancer Treated?

The treatment approach for prostate cancer depends on several factors, including the stage and aggressiveness of the cancer, a man’s age and overall health, and his personal preferences. Here’s a breakdown of some common treatment options:

Active Surveillance:

• Not all prostate cancers require immediate intervention. For some slow-growing, early-stage cancers, especially in older men with other health conditions, active surveillance might be recommended. This involves regular monitoring with PSA tests, DREs, and potentially biopsies to track the cancer’s progress and intervene with treatment if necessary.

Surgery:

• Radical Prostatectomy: This surgery aims to remove the entire prostate gland and some surrounding tissues, including seminal vesicles. It is a curative approach for localized prostate cancer and is often performed laparoscopically (using minimally invasive techniques) or robotically with the assistance of a robotic surgical system.
• Other Surgical Procedures: In some cases, depending on the extent of cancer and other factors, less extensive surgeries like a laparoscopic prostatectomy or robotic prostatectomy may be an option. Nerve-sparing techniques are often employed during surgery to try to preserve sexual function.

Radiation Therapy:

• Radiation therapy uses high-energy X-rays or other forms of radiation to kill cancer cells. It can be delivered:
  • Externally: A machine outside the body directs radiation beams at the prostate gland.
  • Internally (brachytherapy): Radioactive seeds are implanted directly into the prostate gland.
• Radiation therapy can be a primary treatment for localized prostate cancer or used in combination with other therapies, such as hormone therapy after surgery to reduce the risk of recurrence.

Hormone Therapy:

• Androgen deprivation therapy (ADT) lowers testosterone levels in the body. Prostate cancer cells often rely on testosterone to grow. By reducing testosterone, hormone therapy can slow or stop the growth of cancer cells.
• ADT can be used in various ways, including medication, surgery to remove the testicles (orchidectomy), or injections that suppress testosterone production.

Other Treatment Options:

• Cryotherapy: This procedure uses extreme cold to freeze and destroy prostate cancer cells. It is a minimally invasive approach but may not be suitable for all men.
• High-Intensity Focused Ultrasound (HIFU): This treatment uses sound waves to heat and destroy prostate tissue. It is still under development but offers a potential minimally invasive option.

Managing Side Effects:

• Each treatment modality can have potential side effects. Erectile dysfunction, urinary incontinence, and bowel problems are some common side effects. Doctors can offer medications, therapy, and other strategies to manage these side effects and improve quality of life.

What Medications are Most Often Prescribed for Prostate Cancer?

The medications most often prescribed for prostate cancer depend on the specific stage and treatment approach. Hormone therapy medications aim to reduce testosterone levels and starve cancer cells of the hormones they need to grow. Here are some common types:

• Gonadotropin-releasing hormone (GnRH) agonists: These medications (e.g., leuprolide [Lupron], goserelin [Zoladex]) suppress the testicles’ testosterone production by signaling the pituitary gland to stop releasing hormones that stimulate testosterone production.
• Antiandrogens: These medications (e.g., bicalutamide [Casodex], enzalutamide [Xtandi], apalutamide [Erleada]) block the action of testosterone at the cellular level, even if testosterone levels are not directly reduced.

Chemotherapy drugs are typically used for advanced stages of prostate cancer that has spread beyond the prostate gland. They work by killing cancer cells throughout the body. Some common chemotherapy drugs used for prostate cancer include docetaxel (Taxotere), cabazitaxel (Jevtana), and mitoxantrone (Novantrone).

Bisphosphonates help strengthen bones and prevent bone complications from prostate cancer that has spread to the bones. Examples include zoledronic acid (Zometa) and denosumab (Xgeva).