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Prostate Cancer (Part 1)

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Prostate cancer begins when cells in the prostate gland start to grow out of control. In this article, we explore what causes prostate cancer, the risk factors for prostate cancer, and how it is being screened and diagnosed.

In 2008, approximately 14% of all prostate cancers diagnosed worldwide were within the Asia-Pacific region. 3 out of 4 cases were diagnosed in either Japan (32%), China (28%) or Australia (15%). In terms of mortality, about 3 per 100,000 deaths were due to prostate cancer in the Asia-Pacific region. 

What Causes Prostate Cancer? 

The reason for this is due to DNA mutations that: 

  • Keep oncogenes (i.e., genes that help cells grow, divide and stay alive) turned on 
  • Turn off tumour suppressor genes (i.e., genes that either keep cell growth under control, repair DNA mistakes, or cause cells to die at the right time). 

10% of prostate cancers are contributed by inherited gene mutations. This type of cancer is known as hereditary cancer. On the other hand, acquired mutations are due to genes that mutate during a person’s lifetime and would not be passed on to his children. This type of cancer accounts for most cases of prostate cancer. 

What Are The Risk Factors For Prostate Cancer?

  • Age: The chance of prostate cancer rises rapidly after 50 years old. About 6 in 10 cases of prostate cancer are found in men older than 65 years old.
  • Geography: Prostate cancer is more common in North America and Australia than in Asia.
  • Family history: This applies to hereditary cancer. If one or both of your parents have the gene mutation(s) for prostate cancer, you may be at a higher risk of developing it too.
  • Hormone levels: Having higher levels of androgens and testosterone (i.e., male hormones) promotes prostate cell growth and increases prostate cancer risk. This is because in general, as the prostate cells grow and divide faster, there are more chances for mutations to occur during the cell division process, making prostate cancer more likely to develop. 
  • Other risk factors postulated but require further research to confirm include inflammation of the prostate, high levels of insulin-like growth factor-1 (IGF-1), exposure to radiation, and cancer-causing chemicals.

Signs and Symptoms of Prostate Cancer

Early prostate cancer usually causes no symptoms. However, in the advanced stage of prostate cancer, patients might experience the following symptoms:

  • Problems urinating 
  • Difficulty having an erection
  • Pain in the hips, back/spine, chest/ribs (if cancer has spread to the bones)
  • Blood in the urine or semen
  • Weakness or numbness in the legs or feet, or even loss of bladder control (if the cancer growth is pressing on the spinal cord)

Screening and Diagnosis of Prostate Cancer

1.  PSA Blood Test 

Screening for prostate cancer can be done by doing a blood test to measure your prostate-specific antigen (PSA) level. PSA is a protein made by cells in the prostate gland. The higher the PSA level, the higher the chances of developing prostate cancer. There is no specific number, above which your doctor can tell for sure it is prostate cancer. Some doctors might use 4ng/mL as the cut-off to determine if you should be sent for further testing. If your PSA is between 4 and 10, there is a 1 in 4 chance of prostate cancer. If your PSA is more than 10, the chance is 50%. 

Limitations of PSA Blood Test

Your doctor would also do a history taking to ensure there are no interfering factors that would falsely elevate or lower your PSA. For example, if you have prostatitis, your PSA might be falsely elevated. In contrast, your PSA might be falsely lowered if you are taking medication for benign prostatic hyperplasia (i.e., a condition whereby there is a non-cancerous enlargement of the prostate). 

2. Prostate Biopsy

Due to the limitation of a PSA blood test, your doctor might suggest you get a more definitive test, called a prostate biopsy especially if your initial PSA level is high. During the biopsy, a small sample of the prostate is removed and then looked under a microscope to check for the presence of tumour cells.

Treatment Approach for Prostate Cancer

  • Active surveillance: Close monitoring of cancer by regularly going for PSA blood test or prostate biopsy. Treat only when the tumour grows or causes symptoms. 
  • Watchful waiting: Your doctor would only treat when symptoms develop. No blood tests or biopsies are needed. This approach is more suitable for those who are expected to live for 10 years or less. 
  • Prostatectomy: This is a surgery to remove the prostate.
  • Radiation Therapy: There are 2 types of radiation therapy: external and internal. For external radiation therapy, the machine is placed outside the body and directs high-energy rays to the cancer cells to kill cancer. In contrast, internal radiation therapy (also known as brachytherapy) requires your surgeon to place radioactive seeds or pellets near the cancer cells to destroy them.
  • Androgen suppression therapy: As described above, androgens stimulate prostate cancer cells to grow. This hormonal therapy reduces the level of androgens (male hormones) in your body, causing prostate cancer to shrink or grow more slowly. This is usually used together with or before radiation therapy to make the treatment more effective. An example of this medication is leuprolide (LHRH agonist) which is injected once every 6 months. Side effects of this medication include hot flashes, breast tenderness and fatigue. 

Which Treatment Approach Works For You?

The treatment method depends on which stage of cancer you are diagnosed with. For Stages I to III whereby the prostate cancer has not spread to other parts of the body, your doctor would determine your risk group based on the chance of the cancer growing and spreading. This would be useful to determine the treatment approach:

  • Very-low risk: Active surveillance or watchful waiting is recommended if you belong to the very-low risk group. This is because the risks or side effects from treatment such as radiation or surgery outweigh the benefits.
  • Low risk: Active surveillance or radiation therapy is recommended. 
  • Intermediate risk: Radiation therapy with or without androgen suppression therapy can be considered.
  • High risk: Radiation therapy together with androgen suppression therapy should be started and continued for 1 to 3 years.
  • Very high risk: In addition to the treatment approach for high-risk groups, chemotherapy drug docetaxel might be added. 

Conclusion

Prostate cancer in the Asia-Pacific region is prevalent and there is an increase in incidence in many countries as well. Fortunately, treatment options have been well explored, studied, and established. Discuss your concerns and treatment goals with your doctor or healthcare professional so that they can work out what is the best treatment approach for you.

 

 

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