Chemotherapy For Prostate Cancer

Overview

Prostate cancer is one of the leading types of cancer that occurs in the prostate gland; a small walnut-shaped gland located in the pelvis, a part of the assigned male at birth (AMAB) individuals’ reproductive system and its main function is the production of fluid for semen. Prostate cancer occurs when the cells in the prostate gland grow abnormally.¹ Currently, there are various options for treating prostate cancer depending on the severity. As the disease spreads to other parts of the body, chemotherapy is usually the final option if the patient can tolerate it.² In this article, you will find out more about prostate cancer and chemotherapy for prostate cancer.

Introduction 

The prostate gland is found below the bladder and around the urethra. Its primary function is to produce secretions that help in ejaculation and maintenance of sperm viability.³

Prostate cancer is a cancer that occurs in the prostate gland. Many prostate cancerous cells are localised to the prostate gland, spreading slowly, and are not harmful requiring little or no treatment. However, other types of prostate cancer spread rapidly and can cause serious problems.

Chemotherapy commonly called “chemo” is the destruction of cancer cells using chemical substances. It is used to treat prostate cancer if the cancer spreads outside the prostate gland when hormone therapy stops working although it is not the first line of treatment during the early stages of prostate cancer. Chemotherapy for prostate cancer uses drugs that are given mainly through the intravenous (IV) route over a given period.  

Types of prostate cancer 

There are different types of prostate cancers but the majority are adenocarcinomas developing from the cells of the gland. Other types that develop from the prostate include: 

• Small cell carcinomas
• Neuroendocrine tumours 
• Transitional cell carcinomas
• Sarcomas

Incidence and prevalence

According to the World Health Organization, prostate cancer results in 1.41 million cases. It accounts for the fifth leading cause of death in men worldwide. Aside from lung cancer, it is the most frequently diagnosed cancer. It is postulated that the burden of prostate cancer would increase due to economic growth and the ageing population.⁴

Risk factors and symptoms of prostate cancer 

Risk factors range from:

• Race
• Advancing age
• Genetic mutation
• Family history 
• Insulin-like growth factors

Certain lifestyle habits also contribute to the risk of prostate cancer such as:

• Obesity
• Tobacco and alcohol consumption
• Poor diet
• Sedentary lifestyle
• Exposure to certain chemicals and radiation⁵

Prostate cancer is often symptomless except when the cancer grows very large to exact pressure on the urethra (a tube for the passage of urine from the bladder to the penis).  These includes:

• Difficulty starting urination
• Weak or interrupted flow of urine
• Urinating often, especially at night
• Trouble emptying the bladder
• Pain or burning during urination
• Blood in the urine or semen
• Pain in the back, hips, or pelvis that doesn’t go away
• Loss of appetite
• Pain in testicles
• Unintentional weight loss
• Painful ejaculation

Diagnosis and staging 

Diagnosis includes: 

• Blood test to test the level of prostate-specific antigen
• Digital rectal examination
• Biopsy (removal of a small piece of tissue for further examination)⁶

There are four stages of prostate cancer:

• Stage I: the cancer cell is limited to the prostate
• Stage II: small growth in the prostate still confined to the prostate
• Stage III: cancer cells spread outside the superficial layer of the prostate and can be seen around near tissues and seminal vesicles
• Stage IV: the growth extends to other parts of the body specifically the bladder, rectum, bone, liver, lungs, and lymph nodes³

Treatment of prostate cancer

• Active surveillance - an organized way of monitoring patients
• Surgery - the most frequently used method in the treatment of prostate cancer. It is referred to as radical prostatectomy and involves a small cut on the abdomen or through the perineum to remove the prostate gland
• Radiation therapy - a procedure that is used by patients who are unfit for surgical procedures. It makes use of high - energy radiation directly on the prostate without affecting the normal tissues. The level of radiation depends on the stage of the prostate cancer and may be either external beam radiation or internal radiation (brachytherapy)
• Hormone therapy - another technique for treating advanced prostate cancer also known as androgen suppression therapy. It aims to reduce male hormones known as androgens or prevent them from increasing the growth of prostate cancer cells
• Chemotherapy - a procedure for treating prostate cancer when hormone therapy fails. It is the use of drugs to destroy or prevent the growth of prostate cancer cells that spread to other parts of the body
• Immunotherapy - a technique that uses drugs to stimulate a patient’s immune system to identify and kill cancerous cells 
• Targeted drug therapy - treatment that centres on blocking certain anomalies present within the cancerous cells which kills the cancerous cells⁷

Mechanism of action of chemotherapy in prostate cancer

Chemotherapy uses anticancer drugs to kill cancerous cells. It is usually administered or infused into the vein where it travels through the blood to the site of the cancer cell to destroy it, along with those that have spread away from the main tumour in the prostate.

Timing in the treatment plan

Several factors influence the decision on the time to start chemotherapy such as:

• Alternative treatment options and availability of clinical trials
• The tolerance level of the patient to chemotherapy
• Initial therapies received by the patient
• If radiation is needed before chemotherapy to relieve pain quickly

Common drugs used in the treatment of prostate cancer 

The two main chemotherapeutic drugs used in the treatment of prostate cancer are docetaxel and cabazitaxel. Other drugs used are mitoxantrone, estramustine, and carboplatin. Docetaxel is mostly the first drug given combined with a steroid (prednisone or dexamethasone). When docetaxel fails, cabazitaxel is the next drug used in combination with a steroid, although other treatment options may be available.

Side effects 

According to the American Cancer Society, the commonly encountered side effects of chemotherapy include:

• Fatigue      
• Hair loss
• Infection
• Nausea and vomiting
• Mood changes
• Anaemia
• Bleeding
• Sore in mouth, tongue and throat 
• Nail and skin changes
• Loss of appetite
• Constipation
• Fertility issues
• Changes in sexual function

The side effect of chemotherapy usually stops at the end of the treatment, although some measures can be taken to manage the side effects of the treatment. Such measures can be the use of medications to combat constipation or diarrhoea, numbing gels can be used to relieve mouth sores. In addition, the dosage of the drugs can be modified, or an alternative form of chemotherapeutic drug can be used.

Clinical trials 

Clinical trials help bring about life-extending and new curative treatments for patients. Recently, the analysis of cancer medication has taken an outstanding approach towards a more practical, exact, and less invasive cancer treatment in the research of clinical trials. Currently, the frequent entries for clinical trials on cancer therapies are stem cell, target therapy, immunotherapy, and gene therapy because they are promising and highly effective.¹

Potential advancement in chemotherapy

Nanomedicine, in addition to targeted therapy, helped improve the biodistribution (localising where the drug goes in the body) of new or existing tested chemotherapeutic agents around the specific tissue to be treated. However, other approaches provide new hope to cancer patients such as:

• Gene therapy
• Short interfering RNAs (siRNAs) delivery 
• Immunotherapy 
• Antioxidant molecules 

On the other hand, thermal ablation and magnetic hyperthermia are favourable alternatives to cancer resection. Finally, radiomics and pathomics (computer-based approach to traditional pathology) approaches from cancer patients help to improve prognosis and better outcomes.⁸

Summary

Although chemotherapy is a form of treatment for prostate cancer, it is usually not the first line of treatment. It is usually employed when the cancer spreads outside the prostate gland. Chemotherapy for prostate cancer is more effective when combined with other forms of treatment. A few side effects occur when a patient is on chemo although they can be managed and ends at the end of the treatment. Chemotherapy should be started immediately if the tumour grows aggressively and spreads fast or if the tumour is pressing against another vital organ of the body. Early detection is the best way to lower the impact of prostate cancer.