Trelstar®/Prostate Cancer FAQs

Trelstar is a type of prescription drug called a gonadotropin-releasing hormone (GnRH) agonist, used for management of advanced prostate cancer as it lowers testosterone and PSA.

Trelstar is given as an intramuscular injection (a shot) in your doctor’s office by a doctor or nurse. Trelstar is injected into the muscle of your buttocks.

In clinical studies, patients on Trelstar had reduced testosterone levels similar to those achieved with surgery (orchiectomy) and reduced serum prostate-specific antigen (PSA) levels. Trelstar is easily given as an intramuscular (IM) injection.

After your first injection with Trelstar, you might feel a brief increase in your cancer symptoms, such as pain in your bones. This is because the amount of testosterone in your bloodstream actually goes up for a short time after the injection.14 After a few weeks, your testosterone level should go down as your body adjusts to the medicine.14

The most common side effects of 1-month Trelstar 3.75 mg therapy and 3-month Trelstar 11.25 mg therapy are hot flushes and bone pain. The most common side effects of 6-month Trelstar 22.5 mg therapy are hot flushes and impotence/erectile dysfunction (ED).14

Other side effects can include loss of sexual desire and thinning of bones. Every person’s treatment response is different and not every person will have the same side effects. You should discuss potential side effects with your doctor.7

Trelstar comes in three formulations. Your doctor will help you choose the one that is right for you. Trelstar 3.75 mg is given as an intramuscular injection once a month. The medication is released slowly into your bloodstream and keeps your testosterone levels low for the whole month. Trelstar 11.25 mg is given as an intramuscular injection every 3 months. It is also released slowly and keeps testosterone levels low for 3 months. Trelstar 22.5 mg is given as an intramuscular injection and keeps testosterone levels low for 6 months. It is also released slowly and keeps testosterone levels low until your next injection.

Because Trelstar does not cure prostate cancer, your doctor may want you to take it as long as it keeps working. Your doctor may do lab tests such as measuring your blood level of PSA or testosterone to see if it’s working. Your doctor may order imaging studies such as a bone scan while you’re taking Trelstar.

To get the full benefit of taking Trelstar, you should be sure to get your injection when it is due. If you are going to be away from home and have to miss an injection, check with your doctor. If you miss an injection, contact your doctor right away.

Prostate cancer forms in the prostate gland tissues, occurring when cancer cells inside the prostate grow without control and make small tumors.6 These cancer cells outlive normal cells, continuing to form new abnormal cells.

Hormone therapy deprives cancer cells of the male hormones they need to survive and grow.14 Doctors may also use it to try to keep prostate cancer from recurring after surgery or radiation.

Treating advanced prostate cancer with hormone therapy can slow down its growth and decrease symptoms. Testosterone makes prostate cancer cells grow; decreasing the amount of testosterone in the blood slows this process down. Hormone therapy, however, is not a cancer cure.7

The prostate is a male sex gland, about the size of a large walnut. It is located below the bladder and in front of the rectum. The prostate's main function is to make fluid for semen, a white substance that carries sperm.12

The exact cause is unknown. There are some known risk factors, however, such as age, ethnicity, and family history.2

Prostate cancer is the most common cancer among men in the United States affecting 1 in 6 men.1,3 The older you are, the more likely you are to get prostate cancer; up to 65% of all prostate cancers are diagnosed in men over the age of 65.2,9

More men are surviving prostate cancer than ever before. In the past 25 years, the 5-year survival rate has increased from 69% to about 99% for all stages (from early to advanced) combined. This great increase in survival is at least partly due to earlier diagnosis and improvements in treatments.2

When cancer cells break away from the malignant tumor (glossary) in the prostate and spread to another part of the body such as bone, it is called metastatic prostate cancer. Prostate cancer usually metastasizes to the bone first.5

Risk factors include age, ethnicity, and family history.2 Up to 65% of prostate cancer cases are diagnosed in men over age 65.2,9 Prostate cancer is most common in African Americans and least common in Asian and Native Americans. The risk increases if a close male relative, such as a father or brother, has had the disease.3

Diet may be a risk factor for prostate cancer.15 A diet high in animal fat may increase the risk of prostate cancer and a diet high in fruits and vegetables may decrease it. Studies on whether dietary supplements can decrease risk are ongoing.

There is little evidence to show that an enlarged prostate (benign prostatic hyperplasia) or obesity might increase the risk for prostate cancer.9 There is also little evidence to show that lack of exercise, smoking, radiation exposure, and sexually transmitted diseases increase risk.

Early prostate cancer may have no symptoms, but symptoms like these may occur as the cancer grows:

• Need to urinate frequently, especially at night
• Difficulty starting urination or holding back urine
• Inability to urinate
• Weak or interrupted flow of urine
• Painful or burning urination
• Difficulty in having an erection
• Painful ejaculation
• Blood in urine or semen
• Pain or stiffness in the lower back, hips, or upper thighs

Some symptoms caused by prostate cancer may be due to other problems. But if you have any symptoms of prostate cancer, call your doctor to see if you need treatment.

Tests including the digital rectal exam and blood test for PSA are used to detect prostate problems. Results from one of these tests cannot show whether these problems are caused by cancer or another condition, but combined may help the doctor decide whether to check further for signs of cancer:

Digital Rectal Exam. The doctor inserts a lubricated, gloved finger into the rectum and feels the prostate through the rectal wall to check for any problems.

Blood test for PSA. A lab measures PSA levels in a blood sample. These may rise in men with prostate cancer, an enlarged prostate, or a prostate infection.

The doctor may order an ultrasound and a biopsy to learn more about the cause of the symptoms. During a biopsy the doctor uses needles to remove small samples of tissue from the prostate and reviews the samples under a microscope. A diagnosis of prostate cancer can only be made after a biopsy.

Doctors describe how far the cancer has spread in terms of “staging” and “grading.” Staging can show if the cancer has spread to other parts of the body. The higher the stage, the more advanced the cancer. The grade of the cancer refers to how closely the tumor resembles normal tissue. Prostate cancer has four stages:

Stage I. The cancer is too small to be felt during a rectal exam and may cause no symptoms. The doctor may find it by accident when performing surgery for another reason such as an enlarged prostate. The cancer has not spread outside the prostate.

Stage II. The tumor is confined to the prostate but involves more tissue within the prostate. The cancer is large enough to be felt during a rectal exam, or it may be found through a biopsy done due to a high PSA level. It has not spread outside the prostate.

Stage III. The cancer has spread outside the prostate to nearby tissues.

Stage IV. The cancer has spread to lymph nodes, bone, or other parts of the body.

Choice of treatment for prostate cancer depends on disease stage and tumor grade. The doctor may consider age, overall health, and his patient’s feelings about various treatments and possible side effects. Treatment may involve watchful waiting, surgery, radiation therapy, targeted therapy, hormone therapy, or a combination of these.

Surgery, radiation therapy, and hormone therapy may disrupt sexual desire and/or performance. Concerns about these side effects should be discussed with your doctor who may suggest other treatment options.

The urologist may recommend watchful waiting for an individual whose cancer is detected at an early stage and is slowly growing, or is considered at low risk. The patient's condition is monitored closely, but no treatment is recommended unless symptoms manifest or change.

Monitoring may be recommended for older men or those with other serious medical conditions since the side effects and risks of radiation, hormone therapy, or surgery could outweigh possible benefits. These men are monitored with regular checkups.

The goal of watchful waiting is to limit morbidity from the disease and therapy, not to administer curative treatment. For patients choosing active surveillance, curative therapy is delayed until the natural history and threat posed by the cancer can be more accurately assessed. Patients receive frequent, detailed evaluations for as long as they are healthy and young enough for definitive therapy. The goal is to detect cancer progression while a cure is still possible.4

Diet may be a risk factor for developing prostate cancer, particularly in those who eat a lot of red meat. The risk may be decreased in men who eat a lot of fruits and vegetables.

For those who are good candidates for radiation therapy, high-energy x-rays are used to destroy cancer cells and shrink tumors. This treatment may be recommended instead of surgery or after surgery to get rid of any remaining malignant cells. The urologist may recommend radiation to relieve pain or other symptoms in men with advanced disease. Radiation therapy can cause impotence and bowel function problems. Two kinds of radiation therapy are used to treat prostate cancer:

External beam radiation therapy. Patients go to a clinic or hospital to receive this therapy, which is usually given 5 days a week for several weeks. It is useful for men with locally advanced prostate cancer. It is also given in combination with hormone therapy for men with advanced cancer not spread to a distant organ.13

IMRT: Intensity-modulated radiation therapy allows clinicians to change the intensity of the doses and radiation beams to better target the radiation delivered to the prostate. Lower doses are delivered to the tumor cells that are immediately adjacent to the bladder and rectal tissue, thereby lowering side effects while keeping cure rates as high as possible.7

Brachytherapy. Tiny radioactive seeds are implanted inside or near the tumor during an outpatient visit. This procedure is recommended for men with tumors at an early stage, but some are candidates for both types of radiation therapy. It is recommended for men with only a small risk of recurrence.16

Hormone therapy deprives cancer cells of the male hormones they need to survive and grow. It is often used for cancer that has spread to other parts of the body. It is also used to try to prevent cancer from recurring following radiation or surgery. Side effects may include impotence, hot flushes, bone thinning, and decreased interest in sex.

If loss of sexual desire does occur, the doctor can explain whether this side effect is likely to be permanent or temporary. A patient and his partner should discuss their concerns with the doctor and seek other ways to be intimate and loving during and after treatment.

Surgery is a frequent treatment for men whose prostate cancer is in an early stage. In most cases, a radical prostatectomy is done and the entire prostate is removed. In a few men, only part of the prostate gland is removed. Local or nearby lymph nodes may be removed. Possible side effects of surgery include incontinence and impotence.

Following treatment, men suffering from prostate cancer will be monitored closely to see how effective the treatment has been. Monitoring may include:

• Being alert for symptoms or signs that cancer may be progressing, such as increased pain, decreased bladder or bowel function, and fatigue
• A PSA test every 3-12 months
• A complete blood count for detecting symptoms or signs of anemia
• A bone and/or computed tomography (CT) scan to see if the cancer has spread

New, more effective treatments for prostate cancer under development include:

• New ways to use radiation and hormone therapy. Some studies show hormone therapy after radiation can help some whose cancer has spread to nearby tissues
• How effective chemotherapy and biological therapy are for those individuals whose cancer does not respond or stops responding to hormonal therapy
• Cryosurgery, which destroys the cancerous tumor by freezing it, is being studied as an alternative to radiation and surgery

If you have been diagnosed with prostate cancer, you are not alone. Many have gone through this experience before you. Support groups and other resources can provide a wealth of information to help you cope with the disease.

You may have some concerns about living with prostate cancer: “How will I keep my job?”, “Will I be able to still do things I enjoy?”, and “What about medical bills?” Speak with your doctor and other healthcare providers; they can help answer your questions and prepare you for what to expect from treatment.

You may want to meet with a social worker, counselor, support group, or clergy. They can help address many of your concerns. Support groups can share experiences of how group members have coped with prostate cancer and its treatment. Social workers may know resources for financial aid, emotional support, transportation, or home care.

Talk to your loved ones. They may be able help with your treatment, transportation, and emotional needs. Seek information and support from those available to you at this time.