Stage 4 (IV) Prostate Cancer

Introduction

Prostate cancer is a form of cancer which affects men. Prostate cancer begins in the prostate; a gland found below the bladder which produces part of the semeninal fluid.

Over time, prostate cancer may spread and affect other areas of the body. To assess development of this disease, a cancer is 'staged'.

Staging helps a physician make an informed decision about treatment and provides information for a more reliable prognosis (the likely course of this disease).

A diagnosis of stage 4 prostate cancer is given when the disease is at the final stage; there is no stage 5 prostate cancer. Stage 4 may be expressed in Roman numerals: Stage IV.

Diagnosing Stage 4 Prostate Cancer

There are two systems which physicians often use to determine the stage of prostate cancer: the TNM & the Jewett System. Both systems use a four grade scale.

With the TNM system, final stage prostate cancer is stage 4; the final stage of the Jewett System is stage D. Therefore, using both systems, if prostate cancer has spread to areas outside the prostate gland, other than the seminal vesicles, then it is classed as stage 4 or stage D.

If the tumor has extended through the prostate gland cover, and the seminal vesicles are the only affected area outside the prostate, then the cancer is Stage 3 (C).

TNM System

With the TNM staging system, 'T', refers to primary tumor development; 'N', to lymph nodes being affected and 'M' to metastasis. Metastasis is when cancer spreads from the primary area and affects other areas of the body.

The American Joint Committee On Cancer (AJCC) developed the TNM system.

Using TNM classification prostate cancer can be stage IV if either:

• the tumor is fixed, or, it invades adjacent structures other than the seminal vesicles, such as the rectum, external sphincter, bladder, levator muscles, and/or pelvic wall (T4),
  and there is no regional lymph node metastasis (NO)
  and no distant metastasis (MO).
• any of the T categories apply, there is metastasis in the regional lymph nodes (N1) but no distant metastasis (MO).
• any of the T & N categories apply and there is distant metastasis.

The Whitmore-Jewett System

The Whitmore-Jewett system can also be used to stage prostate cancer.

However, the Whitmore-Jewett system is an older system; the TNM system is often favored. The TNM system includes a higher number of T (tumor) categories. Research indicates it is prognostically superior [1].

Using the Jewett system, stage D has 4 sub stages.

• Stage D0 - only a blood test can indicate that cancer has spread from the primary area (prostate gland).
• Stage D1 - the pelvic lymph nodes are affected.
• Stage D2 - cancer has spread to distant lymph nodes, bones or other organs (metastatic prostate cancer).
• Stage D3 - prostate cancer which was treated at stage D2 has returned.

Where prostate cancer has affected areas local to the prostate gland, it is referred to as localized stage 4 prostate cancer (D1). When prostate cancer has metastasized and affected areas away from the prostate, it is known as advanced, metastatic, stage 4 prostate cancer (D2).

Symptoms Of Stage 4 Prostate Cancer

The symptoms of Stage 4 prostate cancer include the urinary and sexual symptoms associated with previous stages 2 and 3.

However, a diagnosis of stage 4 prostate cancer means that other areas of the body are affected, giving rise to a wider range of symptoms.

Bone metastases, in which cancer spreads to the bones, is a common occurrence with stage 4 prostate cancer. Associated symptoms of bone metastasis include pain, a higher risk of bone fracture and a condition known as hypercalcemia. Hypercalcemia is a potentially fatal condition in which the blood has very high levels of calcium.

Where organs of the body are affected, there will symptoms specific to that organs dysfunction.

See also, 'Advanced Prostate Cancer Symptoms'.

Stage 4 Treatment

Whilst there is no cure, there are treatment options available which can help control stage 4 prostate cancer. Where patients have metastatic prostate cancer, and the cancer has spread to other areas of the body, the first treatment administered is often Androgen Deprivation Therapy (ADT). Androgens are male sex hormones such as testosterone. ADT reduces the level of male hormones in the body. This treatment can shrink tumors and slow the cancer. However, ADT is not a cure and the treatment can bring side effects associated with lower levels of male hormones. These include sexual side effects (lack of libido, erectile dysfunction) and physiological side effects (reduced muscle mass, an increase in body fat and weight).

Where the cancer comes back after treatment, which is often within 2 years, a secondary form of hormone therapy may be given to help overcome resistance to ADT.

Other treatments, which can include drug and radiation therapy, may be given if prostate cancer has spread to the bones (bone metastases).

Stage 4 Prostate Cancer Prognosis

About 1 in 3 people diagnosed with advanced stage 4 prostate cancer will survive for 5 years or more.

References

1. Zagars GK, Geara FB, Pollack A, von Eschenbach AC (1994). The T classification of clinically localized prostate cancer. An appraisal based on disease outcome after radiation therapy. Cancer, Apr 1;73(7):1904-12.